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RSS2023 Vol. 35, No. 10
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2023,
35: 1-2.
2023,
35: 101001.
doi: 10.11884/HPLPB202335.230225
Abstract:
The micro-ejection phenomenon and its internal mechanism analysis of metal materials under intense laser shock are the frontier issues in the field of shock compression science and engineering. Related research is of great significance for understanding the dynamic behavior of materials under extreme loading conditions. With the continuous development of laser technology, scientists at home and abroad have carried out numerous micro-ejection diagnostic experiments based on some large laser devices in various countries in recent years, and made a series of significant progress in the properties of ejection, the growth of instability at the metal interface and the mixing mechanism of ejection. By reviewing the research history of ejecta static and dynamic diagnostic experiments, this paper describes the main mechanism of ejection, influencing factors and ejecta interface mixing mechanism in detail, and then it reviews, classifies and summarizes the important applications of micro-ejection experimental diagnostic methods. Finally, according to the current development trend of ejecta diagnostic experiments at home and abroad, the deficiencies in the current ejection experimental research results are summarized, and the future development direction of ejection experimental research is prospected.
2023,
35: 101002.
doi: 10.11884/HPLPB202335.220410
Abstract:
This paper introduces the basic principle of spatiotemporal mode-locking (STML) and the theoretical model of STML—attractor dissection. It presents the recent research progress about STML fiber laser from two aspects of spatial optical structures and all-fiber structures, including the improvement of laser cavity type, the enhancement of output performance, and the observation of real-time dynamics, etc. The advantage and insufficiency of the current STML laser are analyzed, and the development direction is forecasted: STML laser possesses great potential in generating high-power and ultrashort pulse, but to some extent, the poor quality of output modes hinders its application; improving the beam quality by self-similar evolution, wavefront shaping, etc. will be the direction to develop STML laser in the future.
2023,
35: 101003.
doi: 10.11884/HPLPB202335.230166
Abstract:
Driven by the unique polarization distribution characteristics, cylindrical vector beams play an important role in optical tweezers, high resolution imaging, remote sensing, plasma focusing, and other related fields. To realize all-fiber high-power cylindrical vector beams MOPA laser, a mode conversion fiber device based on integrated metasurface is independently designed, whose feasibility is analyzed and verified in this demonstration. The self-designed integrated metasurface mode conversion fiber device can act as a radially polarized vector beam seed with several watts, and the mode purity is more than 95%. In the experiment, a radially polarized vector beam with an output power of 52.2 W was achieved in the case of a single-stage amplifier by decreasing bending loss and controlling the mode. Moreover, the mode field distribution was maintained well during the amplification. To further analyze the obtained mode characteristics, a rotatable polarizer method was used to measure the polarization characteristics and polarization purity, and the mode purity was measured by an incoherent mode superposition method. The results show that the polarization purity of the radially polarized vector beam is approximately 95.2% and the mode purity is about 94% with the maximum output power, which verify the feasibility of the all-fiber scheme.
Driven by the unique polarization distribution characteristics, cylindrical vector beams play an important role in optical tweezers, high resolution imaging, remote sensing, plasma focusing, and other related fields. To realize all-fiber high-power cylindrical vector beams MOPA laser, a mode conversion fiber device based on integrated metasurface is independently designed, whose feasibility is analyzed and verified in this demonstration. The self-designed integrated metasurface mode conversion fiber device can act as a radially polarized vector beam seed with several watts, and the mode purity is more than 95%. In the experiment, a radially polarized vector beam with an output power of 52.2 W was achieved in the case of a single-stage amplifier by decreasing bending loss and controlling the mode. Moreover, the mode field distribution was maintained well during the amplification. To further analyze the obtained mode characteristics, a rotatable polarizer method was used to measure the polarization characteristics and polarization purity, and the mode purity was measured by an incoherent mode superposition method. The results show that the polarization purity of the radially polarized vector beam is approximately 95.2% and the mode purity is about 94% with the maximum output power, which verify the feasibility of the all-fiber scheme.
2023,
35: 101004.
doi: 10.11884/HPLPB202335.230063
Abstract:
Target detection by lidar is challenging due to the difficulty in obtaining the complex attitude of targets and capturing the real coincidence between target and facula. To address this problem, in this paper, a real-time mapping method of laser beam to complex targets based on GPU programming is proposed. By taking advantages of modern graphics hardware with respect to GPU programming technology and frame buffer object merit, the proposed approach takes each surface light source matrix as the observer, renders the current scene in the light source spatial coordinate system, and records the rendering results into the memory texture. To realize real-time mapping and rendering, the results observed by the light source in the world coordinates are restored and mapped to the model. Based on deep cache principle of Zbuffer and texture mapping principle, the model information (e.g., light source irradiance, vertex position and patch normal on the vertex of each triangular patch) can be correctly obtained with virtue OSG file reading-writing plug-in. Extensive experiments demonstrate the strong universality of the proposed algorithm. It is powerful in reading three-dimension files of various formats and is suitable for uniform or non-uniform surface light sources. It meets the quasi real-time computational requirements of two surface light sources with low requirements on system graphics hardware. Various model information could be acquired in quasi real-time, e.g., the components of the illuminated surface piece, the vertices of the illuminated triangular surface, the normal information and the irradiation intensity received by the vertex of the triangular patch. The algorithm is novel in providing reference and basis for laser illumination, recognition and detection.
Target detection by lidar is challenging due to the difficulty in obtaining the complex attitude of targets and capturing the real coincidence between target and facula. To address this problem, in this paper, a real-time mapping method of laser beam to complex targets based on GPU programming is proposed. By taking advantages of modern graphics hardware with respect to GPU programming technology and frame buffer object merit, the proposed approach takes each surface light source matrix as the observer, renders the current scene in the light source spatial coordinate system, and records the rendering results into the memory texture. To realize real-time mapping and rendering, the results observed by the light source in the world coordinates are restored and mapped to the model. Based on deep cache principle of Zbuffer and texture mapping principle, the model information (e.g., light source irradiance, vertex position and patch normal on the vertex of each triangular patch) can be correctly obtained with virtue OSG file reading-writing plug-in. Extensive experiments demonstrate the strong universality of the proposed algorithm. It is powerful in reading three-dimension files of various formats and is suitable for uniform or non-uniform surface light sources. It meets the quasi real-time computational requirements of two surface light sources with low requirements on system graphics hardware. Various model information could be acquired in quasi real-time, e.g., the components of the illuminated surface piece, the vertices of the illuminated triangular surface, the normal information and the irradiation intensity received by the vertex of the triangular patch. The algorithm is novel in providing reference and basis for laser illumination, recognition and detection.
2023,
35: 101005.
doi: 10.11884/HPLPB202335.230111
Abstract:
Compared with other vortex beams, the perfect optical vortex (POV) beam has a more stable spatial intensity distribution because the beam radius is independent of the topological charge. In this paper, the transmission characteristics of the POV beam in slant path atmospheric turbulence are studied by means of multi-phase screen method and Fourier transform method. The influence of atmospheric turbulence on beam quality is analyzed by using beam drift and aperture average scintillation index. Then the beam quality of the POV beam and Gaussian vortex beam under the same transmission conditions is compared. The results show that POV beam has better beam stability than Gaussian vortex beam. When the topological load increases or the zenith angle decreases, the ability of POV beam to resist atmospheric turbulence increases. The resistance of POV beam to atmospheric turbulence can be improved by increasing the beam radius without changing the topological charge of the POV beam.
Compared with other vortex beams, the perfect optical vortex (POV) beam has a more stable spatial intensity distribution because the beam radius is independent of the topological charge. In this paper, the transmission characteristics of the POV beam in slant path atmospheric turbulence are studied by means of multi-phase screen method and Fourier transform method. The influence of atmospheric turbulence on beam quality is analyzed by using beam drift and aperture average scintillation index. Then the beam quality of the POV beam and Gaussian vortex beam under the same transmission conditions is compared. The results show that POV beam has better beam stability than Gaussian vortex beam. When the topological load increases or the zenith angle decreases, the ability of POV beam to resist atmospheric turbulence increases. The resistance of POV beam to atmospheric turbulence can be improved by increasing the beam radius without changing the topological charge of the POV beam.
2023,
35: 101006.
doi: 10.11884/HPLPB202335.230115
Abstract:
The basic working principle of the vacuum channel stress compensation structure is introduced. The adaptive compensation technology and the optical cabin structure deformation suppression technology subjected to the vacuum negative pressure stress, thermal expansion and cold contraction stresses of the laser beam long-distance vacuum transmission channel in large temperature difference environments are investigated. The installation, debugging and evaluation of the vacuum channel stress compensation structure are carried out with the whole optical system, and the optical transmission stability is verified by some experiments with ambient temperature difference. The experimental results show that the problem of adaptive compensation for vacuum negative pressure stress and thermal expansion and cold contraction stress in the ultra-long laser beam vacuum transmission channel under vacuum negative pressure and large temperature difference environments, and the problem of deformation suppression of the optical cabin structure are solved. The automatic balance of vacuum negative pressure stress in the transmission channel is achieved, and the laser beam drift caused by vacuum negative pressure stress is eliminated. The release of thermal expansion and cold contraction stresses in the vacuum negative pressure channel structure under large temperature difference environments is achieved, the actual effect of maintaining stability of the optical path for a long time is achieved.
The basic working principle of the vacuum channel stress compensation structure is introduced. The adaptive compensation technology and the optical cabin structure deformation suppression technology subjected to the vacuum negative pressure stress, thermal expansion and cold contraction stresses of the laser beam long-distance vacuum transmission channel in large temperature difference environments are investigated. The installation, debugging and evaluation of the vacuum channel stress compensation structure are carried out with the whole optical system, and the optical transmission stability is verified by some experiments with ambient temperature difference. The experimental results show that the problem of adaptive compensation for vacuum negative pressure stress and thermal expansion and cold contraction stress in the ultra-long laser beam vacuum transmission channel under vacuum negative pressure and large temperature difference environments, and the problem of deformation suppression of the optical cabin structure are solved. The automatic balance of vacuum negative pressure stress in the transmission channel is achieved, and the laser beam drift caused by vacuum negative pressure stress is eliminated. The release of thermal expansion and cold contraction stresses in the vacuum negative pressure channel structure under large temperature difference environments is achieved, the actual effect of maintaining stability of the optical path for a long time is achieved.
2023,
35: 101007.
doi: 10.11884/HPLPB202335.230099
Abstract:
Piezoelectric ceramic is the main actuator of deformable mirror, which is the core device of adaptive optics system. Its performance directly affects the correction ability of deformable mirror and even adaptive optics system. Performance parameters of the tensile/compressible piezoelectric ceramics (5 mm×5 mm×38 mm) with loading voltage of ±350 V were tested, including displacement, hysteresis, capacitance, impedance and coefficient of thermal expansion, etc. The test results show the tensile capacity of three samples was more than 250 N, and 10 million fatigue tests (±150 N@5 Hz sinusoidal load) were carried out on 5# sample. The experimental results show that the displacement and capacitance of the sample reduced than 5%. Through the tensile/pressure and fatigue test, the properties and service life of the piezoelectric ceramic were examined, which provides some supporting data for the development of deformable mirrors.
Piezoelectric ceramic is the main actuator of deformable mirror, which is the core device of adaptive optics system. Its performance directly affects the correction ability of deformable mirror and even adaptive optics system. Performance parameters of the tensile/compressible piezoelectric ceramics (5 mm×5 mm×38 mm) with loading voltage of ±350 V were tested, including displacement, hysteresis, capacitance, impedance and coefficient of thermal expansion, etc. The test results show the tensile capacity of three samples was more than 250 N, and 10 million fatigue tests (±150 N@5 Hz sinusoidal load) were carried out on 5# sample. The experimental results show that the displacement and capacitance of the sample reduced than 5%. Through the tensile/pressure and fatigue test, the properties and service life of the piezoelectric ceramic were examined, which provides some supporting data for the development of deformable mirrors.
2023,
35: 102001.
doi: 10.11884/HPLPB202335.230146
Abstract:
Rayleigh-Taylor instability (RTI) research in inertial confinement fusion (ICF) is based on modulation targets with multiple structures. In this paper, aiming at the present problems existing in the preparation of modulation targets, three typical modulation targets of planar modulation, planar composite modulation and spherical shell modulation have been prepared by two-photon 3D printing process. The target material is photosensitive resin (95%: C23H38N2O8, 5%: C4H6O2). The actual structural parameters of the three modulation targets were analyzed using laser confocal microscopy imaging. The measured morphologies and parameters of the three targets show good matching with the designed structures. To further validate the feasibility of using new two-photon 3D printing process for preparing modulation targets, nanosecond laser targeting experiments were conducted on the “Shenguang II” high-power laser experimental facility. The results show that the modulation of the target surface increased with time due to the action of RTI under direct laser driving. The modulation with an initial peak valley value of 4 μm formed a high-density jet with a length of up to 100 μm after 2.5 ns of laser driving, which indicates that the preparation of complex modulation targets based on high-precision 3D printing technology is highly feasible for RTI research.
Rayleigh-Taylor instability (RTI) research in inertial confinement fusion (ICF) is based on modulation targets with multiple structures. In this paper, aiming at the present problems existing in the preparation of modulation targets, three typical modulation targets of planar modulation, planar composite modulation and spherical shell modulation have been prepared by two-photon 3D printing process. The target material is photosensitive resin (95%: C23H38N2O8, 5%: C4H6O2). The actual structural parameters of the three modulation targets were analyzed using laser confocal microscopy imaging. The measured morphologies and parameters of the three targets show good matching with the designed structures. To further validate the feasibility of using new two-photon 3D printing process for preparing modulation targets, nanosecond laser targeting experiments were conducted on the “Shenguang II” high-power laser experimental facility. The results show that the modulation of the target surface increased with time due to the action of RTI under direct laser driving. The modulation with an initial peak valley value of 4 μm formed a high-density jet with a length of up to 100 μm after 2.5 ns of laser driving, which indicates that the preparation of complex modulation targets based on high-precision 3D printing technology is highly feasible for RTI research.
2023,
35: 103001.
doi: 10.11884/HPLPB202335.230192
Abstract:
This paper presents the problem of the parasitic effect of the transistor for the practical design of high power and high-efficiency power amplifiers (PAs). To solve the problem, we propose a new method: transferring the impedances at the intrinsic plane into those at the package plane with the help of the package model. In this case, the convenience of the design of the output matching network is improved a lot. Moreover, the design methodology of PAs with compact microstrip resonant cell (CMRC) as well as the topology of the transmission-lines (TLs) are also proposed. The CMRC can provide the required open-circuit for the third harmonic. On this basis, the harmonic impedance conditions can be easily realized by the tuning TLs. The insertion loss of the proposed CMRC at the fundamental is low and the physical dimension is relatively small. To verify the feasibility of the proposed circuit, using a 10W GaN HEMT CGH40010F transistor, a switch-mode class E/F PA operating at 2.2 GHz is designed as a prototype. Simulation results show the power-added efficiency of 78.4%, output power of 40.1 dBm, and power gain of 12.1 dB.
This paper presents the problem of the parasitic effect of the transistor for the practical design of high power and high-efficiency power amplifiers (PAs). To solve the problem, we propose a new method: transferring the impedances at the intrinsic plane into those at the package plane with the help of the package model. In this case, the convenience of the design of the output matching network is improved a lot. Moreover, the design methodology of PAs with compact microstrip resonant cell (CMRC) as well as the topology of the transmission-lines (TLs) are also proposed. The CMRC can provide the required open-circuit for the third harmonic. On this basis, the harmonic impedance conditions can be easily realized by the tuning TLs. The insertion loss of the proposed CMRC at the fundamental is low and the physical dimension is relatively small. To verify the feasibility of the proposed circuit, using a 10W GaN HEMT CGH40010F transistor, a switch-mode class E/F PA operating at 2.2 GHz is designed as a prototype. Simulation results show the power-added efficiency of 78.4%, output power of 40.1 dBm, and power gain of 12.1 dB.
2023,
35: 103002.
doi: 10.11884/HPLPB202335.230224
Abstract:
A dual band dual circularly polarized shared-aperture microstrip antenna is designed and fabricated, which can operate in the dual circular polarization mode in the C/X band, and the aperture utilization rate of the antenna is effectively improved. The parasitic structure and the L-shaped probe are applied to improve the impedance bandwidth. The shared aperture design is realized by placing the X-band antenna in the gap of the C-band antenna. The good cross-polarization ratio is realized by the symmetrical inversed phase feeding technique. The measurement results show that the impedance bandwidth and 3 dB axial ratio bandwidth of C-band are greater than 23% and 17%, respectively. The impedance bandwidth and 3 dB axial ratio bandwidth of X-band are greater than 28% and 18% respectively. The cross-polarization ratio at the test frequency points is greater than 25 dB.
A dual band dual circularly polarized shared-aperture microstrip antenna is designed and fabricated, which can operate in the dual circular polarization mode in the C/X band, and the aperture utilization rate of the antenna is effectively improved. The parasitic structure and the L-shaped probe are applied to improve the impedance bandwidth. The shared aperture design is realized by placing the X-band antenna in the gap of the C-band antenna. The good cross-polarization ratio is realized by the symmetrical inversed phase feeding technique. The measurement results show that the impedance bandwidth and 3 dB axial ratio bandwidth of C-band are greater than 23% and 17%, respectively. The impedance bandwidth and 3 dB axial ratio bandwidth of X-band are greater than 28% and 18% respectively. The cross-polarization ratio at the test frequency points is greater than 25 dB.
2023,
35: 103003.
doi: 10.11884/HPLPB202335.230216
Abstract:
A broadband dual-band dual circularly polarized millimeter wave single-fed antenna is designed. The antenna operates in n257(26.5−29.5 GHz) and n260(37.0−40.0 GHz) bands simultaneously. Compared with the traditional circularly polarized antenna, irregular patches stacked up and down are used to realize dual-band dual-circular polarization and improve the isolation of signal reception and transmission. By adding a curved parasitic patch, the antenna extends the axial ratio bandwidth. Rectangular gaps in the metal-frame are used to improve the antenna gain and expand the antenna bandwidth. The measurement results show that the relative impedance (<−10 dB) bandwidth at low frequency and high frequency are 20.4% and 17.0% respectively, and the relative axial ratio (<3 dB) bandwidth of dual-band dual-circular polarization are 14.9% and 11.4% respectively. The antenna bandwidth covers n257 and n260 bands, which can be used for communication between 5G mobile devices and LEO satellites.
A broadband dual-band dual circularly polarized millimeter wave single-fed antenna is designed. The antenna operates in n257(26.5−29.5 GHz) and n260(37.0−40.0 GHz) bands simultaneously. Compared with the traditional circularly polarized antenna, irregular patches stacked up and down are used to realize dual-band dual-circular polarization and improve the isolation of signal reception and transmission. By adding a curved parasitic patch, the antenna extends the axial ratio bandwidth. Rectangular gaps in the metal-frame are used to improve the antenna gain and expand the antenna bandwidth. The measurement results show that the relative impedance (<−10 dB) bandwidth at low frequency and high frequency are 20.4% and 17.0% respectively, and the relative axial ratio (<3 dB) bandwidth of dual-band dual-circular polarization are 14.9% and 11.4% respectively. The antenna bandwidth covers n257 and n260 bands, which can be used for communication between 5G mobile devices and LEO satellites.
2023,
35: 103004.
doi: 10.11884/HPLPB202335.230106
Abstract:
To study the high-power microwave front door effect of system-level RF equipment, the injection method was used to conduct experimental research on the RF front end composed of filter, circulator, low-noise amplifier and power amplifier of a 4G base station. The results show that the rising and falling edges of the high-power microwave pulse are strongly reflected by the RF front-end filter, and the reflection of the pulse flat top section is small. The reflected waveform spikes on the rising and falling edges, and the flattened part in the middle of the pulse, showing that the rich out-of-band frequency components of the filter contained in the steep rising and falling edges of the high-power microwaves are reflected, resulting in weakened pulses passing through the filter. After passing through the filter, the high-power microwave pulse can enter the upstream channel low noise amplifier from the circulator, and then be reflected, circulate into the downlink channel power amplifier, be reflected again, and then loop through the injection port output. High-power microwave pulses traveling through two reflection loops were detected in the experiment. This shows that under high-power pulse conditions, the downlink channel power amplifier originally isolated by the circulator is also at risk of damage from the high-power microwave pulse entering the upstream channel. This study has certain reference significance for the study of system-level high-power microwave front door effect.
To study the high-power microwave front door effect of system-level RF equipment, the injection method was used to conduct experimental research on the RF front end composed of filter, circulator, low-noise amplifier and power amplifier of a 4G base station. The results show that the rising and falling edges of the high-power microwave pulse are strongly reflected by the RF front-end filter, and the reflection of the pulse flat top section is small. The reflected waveform spikes on the rising and falling edges, and the flattened part in the middle of the pulse, showing that the rich out-of-band frequency components of the filter contained in the steep rising and falling edges of the high-power microwaves are reflected, resulting in weakened pulses passing through the filter. After passing through the filter, the high-power microwave pulse can enter the upstream channel low noise amplifier from the circulator, and then be reflected, circulate into the downlink channel power amplifier, be reflected again, and then loop through the injection port output. High-power microwave pulses traveling through two reflection loops were detected in the experiment. This shows that under high-power pulse conditions, the downlink channel power amplifier originally isolated by the circulator is also at risk of damage from the high-power microwave pulse entering the upstream channel. This study has certain reference significance for the study of system-level high-power microwave front door effect.
2023,
35: 104001.
doi: 10.11884/HPLPB202335.220356
Abstract:
The control system for the ion source of the JUNA（Jinping Underground laboratory for Nuclear Astro-physics) was designed and implemented. It is built by using a distributed system model. The hardware adopts PLC, serial device server, servo motor, industrial computer, and other components to realize the remote monitoring and controlling of ion source devices. The software integrates all controlled devices by establishing the EPICS IOC run-time databases. The user interface layer is developed by using Control System Studio to achieve transparent access to all controlled devices by operators. The machine protection system is designed based on safety rules to realize protection in the case of abnormal operations. It is used in the first underground ECR ion source in China and is stable and reliable, which fully meets the needs of the JUNA tuning and physical experiments.
The control system for the ion source of the JUNA（Jinping Underground laboratory for Nuclear Astro-physics) was designed and implemented. It is built by using a distributed system model. The hardware adopts PLC, serial device server, servo motor, industrial computer, and other components to realize the remote monitoring and controlling of ion source devices. The software integrates all controlled devices by establishing the EPICS IOC run-time databases. The user interface layer is developed by using Control System Studio to achieve transparent access to all controlled devices by operators. The machine protection system is designed based on safety rules to realize protection in the case of abnormal operations. It is used in the first underground ECR ion source in China and is stable and reliable, which fully meets the needs of the JUNA tuning and physical experiments.
2023,
35: 104002.
doi: 10.11884/HPLPB202335.230149
Abstract:
Based on the correlation between ground neutron detection and the cosmic ray environment, a dataset was constructed using the detection data of geostationary operational environmental satellites and various neutron detection stations worldwide for the solar activity quiet period. Models for inverting the cosmic ray proton environment from ground neutron detection data were established based on the extreme gradient boost decision tree (XGBoost) and artificial neural network. They use genetic algorithm to solve the optimal hyperparameter and train the parameters of each neuron of the neural network to realize the inversion of the cosmic ray proton environment. The mean square error of the model training is 0.499, and the average inversion error of the test set is 26.9% respectively. Compared with the radiation environment model commonly used in aerospace, the error is usually within 200%, which is significantly improved. Multiple other machine learning algorithms, including support vector regression, error back propagation training, long short-term memory network, were compared and the results show that the model established in this paper has the advantages of short training time, fast computation speed, and low resource consumption.
Based on the correlation between ground neutron detection and the cosmic ray environment, a dataset was constructed using the detection data of geostationary operational environmental satellites and various neutron detection stations worldwide for the solar activity quiet period. Models for inverting the cosmic ray proton environment from ground neutron detection data were established based on the extreme gradient boost decision tree (XGBoost) and artificial neural network. They use genetic algorithm to solve the optimal hyperparameter and train the parameters of each neuron of the neural network to realize the inversion of the cosmic ray proton environment. The mean square error of the model training is 0.499, and the average inversion error of the test set is 26.9% respectively. Compared with the radiation environment model commonly used in aerospace, the error is usually within 200%, which is significantly improved. Multiple other machine learning algorithms, including support vector regression, error back propagation training, long short-term memory network, were compared and the results show that the model established in this paper has the advantages of short training time, fast computation speed, and low resource consumption.
2023,
35: 104003.
doi: 10.11884/HPLPB202335.230154
Abstract:
7075 aluminum alloy is widely used in the field of aerospace materials as a structural component due to its excellent properties. There are various radiation particles in the spacecraft space environment, which will cause different degrees of irradiation damage to spacecraft materials, and threaten their reliability, and even lead to failure of space missions. Selecting different doses of 3 MeV Fe11+ ions to radiate the 7075 aluminum alloy, using XRD, AFM and nanoindentation to study the microstructure, surface morphology and hardness changes before and after irradiation, the tapered protrusions caused by cascade collision evolution and surface defect diffusion are found on the surface and the surface roughness of the sample increased first and then decreased with the increase of dose. In addition, the nanoindentation test shows that the hardness of the sample increased after irradiation, and with the increase of dose, the hardness gradually became saturated. The analysis shows that the irradiation hardening of the sample is caused by the irradiation defects impeding the slippage of dislocations.
7075 aluminum alloy is widely used in the field of aerospace materials as a structural component due to its excellent properties. There are various radiation particles in the spacecraft space environment, which will cause different degrees of irradiation damage to spacecraft materials, and threaten their reliability, and even lead to failure of space missions. Selecting different doses of 3 MeV Fe11+ ions to radiate the 7075 aluminum alloy, using XRD, AFM and nanoindentation to study the microstructure, surface morphology and hardness changes before and after irradiation, the tapered protrusions caused by cascade collision evolution and surface defect diffusion are found on the surface and the surface roughness of the sample increased first and then decreased with the increase of dose. In addition, the nanoindentation test shows that the hardness of the sample increased after irradiation, and with the increase of dose, the hardness gradually became saturated. The analysis shows that the irradiation hardening of the sample is caused by the irradiation defects impeding the slippage of dislocations.
2023,
35: 104004.
doi: 10.11884/HPLPB202335.220311
Abstract:
The cyclotron is designed as the injector of the Heavy Ion Medical Machines (HIMMs) in Wuwei city and Lanzhou city, China. It provides 10 µA carbon ion beams to fulfill the accumulation requirement in the following synchrotron. Four picoammeters acquire the beam current signals gathered by the radial detectors; meanwhile, the beam time structure is measured with Field Programmable Gate Arrays and a real-time operating system. This paper introduces the mechanical design of the radial detectors and further provides the thermal structure analysis result of probe tips with and without water cooling. Moreover, the hardware and software architecture of the control system for this detector is described, including the motion control and data acquisition system, which can implement simultaneous acquisition of beam current data and position at more than 10 kS/s. At last, the laboratory test and acceptance scheme of both mechanical and control systems are listed, and the beam current and turn pattern measurement results at HIMMs are presented in this paper.
Precise control of high-energy protons transport in space environment by using bayesian optimization
2023,
35: 104005.
doi: 10.11884/HPLPB202335.230231
Abstract:
Considering the geomagnetic field, the relativistic effect and bremsstrahlung radiation of high-energy protons, a single particle motion model of proton transport in the space environment is established. Based on this model, the Bayesian optimization method is proposed to realize the precise control of protons transport from the initial position to the target under a given proton energy. The dependence of the proton launch angle on the launch height is obtained, that is, when the coordinate radial angle is 0° and 180°, the value of the coordinate axial angle will not change the optimal emission direction of the particles. The results can provide theoretical references for long-distance transport of proton beams in the space environment.
Considering the geomagnetic field, the relativistic effect and bremsstrahlung radiation of high-energy protons, a single particle motion model of proton transport in the space environment is established. Based on this model, the Bayesian optimization method is proposed to realize the precise control of protons transport from the initial position to the target under a given proton energy. The dependence of the proton launch angle on the launch height is obtained, that is, when the coordinate radial angle is 0° and 180°, the value of the coordinate axial angle will not change the optimal emission direction of the particles. The results can provide theoretical references for long-distance transport of proton beams in the space environment.
2023,
35: 104006.
doi: 10.11884/HPLPB202335.230132
Abstract:
Using dual energy CT method to detect multilayer spherical shell components with great density difference, it is necessary to study the image reconstruction method based on two sets of projection data. The Method of Reconstructed at First and then Fused Based on Images cannot make full use of dual energy X-ray projection information, by which simulation research shows it is difficult to get good reconstructed image. On this basis, the paper focuses on the Method of Fused Based on Projection Data at First and then Reconstructed. Firstly, considering the structure characteristics of the multilayer spherical shell components with great density difference, the X-ray projection sinogram with clear regional distribution can be obtained through a specially designed scanning mode. Then extract effective projection data respectively from the high and low energy X-ray projection sinogram, do the consistency processing, and integrate them to become one sinogram. Finally use the FBP algorithm to complete the image reconstruction process. The concrete realization of the algorithm based on projection data fuse for dual energy CT of multilayer spherical shell is summarized, and computer simulation shows that better reconstructed images can be obtained.
Using dual energy CT method to detect multilayer spherical shell components with great density difference, it is necessary to study the image reconstruction method based on two sets of projection data. The Method of Reconstructed at First and then Fused Based on Images cannot make full use of dual energy X-ray projection information, by which simulation research shows it is difficult to get good reconstructed image. On this basis, the paper focuses on the Method of Fused Based on Projection Data at First and then Reconstructed. Firstly, considering the structure characteristics of the multilayer spherical shell components with great density difference, the X-ray projection sinogram with clear regional distribution can be obtained through a specially designed scanning mode. Then extract effective projection data respectively from the high and low energy X-ray projection sinogram, do the consistency processing, and integrate them to become one sinogram. Finally use the FBP algorithm to complete the image reconstruction process. The concrete realization of the algorithm based on projection data fuse for dual energy CT of multilayer spherical shell is summarized, and computer simulation shows that better reconstructed images can be obtained.
2023,
35: 105001.
doi: 10.11884/HPLPB202335.230088
Abstract:
An improved spiral generator is studied to solve the problem that the second peak value of output voltage waveform is larger than the first peak value and the peak current of input switch and its current rise rate are larger when the number of turns of the traditional spiral generator is large. Numerical simulation and experimental verification are carried out, and the simulation results are basically consistent with the experimental results. Through electromagnetic field analysis of the wave transmission process, it is shown that the additional winding of the improved structure will cause extra reflection, which changes the time when the voltage between the layers is superimposed in the same direction, thus reducing the subsequent oscillations of higher peaks. Finally, an improved spiral generator is tested and it can generate a high voltage pulse with the first peak voltage of 51 kV and the leading edge of 50 ns on a high voltage capacitor load of 15 pF. The volume of the whole generator is less than 0.5 L. The improved spiral generator will then be combined with the semiconductor switch to achieve an all-solid-state design of a high-voltage nanosecond pulse trigger generator in the future.
An improved spiral generator is studied to solve the problem that the second peak value of output voltage waveform is larger than the first peak value and the peak current of input switch and its current rise rate are larger when the number of turns of the traditional spiral generator is large. Numerical simulation and experimental verification are carried out, and the simulation results are basically consistent with the experimental results. Through electromagnetic field analysis of the wave transmission process, it is shown that the additional winding of the improved structure will cause extra reflection, which changes the time when the voltage between the layers is superimposed in the same direction, thus reducing the subsequent oscillations of higher peaks. Finally, an improved spiral generator is tested and it can generate a high voltage pulse with the first peak voltage of 51 kV and the leading edge of 50 ns on a high voltage capacitor load of 15 pF. The volume of the whole generator is less than 0.5 L. The improved spiral generator will then be combined with the semiconductor switch to achieve an all-solid-state design of a high-voltage nanosecond pulse trigger generator in the future.
2023,
35: 105002.
doi: 10.11884/HPLPB202335.230068
Abstract:
There is an increasingly higher requirement on the pulse source of kicker in the injection and extraction system with the development of accelerators. As a special nanosecond switch, Drift Step Recovery Diode (DSRD) has a great application prospect in pulse power technology for its notably short switching-off time and large working current. However, there are some factors such as pre-pulse that make the pulse waveform deviate from the ideal shape. A prototype of pulse generator was designed and tested. It is based on a basic DSRD circuit, at the same time, the Non-Linear Transmission Line (NTL) is used to shape the pulse, compress the edge and reduce the residual voltage. Its circuit experiment shows that the pulse amplitude on resistor load of 50 Ω is about 10 kV, the rise time and fall time are about 2 ns (10%−90%) and the bottom width (3%−3%) is less than 8 ns.
There is an increasingly higher requirement on the pulse source of kicker in the injection and extraction system with the development of accelerators. As a special nanosecond switch, Drift Step Recovery Diode (DSRD) has a great application prospect in pulse power technology for its notably short switching-off time and large working current. However, there are some factors such as pre-pulse that make the pulse waveform deviate from the ideal shape. A prototype of pulse generator was designed and tested. It is based on a basic DSRD circuit, at the same time, the Non-Linear Transmission Line (NTL) is used to shape the pulse, compress the edge and reduce the residual voltage. Its circuit experiment shows that the pulse amplitude on resistor load of 50 Ω is about 10 kV, the rise time and fall time are about 2 ns (10%−90%) and the bottom width (3%−3%) is less than 8 ns.
2023,
35: 105003.
doi: 10.11884/HPLPB202335.230153
Abstract:
To evaluate the applicability of lithium-titanate oxide (LTO) battery in pulsed high power laser system (PHPLS), this paper summarizes the requirements of the PHPLS for the primary energy storage device based on the discharge capacity and safety application characteristics of the energy storage medium, analyzes the applicability of the common energy storage medium through analogy and theoretical calculation, and verifies the engineering application feasibility of LTO by discharge performance test and safety test. The results show that the LTO has high discharge capacity and high safety, which can meet the application requirements of the PHPLS, and has the conditions for promotion.
To evaluate the applicability of lithium-titanate oxide (LTO) battery in pulsed high power laser system (PHPLS), this paper summarizes the requirements of the PHPLS for the primary energy storage device based on the discharge capacity and safety application characteristics of the energy storage medium, analyzes the applicability of the common energy storage medium through analogy and theoretical calculation, and verifies the engineering application feasibility of LTO by discharge performance test and safety test. The results show that the LTO has high discharge capacity and high safety, which can meet the application requirements of the PHPLS, and has the conditions for promotion.
2023,
35: 105004.
doi: 10.11884/HPLPB202335.230123
Abstract:
Based on the theory of multiple avalanche domains, a two-dimensional numerical model for GaAs PCSS with opposed electrode structure is established. The influence of the width of the trigger region on the output characteristics of GaAs PCSS is investigated. Firstly, the switching transient of PCSS is analyzed. The results show that the rapid increase of the carrier concentration and the drastic evolution of the charge domain make PCSS operate in the ultrafast-switching mode. On this basis, this paper studies the influence of the width on the output characteristics of PCSS. The results show that the increase in the width can accelerate the rapid multiplication of carrier concentration and the rapid evolution of avalanche ionization domain, thus shorten the delay time and switching time of PCSS. Further more, the effects of different trigger positions on the delay time and switching time are analyzed. The results show that the delay time under cathode triggering is significantly lower than that under anode triggering, and the switching time is almost unaffected by the trigger position. The above conclusions can provide significant reference for the study on time jitter and synchronization of GaAs PCSS.
Based on the theory of multiple avalanche domains, a two-dimensional numerical model for GaAs PCSS with opposed electrode structure is established. The influence of the width of the trigger region on the output characteristics of GaAs PCSS is investigated. Firstly, the switching transient of PCSS is analyzed. The results show that the rapid increase of the carrier concentration and the drastic evolution of the charge domain make PCSS operate in the ultrafast-switching mode. On this basis, this paper studies the influence of the width on the output characteristics of PCSS. The results show that the increase in the width can accelerate the rapid multiplication of carrier concentration and the rapid evolution of avalanche ionization domain, thus shorten the delay time and switching time of PCSS. Further more, the effects of different trigger positions on the delay time and switching time are analyzed. The results show that the delay time under cathode triggering is significantly lower than that under anode triggering, and the switching time is almost unaffected by the trigger position. The above conclusions can provide significant reference for the study on time jitter and synchronization of GaAs PCSS.
Numerical simulation of hydrogen distribution characteristics in reactor space under severe accident
2023,
35: 106001.
doi: 10.11884/HPLPB202335.230093
Abstract:
The effects of zero equation model and k-ε model on hydrogen distribution have been analyzed by computational fluid dynamics program CFX, and the hydrogen distribution characteristics in the reactor space of marine reactor under typical water loss induced severe accident could be numerically simulated. The results show that it is more reasonable to use the k-ε model to simulate the hydrogen distribution in the reactor space during the concentrated release stage of hydrogen. During the period of severe accidents, the pressure changes at each point in the reactor space could be regarded as basically the same, and the temperature in the space will not continue to rise. Hydrogen forms a relatively obvious concentration gradient in the reactor space. At the top area of the reactor space and the area near the break the hydrogen concentration is abviously rising. After the hydrogen injection, the average vapor concentration in the reactor space is not high enough to maintain the inert environment, and there is a possibility of hydrogen combustion in the reactor cabin space. This study provide a basis for the research of hydrogen risk of marine reactor.
The effects of zero equation model and k-ε model on hydrogen distribution have been analyzed by computational fluid dynamics program CFX, and the hydrogen distribution characteristics in the reactor space of marine reactor under typical water loss induced severe accident could be numerically simulated. The results show that it is more reasonable to use the k-ε model to simulate the hydrogen distribution in the reactor space during the concentrated release stage of hydrogen. During the period of severe accidents, the pressure changes at each point in the reactor space could be regarded as basically the same, and the temperature in the space will not continue to rise. Hydrogen forms a relatively obvious concentration gradient in the reactor space. At the top area of the reactor space and the area near the break the hydrogen concentration is abviously rising. After the hydrogen injection, the average vapor concentration in the reactor space is not high enough to maintain the inert environment, and there is a possibility of hydrogen combustion in the reactor cabin space. This study provide a basis for the research of hydrogen risk of marine reactor.
2023,
35: 106002.
doi: 10.11884/HPLPB202335.230129
Abstract:
As a key component of accelerators, beam collimators are used to absorb the beam halo particles that are not in the predetermined orbit. Due to its good conductivity and collimation efficiency, copper is widely used in beam collimators as the absorber material. In general, absorbers are located in ultra-high vacuum environment, and also loaded with high beam power, different surface treatment processes of the absorber will directly affect its heat transfer performance and vacuum performance. To evaluate the effect of the surface treatment of oxygen-free copper, the surface chemical corrosion blackening treatment, high temperature oxidation treatment and mechanical processing treatment are carried out respectively. The test results show that the thermal radiation coefficient and outgassing rate of copper blocks are increased obviously with surface blackening, however, the surface heat radiation coefficient of the copper blocks after high temperature oxidation is close to that of the machined copper block, while the outgassing rate increases a little. Taking the CSNS-II momentum collimator as the research object, with the beam load, blackening oxygen-free copper is used as the absorber, the maximum temperature can be controlled below 125 ℃, and the pressure of the collimator can meet the operation requirements by adding two ion pumps.
As a key component of accelerators, beam collimators are used to absorb the beam halo particles that are not in the predetermined orbit. Due to its good conductivity and collimation efficiency, copper is widely used in beam collimators as the absorber material. In general, absorbers are located in ultra-high vacuum environment, and also loaded with high beam power, different surface treatment processes of the absorber will directly affect its heat transfer performance and vacuum performance. To evaluate the effect of the surface treatment of oxygen-free copper, the surface chemical corrosion blackening treatment, high temperature oxidation treatment and mechanical processing treatment are carried out respectively. The test results show that the thermal radiation coefficient and outgassing rate of copper blocks are increased obviously with surface blackening, however, the surface heat radiation coefficient of the copper blocks after high temperature oxidation is close to that of the machined copper block, while the outgassing rate increases a little. Taking the CSNS-II momentum collimator as the research object, with the beam load, blackening oxygen-free copper is used as the absorber, the maximum temperature can be controlled below 125 ℃, and the pressure of the collimator can meet the operation requirements by adding two ion pumps.
