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, Available online ,
doi: 10.11884/HPLPB202537.240290
Abstract:
Inthe development of high-energy chemical laser, the research of diffuser pressure recovery has important engineering application value. In this paper,the diffuser of DF chemical laser is studied by numerical simulation and experiment. The effects of diffuser divergence angle and secondary-throat on diffuser performance are calculated, analyzed and verified by experiments. The results show that the diffuser with 8°divergence angle has weak ability to resist back pressure, reducing the divergence angle to 5° can effectively improve the ability to resist back pressure. The further optimized supersonic diffuser with secondary-throat can increase the recovery pressure of the diffuser again, reduce the energy loss of the air flow and improve the anti-backpressure characterisitics.At the same time, experimental verification is carried out for different models of diffusers, which is consistent with the trend of numerical simulation results.
Inthe development of high-energy chemical laser, the research of diffuser pressure recovery has important engineering application value. In this paper,the diffuser of DF chemical laser is studied by numerical simulation and experiment. The effects of diffuser divergence angle and secondary-throat on diffuser performance are calculated, analyzed and verified by experiments. The results show that the diffuser with 8°divergence angle has weak ability to resist back pressure, reducing the divergence angle to 5° can effectively improve the ability to resist back pressure. The further optimized supersonic diffuser with secondary-throat can increase the recovery pressure of the diffuser again, reduce the energy loss of the air flow and improve the anti-backpressure characterisitics.At the same time, experimental verification is carried out for different models of diffusers, which is consistent with the trend of numerical simulation results.
, Available online ,
doi: 10.11884/HPLPB202537.240399
Abstract:
The system-level cable coupling characteristics of UAVs are of great significance for the analysis of electromagnetic effects and mechanisms of UAVs. Based on the surface current distribution of the UAV system, voltage monitoring points are set up at the UAV flight control port cables, wing cables, and rotor cables are set up to monitor the voltage distribution of the UAV system cables, and the weak links of the UAV system cable coupling are obtained by monitoring the voltage distribution of the UAV system cables. The simulation results show that when the plane wave is incident on the same length of cable at different angles, the coupling peak voltage is the largest when the electric field vector is parallel to the direction of the cable, and the coupling sensitive frequency point of different types of cables is the same, and when the plane wave incident on different lengths of cable at the same angle, the reciprocal of the resonant frequency point satisfies the same multiple relationship with the cable length. In the actual UAV system cable irradiation scenario, the sensitive frequency band of flight control cable coupling is 300-600 MHz. The sensitive frequency band of the coupling of the UAV wing cable and the rotor cable is 300-430 MHz, and the peak voltage of the coupling of the flight control cable is significantly greater than that of the wing cable and the rotor cable.
The system-level cable coupling characteristics of UAVs are of great significance for the analysis of electromagnetic effects and mechanisms of UAVs. Based on the surface current distribution of the UAV system, voltage monitoring points are set up at the UAV flight control port cables, wing cables, and rotor cables are set up to monitor the voltage distribution of the UAV system cables, and the weak links of the UAV system cable coupling are obtained by monitoring the voltage distribution of the UAV system cables. The simulation results show that when the plane wave is incident on the same length of cable at different angles, the coupling peak voltage is the largest when the electric field vector is parallel to the direction of the cable, and the coupling sensitive frequency point of different types of cables is the same, and when the plane wave incident on different lengths of cable at the same angle, the reciprocal of the resonant frequency point satisfies the same multiple relationship with the cable length. In the actual UAV system cable irradiation scenario, the sensitive frequency band of flight control cable coupling is 300-600 MHz. The sensitive frequency band of the coupling of the UAV wing cable and the rotor cable is 300-430 MHz, and the peak voltage of the coupling of the flight control cable is significantly greater than that of the wing cable and the rotor cable.
, Available online ,
doi: 10.11884/HPLPB202537.240255
Abstract:
Aiming at the problems of high failure rate, difficult maintenance, poor flexibility, and dangerous manual operation of the traditional stand-alone control of the proton beam irradiation thorium target loading and unloading system under the operating environment of low radiation, large scale, and high complexity, a control method of digital twin proton beam irradiation thorium target loading and unloading system based on the redundancy of programmable logic controller (PLC) is proposed. Firstly, the method adopts a multifactor coordinated control strategy such as CPU redundancy, I/O redundancy, and power supply redundancy, and enables the control system to run uninterruptedly by constructing a hardware hot-standby redundancy system and organizing, programming, and simulating a software redundancy system. Secondly, based on the architecture of “NX MCD+PLC SIM+OPC”, the control system of digital twin virtual-reality interaction is designed, and the twin model of target loading/unloading system is constructed in the virtual space for the data information in the physical space, so as to realize the unattended and continuous monitoring in the radiation environment. Finally, after experiments and reliability analysis, the proposed method improves the stability of this control system to 99%, which provides a new idea for the control of operating system under irradiation environment.
Aiming at the problems of high failure rate, difficult maintenance, poor flexibility, and dangerous manual operation of the traditional stand-alone control of the proton beam irradiation thorium target loading and unloading system under the operating environment of low radiation, large scale, and high complexity, a control method of digital twin proton beam irradiation thorium target loading and unloading system based on the redundancy of programmable logic controller (PLC) is proposed. Firstly, the method adopts a multifactor coordinated control strategy such as CPU redundancy, I/O redundancy, and power supply redundancy, and enables the control system to run uninterruptedly by constructing a hardware hot-standby redundancy system and organizing, programming, and simulating a software redundancy system. Secondly, based on the architecture of “NX MCD+PLC SIM+OPC”, the control system of digital twin virtual-reality interaction is designed, and the twin model of target loading/unloading system is constructed in the virtual space for the data information in the physical space, so as to realize the unattended and continuous monitoring in the radiation environment. Finally, after experiments and reliability analysis, the proposed method improves the stability of this control system to 99%, which provides a new idea for the control of operating system under irradiation environment.
, Available online ,
doi: 10.11884/HPLPB202537.240307
Abstract:
The construction of the burnup lib determines the accuracy of burnup and decay heat calculations. The evaluation of burnup information in the nuclear lib is complex, leading to a large, rigid, and inefficient burnup matrix. This paper begins with the basic composition of the burnup lib, considering the impact of each nuclide and its transformation relationships on the accuracy of neutronics calculations and target nuclide nuclear density calculations, which serves as the basis for the compression of the burnup lib. To address the decay heat calculation accuracy loss caused by the compression of fission products, a nonlinear least squares optimization algorithm is used to fit the decay heat release function, and pseudo-decay nuclides are constructed to replace the fission product decay heat calculation, thereby maintaining the accuracy of decay heat calculations. Verification results show that the original detailed burnup lib contains more than 1 500 nuclides, which are reduced to fewer than 200 nuclides after compression. The compressed burnup lib does not introduce significant deviations in the calculation of the effective multiplication factor and nuclear density. In terms of decay heat calculations, the pseudo-decay nuclides significantly restore the decay heat calculation accuracy, with the contribution of decay heat to total power having a calculation deviation of less than 0.5%, meeting the required accuracy for decay heat calculations.
The construction of the burnup lib determines the accuracy of burnup and decay heat calculations. The evaluation of burnup information in the nuclear lib is complex, leading to a large, rigid, and inefficient burnup matrix. This paper begins with the basic composition of the burnup lib, considering the impact of each nuclide and its transformation relationships on the accuracy of neutronics calculations and target nuclide nuclear density calculations, which serves as the basis for the compression of the burnup lib. To address the decay heat calculation accuracy loss caused by the compression of fission products, a nonlinear least squares optimization algorithm is used to fit the decay heat release function, and pseudo-decay nuclides are constructed to replace the fission product decay heat calculation, thereby maintaining the accuracy of decay heat calculations. Verification results show that the original detailed burnup lib contains more than 1 500 nuclides, which are reduced to fewer than 200 nuclides after compression. The compressed burnup lib does not introduce significant deviations in the calculation of the effective multiplication factor and nuclear density. In terms of decay heat calculations, the pseudo-decay nuclides significantly restore the decay heat calculation accuracy, with the contribution of decay heat to total power having a calculation deviation of less than 0.5%, meeting the required accuracy for decay heat calculations.
, Available online ,
doi: 10.11884/HPLPB202537.240312
Abstract:
With the increasing demand for diagnostics of high-energy-density (HED) materials, X-ray interferometric imaging technology has gained significant attention and application in this field. This paper primarily reviews the latest domestic and international advancements in X-ray interferometric imaging techniques and systems, focusing on the principles and capabilities of X-ray grating imaging based on Talbot and Talbot-Lau interferometry. Talbot and Talbot-Lau interferometry utilize gratings with periodic structures to perform high-precision measurements of X-ray phase, absorption, and scattering properties, enabling non-destructive inspection and imaging of internal structures of samples. This work summarizes the application of these techniques in diagnostic experiments for HED materials, introduces the Talbot Interferometric Analysis (TIA) code, and demonstrates an initial simulation by integrating the TIA program with the Flash hydrodynamics code. The simulation successfully retrieved three types of information: absorption, phase, and dark-field from the Flash model. Finally, the paper concludes with a summary and outlook on the application of X-ray Talbot-Lau interferometric diagnostic technology in high-energy-density plasma experiments.
With the increasing demand for diagnostics of high-energy-density (HED) materials, X-ray interferometric imaging technology has gained significant attention and application in this field. This paper primarily reviews the latest domestic and international advancements in X-ray interferometric imaging techniques and systems, focusing on the principles and capabilities of X-ray grating imaging based on Talbot and Talbot-Lau interferometry. Talbot and Talbot-Lau interferometry utilize gratings with periodic structures to perform high-precision measurements of X-ray phase, absorption, and scattering properties, enabling non-destructive inspection and imaging of internal structures of samples. This work summarizes the application of these techniques in diagnostic experiments for HED materials, introduces the Talbot Interferometric Analysis (TIA) code, and demonstrates an initial simulation by integrating the TIA program with the Flash hydrodynamics code. The simulation successfully retrieved three types of information: absorption, phase, and dark-field from the Flash model. Finally, the paper concludes with a summary and outlook on the application of X-ray Talbot-Lau interferometric diagnostic technology in high-energy-density plasma experiments.
, Available online ,
doi: 10.11884/HPLPB202537.240253
Abstract:
Based on the self-triggering technology, a square wave pulse adder with truncation function is proposed based on the self-triggering technology. The N-type switch and the P-type switch are connected in series to form a special half-bridge structure, which only needs to provide an isolated bipolar signal to control the first-stage charging and discharging switches. All other switches are turned on and off step by step to generate high-voltage square wave pulses. This technology not only greatly simplifies the driving circuit of the pulse adder, but also realizes the truncation function to generate quasi-square wave pulses with fast front and back edges. By using the automatic conduction characteristics of the depleted N-type switch, the self-charging without control is realized, and the insulation level of the drive circuit is significantly improved. A 9-stage power supply prototype is built for experimental verification, the experimental results show that a stable repetitive positive square wave pulse is generated on a 10 kΩ resistive load. The voltage amplitude is adjustable from 2.3 kV to 3.6 kV, the pulse width is adjustable from 1 μs to 10 μs, and the frequency is adjustable from 0 kHz to 1 kHz. The front and rear edges are about 100 ns, and accelerate with the increase of operating voltage. The waveform under 10 kΩ and 3 nF resistance-capacitance series load is still a good square wave pulse, and the front and rear edges of the pulse do not slow down significantly with the resistance load. The compact structure of the pulse adder can help to miniaturize solid-state pulse generators.
Based on the self-triggering technology, a square wave pulse adder with truncation function is proposed based on the self-triggering technology. The N-type switch and the P-type switch are connected in series to form a special half-bridge structure, which only needs to provide an isolated bipolar signal to control the first-stage charging and discharging switches. All other switches are turned on and off step by step to generate high-voltage square wave pulses. This technology not only greatly simplifies the driving circuit of the pulse adder, but also realizes the truncation function to generate quasi-square wave pulses with fast front and back edges. By using the automatic conduction characteristics of the depleted N-type switch, the self-charging without control is realized, and the insulation level of the drive circuit is significantly improved. A 9-stage power supply prototype is built for experimental verification, the experimental results show that a stable repetitive positive square wave pulse is generated on a 10 kΩ resistive load. The voltage amplitude is adjustable from 2.3 kV to 3.6 kV, the pulse width is adjustable from 1 μs to 10 μs, and the frequency is adjustable from 0 kHz to 1 kHz. The front and rear edges are about 100 ns, and accelerate with the increase of operating voltage. The waveform under 10 kΩ and 3 nF resistance-capacitance series load is still a good square wave pulse, and the front and rear edges of the pulse do not slow down significantly with the resistance load. The compact structure of the pulse adder can help to miniaturize solid-state pulse generators.
, Available online ,
doi: 10.11884/HPLPB202537.240369
Abstract:
Fast Burst Reactors (FBRs) are important subjects for criticality safety analysis research. They are characterized by irregular geometry, strong transient processes, tight multi-physics coupling, and complex feedback characteristics. This paper introduces an OpenFOAM based multi-physics nuclear criticality safety analysis code named INSL-UniFoam. It integrates discrete ordinate neutron transport solver, heat transfer and stress-strain solvers to detailed model the prompt super-critical burst pulse of FBRs. The UniFoam is first verified in the Godiva-I benchmark at both the steady-state condition and several transient scenarios. The results demonstrate that the program aligns well with the reference solution in terms of Keff calculation, peak power, and fission yield. Furthermore, it is capable of comprehensively outputting the distributions of power, temperature, and stress-strain throughout the pulse process.
Fast Burst Reactors (FBRs) are important subjects for criticality safety analysis research. They are characterized by irregular geometry, strong transient processes, tight multi-physics coupling, and complex feedback characteristics. This paper introduces an OpenFOAM based multi-physics nuclear criticality safety analysis code named INSL-UniFoam. It integrates discrete ordinate neutron transport solver, heat transfer and stress-strain solvers to detailed model the prompt super-critical burst pulse of FBRs. The UniFoam is first verified in the Godiva-I benchmark at both the steady-state condition and several transient scenarios. The results demonstrate that the program aligns well with the reference solution in terms of Keff calculation, peak power, and fission yield. Furthermore, it is capable of comprehensively outputting the distributions of power, temperature, and stress-strain throughout the pulse process.
, Available online ,
doi: 10.11884/HPLPB202537.240335
Abstract:
This paper will discuss early experiments on laser-driven indirect drive implosion of double-metal-shell targets conducted with a hundred-kilojoule-class laser facility. The design of the double-metal-shell target is derived from the volume ignition scheme, which decouples the radiation ablation and implosion compression processes, thereby improving the robustness of the implosion. However, due to the high difficulty in manufacturing the double-metal-shell target, the neutron yield in the initial experiments was much lower than expected from simulations. To address this issue, two key improvements are proposed: first, optimizing the joint design of the outer shell to reduce the impact of hydrodynamic instability, thus improving the collision efficiency of the inner and outer shells and the implosion efficiency of the inner core; second, enhancing the coupling efficiency of the hohlraum-target to improve the effective transfer of laser energy. With these improvements, the compression performance and implosion efficiency of the target were significantly enhanced, resulting in a substantial increase in neutron yield, from\begin{document}$ 5.0\times {10}^{7} $\end{document} ![]()
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This paper will discuss early experiments on laser-driven indirect drive implosion of double-metal-shell targets conducted with a hundred-kilojoule-class laser facility. The design of the double-metal-shell target is derived from the volume ignition scheme, which decouples the radiation ablation and implosion compression processes, thereby improving the robustness of the implosion. However, due to the high difficulty in manufacturing the double-metal-shell target, the neutron yield in the initial experiments was much lower than expected from simulations. To address this issue, two key improvements are proposed: first, optimizing the joint design of the outer shell to reduce the impact of hydrodynamic instability, thus improving the collision efficiency of the inner and outer shells and the implosion efficiency of the inner core; second, enhancing the coupling efficiency of the hohlraum-target to improve the effective transfer of laser energy. With these improvements, the compression performance and implosion efficiency of the target were significantly enhanced, resulting in a substantial increase in neutron yield, from
, Available online ,
doi: 10.11884/HPLPB202537.240247
Abstract:
CUP-VISAR system is a new technology that combines Compressed Ultrafast Photography (CUP) with two-dimensional Velocity Interferometer System for Any Reflector (VISAR). To solve the problem that the image reconstruction quality of CUP-VISAR system decreases obviously under the condition of large noise, a compressed ultrafast photography reconstruction method based on iteration-interframe dual prediction is proposed. In this method, the correlation of inter-frame image data and the correlation of iterations before and after the same frame image are studied. The compressed image reconstruction problem is presented as an iteration-inter-frame dual prediction optimization problem based on Kalman prediction and inter-frame prediction, and the Plug-and-Play Generalized Alternating Projection (PnP-GAP) framework is used to solve the optimization problem effectively. Simulation results show that the minimum Peak Signal-to-Noise Ratio (PSNR) and minimum Structure Similarity Index Measure (SSIM) of the proposed method are increased by 3.18～2.11 dB and 20.30%～8.22% under large Gaussian noise conditions. The practical results show that the proposed method can obtain higher definition of fringe image, and the reconstructed line-VISAR (1D-VISAR) fringe movement trend is clearer, which verifies the effectiveness of the algorithm.
CUP-VISAR system is a new technology that combines Compressed Ultrafast Photography (CUP) with two-dimensional Velocity Interferometer System for Any Reflector (VISAR). To solve the problem that the image reconstruction quality of CUP-VISAR system decreases obviously under the condition of large noise, a compressed ultrafast photography reconstruction method based on iteration-interframe dual prediction is proposed. In this method, the correlation of inter-frame image data and the correlation of iterations before and after the same frame image are studied. The compressed image reconstruction problem is presented as an iteration-inter-frame dual prediction optimization problem based on Kalman prediction and inter-frame prediction, and the Plug-and-Play Generalized Alternating Projection (PnP-GAP) framework is used to solve the optimization problem effectively. Simulation results show that the minimum Peak Signal-to-Noise Ratio (PSNR) and minimum Structure Similarity Index Measure (SSIM) of the proposed method are increased by 3.18～2.11 dB and 20.30%～8.22% under large Gaussian noise conditions. The practical results show that the proposed method can obtain higher definition of fringe image, and the reconstructed line-VISAR (1D-VISAR) fringe movement trend is clearer, which verifies the effectiveness of the algorithm.
, Available online ,
doi: 10.11884/HPLPB202537.240248
Abstract:
Many applications including plasma excitation and high-power microwave sources require miniaturized high-voltage pulse generators. A miniaturized Marx generator with a novel magnetic isolated drive circuit is proposed. Founding that the source terminals of the charging MOSFET and discharging MOSFET in adjacent stages are shorted in Marx generators based on half-bridge circuits, we apply a bipolar signal to both gates of these two MOSFETs and control both their switching. Combined with magnetic isolated driver with primary windings in series, only one bipolar signal from the primary side can synchronously drive all switches in the Marx generator, which considerably reduces the number of required components in the drive circuits. A 14-level experimental prototype was built, with a total weight of only 314 g, a width of 15 cm, a length of 8 cm, and a height of 5 cm. High-voltage square wave pulses with a peak voltage of 10 kV, a repetition frequency of 10 kHz, and a pulse width ranging from 200 ns to 5 μs were obtained over a resistive load. The 500 ns, 10 kV, and 1 kHz square wave pulses generated by the prototype were used to drive the dielectric barrier discharge load, and a uniform and strong discharge was generated, indicating that the miniaturized Marx generator is suitable for driving the dielectric barrier discharge load and being used as a low-temperature plasma source.
Many applications including plasma excitation and high-power microwave sources require miniaturized high-voltage pulse generators. A miniaturized Marx generator with a novel magnetic isolated drive circuit is proposed. Founding that the source terminals of the charging MOSFET and discharging MOSFET in adjacent stages are shorted in Marx generators based on half-bridge circuits, we apply a bipolar signal to both gates of these two MOSFETs and control both their switching. Combined with magnetic isolated driver with primary windings in series, only one bipolar signal from the primary side can synchronously drive all switches in the Marx generator, which considerably reduces the number of required components in the drive circuits. A 14-level experimental prototype was built, with a total weight of only 314 g, a width of 15 cm, a length of 8 cm, and a height of 5 cm. High-voltage square wave pulses with a peak voltage of 10 kV, a repetition frequency of 10 kHz, and a pulse width ranging from 200 ns to 5 μs were obtained over a resistive load. The 500 ns, 10 kV, and 1 kHz square wave pulses generated by the prototype were used to drive the dielectric barrier discharge load, and a uniform and strong discharge was generated, indicating that the miniaturized Marx generator is suitable for driving the dielectric barrier discharge load and being used as a low-temperature plasma source.
, Available online ,
doi: 10.11884/HPLPB202537.240272
Abstract:
Spacecraft have to be exposed to complex and harsh space radiation environments for a long time during their in-orbit service. III-V compound solar cells, represented by GaAs, are widely used in the aerospace field due to their high photoelectric conversion efficiency and radiation resistance. The spatial radiation damage effect of GaAs solar cells was studied using finite element method and computer-aided design technology (TCAD). Based on the electrical parameters of GaAs solar cells under AM0 spectral irradiation, a three- junction solar cell structure model and irradiation damage model were established. The volt ampere characteristic curves of the cells under different electron irradiation conditions were obtained, and the simulation results in this paper were verified with existing experimental results. The degradation law of GaAs solar cell electrical performance under space environment irradiation was analyzed. The results indicate that irradiation damage defects reduce the diffusion length of minority carriers and decrease the collection efficiency of photo generated carriers. At a certain electron energy, the degradation amplitude of the electrical performance of solar cells increases with the increase of irradiation dose level.
Spacecraft have to be exposed to complex and harsh space radiation environments for a long time during their in-orbit service. III-V compound solar cells, represented by GaAs, are widely used in the aerospace field due to their high photoelectric conversion efficiency and radiation resistance. The spatial radiation damage effect of GaAs solar cells was studied using finite element method and computer-aided design technology (TCAD). Based on the electrical parameters of GaAs solar cells under AM0 spectral irradiation, a three- junction solar cell structure model and irradiation damage model were established. The volt ampere characteristic curves of the cells under different electron irradiation conditions were obtained, and the simulation results in this paper were verified with existing experimental results. The degradation law of GaAs solar cell electrical performance under space environment irradiation was analyzed. The results indicate that irradiation damage defects reduce the diffusion length of minority carriers and decrease the collection efficiency of photo generated carriers. At a certain electron energy, the degradation amplitude of the electrical performance of solar cells increases with the increase of irradiation dose level.
, Available online ,
doi: 10.11884/HPLPB202537.240233
Abstract:
During the charging period of capacitor charging power supply, the input power gradually increases with the increase of output voltage, which not only requires the power grid to provide a larger peak power, but also causes larger current harmonics. This paper proposes a new control algorithm based on a single-stage charging scheme with buffered energy storage capacitor that realizes the function of constant power input and constant current output only by using single-stage energy conversion. The algorithm not only achieves better constant power characteristics, but also lifts the restriction on the auxiliary energy storage capacitor. It can improve the equivalent excitation voltage by controlling the voltage of the energy storage capacitor. Matlab/Simulink was used to build a simulation model of capacitor charging with constant power input. The simulation results show that the constant power at the input end is realized during the 400−2 000 V stage of capacitor charging, the initial voltage of auxiliary capacitor is increased, and the voltage of load capacitor is increased at the same time. This shows that the algorithm can achieve better input constant power characteristics and circuit boost function.
During the charging period of capacitor charging power supply, the input power gradually increases with the increase of output voltage, which not only requires the power grid to provide a larger peak power, but also causes larger current harmonics. This paper proposes a new control algorithm based on a single-stage charging scheme with buffered energy storage capacitor that realizes the function of constant power input and constant current output only by using single-stage energy conversion. The algorithm not only achieves better constant power characteristics, but also lifts the restriction on the auxiliary energy storage capacitor. It can improve the equivalent excitation voltage by controlling the voltage of the energy storage capacitor. Matlab/Simulink was used to build a simulation model of capacitor charging with constant power input. The simulation results show that the constant power at the input end is realized during the 400−2 000 V stage of capacitor charging, the initial voltage of auxiliary capacitor is increased, and the voltage of load capacitor is increased at the same time. This shows that the algorithm can achieve better input constant power characteristics and circuit boost function.
, Available online ,
doi: 10.11884/HPLPB202537.240319
Abstract:
A D-dot monitor for measuring nanosecond high voltage pulses is designed in this paper. The design, simulation, and experiments of the probe and integrator are introduced. The electrode of the probe can be replaced and its axial length can be adjusted according to different measurement requirements. The structure of the probe is optimized according to the results of simulation on electrostatic field by CST. The amplitude-frequency response of the monitor is simulated by Pspice to ensure that the operating frequency of the monitor meets the design requirements. The D-dot monitor is applied to measure the high voltage pulses with nanosecond level pulse width. The experimental results showed that the designed D-dot monitor meets the measurement requirements for high voltage pulses with rise time of about 37ns and voltage amplitude of about 597kV.
A D-dot monitor for measuring nanosecond high voltage pulses is designed in this paper. The design, simulation, and experiments of the probe and integrator are introduced. The electrode of the probe can be replaced and its axial length can be adjusted according to different measurement requirements. The structure of the probe is optimized according to the results of simulation on electrostatic field by CST. The amplitude-frequency response of the monitor is simulated by Pspice to ensure that the operating frequency of the monitor meets the design requirements. The D-dot monitor is applied to measure the high voltage pulses with nanosecond level pulse width. The experimental results showed that the designed D-dot monitor meets the measurement requirements for high voltage pulses with rise time of about 37ns and voltage amplitude of about 597kV.
, Available online ,
doi: 10.11884/HPLPB202537.240347
Abstract:
Introduced the overall layout of the Free Electron Laser & High Magnetic Field device under construction at Anhui University, and analyzed in detail the design requirements and difficulties of the water-cooling system for the stable operation of the device, and completed the design and development of the water-cooling system of the whole device according to the requirements, the water-cooling system of the device contains two independent water-cooling unit systems, with the design temperatures of (42±0.1)℃ and (25±0.5)℃, and can be adjusted within a certain range. The device water-cooling control system is developed based on EPICS ( Experimental Physics and Industrial Control System ) framework, the temperature regulation control function is realized by PLC ( Programmable Logic Controller ) program, and the PID (Proportion Integration Differentiation) parameter configuration is realized by PID regulator. The software development of the control system is mainly to realize the setting of the device parameters and the reading back of the status data under the EPICS environment, and to store the historical data into the Archiver Appliances database. The temperature control accuracy of the water-cooling control system during the trial operation reaches (42±0.03)℃ and (25±0.08)℃, which is in line with the design requirements, and the system is stable and reliable during the operation, which can well guarantee the safe and stable operation of the device.
Introduced the overall layout of the Free Electron Laser & High Magnetic Field device under construction at Anhui University, and analyzed in detail the design requirements and difficulties of the water-cooling system for the stable operation of the device, and completed the design and development of the water-cooling system of the whole device according to the requirements, the water-cooling system of the device contains two independent water-cooling unit systems, with the design temperatures of (42±0.1)℃ and (25±0.5)℃, and can be adjusted within a certain range. The device water-cooling control system is developed based on EPICS ( Experimental Physics and Industrial Control System ) framework, the temperature regulation control function is realized by PLC ( Programmable Logic Controller ) program, and the PID (Proportion Integration Differentiation) parameter configuration is realized by PID regulator. The software development of the control system is mainly to realize the setting of the device parameters and the reading back of the status data under the EPICS environment, and to store the historical data into the Archiver Appliances database. The temperature control accuracy of the water-cooling control system during the trial operation reaches (42±0.03)℃ and (25±0.08)℃, which is in line with the design requirements, and the system is stable and reliable during the operation, which can well guarantee the safe and stable operation of the device.
, Available online ,
doi: 10.11884/HPLPB202537.240310
Abstract:
In order to solve the problem of hard connection in waveguide transmission line, some waveguide components will use flexible waveguide, but the use of flexible waveguide will bring about the increase of transmission line loss. In aiming to investigate its loss and electrical heating under real operating conditions, we built a test platform based on a resonant ring with a 13.4 dB power gain in the traveling wave of the resonant ring, which successfully achieves an equivalent power of 140 kW at the position of the antinode by means of two 2 kW power amplifiers. Based on the results of simulations and experiments, we optimized the design of the rectangular flexible waveguide and improved its structure and materials to better cope with the thermal deformation and stress under high power input. The optimized flexible waveguide's electrical and thermal performance is better than that of similar foreign products.
In order to solve the problem of hard connection in waveguide transmission line, some waveguide components will use flexible waveguide, but the use of flexible waveguide will bring about the increase of transmission line loss. In aiming to investigate its loss and electrical heating under real operating conditions, we built a test platform based on a resonant ring with a 13.4 dB power gain in the traveling wave of the resonant ring, which successfully achieves an equivalent power of 140 kW at the position of the antinode by means of two 2 kW power amplifiers. Based on the results of simulations and experiments, we optimized the design of the rectangular flexible waveguide and improved its structure and materials to better cope with the thermal deformation and stress under high power input. The optimized flexible waveguide's electrical and thermal performance is better than that of similar foreign products.
, Available online ,
doi: 10.11884/HPLPB202537.240274
Abstract:
This paper investigates the application of waveguide slot array antennas in high-power microwave technology and proposes a novel design method, with particular emphasis on the slot coupling, sidelobe levels, and matching between the antenna and the feed. The new method leverages modern computing technology to rapidly compute the slot conductance function considering slot coupling effects, thereby enabling efficient design of waveguide slot array antennas. This approach avoids complex calculations or external structures, ensuring system compactness and demonstrating higher effectiveness in designing waveguide slot planar arrays. Simulation results indicate that antennas designed using the new method exhibit excellent matching performance. At the center frequency f = 2.458 GHz, the reflection coefficient for each port of antenna designed using the new method ranges from −37.2 dB to −27.7 dB. In comparison, antennas designed using the Stevenson formula for the same target parameters have reflection coefficients ranging from −11 dB to −8.7 dB, with the reflection coefficients of antennas designed with the new method being reduced by at least 19 dB. Moreover, the antennas designed with this new method achieve a low sidelobe level of −30.2 dB and a high power capacity of 332.6 MW.
This paper investigates the application of waveguide slot array antennas in high-power microwave technology and proposes a novel design method, with particular emphasis on the slot coupling, sidelobe levels, and matching between the antenna and the feed. The new method leverages modern computing technology to rapidly compute the slot conductance function considering slot coupling effects, thereby enabling efficient design of waveguide slot array antennas. This approach avoids complex calculations or external structures, ensuring system compactness and demonstrating higher effectiveness in designing waveguide slot planar arrays. Simulation results indicate that antennas designed using the new method exhibit excellent matching performance. At the center frequency f = 2.458 GHz, the reflection coefficient for each port of antenna designed using the new method ranges from −37.2 dB to −27.7 dB. In comparison, antennas designed using the Stevenson formula for the same target parameters have reflection coefficients ranging from −11 dB to −8.7 dB, with the reflection coefficients of antennas designed with the new method being reduced by at least 19 dB. Moreover, the antennas designed with this new method achieve a low sidelobe level of −30.2 dB and a high power capacity of 332.6 MW.
, Available online ,
doi: 10.11884/HPLPB202537.240334
Abstract:
Aiming at the pulse operating characteristics of voltage-controlled thyristors, a cascadable driving circuit is designed to realize the synchronous opening of multi-stage series-connected voltage-controlled thyristors. Firstly, the circuit topology and working principle is analysed. in which the coupled inductor is used to isolate the driver signal and transfer power to open the switch. Based on blumein PFN, an experimental test circuit is built, in which a 6-stage mos-controlled thyristor is series connected to be the discharge switch. A quasi-square-wave pulse current with an amplitude of 1.958 kA is obtained on a 4 Ω resistor.
Aiming at the pulse operating characteristics of voltage-controlled thyristors, a cascadable driving circuit is designed to realize the synchronous opening of multi-stage series-connected voltage-controlled thyristors. Firstly, the circuit topology and working principle is analysed. in which the coupled inductor is used to isolate the driver signal and transfer power to open the switch. Based on blumein PFN, an experimental test circuit is built, in which a 6-stage mos-controlled thyristor is series connected to be the discharge switch. A quasi-square-wave pulse current with an amplitude of 1.958 kA is obtained on a 4 Ω resistor.
, Available online ,
doi: 10.11884/HPLPB202537.240223
Abstract:
Due to the comprehensive performance advantages, GaN-based power devices are more suitable for the future development needs of RF power amplifier modules in the space equipment such as satellite electronic systems．Therefore, the degradation of electrical characteristics and damage mechanism of the enhancement-mode Cascode structure GaN HEMT devices were studied by irradiation experiments with 5 MeV, 60 MeV and 300 MeV protons at the irradiation dose of 2×1012～1×1014 p/cm2. The experimental results show that when the irradiation dose is 2×1012 p/cm2, the threshold voltage of Cascode structure GaN HEMT device is significantly reduced, the transconductance peak is negative drift and the peak transconductance is reduced, the saturated drain current is significantly increased, and the gate leakage current has no significant change. When the irradiation dose reaches 1×1013 p/cm2, the degradation of electrical properties is inhibited and tends to saturation. It is concluded that the existence of cascaded silicon MOSFET in Cascode structure GaN HEMT is the internal cause of threshold voltage negative drift and drain current increase after proton irradiation. Combined with low-frequency noise test analysis, it is found that the higher the proton irradiation dose, the larger the noise power spectral density of the device, indicating that the more defects introduced by irradiation, the more serious the irradiation damage. Compared with the results of 60 MeV and 300 MeV proton irradiation, the degradation of electrical characteristics of the device after 5 MeV proton irradiation is the most serious. SRIM simulation results show that the lower the proton irradiation energy, the greater the number of vacancies (gallium vacancy is dominated), and the more significant the degradation of electrical characteristics of the device.
Due to the comprehensive performance advantages, GaN-based power devices are more suitable for the future development needs of RF power amplifier modules in the space equipment such as satellite electronic systems．Therefore, the degradation of electrical characteristics and damage mechanism of the enhancement-mode Cascode structure GaN HEMT devices were studied by irradiation experiments with 5 MeV, 60 MeV and 300 MeV protons at the irradiation dose of 2×1012～1×1014 p/cm2. The experimental results show that when the irradiation dose is 2×1012 p/cm2, the threshold voltage of Cascode structure GaN HEMT device is significantly reduced, the transconductance peak is negative drift and the peak transconductance is reduced, the saturated drain current is significantly increased, and the gate leakage current has no significant change. When the irradiation dose reaches 1×1013 p/cm2, the degradation of electrical properties is inhibited and tends to saturation. It is concluded that the existence of cascaded silicon MOSFET in Cascode structure GaN HEMT is the internal cause of threshold voltage negative drift and drain current increase after proton irradiation. Combined with low-frequency noise test analysis, it is found that the higher the proton irradiation dose, the larger the noise power spectral density of the device, indicating that the more defects introduced by irradiation, the more serious the irradiation damage. Compared with the results of 60 MeV and 300 MeV proton irradiation, the degradation of electrical characteristics of the device after 5 MeV proton irradiation is the most serious. SRIM simulation results show that the lower the proton irradiation energy, the greater the number of vacancies (gallium vacancy is dominated), and the more significant the degradation of electrical characteristics of the device.
, Available online ,
doi: 10.11884/HPLPB202537.240216
Abstract:
In the process of high energy and high power extreme ultraviolet (EUV) irradiation, carbon deposition and surface oxidation are easy to form on the surface of the EUV mirror, which will affect its reflectivity and shorten its service life. To solve this problem, technology of nitride and oxide capping coating on the surface of extreme ultraviolet multilayer film was studied experimentally and characterized. In the preparation process, based on DC reactive magnetron sputtering coating technology, the "hyperbola" relationship between process gas flow and sputtering voltage was studied, to optimize the control of the amount of reactive gas, and then reduce the influence of reactive gas on Mo/Si multilayer films during reactive sputtering. Based on this method, TiN, ZrN and TiO2 capping layer were plated on the surface of Mo/Si multilayer films and were characterized by grazing incident X-ray reflection (GIXR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). It is proved that the nitride capping layer has certain performance advantages.
In the process of high energy and high power extreme ultraviolet (EUV) irradiation, carbon deposition and surface oxidation are easy to form on the surface of the EUV mirror, which will affect its reflectivity and shorten its service life. To solve this problem, technology of nitride and oxide capping coating on the surface of extreme ultraviolet multilayer film was studied experimentally and characterized. In the preparation process, based on DC reactive magnetron sputtering coating technology, the "hyperbola" relationship between process gas flow and sputtering voltage was studied, to optimize the control of the amount of reactive gas, and then reduce the influence of reactive gas on Mo/Si multilayer films during reactive sputtering. Based on this method, TiN, ZrN and TiO2 capping layer were plated on the surface of Mo/Si multilayer films and were characterized by grazing incident X-ray reflection (GIXR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). It is proved that the nitride capping layer has certain performance advantages.
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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, Available online ,
doi: 10.11884/HPLPB202537.240225
Abstract:
High power microwave is easy to enter the system through the main coupling path of interconnection cables between electronic devices, disrupting or even damaging sensitive circuits or devices. To guide the rational wiring in engineering and improve the survival ability of electronic system under high power microwave, the coupling effect between HPM and cable under different parameters (cable length, height from ground, terminal load resistance, radiation field incidence angle) is systematically studied by combining simulation analysis and test verification. The coupling response law is obtained and the internal reasons are analyzed. The results show that with the increase of cable length, the coupling signal oscillates first and then tends to be stable gradually, and the oscillation period is equal to the wavelength of the incident wave. The coupling signal oscillates with the change of the height from the cable to the ground, and the maximum and minimum values appear when the height from the ground is odd times of 1/4 wavelength and integer times of 1/2 wavelength of the incident wave respectively. The coupling signal decreases first and then increases with the increase of terminal load resistance. When the load resistance matches the cable characteristic impedance, the coupling signal is the smallest. The coupling signal increases with the increase of the angle between the incoming wave direction and the cable layout direction, and the coupling signal is the largest when the two are perpendicular. On this basis, some optimization suggestions of cable laying in practical engineering are given, which provides guidance for system-level electromagnetic compatibility and high-power microwave protection design.
High power microwave is easy to enter the system through the main coupling path of interconnection cables between electronic devices, disrupting or even damaging sensitive circuits or devices. To guide the rational wiring in engineering and improve the survival ability of electronic system under high power microwave, the coupling effect between HPM and cable under different parameters (cable length, height from ground, terminal load resistance, radiation field incidence angle) is systematically studied by combining simulation analysis and test verification. The coupling response law is obtained and the internal reasons are analyzed. The results show that with the increase of cable length, the coupling signal oscillates first and then tends to be stable gradually, and the oscillation period is equal to the wavelength of the incident wave. The coupling signal oscillates with the change of the height from the cable to the ground, and the maximum and minimum values appear when the height from the ground is odd times of 1/4 wavelength and integer times of 1/2 wavelength of the incident wave respectively. The coupling signal decreases first and then increases with the increase of terminal load resistance. When the load resistance matches the cable characteristic impedance, the coupling signal is the smallest. The coupling signal increases with the increase of the angle between the incoming wave direction and the cable layout direction, and the coupling signal is the largest when the two are perpendicular. On this basis, some optimization suggestions of cable laying in practical engineering are given, which provides guidance for system-level electromagnetic compatibility and high-power microwave protection design.
, Available online ,
doi: 10.11884/HPLPB202537.240282
Abstract:
Double energy accelerator used in custom security monitoring is powered by the high-power magnetron, the top of pulse current waveform through the magnetron varies greatly in the double energy operation mode of the ordinary solid-state modulator due to nonlinear impedance of the magnetron, thus it is difficult to precisely distinguish contraband from the commodity in the cargo. To make the top of the pulse current waveform through the magnetron used in the double energy accelerator flat in the double energy operation mode, we developed a solid state modulator based on dual-loop parallel circuit topology, parallel IGBT solid state switch, high ratio pulse transformer technology and waveform correction technique for double energy accelerator. When the operating current through the magnetron is in the range of 70～120 A , this solid state modulator can output quasi-trapezoid current waveform in the double energy operation mode, and the relative top fluctuation of the pulse waveforms through the magnetron is less than 5%.
Double energy accelerator used in custom security monitoring is powered by the high-power magnetron, the top of pulse current waveform through the magnetron varies greatly in the double energy operation mode of the ordinary solid-state modulator due to nonlinear impedance of the magnetron, thus it is difficult to precisely distinguish contraband from the commodity in the cargo. To make the top of the pulse current waveform through the magnetron used in the double energy accelerator flat in the double energy operation mode, we developed a solid state modulator based on dual-loop parallel circuit topology, parallel IGBT solid state switch, high ratio pulse transformer technology and waveform correction technique for double energy accelerator. When the operating current through the magnetron is in the range of 70～120 A , this solid state modulator can output quasi-trapezoid current waveform in the double energy operation mode, and the relative top fluctuation of the pulse waveforms through the magnetron is less than 5%.
, Available online ,
doi: 10.11884/HPLPB202537.240150
Abstract:
This paper presents a model for aerosol inertial collision removal under mixed gas jet conditions with high Weber number, based on the hydrodynamic model of jet penetration length and entrained droplet fraction. An analysis code of the aerosol pool scrubbing is constructed by spatial discretization of the injection zone. The experimental cases are adopted to validate the model, including two cases of 64% steam fraction, 0.7 m submergence depth, and mass fluxes of 217 kg/(m2·s) and 120 kg/(m2·s), conducted by small scale aerosol pool scrubbing facility, and one Reinforced Concerted Action 2 (RCA2) experiment with non-condensable gas-carrying aerosols at 0.5 m submergence depth and mass fluxes of 95 kg/(m2·s). The results show that the predictions of the model considering the jet hydrodynamic characteristics are in good agreement with the experimental values. Parameter analysis shows that as the Weber number of immersed jet increases, both jet penetration length and entrained droplet fraction increase, thereby enhancing the inertial collision between aerosols and droplets.
This paper presents a model for aerosol inertial collision removal under mixed gas jet conditions with high Weber number, based on the hydrodynamic model of jet penetration length and entrained droplet fraction. An analysis code of the aerosol pool scrubbing is constructed by spatial discretization of the injection zone. The experimental cases are adopted to validate the model, including two cases of 64% steam fraction, 0.7 m submergence depth, and mass fluxes of 217 kg/(m2·s) and 120 kg/(m2·s), conducted by small scale aerosol pool scrubbing facility, and one Reinforced Concerted Action 2 (RCA2) experiment with non-condensable gas-carrying aerosols at 0.5 m submergence depth and mass fluxes of 95 kg/(m2·s). The results show that the predictions of the model considering the jet hydrodynamic characteristics are in good agreement with the experimental values. Parameter analysis shows that as the Weber number of immersed jet increases, both jet penetration length and entrained droplet fraction increase, thereby enhancing the inertial collision between aerosols and droplets.
, Available online ,
doi: 10.11884/HPLPB202537.240154
Abstract:
In large current accelerator beam tubes, high-frequency fields are generated when charged particles circulate within the beam pipe. To mitigate the impact on beam current, it is essential to use high-order mode damper to convert the high field energy into heat, which can then be dissipated by a cooling system. This paper presents the research, fabrication, and key performance characteristics of a hybrid high-order mode damper. The absorbing materials utilized in the damper include ferrite and silicon carbide, which can be welded to metal substrates through metallization and welding techniques. Microwave performance simulations and thermal simulations were conducted using CST and COMSOL software, respectively, leading to an optimized damper structure. Test results demonstrate that the absorption efficiency of the hybrid damper aligns closely with the calculated values in the frequency range below 1.7 GHz. However, the simulated absorption efficiency exceeds the measured results significantly above 1.7 GHz. Additionally, the vacuum leak rates, ultimate vacuum, and water resistance meet the design requirements for superconducting high-frequency cavities.
In large current accelerator beam tubes, high-frequency fields are generated when charged particles circulate within the beam pipe. To mitigate the impact on beam current, it is essential to use high-order mode damper to convert the high field energy into heat, which can then be dissipated by a cooling system. This paper presents the research, fabrication, and key performance characteristics of a hybrid high-order mode damper. The absorbing materials utilized in the damper include ferrite and silicon carbide, which can be welded to metal substrates through metallization and welding techniques. Microwave performance simulations and thermal simulations were conducted using CST and COMSOL software, respectively, leading to an optimized damper structure. Test results demonstrate that the absorption efficiency of the hybrid damper aligns closely with the calculated values in the frequency range below 1.7 GHz. However, the simulated absorption efficiency exceeds the measured results significantly above 1.7 GHz. Additionally, the vacuum leak rates, ultimate vacuum, and water resistance meet the design requirements for superconducting high-frequency cavities.
, Available online ,
doi: 10.11884/HPLPB202537.240261
Abstract:
Photocathode electron sources play a crucial role in advanced accelerator facilities. Recent advancements in electron accelerator facilities have continually pushed the parameter boundaries of electrons sources, which in turn necessitate photocathode drive lasers that possess high power, high stability, and the ability to control spatiotemporal distributions. For such a purpose, lots of efforts have been made to achieve high-quality amplification, harmonic generation, and spatiotemporal shaping of the drive laser systems. This paper presents a comprehensive review of the primary technological approaches and status of drive lasers for high-brightness electron sources worldwide. Analysis of representative drive laser schemes and discussion on the future trends are also included, aiming to provide a helpful reference for planning and developing high-performance photocathode drive laser system.
Photocathode electron sources play a crucial role in advanced accelerator facilities. Recent advancements in electron accelerator facilities have continually pushed the parameter boundaries of electrons sources, which in turn necessitate photocathode drive lasers that possess high power, high stability, and the ability to control spatiotemporal distributions. For such a purpose, lots of efforts have been made to achieve high-quality amplification, harmonic generation, and spatiotemporal shaping of the drive laser systems. This paper presents a comprehensive review of the primary technological approaches and status of drive lasers for high-brightness electron sources worldwide. Analysis of representative drive laser schemes and discussion on the future trends are also included, aiming to provide a helpful reference for planning and developing high-performance photocathode drive laser system.
, Available online ,
doi: 10.11884/HPLPB202537.240199
Abstract:
In laser-driven inertial confinement fusion experiments, the CR-39 detector, a commonly-used recording medium for proton energy spectrum diagnosis, has timeliness and consistency flaws in energy spectrum measurement. However, the Timepix detector with the ability to obtain online signals can overcome these problems. To apply the Timepix detector to detect implosion proton energy spectra, it is essential to study the response of the Timepix detector to proton energies and incident angles. This work analyzes the response of the Timepix detector to proton beams in different energies and incident angles within the Allpix2 framework using Monte Carlo methods. The simulation results show that the response of the Timepix detector to proton beams in different energies and incident angles exhibits significant differences in cluster morphology, cluster size distribution, and cluster charge distribution. When incident proton beam energy is below 6 MeV, the Timepix detector exhibits high detection efficiency, and the angle of proton incidence does not significantly affect the energy response of the detector.
In laser-driven inertial confinement fusion experiments, the CR-39 detector, a commonly-used recording medium for proton energy spectrum diagnosis, has timeliness and consistency flaws in energy spectrum measurement. However, the Timepix detector with the ability to obtain online signals can overcome these problems. To apply the Timepix detector to detect implosion proton energy spectra, it is essential to study the response of the Timepix detector to proton energies and incident angles. This work analyzes the response of the Timepix detector to proton beams in different energies and incident angles within the Allpix2 framework using Monte Carlo methods. The simulation results show that the response of the Timepix detector to proton beams in different energies and incident angles exhibits significant differences in cluster morphology, cluster size distribution, and cluster charge distribution. When incident proton beam energy is below 6 MeV, the Timepix detector exhibits high detection efficiency, and the angle of proton incidence does not significantly affect the energy response of the detector.
, Available online ,
doi: 10.11884/HPLPB202537.240371
Abstract:
Multiple switches need to be triggered in parallel in an LTD cavity where tens of bricks connect in parallel. In that case, switch-to-switch isolation is necessary. The lack of transient isolation will result in poor tolerance to switch jitter which manifests as increased probability of late-firing switches and further affect the output performance of LTD cavity. In order to optimize the type and parameter of the isolation element, the resistive and inductive isolation modes were compared in circuit simulation and experiments. As a results, the inductive isolation has better effect than resistive isolation both for synchronization of switches and the load voltage of LTD cavity. Among the inductors with different inductance, 5 μH inductor has the best behaviour.
Multiple switches need to be triggered in parallel in an LTD cavity where tens of bricks connect in parallel. In that case, switch-to-switch isolation is necessary. The lack of transient isolation will result in poor tolerance to switch jitter which manifests as increased probability of late-firing switches and further affect the output performance of LTD cavity. In order to optimize the type and parameter of the isolation element, the resistive and inductive isolation modes were compared in circuit simulation and experiments. As a results, the inductive isolation has better effect than resistive isolation both for synchronization of switches and the load voltage of LTD cavity. Among the inductors with different inductance, 5 μH inductor has the best behaviour.
, Available online ,
doi: 10.11884/HPLPB202537.240209
Abstract:
Compared with vacuum tank system, supersonic injection technology has significant advantages in pressure recovery of chemical laser weapons, among them, the supersonic center injector has greater injection potential due to its smaller total pressure loss. Simulation and experimental studies were conducted on the supersonic center injector. The results show that for the supersonic center injector with a contraction-type mixing chamber, although it is easier to reach the working state, it is not superior to the straight-type injector under the condition of fixed injection coefficient and maintaining a lower blind cavity pressure. Under the condition of variable injection coefficient (fixed secondary mass flow rate), for every 0.05 increase in the area contraction ratio of the mixing chamber, the primary mass flow rate needs to be increased by approximately 0.3 kg/s to reach the critical start-up state. The overall injection performance of the supersonic injector reaches its highest when it is at the critical start-up state. In terms of blind cavity extraction capability, the single-stage supersonic center injector is significantly superior to other types of injectors, with a minimum of 1.3 kPa achievable.
Compared with vacuum tank system, supersonic injection technology has significant advantages in pressure recovery of chemical laser weapons, among them, the supersonic center injector has greater injection potential due to its smaller total pressure loss. Simulation and experimental studies were conducted on the supersonic center injector. The results show that for the supersonic center injector with a contraction-type mixing chamber, although it is easier to reach the working state, it is not superior to the straight-type injector under the condition of fixed injection coefficient and maintaining a lower blind cavity pressure. Under the condition of variable injection coefficient (fixed secondary mass flow rate), for every 0.05 increase in the area contraction ratio of the mixing chamber, the primary mass flow rate needs to be increased by approximately 0.3 kg/s to reach the critical start-up state. The overall injection performance of the supersonic injector reaches its highest when it is at the critical start-up state. In terms of blind cavity extraction capability, the single-stage supersonic center injector is significantly superior to other types of injectors, with a minimum of 1.3 kPa achievable.
, Available online ,
doi: 10.11884/HPLPB202537.240338
Abstract:
The matching theory based on a equivalent circuit model is outlined that self-consistently determines the modulation of a klystron output cavity for an arbitrary coupling of the output waveguide to the cavity and arbitrary cavity parameters. The model including a mutual inductance and the induced current is established, the output power and the reflected power are discussed . When the complex coupling coefficient equals 1 or not, we find two expressions for the reflected power. We find an expression for the output power corresponding to the gap voltage for both the case when the coupling is perfectly matched to the output waveguide, and also for case of arbitrary coupling. We find expressions for the resonant frequency of the output cavity and externally-loaded Q leading to the matching conditions. If the matching conditions are satisfied, the output power corresponding to the new theory equals approximately to the output power corresponding to the traditional theory.
The matching theory based on a equivalent circuit model is outlined that self-consistently determines the modulation of a klystron output cavity for an arbitrary coupling of the output waveguide to the cavity and arbitrary cavity parameters. The model including a mutual inductance and the induced current is established, the output power and the reflected power are discussed . When the complex coupling coefficient equals 1 or not, we find two expressions for the reflected power. We find an expression for the output power corresponding to the gap voltage for both the case when the coupling is perfectly matched to the output waveguide, and also for case of arbitrary coupling. We find expressions for the resonant frequency of the output cavity and externally-loaded Q leading to the matching conditions. If the matching conditions are satisfied, the output power corresponding to the new theory equals approximately to the output power corresponding to the traditional theory.
, Available online ,
doi: 10.11884/HPLPB202537.240228
Abstract:
To assess the susceptibility of road vehicles in complex electromagnetic environments, this paper proposes a radiation immunity testing method of vehicles based on actual electromagnetic environments in reverberation chambers (RCs), which records the actual electromagnetic signals, constructs a complex signal playback system in an RC, and gives the cumulative distribution function (CDF) of the received power. Moreover, this paper provides a field strength calibration method and the radiation immunity testing in an RC. The radiation immunity testing of vehicle was conducted, and the results show that in the complex RC electromagnetic environment, some vehicles have electromagnetic safety risks. The study method provides important support for enterprises to evaluate the electromagnetic compatibility quality of vehicles.
To assess the susceptibility of road vehicles in complex electromagnetic environments, this paper proposes a radiation immunity testing method of vehicles based on actual electromagnetic environments in reverberation chambers (RCs), which records the actual electromagnetic signals, constructs a complex signal playback system in an RC, and gives the cumulative distribution function (CDF) of the received power. Moreover, this paper provides a field strength calibration method and the radiation immunity testing in an RC. The radiation immunity testing of vehicle was conducted, and the results show that in the complex RC electromagnetic environment, some vehicles have electromagnetic safety risks. The study method provides important support for enterprises to evaluate the electromagnetic compatibility quality of vehicles.
, Available online ,
doi: 10.11884/HPLPB202537.240273
Abstract:
Shenzhen’s medium-energy high-repetition-rate X-ray free electron laser (Shenzhen Superconducting Soft X-ray Free Electron Laser, S3FEL) requires 1 MHz high-repetition-rate and high-stability kicker. Transmission line structure kicker is an effective way to achieve high repetition rate. However, the insufficient waveform stability of the transmission line structure kicker limits the application of this type of kicker in large particle accelerators. To solve the above problem, this paper studies the input waveform and circuit structure parameters of the transmission line structure kicker. It analyzes the main factors affecting the stability of kicker’s working waveform using mathematical tools such as Fourier analysis, and reveals the relationship between the harmonic order of kicker ideal waveform and the cut-off frequency of kicker transmission line structure. On this basis, this paper proposes a method to reduce the deviation between the actual waveform and the ideal waveform of kicker. This method can obtain the ideal working waveform of kicker within a certain range by adjusting the input waveform parameters or the cut-off frequency of kicker. To verify the above relationship, this paper uses circuit simulation software to simulate different waveforms and different circuit parameters of kicker. The simulation results verify that the above relationship revealed and confirm the effectiveness of the method mentioned.
Shenzhen’s medium-energy high-repetition-rate X-ray free electron laser (Shenzhen Superconducting Soft X-ray Free Electron Laser, S3FEL) requires 1 MHz high-repetition-rate and high-stability kicker. Transmission line structure kicker is an effective way to achieve high repetition rate. However, the insufficient waveform stability of the transmission line structure kicker limits the application of this type of kicker in large particle accelerators. To solve the above problem, this paper studies the input waveform and circuit structure parameters of the transmission line structure kicker. It analyzes the main factors affecting the stability of kicker’s working waveform using mathematical tools such as Fourier analysis, and reveals the relationship between the harmonic order of kicker ideal waveform and the cut-off frequency of kicker transmission line structure. On this basis, this paper proposes a method to reduce the deviation between the actual waveform and the ideal waveform of kicker. This method can obtain the ideal working waveform of kicker within a certain range by adjusting the input waveform parameters or the cut-off frequency of kicker. To verify the above relationship, this paper uses circuit simulation software to simulate different waveforms and different circuit parameters of kicker. The simulation results verify that the above relationship revealed and confirm the effectiveness of the method mentioned.
, Available online ,
doi: 10.11884/HPLPB202537.240183
Abstract:
Neutral beam injection heating is an effective heating method in magnetic confinement fusion experiments. If the ion source ignites during experimental operation, the extraction of the ion beam is terminated, reducing the efficiency and power of the neutral beam ion source beam extraction. To prolong the extraction of the ion source beam in case of abnormal situations, research on high-voltage power fast recovery technology was carried out, in which the beam was re-extracted by running the high-voltage power supply again. A fast recovery control system was developed based on PXI Express technology, using the PXIe-8861 processor and PXIe-7820R programmable logic gate array hardware board for fast recovery technology. The control system adopts a heartbeat packet mechanism for board and communication status monitoring, with two parameter configuration methods for client and upper computer, realizing the functions of online/offline data viewing and analysis. Through the configuration of the upper computer mode, the control system supports voltage and quantity control, meeting multiple working modes such as modulation, fast recovery, and single operation. Test results on a megawatt-class strong ion source show that the control system interface is user-friendly, the logical structure is designed clearly, and it has various control modes. Furthermore, the system can restart the high-voltage power supply to improve the extraction power of the ion source beam during the experiment.
Neutral beam injection heating is an effective heating method in magnetic confinement fusion experiments. If the ion source ignites during experimental operation, the extraction of the ion beam is terminated, reducing the efficiency and power of the neutral beam ion source beam extraction. To prolong the extraction of the ion source beam in case of abnormal situations, research on high-voltage power fast recovery technology was carried out, in which the beam was re-extracted by running the high-voltage power supply again. A fast recovery control system was developed based on PXI Express technology, using the PXIe-8861 processor and PXIe-7820R programmable logic gate array hardware board for fast recovery technology. The control system adopts a heartbeat packet mechanism for board and communication status monitoring, with two parameter configuration methods for client and upper computer, realizing the functions of online/offline data viewing and analysis. Through the configuration of the upper computer mode, the control system supports voltage and quantity control, meeting multiple working modes such as modulation, fast recovery, and single operation. Test results on a megawatt-class strong ion source show that the control system interface is user-friendly, the logical structure is designed clearly, and it has various control modes. Furthermore, the system can restart the high-voltage power supply to improve the extraction power of the ion source beam during the experiment.
, Available online ,
doi: 10.11884/HPLPB202537.240340
Abstract:
The complexity of unmanned aerial vehicle (UAV) systems and the diversity of their fault modes present significant challenges to their reliability, stability, and safety. To address the issue of incomplete fault UAV data samples, a fault simulation dataset was constructed using a predefined fault injection method. This dataset is based on four models of faults: bias faults, drift faults, lock faults, and scale faults, allowing equivalent simulation of the drone in fault-free states, actuator failures, and sensor failures. Furthermore, the dataset was evaluated using deep learning networks. Simulation results demonstrate that the three deep learning architectures—WDCNN, ResNet, and QCNN—validate the completeness and effectiveness of the construction method and the fault simulation dataset in this paper. In terms of precision, WDCNN achieved over 82%, ResNet exceeded 90%, and QCNN surpassed 92%. The methods proposed in this study provides a complete dataset and evaluation method for data-driven research on UAV fault diagnosis.
The complexity of unmanned aerial vehicle (UAV) systems and the diversity of their fault modes present significant challenges to their reliability, stability, and safety. To address the issue of incomplete fault UAV data samples, a fault simulation dataset was constructed using a predefined fault injection method. This dataset is based on four models of faults: bias faults, drift faults, lock faults, and scale faults, allowing equivalent simulation of the drone in fault-free states, actuator failures, and sensor failures. Furthermore, the dataset was evaluated using deep learning networks. Simulation results demonstrate that the three deep learning architectures—WDCNN, ResNet, and QCNN—validate the completeness and effectiveness of the construction method and the fault simulation dataset in this paper. In terms of precision, WDCNN achieved over 82%, ResNet exceeded 90%, and QCNN surpassed 92%. The methods proposed in this study provides a complete dataset and evaluation method for data-driven research on UAV fault diagnosis.
, Available online ,
doi: 10.11884/HPLPB202537.240288
Abstract:
In this paper, four typical types of high purity graphite and their titanium carbide coating modified materials were tested as anodes in high current electron beam diodes. The results show that the currents of the diodes were obviously different when the graphite anodes were under electron beam bombardment with voltage 860 kV, current 11 kA and pulse width 40 ns. The current curve for graphite 4# was normal even after interaction of 167 electron pulses while the other graphite current curves showed different degrees of tail erosion. The ablative experiments of titanium carbide coating on graphite further verified the difference of the graphite, indicating that the thermal conductivity of graphite has an important effect on its ablative resistance. The higher the thermal conductivity of graphite, the lower the degree of recrystallization of titanium carbide, the better the corrosion resistance of graphite. Therefore, graphite 4# has an excellent resistance to electron beam bombardment and would be promising for application as collector materials in relativistic traveling wave tubes.
In this paper, four typical types of high purity graphite and their titanium carbide coating modified materials were tested as anodes in high current electron beam diodes. The results show that the currents of the diodes were obviously different when the graphite anodes were under electron beam bombardment with voltage 860 kV, current 11 kA and pulse width 40 ns. The current curve for graphite 4# was normal even after interaction of 167 electron pulses while the other graphite current curves showed different degrees of tail erosion. The ablative experiments of titanium carbide coating on graphite further verified the difference of the graphite, indicating that the thermal conductivity of graphite has an important effect on its ablative resistance. The higher the thermal conductivity of graphite, the lower the degree of recrystallization of titanium carbide, the better the corrosion resistance of graphite. Therefore, graphite 4# has an excellent resistance to electron beam bombardment and would be promising for application as collector materials in relativistic traveling wave tubes.
, Available online ,
doi: 10.11884/HPLPB202537.240315
Abstract:
Pulsed power drive source is a key part of high power microwave technology. The quality of the output waveform of pulsed power drive source directly affects the output of high power microwave devices. Aiming at the oscillation problem of the flat-top output waveform of pulse power drive source, we designed and developed a compact pulsed power drive source based on PFN-Marx, and optimized the waveform. The parameters of PFN-Marx generators with different structures are analyzed by PSpice simulation, so as to determine the number of sections and levels of the PFN-Marx generator; the oscillation problem of the output waveform is converted into the degree of deviation of each extreme point from the reference value in the flat-top area of the waveform. The objective function is constructed with the root mean square error with the minimum flat-top ripple error as the goal, and the circuit model is established in Simulink. Combined with the MATLAB genetic algorithm, the inductance of the PFN is continuously iteratively optimized. Finally, a set of optimal values is determined, and the inductance structure is redesigned to adjust the inductance value conveniently and to achieve quick waveform optimization. The optimized single-stage PFN outputs a waveform with a leading edge of 24.4 ns and a pulse width of 93.6 ns on a 10 Ω load, and it has good flat-top performance. The assembled 7-stage PFN-Marx generator has an output quasi-square wave under a charging voltage of 53.8 kV and a load impedance of 75 Ω. The pulse peak amplitude is 189.2 kV, pulse width is 93.2 ns, rise time is 8.4 ns, decrease time is 33.6 ns, and the ripple coefficient is 3.5%.
Pulsed power drive source is a key part of high power microwave technology. The quality of the output waveform of pulsed power drive source directly affects the output of high power microwave devices. Aiming at the oscillation problem of the flat-top output waveform of pulse power drive source, we designed and developed a compact pulsed power drive source based on PFN-Marx, and optimized the waveform. The parameters of PFN-Marx generators with different structures are analyzed by PSpice simulation, so as to determine the number of sections and levels of the PFN-Marx generator; the oscillation problem of the output waveform is converted into the degree of deviation of each extreme point from the reference value in the flat-top area of the waveform. The objective function is constructed with the root mean square error with the minimum flat-top ripple error as the goal, and the circuit model is established in Simulink. Combined with the MATLAB genetic algorithm, the inductance of the PFN is continuously iteratively optimized. Finally, a set of optimal values is determined, and the inductance structure is redesigned to adjust the inductance value conveniently and to achieve quick waveform optimization. The optimized single-stage PFN outputs a waveform with a leading edge of 24.4 ns and a pulse width of 93.6 ns on a 10 Ω load, and it has good flat-top performance. The assembled 7-stage PFN-Marx generator has an output quasi-square wave under a charging voltage of 53.8 kV and a load impedance of 75 Ω. The pulse peak amplitude is 189.2 kV, pulse width is 93.2 ns, rise time is 8.4 ns, decrease time is 33.6 ns, and the ripple coefficient is 3.5%.
, Available online ,
doi: 10.11884/HPLPB202537.240254
Abstract:
To reduce the threshold of using pulse power source, a compact pulse power source based on Marx generator is designed and implemented. The Marx generator is a 7-stage unipolar charging coaxial structure with low inductance ceramic capacitor and ultraviolet preionization output narrow pulse. It uses adjustable primary high voltage power supply and 2-way synchronous trigger switch, and metal shell as grounding shield and discharge circuit; it is filled with high pressure N2. Using the power source based on the above design, when the charging voltage is 26 kV and the charging voltage is 0.3 MPa, the high voltage pulse of 33 ns rise time, 59 ns pulse width and 109.2 kV amplitude is obtained on the 60 Ω load. The power source is housed in an aluminum alloy cylinder with a diameter of 0.2 m and a length of 1.1m. This paper provides a design idea and a reference prototype for compact and modular pulse power source, which can be used as flash X-ray radiography drive source.
To reduce the threshold of using pulse power source, a compact pulse power source based on Marx generator is designed and implemented. The Marx generator is a 7-stage unipolar charging coaxial structure with low inductance ceramic capacitor and ultraviolet preionization output narrow pulse. It uses adjustable primary high voltage power supply and 2-way synchronous trigger switch, and metal shell as grounding shield and discharge circuit; it is filled with high pressure N2. Using the power source based on the above design, when the charging voltage is 26 kV and the charging voltage is 0.3 MPa, the high voltage pulse of 33 ns rise time, 59 ns pulse width and 109.2 kV amplitude is obtained on the 60 Ω load. The power source is housed in an aluminum alloy cylinder with a diameter of 0.2 m and a length of 1.1m. This paper provides a design idea and a reference prototype for compact and modular pulse power source, which can be used as flash X-ray radiography drive source.
, Available online ,
doi: 10.11884/HPLPB202436.240163
Abstract:
The quantitative study of combat effectiveness index is crucial for the informatization construction of the armed forces. To solve the problems of limits of quantitative research, low method accuracy, and weak robustness in the study of combat effectiveness index, and to break through the limitations of dominating complex rules, multivariate mathematical models, and strong coupling of influencing factors in the combat effectiveness index function, inspired by the mathematical analysis methods of rules in fuzzy logic theory, we proposed a local approximation based method for fitting combat effectiveness index function. Combining the powerful self-learning and self-deduction capabilities of neural networks, we constructed a corresponding quantitative calculation model based on radial basis function (RBF). Simulation comparative experiments show that the proposed method has an error rate of about 2% and 6% lower than the current best performing method using global approximation, and exhibits stronger robustness. Our method has strong practicality, can be migrated to other military fields, and has good engineering application prospects.
The quantitative study of combat effectiveness index is crucial for the informatization construction of the armed forces. To solve the problems of limits of quantitative research, low method accuracy, and weak robustness in the study of combat effectiveness index, and to break through the limitations of dominating complex rules, multivariate mathematical models, and strong coupling of influencing factors in the combat effectiveness index function, inspired by the mathematical analysis methods of rules in fuzzy logic theory, we proposed a local approximation based method for fitting combat effectiveness index function. Combining the powerful self-learning and self-deduction capabilities of neural networks, we constructed a corresponding quantitative calculation model based on radial basis function (RBF). Simulation comparative experiments show that the proposed method has an error rate of about 2% and 6% lower than the current best performing method using global approximation, and exhibits stronger robustness. Our method has strong practicality, can be migrated to other military fields, and has good engineering application prospects.
Column
- Cover and Contents
- High Power Laser Physics and Technology
- Inertial Confinement Fusion Physics and Technology
- High Power Microwave Technology
- Particle Beams and Accelerator Technology
- Pulsed Power Technology
- Nuclear Science and Engineering
- Advanced Interdisciplinary Science
- Special Column of 4th Symposium on Frontier of HPLPB
Display Method:
2025, 37: 011001.
doi: 10.11884/HPLPB202537.240437
Abstract:
Thanks to the advantages of compact, high beam quality and high conversion efficiency, narrow linewidth high pulse energy single mode nanosecond-pulsed fiber amplifier is highly desired in laser detection and industry applications. Recently, an all-fiber amplifier with a home-made Yb-doped tapered fiber produces linearly polarized (12.3 dB PER) 100 ns, 1 mJ pulses with 0.49 nm linewidth, M2=1.49, 100 W of average output power and 10 kW peak power at 1 064 nm. It is believed that the pulse energy, output power and beam quality can be further improved by optimizing the Yb-doped fiber and design of amplifier.
Thanks to the advantages of compact, high beam quality and high conversion efficiency, narrow linewidth high pulse energy single mode nanosecond-pulsed fiber amplifier is highly desired in laser detection and industry applications. Recently, an all-fiber amplifier with a home-made Yb-doped tapered fiber produces linearly polarized (12.3 dB PER) 100 ns, 1 mJ pulses with 0.49 nm linewidth, M2=1.49, 100 W of average output power and 10 kW peak power at 1 064 nm. It is believed that the pulse energy, output power and beam quality can be further improved by optimizing the Yb-doped fiber and design of amplifier.
2025, 37: 011002.
doi: 10.11884/HPLPB202537.240354
Abstract:
To research the recoverey pressure of DF laser, experiments were carried out with different mass flowrate on a test bench. Thermal blockage was discovered when the mass flowrate reached 2.475 g·s−1·cm−2. The simulation model of laser cavity and diffuser was established, and the flow fluid was obtained. The simulation showed that the cavity’s pressure rose up quickly when the mass flowrate was 2.475 g·s−1·cm−2, which is coincident with the experiment. The design was optimized based on the result of the simulation and the corresponding experiment was proceeded. The result shows that the thermal blockage was solved with the optimized laser cavity. The laser’s recovery pressure reached 22 kPa with mass flowrate 2.475 g·s−1·cm−2.
To research the recoverey pressure of DF laser, experiments were carried out with different mass flowrate on a test bench. Thermal blockage was discovered when the mass flowrate reached 2.475 g·s−1·cm−2. The simulation model of laser cavity and diffuser was established, and the flow fluid was obtained. The simulation showed that the cavity’s pressure rose up quickly when the mass flowrate was 2.475 g·s−1·cm−2, which is coincident with the experiment. The design was optimized based on the result of the simulation and the corresponding experiment was proceeded. The result shows that the thermal blockage was solved with the optimized laser cavity. The laser’s recovery pressure reached 22 kPa with mass flowrate 2.475 g·s−1·cm−2.
2025, 37: 011003.
doi: 10.11884/HPLPB202537.240232
Abstract:
Stimulated Raman scattering is an effective non-linear frequency conversion method, and has received much attention. However, Raman lasers also have drawbacks, such as wavelength of Raman lasers could not be tuned continuously, and the coverage of Raman laser wavelength is limited. Therefore, more Raman active media are required to improve the coverage of Raman lasers. In this work,1064 nm laser was used as pump source, and pressurized ethane was used as Raman active medium, and 1550 nm Raman laser was produced. Neither obvious backward Raman laser nor higher orders of Stokes Raman lasers were observed in this experiment. By the optimization of experimental parameters, laser induced breakdown was reduced; the first order Stokes(S1) Raman laser photon conversion efficiency was improved to 20.7%, and the maximum S1 energy was 21.2 mJ. Ethane was found to have significant absorption at wavelength of 1550 nm, this was the major reason for the limited photon conversion efficiency and pulse energy of S1 laser. The absorption coefficient of ethane at 1550 nm was measured to be 5.71\begin{document}$ \times {{10}}^{-{8}} $\end{document} ![]()
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Stimulated Raman scattering is an effective non-linear frequency conversion method, and has received much attention. However, Raman lasers also have drawbacks, such as wavelength of Raman lasers could not be tuned continuously, and the coverage of Raman laser wavelength is limited. Therefore, more Raman active media are required to improve the coverage of Raman lasers. In this work,
2025, 37: 012001.
doi: 10.11884/HPLPB202537.240224
Abstract:
To realize high voltage threshold, high linear slope, simple circuit and easy debugging of ramp signal from the scan control module of streak camera, utilizing the advantages of high voltage generated by switching discharge and good linearity of constant current charging slope, we designed a simple circuit to generate high voltage ramp signal. The circuit can adjust and optimize the slope and linear rate of the linear slope signal by adjusting the resistance. The experimental results show that the linear high voltage ramp signal generated by the circuit can provide a voltage of up to 1 700 V, the nonlinear precision of the ramp is less than 3%, and the scanning time is adjustable from 200 ns to 50 μs. Compared with the traditional high voltage ramp signal circuit, the circuit is simple in structure and convenient to debug, and the ramp time can be adjusted steplessly from nanoseconds to microseconds. This can effectively improve the scanning time accuracy of the fringe camera and effectively reduce problems such as circuit crosstalk.
To realize high voltage threshold, high linear slope, simple circuit and easy debugging of ramp signal from the scan control module of streak camera, utilizing the advantages of high voltage generated by switching discharge and good linearity of constant current charging slope, we designed a simple circuit to generate high voltage ramp signal. The circuit can adjust and optimize the slope and linear rate of the linear slope signal by adjusting the resistance. The experimental results show that the linear high voltage ramp signal generated by the circuit can provide a voltage of up to 1 700 V, the nonlinear precision of the ramp is less than 3%, and the scanning time is adjustable from 200 ns to 50 μs. Compared with the traditional high voltage ramp signal circuit, the circuit is simple in structure and convenient to debug, and the ramp time can be adjusted steplessly from nanoseconds to microseconds. This can effectively improve the scanning time accuracy of the fringe camera and effectively reduce problems such as circuit crosstalk.
2025, 37: 012002.
doi: 10.11884/HPLPB202537.240266
Abstract:
During the operation of vacuum system in high-flux laser device, molecular contamination generated by the pump lubricating oil in the vacuum environment may diffuse and deposit on the surface of optical system components, induce damage under high-flux laser irradiation, and reduce the devices’ load capacity. Research has been conducted on the cleanliness control of vacuum systems, and a series of technical measures have been developed to control the vacuum system cleanliness, including optimizing the vacuum pump group, increasing low-temperature cold trap adsorption, and adding online heating regeneration technology for the cold trap. The experimental research results show that after 120 h of continuous operation, the average surface deposition of non-volatile residues in the vacuum system reaches a clean level of 2.86 × 10−9 g/cm2 after 24 h; The transmittance at 350 nm and the damage density curve below 12.3 J/cm2 flux of the fused quartz optical test piece assessment group and control group are basically consistent, proving the effectiveness of this method.
During the operation of vacuum system in high-flux laser device, molecular contamination generated by the pump lubricating oil in the vacuum environment may diffuse and deposit on the surface of optical system components, induce damage under high-flux laser irradiation, and reduce the devices’ load capacity. Research has been conducted on the cleanliness control of vacuum systems, and a series of technical measures have been developed to control the vacuum system cleanliness, including optimizing the vacuum pump group, increasing low-temperature cold trap adsorption, and adding online heating regeneration technology for the cold trap. The experimental research results show that after 120 h of continuous operation, the average surface deposition of non-volatile residues in the vacuum system reaches a clean level of 2.86 × 10−9 g/cm2 after 24 h; The transmittance at 350 nm and the damage density curve below 12.3 J/cm2 flux of the fused quartz optical test piece assessment group and control group are basically consistent, proving the effectiveness of this method.
2025, 37: 013001.
doi: 10.11884/HPLPB202537.240243
Abstract:
Accurate and fast solution of the electromagnetic characteristics problems is of great significance for the study of dynamic characteristics and reliability design of electromagnetic railguns. Based on the COMSOL moving mesh function, a new form of meshing—slip mesh combined with moving mesh—is proposed. The armature area and the track part where the pivot rail is in contact are meshed in to slip mesh, and the rest of the track part is dynamically meshed. This division method can not only solve the problems of low computational accuracy (coarse mesh) and high computational complexity (fine mesh) of “static mesh”, but also accurately solve the dynamic electromagnetic characteristics problems of transient and fast-moving models. The pulsed excitation current was used to simulate and analyze the established electromagnetic railgun model. The computing time and number of computational units of the three static meshes are compared with the meshing method proposed in this paper. The simulation results of different meshing methods on the armature motion velocity and the current density distribution at the armature center position are compared, and it is proved that the proposed meshing method is effective and efficient.
Accurate and fast solution of the electromagnetic characteristics problems is of great significance for the study of dynamic characteristics and reliability design of electromagnetic railguns. Based on the COMSOL moving mesh function, a new form of meshing—slip mesh combined with moving mesh—is proposed. The armature area and the track part where the pivot rail is in contact are meshed in to slip mesh, and the rest of the track part is dynamically meshed. This division method can not only solve the problems of low computational accuracy (coarse mesh) and high computational complexity (fine mesh) of “static mesh”, but also accurately solve the dynamic electromagnetic characteristics problems of transient and fast-moving models. The pulsed excitation current was used to simulate and analyze the established electromagnetic railgun model. The computing time and number of computational units of the three static meshes are compared with the meshing method proposed in this paper. The simulation results of different meshing methods on the armature motion velocity and the current density distribution at the armature center position are compared, and it is proved that the proposed meshing method is effective and efficient.
2025, 37: 013002.
doi: 10.11884/HPLPB202537.240342
Abstract:
A new method of waveform reconstruction based on neural network is proposed to solve the problem of nano-second pulse distortion, which is caused by the existence of parasitic parameters and insufficient bandwidth in high-speed digital acquisition channels. The local mapping relationship between the distortion waveform acquired by the high-speed digital acquisition system and the reference waveform obtained from the oscilloscope is identified through single neural networks. Then, the global waveform is reconstructed by a series of neural networks. The experimental results show that the proposed method can obviously alleviate the problems such as the edge delay, overshoot of the distortion waveform, thus it can improve the power estimation accuracy by 32.5%, as well as improve the frequency response characteristics of the high-speed digital acquisition system.
A new method of waveform reconstruction based on neural network is proposed to solve the problem of nano-second pulse distortion, which is caused by the existence of parasitic parameters and insufficient bandwidth in high-speed digital acquisition channels. The local mapping relationship between the distortion waveform acquired by the high-speed digital acquisition system and the reference waveform obtained from the oscilloscope is identified through single neural networks. Then, the global waveform is reconstructed by a series of neural networks. The experimental results show that the proposed method can obviously alleviate the problems such as the edge delay, overshoot of the distortion waveform, thus it can improve the power estimation accuracy by 32.5%, as well as improve the frequency response characteristics of the high-speed digital acquisition system.
2025, 37: 013003.
doi: 10.11884/HPLPB202537.240296
Abstract:
Studying the transmission characteristics of high-frequency microwaves in plasma can effectively analyze and assess the information transfer process in microwave communication and radar technology. Numerical simulations were employed to analyze the effects of plasma electron density, thickness, and incident wave frequency on microwave reflection, absorption, and transmission. The results indicate that increased plasma thickness and electron density lead to enhanced absorption and reduced transmission; reflection increases slightly with decreased thickness and increased electron density. High-frequency microwaves are more easily transmitted through plasma, with transmission enhancing as frequency increases. Furthermore, the research shows that electron density not only affects energy transmission but also alters the electromagnetic wave shape, causing its broadening. High-density plasma significantly broadens microwave waveforms both spatially and temporally, with inelastic collisions contributing prominently to this broadening. The patterns of waveform changes can provide theoretical support for the restoration of information carried by radar echoes and microwave communications.
Studying the transmission characteristics of high-frequency microwaves in plasma can effectively analyze and assess the information transfer process in microwave communication and radar technology. Numerical simulations were employed to analyze the effects of plasma electron density, thickness, and incident wave frequency on microwave reflection, absorption, and transmission. The results indicate that increased plasma thickness and electron density lead to enhanced absorption and reduced transmission; reflection increases slightly with decreased thickness and increased electron density. High-frequency microwaves are more easily transmitted through plasma, with transmission enhancing as frequency increases. Furthermore, the research shows that electron density not only affects energy transmission but also alters the electromagnetic wave shape, causing its broadening. High-density plasma significantly broadens microwave waveforms both spatially and temporally, with inelastic collisions contributing prominently to this broadening. The patterns of waveform changes can provide theoretical support for the restoration of information carried by radar echoes and microwave communications.
2025, 37: 013004.
doi: 10.11884/HPLPB202537.240353
Abstract:
The design of permanent magnet packaging for a compact S-band 8-cavity all-cavity axial extraction relativistic magnetron (R8 ACAE-RM) with an output mode of TE11 is preliminarily explored. The inner magnetic block is placed at both ends of the anode block in the anode cylinder, and the outer magnetic block is placed outside the RM, which generates a magnetic field of about 0.34 T and a length of 72 mm on the axial uniform zone in the interaction zone, and the weight of the permanent magnet is only 21 kg. Compared with the traditional external magnet system, this design can reduce the weight of the magnet, the magnetic field strength in the interaction zone is more uniform, and the system structure is more compact, which can meet the lightweight and miniaturization requirements of high-power microwave source systems. The device applies π mode as its operating mode, four 90° sector TE11 modes are extracted through all-cavity axial extraction structure, and a coaxial-plate-inserted mode converter is designed for mode conversion, thus to obtain TE11 mode in circular waveguide. In particle-in-cell (PIC) simulation, the proposed R8 ACAE-RM can generate a microwave power of 1.06 GW with a pure TE11 mode at the frequency of 2.44 GHz under the conditions of a guiding magnetic generated by the inner and outer magnetic blocks, a diode voltage of 320 kV, and power conversion efficiency of 47%.
The design of permanent magnet packaging for a compact S-band 8-cavity all-cavity axial extraction relativistic magnetron (R8 ACAE-RM) with an output mode of TE11 is preliminarily explored. The inner magnetic block is placed at both ends of the anode block in the anode cylinder, and the outer magnetic block is placed outside the RM, which generates a magnetic field of about 0.34 T and a length of 72 mm on the axial uniform zone in the interaction zone, and the weight of the permanent magnet is only 21 kg. Compared with the traditional external magnet system, this design can reduce the weight of the magnet, the magnetic field strength in the interaction zone is more uniform, and the system structure is more compact, which can meet the lightweight and miniaturization requirements of high-power microwave source systems. The device applies π mode as its operating mode, four 90° sector TE11 modes are extracted through all-cavity axial extraction structure, and a coaxial-plate-inserted mode converter is designed for mode conversion, thus to obtain TE11 mode in circular waveguide. In particle-in-cell (PIC) simulation, the proposed R8 ACAE-RM can generate a microwave power of 1.06 GW with a pure TE11 mode at the frequency of 2.44 GHz under the conditions of a guiding magnetic generated by the inner and outer magnetic blocks, a diode voltage of 320 kV, and power conversion efficiency of 47%.
2025, 37: 013005.
doi: 10.11884/HPLPB202537.250006
Abstract:
In complex electromagnetic countermeasure environments, it is necessary to take electromagnetic protection measures for the radio frequency front-end of electronic information equipment to resist strong electromagnetic interference and even damage. In response to the problem that existing protective devices reflect strong interference signals exceeding the threshold during operation, which can easily cause secondary electromagnetic threats, we propose a design for a broadband absorptive electromagnetic pulse protection device. By introducing a microstrip line matching stub in the main protection path, the electromagnetic pulse signal is isolated from the output port and transmitted to the matching load for broadband absorption. Within the frequency range of 0.5 GHz to 1.5 GHz (relative bandwidth > 90%), the device achieves good performance with insertion loss less than 1 dB for low-power signals, electromagnetic pulse signal protection isolation greater than 10 dB, and input port return loss greater than 10 dB.
In complex electromagnetic countermeasure environments, it is necessary to take electromagnetic protection measures for the radio frequency front-end of electronic information equipment to resist strong electromagnetic interference and even damage. In response to the problem that existing protective devices reflect strong interference signals exceeding the threshold during operation, which can easily cause secondary electromagnetic threats, we propose a design for a broadband absorptive electromagnetic pulse protection device. By introducing a microstrip line matching stub in the main protection path, the electromagnetic pulse signal is isolated from the output port and transmitted to the matching load for broadband absorption. Within the frequency range of 0.5 GHz to 1.5 GHz (relative bandwidth > 90%), the device achieves good performance with insertion loss less than 1 dB for low-power signals, electromagnetic pulse signal protection isolation greater than 10 dB, and input port return loss greater than 10 dB.
2025, 37: 014001.
doi: 10.11884/HPLPB202537.240210
Abstract:
To improve the design efficiency and construction quality of accelerator facility, and to solve the problems in the design and construction process of existing accelerator facilities, such as the multidisciplinary data island, the poor real-time interaction of data and the weak consistency of data in each system, and long design cycle and high cost, focusing on the construction requirements of accelerator devices, the collaborative design of α irradiation device for CS30 accelerator based on 3DE platform is proposed. On this basis a relatively complete set of accelerator facility collaborative design processes are sorted out, the multidimensional collaborative design of structure, piping, electrical and civil construction is realized, the whole design process is standardized, the design errors are reduced, the design efficiency and quality are improved, and the design cost is saved. Accordingly, the application of 3DE platform in accelerator facility design is promoted, and the construction time of the accelerator facility is effectively shortened.
To improve the design efficiency and construction quality of accelerator facility, and to solve the problems in the design and construction process of existing accelerator facilities, such as the multidisciplinary data island, the poor real-time interaction of data and the weak consistency of data in each system, and long design cycle and high cost, focusing on the construction requirements of accelerator devices, the collaborative design of α irradiation device for CS30 accelerator based on 3DE platform is proposed. On this basis a relatively complete set of accelerator facility collaborative design processes are sorted out, the multidimensional collaborative design of structure, piping, electrical and civil construction is realized, the whole design process is standardized, the design errors are reduced, the design efficiency and quality are improved, and the design cost is saved. Accordingly, the application of 3DE platform in accelerator facility design is promoted, and the construction time of the accelerator facility is effectively shortened.
2025, 37: 014002.
doi: 10.11884/HPLPB202537.240153
Abstract:
The RF linac dedicated to boron neutron capture therapy (BNCT02) in our institute is mainly composed of an ion source, a low energy beam transport line, a radio frequency quadrupole accelerator and three high energy beam transport lines. To ensure the safe operation of the BNCT02 accelerator, a machine protection system (MPS) was designed based on Yokogawa PLC and Experimental Physics and Industrial Control System (EPICS) software toolkit. The MPS adopts a redundant design, consisting of two completely independent subsystems with consistent main input and output signals. The test results show that the response time of the MPS is less than 1.6 ms, and it has the characteristics of high stability and reliability, which meets the operational requirements of the BNCT02 accelerator.
The RF linac dedicated to boron neutron capture therapy (BNCT02) in our institute is mainly composed of an ion source, a low energy beam transport line, a radio frequency quadrupole accelerator and three high energy beam transport lines. To ensure the safe operation of the BNCT02 accelerator, a machine protection system (MPS) was designed based on Yokogawa PLC and Experimental Physics and Industrial Control System (EPICS) software toolkit. The MPS adopts a redundant design, consisting of two completely independent subsystems with consistent main input and output signals. The test results show that the response time of the MPS is less than 1.6 ms, and it has the characteristics of high stability and reliability, which meets the operational requirements of the BNCT02 accelerator.
2025, 37: 014003.
doi: 10.11884/HPLPB202537.240202
Abstract:
A novel service-based EPICS and new front-end data acquisition method based on a high-availability Kubernetes cluster built on the Proxmox VE platform is proposed in this paper to enhance the performance and stability of the data acquisition system. By deploying EPICS services on the Kubernetes cluster, a new efficient front-end data processing and acquisition method is realized. The data acquisition method utilizes distributed data sharing based on the Channel Access protocol to perform real-time processing and analysis of data. This approach offers advantages such as reducing hardware and maintenance costs, improving portability and flexibility, and enhancing data acquisition and processing efficiency. The practical application and testing have demonstrated that this method has the potential for use in large scientific facilities. In the future, its application value in other fields will be explored.
A novel service-based EPICS and new front-end data acquisition method based on a high-availability Kubernetes cluster built on the Proxmox VE platform is proposed in this paper to enhance the performance and stability of the data acquisition system. By deploying EPICS services on the Kubernetes cluster, a new efficient front-end data processing and acquisition method is realized. The data acquisition method utilizes distributed data sharing based on the Channel Access protocol to perform real-time processing and analysis of data. This approach offers advantages such as reducing hardware and maintenance costs, improving portability and flexibility, and enhancing data acquisition and processing efficiency. The practical application and testing have demonstrated that this method has the potential for use in large scientific facilities. In the future, its application value in other fields will be explored.
2025, 37: 01500.
doi: 10.11884/HPLPB202537.240158
Abstract:
To enhance the shock wave generated by underwater electrical wire explosion(UEWE), wires are connected in parallel to form wire-array, but wire-array’s low resistance results in low deposition power. To solve the problem, by using copper sheets, parallel-series wire-arrays with different resistance and same mass were designed, and it was proposed that resistance matching between wire-array and power source is the ideal discharge mode. By parallel-series wire-array, single wire discharge similarity was verified, and miniaturization verification of large devices with high voltage was achieved. With the help of discharge similarity and parallel-series wire-array, the optimal wire-array design of UEWE was proposed at a given energy and wire mass.
To enhance the shock wave generated by underwater electrical wire explosion(UEWE), wires are connected in parallel to form wire-array, but wire-array’s low resistance results in low deposition power. To solve the problem, by using copper sheets, parallel-series wire-arrays with different resistance and same mass were designed, and it was proposed that resistance matching between wire-array and power source is the ideal discharge mode. By parallel-series wire-array, single wire discharge similarity was verified, and miniaturization verification of large devices with high voltage was achieved. With the help of discharge similarity and parallel-series wire-array, the optimal wire-array design of UEWE was proposed at a given energy and wire mass.
2025, 37: 015002.
doi: 10.11884/HPLPB202537.240367
Abstract:
This paper proposes a layout structure of the pulsed power generator based on the bipolar linear transformer driver, achieving flexible stacking of the bipolar linear transformer driver modules. The conduction time of the metal-oxide-semiconductor field effect transistor is regulated by adjusting the voltage of the driver circuit, enabling precise control over the rise time of the pulsed voltage. An integrated core-copper pillar structure and a reverse overshoot discharge circuit are introduced in the linear transformer driver structure, which optimizes the electromagnetic compatibility and reduces the reverse overshoot at the tail of the pulsed waveform. The developed bipolar linear transformer driver device can stably output ±5 kV pulsed voltage with 1 kHz frequency and 1 μs pulse width. The rise time of the pulsed voltage is continuously adjustable from 30 ns to 100 ns. The irreversible electroporation experiments on cells are carried out using the bipolar linear transformer driver.
This paper proposes a layout structure of the pulsed power generator based on the bipolar linear transformer driver, achieving flexible stacking of the bipolar linear transformer driver modules. The conduction time of the metal-oxide-semiconductor field effect transistor is regulated by adjusting the voltage of the driver circuit, enabling precise control over the rise time of the pulsed voltage. An integrated core-copper pillar structure and a reverse overshoot discharge circuit are introduced in the linear transformer driver structure, which optimizes the electromagnetic compatibility and reduces the reverse overshoot at the tail of the pulsed waveform. The developed bipolar linear transformer driver device can stably output ±5 kV pulsed voltage with 1 kHz frequency and 1 μs pulse width. The rise time of the pulsed voltage is continuously adjustable from 30 ns to 100 ns. The irreversible electroporation experiments on cells are carried out using the bipolar linear transformer driver.
2025, 37: 016001.
doi: 10.11884/HPLPB202537.240211
Abstract:
The Monte Carlo (MC) method is one of the most widely applied methods in the simulation study of radiation damage and radiation shielding. When conducting radiation damage studies on large targets such as airports, railways, and ships, the focus is generally on 3D modeling and radiation calculations of these targets; however, the post-calculation data analysis often relies on manual methods, making this aspect of the research technically challenging and inefficient, thus becoming a bottleneck in related research efforts. In this paper, a visualization post-processing method for MC calculations of target particle irradiation is studied, and a post-processing model based on k-dimensional tree (KDtree) + inverse distance weighting (IDW) and genetic algorithm based backpropagation (GABP) neural network is established to realize the visualization analysis of data combined with the model. Compared with traditional data analysis methods, the method proposed in this paper can greatly reduce the difficulty of researchers’ work, improve the speed of data processing, realize the visual display of radiation effects, and enhance the efficiency of post-processing in radiation effects research.
The Monte Carlo (MC) method is one of the most widely applied methods in the simulation study of radiation damage and radiation shielding. When conducting radiation damage studies on large targets such as airports, railways, and ships, the focus is generally on 3D modeling and radiation calculations of these targets; however, the post-calculation data analysis often relies on manual methods, making this aspect of the research technically challenging and inefficient, thus becoming a bottleneck in related research efforts. In this paper, a visualization post-processing method for MC calculations of target particle irradiation is studied, and a post-processing model based on k-dimensional tree (KDtree) + inverse distance weighting (IDW) and genetic algorithm based backpropagation (GABP) neural network is established to realize the visualization analysis of data combined with the model. Compared with traditional data analysis methods, the method proposed in this paper can greatly reduce the difficulty of researchers’ work, improve the speed of data processing, realize the visual display of radiation effects, and enhance the efficiency of post-processing in radiation effects research.
2025, 37: 016002.
doi: 10.11884/HPLPB202537.240192
Abstract:
To study the characteristics and evolution of the gas-liquid two-phase flow pattern in the rod bundle channel of pressurized water reactor, based on the double-layer wire mesh sensor, the air-water two-phase flow pattern experiment of the 3×3 rod bundle channels was carried out at room temperature and pressure. The flow patterns include bubble flow, cap flow and slug flow. The experimental results show that, the critical bubble diameter range for the reversal of lateral lift direction under normal temperature and pressure is 4 to 5.8 mm. In addition, for bubbly flow, the time-averaged void fraction exhibits a “wall peak” distribution at lower superficial gas velocities and a “central peak” distribution at higher superficial gas velocities. For the cap flow, the cross distribution of cap shaped bubbles within adjacent subchannels triggers large-scale mixing of the liquid phase between adjacent subchannels, and the time-averaged void fraction exhibits a “central peak” distribution. For slug flow, large-sized bubbles develop along the axis and cross subchannel gaps to aggregate into slug shaped bubbles, with a more pronounced distribution of the central peak of void fraction. The experimental data are used to evaluate three drift-flux models. The Bestion’s drift-flux model overestimates the drift velocity, resulting in underestimated void fraction predictions. The Ozaki’s drift-flux model provides more accurate predictions of void fraction than the Xu Han model, with an average relative error of 9.8%.
To study the characteristics and evolution of the gas-liquid two-phase flow pattern in the rod bundle channel of pressurized water reactor, based on the double-layer wire mesh sensor, the air-water two-phase flow pattern experiment of the 3×3 rod bundle channels was carried out at room temperature and pressure. The flow patterns include bubble flow, cap flow and slug flow. The experimental results show that, the critical bubble diameter range for the reversal of lateral lift direction under normal temperature and pressure is 4 to 5.8 mm. In addition, for bubbly flow, the time-averaged void fraction exhibits a “wall peak” distribution at lower superficial gas velocities and a “central peak” distribution at higher superficial gas velocities. For the cap flow, the cross distribution of cap shaped bubbles within adjacent subchannels triggers large-scale mixing of the liquid phase between adjacent subchannels, and the time-averaged void fraction exhibits a “central peak” distribution. For slug flow, large-sized bubbles develop along the axis and cross subchannel gaps to aggregate into slug shaped bubbles, with a more pronounced distribution of the central peak of void fraction. The experimental data are used to evaluate three drift-flux models. The Bestion’s drift-flux model overestimates the drift velocity, resulting in underestimated void fraction predictions. The Ozaki’s drift-flux model provides more accurate predictions of void fraction than the Xu Han model, with an average relative error of 9.8%.
2025, 37: 016003.
doi: 10.11884/HPLPB202537.240265
Abstract:
On the pulsed fusion sources such as laser ICF device, Z pinch facility and dense plasma focus device, the neutron activation method are widely applied, which can measure the neutron flux and diagnose the neutron yield from the source. Based on the inorganic scintillation detector, the 909 keV monoenergetic gammas, which are emitted from decay of the activated yttrium nuclei after the inelastic scattering on neutrons, can be measured, and the flux of the DD fusion neutrons can be diagnosed. In this work, an activation detection system using yttrium is developed, in which the LaBr3:Ce scintillator detector is chosen as the gamma sensitive material. The accumulation process of yttrium activation products under continuous irradiation has been physically analyzed, with respect to their half-life of only 15.663 s. An experimental method of calibrating the incident neutron detection efficiency by accelerator-based DD neutron source is thus established. In the experiments, the gamma detector is served as both neutron flux rate monitor and activation gamma measurements. The variation of radiation activity of the yttrium target with the neutron flux rate are simulated. Therefore, the in-situ calibration of the detection efficiency of this yttrium activation system for incident neutrons is achieved, with an accuracy of about 3.8%.
On the pulsed fusion sources such as laser ICF device, Z pinch facility and dense plasma focus device, the neutron activation method are widely applied, which can measure the neutron flux and diagnose the neutron yield from the source. Based on the inorganic scintillation detector, the 909 keV monoenergetic gammas, which are emitted from decay of the activated yttrium nuclei after the inelastic scattering on neutrons, can be measured, and the flux of the DD fusion neutrons can be diagnosed. In this work, an activation detection system using yttrium is developed, in which the LaBr3:Ce scintillator detector is chosen as the gamma sensitive material. The accumulation process of yttrium activation products under continuous irradiation has been physically analyzed, with respect to their half-life of only 15.663 s. An experimental method of calibrating the incident neutron detection efficiency by accelerator-based DD neutron source is thus established. In the experiments, the gamma detector is served as both neutron flux rate monitor and activation gamma measurements. The variation of radiation activity of the yttrium target with the neutron flux rate are simulated. Therefore, the in-situ calibration of the detection efficiency of this yttrium activation system for incident neutrons is achieved, with an accuracy of about 3.8%.
2025, 37: 019001.
doi: 10.11884/HPLPB202537.240373
Abstract:
Ionic liquid ion sources have the capability of generating diverse heavy molecular ions, and their applications have been investigated in the field of ion thrusters. This study aims to determine the quality parameters of ionic liquid ion beams and establish methods for their control. Firstly, the beam acceleration process in an ionic liquid ion source was simulated using Particle-in-Cell (PIC) simulation methods, and the effects of the beam current, acceleration voltage, and emitter-extraction gap on the beam emittance and Twiss parameters were investigated. The results indicate that the normalized emittance decreases with a reduction in the beam current and emitter-extraction gap, as well as with an increase in the acceleration voltage. The kinetic energy broadens during the acceleration process. The acceleration efficiency is not obviously affected by the beam current or acceleration voltage. However, it increases with the expansion of the emitter-extraction gap. Secondly, the control of a centimeter-scale beam was simulated by utilizing the beam parameters derived from the simulation of the acceleration process. The results demonstrate that the divergence, velocity distribution, and specific impulse can be controlled by a set of three-electrode electrostatic lenses without imposing additional demands on the power source on the ionic liquid electric thruster.
Ionic liquid ion sources have the capability of generating diverse heavy molecular ions, and their applications have been investigated in the field of ion thrusters. This study aims to determine the quality parameters of ionic liquid ion beams and establish methods for their control. Firstly, the beam acceleration process in an ionic liquid ion source was simulated using Particle-in-Cell (PIC) simulation methods, and the effects of the beam current, acceleration voltage, and emitter-extraction gap on the beam emittance and Twiss parameters were investigated. The results indicate that the normalized emittance decreases with a reduction in the beam current and emitter-extraction gap, as well as with an increase in the acceleration voltage. The kinetic energy broadens during the acceleration process. The acceleration efficiency is not obviously affected by the beam current or acceleration voltage. However, it increases with the expansion of the emitter-extraction gap. Secondly, the control of a centimeter-scale beam was simulated by utilizing the beam parameters derived from the simulation of the acceleration process. The results demonstrate that the divergence, velocity distribution, and specific impulse can be controlled by a set of three-electrode electrostatic lenses without imposing additional demands on the power source on the ionic liquid electric thruster.
2025, 37: 011004.
doi: 10.11884/HPLPB202537.240304
Abstract:
Femtosecond laser precision machining technology has three characteristics: extremely short duration time to avoid or alleviate thermal effects, extremely high peak power density suitable for any solid material and extremely small focal spot size to achieve precise removal or modification of micro areas, meeting the safety and precision machining needs of various difficult to machine and special materials involved in precision diagnosis/measurement experiments. The application of high stability and high repetition rate femtosecond lasers fills in the gap of low repetition rate femtosecond lasers that cannot achieve high-speed scanning, providing an important energy source for efficient and precise processing of various precision samples/specimens required for precision diagnosis/measurement experiments. This article takes the precision diagnosis/measurement experiments of various institutes of China Academy of Engineering Physics as the starting point for safe, efficient and precise processing requirements of precision samples/specimens. Taking typical application scenarios such as laser X-ray precision target materials and structures, explosive material microstructures, superhard material composite refractive lens structures, micro probe fiber precision fixed structures, and terahertz filter core structures as examples, it introduces the research progress of high-frequency femtosecond laser precision processing technology in the safe, efficient and precise processing of difficult to-machine materials and special materials.
Femtosecond laser precision machining technology has three characteristics: extremely short duration time to avoid or alleviate thermal effects, extremely high peak power density suitable for any solid material and extremely small focal spot size to achieve precise removal or modification of micro areas, meeting the safety and precision machining needs of various difficult to machine and special materials involved in precision diagnosis/measurement experiments. The application of high stability and high repetition rate femtosecond lasers fills in the gap of low repetition rate femtosecond lasers that cannot achieve high-speed scanning, providing an important energy source for efficient and precise processing of various precision samples/specimens required for precision diagnosis/measurement experiments. This article takes the precision diagnosis/measurement experiments of various institutes of China Academy of Engineering Physics as the starting point for safe, efficient and precise processing requirements of precision samples/specimens. Taking typical application scenarios such as laser X-ray precision target materials and structures, explosive material microstructures, superhard material composite refractive lens structures, micro probe fiber precision fixed structures, and terahertz filter core structures as examples, it introduces the research progress of high-frequency femtosecond laser precision processing technology in the safe, efficient and precise processing of difficult to-machine materials and special materials.
2025, 37: 013006.
doi: 10.11884/HPLPB202537.240159
Abstract:
To solve the problems of low inhibition of parasitic mode and measurement accuracy is susceptible to interference of parasitic modes in traditional high power microwave online measurement devices, a high-power TM01 mode coupling device is studied, which is applied to the Ku-band relativistic backward wave oscillator (RBWO) online measurement system. Due to the RBWO emission’s angular inhomogeneity, asymmetric modes is generated, and the traditional single-arm porous circular waveguide coupler cannot solve the competition problem between the TM01 mode and the asymmetric modes, which generally leads to the detection waveform distortion and coupling degree judgment deviation and seriously affects the accuracy of the online evaluation of the output power of TM01 mode of the RBWO. For this reason, combining the four-arm porous coupling structure with the TM01 mode selection network, a novel online mode-selective coupling device is proposed in this paper. Using the field structure difference of different waveguide modes, the proposed device realizes the differential coupling of TM01 mode and other parasitic modes and solves the problem of inaccurate online test power caused by parasitic mode interference. The simulation results show that the coupling degree of the proposed new coupler to TM01 mode is more than 20 dB higher than that of the other modes, and the on-line test waveform and power measured in the high-power experiment are in good agreement with the radiated field test waveform and power, and the coupling stability is significantly improved.
To solve the problems of low inhibition of parasitic mode and measurement accuracy is susceptible to interference of parasitic modes in traditional high power microwave online measurement devices, a high-power TM01 mode coupling device is studied, which is applied to the Ku-band relativistic backward wave oscillator (RBWO) online measurement system. Due to the RBWO emission’s angular inhomogeneity, asymmetric modes is generated, and the traditional single-arm porous circular waveguide coupler cannot solve the competition problem between the TM01 mode and the asymmetric modes, which generally leads to the detection waveform distortion and coupling degree judgment deviation and seriously affects the accuracy of the online evaluation of the output power of TM01 mode of the RBWO. For this reason, combining the four-arm porous coupling structure with the TM01 mode selection network, a novel online mode-selective coupling device is proposed in this paper. Using the field structure difference of different waveguide modes, the proposed device realizes the differential coupling of TM01 mode and other parasitic modes and solves the problem of inaccurate online test power caused by parasitic mode interference. The simulation results show that the coupling degree of the proposed new coupler to TM01 mode is more than 20 dB higher than that of the other modes, and the on-line test waveform and power measured in the high-power experiment are in good agreement with the radiated field test waveform and power, and the coupling stability is significantly improved.
2025, 37: 014004.
doi: 10.11884/HPLPB202537.240168
Abstract:
The terahertz near-field high-throughput material physical property testing system (NFTHZ) integrates a wavelength-tunable terahertz free electron laser (THz-FEL). The instrument uses a linear accelerator with tunable electron energy of 10-18 MeV as the injector. A pre-bunched electron beam can be formed by adjusting the longitudinal/temporal structure of the driving laser. By matching the relationship between the bunching factor, energy of the electron beam at the undulator entrance and the K value of undulator, a terahertz free electron laser with megawatts peak power and an adjustable center wavelength of 0.5-5.0 THz can be achieved. The microwave system provides high-power microwave electric field, accelerating structure and microwave amplitude and phase control system to accelerate the electron beam to the target energy. This article will introduce the development of the microwave system of the NFTHZ facility and the construction progress of the electron linear accelerator.
The terahertz near-field high-throughput material physical property testing system (NFTHZ) integrates a wavelength-tunable terahertz free electron laser (THz-FEL). The instrument uses a linear accelerator with tunable electron energy of 10-18 MeV as the injector. A pre-bunched electron beam can be formed by adjusting the longitudinal/temporal structure of the driving laser. By matching the relationship between the bunching factor, energy of the electron beam at the undulator entrance and the K value of undulator, a terahertz free electron laser with megawatts peak power and an adjustable center wavelength of 0.5-5.0 THz can be achieved. The microwave system provides high-power microwave electric field, accelerating structure and microwave amplitude and phase control system to accelerate the electron beam to the target energy. This article will introduce the development of the microwave system of the NFTHZ facility and the construction progress of the electron linear accelerator.
2025, 37: 014005.
doi: 10.11884/HPLPB202537.240195
Abstract:
The C-band photocathode electron gun is designed. As one of important equipments for the linear injector of the Southern Advanced Photon Source. This paper discusses its RF and coupler design. The C-band electron gun has a working frequency of 5.712 GHz, a 3.6-cell structure, a π-mode acceleration mode, and it adopts a coaxial coupling method. The CST and Superfish codes are used to optimize the cavity microwave structure, reducing the surface electric field of the cavity to enhance the accelerating field strength and suppressing the multimode transmission. Furthermore, COMSOL Multiphysics is applied to analyze the cavity cooling system, reducing frequency drift caused by the cavity heating. Additionally, a water cooling design for the cavity ensures that the maximum temperature rise of the cavity is less than 20 ℃. Under an input power of 18.15 MW, the acceleration gradient of 180 MV/m on the cathode surface is achieved, the ratio of the acceleration gradient to the cathode surface electric field is approximately 0.93, and the cavity quality factor is greater than10000 . The design of the coupler suppresses the transmission of dipole and quadrupole modes, with the S11 parameter being less than −40 dB.
The C-band photocathode electron gun is designed. As one of important equipments for the linear injector of the Southern Advanced Photon Source. This paper discusses its RF and coupler design. The C-band electron gun has a working frequency of 5.712 GHz, a 3.6-cell structure, a π-mode acceleration mode, and it adopts a coaxial coupling method. The CST and Superfish codes are used to optimize the cavity microwave structure, reducing the surface electric field of the cavity to enhance the accelerating field strength and suppressing the multimode transmission. Furthermore, COMSOL Multiphysics is applied to analyze the cavity cooling system, reducing frequency drift caused by the cavity heating. Additionally, a water cooling design for the cavity ensures that the maximum temperature rise of the cavity is less than 20 ℃. Under an input power of 18.15 MW, the acceleration gradient of 180 MV/m on the cathode surface is achieved, the ratio of the acceleration gradient to the cathode surface electric field is approximately 0.93, and the cavity quality factor is greater than
2025, 37: 014006.
doi: 10.11884/HPLPB202537.240289
Abstract:
Negative hydrogen stripping injection is the only feasible scheme for accumulating beam in high current proton synchrotrons. Currently, the China Spallation Neutron Source (CSNS) employs negative hydrogen stripping injection by using a stripping foil. The intense temperature rising of the foil caused by energy deposition from the negative hydrogen beam passing through the foil is a critical issue which affecting the foil's lifetime and the stable operation of the accelerator. Additionally, the residual high power electron beam generated during the stripping process may have severe consequences, including electron ionization within the foil causing further temperature increase, thermal damage to the vacuum box from electron impacts, e-p instability from electrons captured by the proton beam in the vacuum tube, and significant electron cloud effects from secondary electrons. This paper focuses on two main topics: first, comprehensive simulations of the foil’s temperature rise have been conducted using finite element analysis software, taking into account various parameters, including the average number of particle crossings. Simulation results under various software conditions are compared to obtain the temperature field distribution on the stripping foil and predict surface temperature increases for future higher beam power. Secondly, the electron distribution following the stripping process is analyzed based on theoretical calculations and Geant4 simulations. The 3D computational model is refined by considering the electromagnetic field and beam conditions in the CSNS injection area, and a scheme for capturing stripping electrons is proposed by determining the optimal position for the electron collection device.
Negative hydrogen stripping injection is the only feasible scheme for accumulating beam in high current proton synchrotrons. Currently, the China Spallation Neutron Source (CSNS) employs negative hydrogen stripping injection by using a stripping foil. The intense temperature rising of the foil caused by energy deposition from the negative hydrogen beam passing through the foil is a critical issue which affecting the foil's lifetime and the stable operation of the accelerator. Additionally, the residual high power electron beam generated during the stripping process may have severe consequences, including electron ionization within the foil causing further temperature increase, thermal damage to the vacuum box from electron impacts, e-p instability from electrons captured by the proton beam in the vacuum tube, and significant electron cloud effects from secondary electrons. This paper focuses on two main topics: first, comprehensive simulations of the foil’s temperature rise have been conducted using finite element analysis software, taking into account various parameters, including the average number of particle crossings. Simulation results under various software conditions are compared to obtain the temperature field distribution on the stripping foil and predict surface temperature increases for future higher beam power. Secondly, the electron distribution following the stripping process is analyzed based on theoretical calculations and Geant4 simulations. The 3D computational model is refined by considering the electromagnetic field and beam conditions in the CSNS injection area, and a scheme for capturing stripping electrons is proposed by determining the optimal position for the electron collection device.
