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RSS2023 Vol. 35, No. 5
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2023,
35: 1-2.
2023,
35: 051001.
doi: 10.11884/HPLPB202335.220235
Abstract:
The increase in junction temperature is an important factor affecting the output power of master oscillator power amplifier (MOPA) diode laser chip. To achieve the packaging and efficient heat dissipation of the multi-electrode MOPA semiconductor laser chip, a packaging structure that combining P-side up with heat spreader was proposed. An analytical three-dimensional thermal model was employed to study the influence on junction temperature between the P-side down, P-side up without heat spreader and P-side up with heat spreader. According to the three-dimensional thermal model, the conduction-cooled capability between P-side up with heat spreader and P-side down is uniform in this paper. Moreover, the packaging can lead to a maximal 40% decrease on junction temperature. By the way, the P-side up with heat spreader structure was used in MOPA diode laser chip in experiment then 10.5 W output power and the spectrum width (FWHM)＜0.1 nm of the MOPA chip were obtained in CW mode.
The increase in junction temperature is an important factor affecting the output power of master oscillator power amplifier (MOPA) diode laser chip. To achieve the packaging and efficient heat dissipation of the multi-electrode MOPA semiconductor laser chip, a packaging structure that combining P-side up with heat spreader was proposed. An analytical three-dimensional thermal model was employed to study the influence on junction temperature between the P-side down, P-side up without heat spreader and P-side up with heat spreader. According to the three-dimensional thermal model, the conduction-cooled capability between P-side up with heat spreader and P-side down is uniform in this paper. Moreover, the packaging can lead to a maximal 40% decrease on junction temperature. By the way, the P-side up with heat spreader structure was used in MOPA diode laser chip in experiment then 10.5 W output power and the spectrum width (FWHM)＜0.1 nm of the MOPA chip were obtained in CW mode.
2023,
35: 051002.
doi: 10.11884/HPLPB202335.220347
Abstract:
To investigate the effects of the high-speed airflow on the laser ablation characteristics of C/SiC composites, comparative study of laser ablation experiments under different environment conditions, including static air, Mach 1.8, Mach 3.0, Mach 6.0, were conducted by utilizing the joint experiment system integrating the laser and wind tunnel device. Experimental results show that, compared with the static air condition, the high-speed airflow had a remarkable impact on the laser ablation characteristics of C/SiC composites. The “washing effects” induced by the high-speed airflow made the ablation pit wider, deeper, smoother. Meanwhile, the linear ablation rate and mass ablation rate enlarged with the increasing airflow velocity, which was mainly due to the increased sublimation rate and erosion rate caused by the decreased local static pressure and increased dynamic pressure, respectively. Besides, the contrast experimental study of 2D and 3DN C/SiC composites were conducted to investigate the influences of braided structure of C/SiC composites. Results show thatdue to the factors suchas lower heat conduction capacity along the thickness direction, the lower porosity, the ablation resistance performance of 2D C/SiC composites was superior to that of 3D C/SiC.
To investigate the effects of the high-speed airflow on the laser ablation characteristics of C/SiC composites, comparative study of laser ablation experiments under different environment conditions, including static air, Mach 1.8, Mach 3.0, Mach 6.0, were conducted by utilizing the joint experiment system integrating the laser and wind tunnel device. Experimental results show that, compared with the static air condition, the high-speed airflow had a remarkable impact on the laser ablation characteristics of C/SiC composites. The “washing effects” induced by the high-speed airflow made the ablation pit wider, deeper, smoother. Meanwhile, the linear ablation rate and mass ablation rate enlarged with the increasing airflow velocity, which was mainly due to the increased sublimation rate and erosion rate caused by the decreased local static pressure and increased dynamic pressure, respectively. Besides, the contrast experimental study of 2D and 3DN C/SiC composites were conducted to investigate the influences of braided structure of C/SiC composites. Results show thatdue to the factors suchas lower heat conduction capacity along the thickness direction, the lower porosity, the ablation resistance performance of 2D C/SiC composites was superior to that of 3D C/SiC.
2023,
35: 051003.
doi: 10.11884/HPLPB202335.220256
Abstract:
Vortex beams with ultra-high brilliance can greatly enrich the light and matter interaction process and even shed light on the unexpected information in relativistic nonlinear optics. Thus, we propose a scheme for relativistic intense vortex harmonic radiation by use of bi-circular Laguerre-Gaussian lasers irradiating relativistic plasmas. According to the law of conservation of photon energy and angular momentum during the generation of higher-order harmonics, the emitted harmonics own controllable spin and orbital angular momentum simultaneously, as the three-dimensional particle-in-cell simulation results shown. Based on this discussion, the methods of adjusting harmonic order, polarization state (spin angular momentum) and topological charge number (orbital angular momentum) are proposed. It is found that if frequency ratio and circular polarization state of the bi-chromatic Laguerre-Gaussian laser are changed, such as with the same right-handed or left-handed circular polarization. The harmonic characteristics, including the harmonic order, the polarization state and the vortex order are flexibly controlled. Therefore, this work provides an efficient and practical approach to produce bright, spectral tunable harmonic radiation with designable spin and orbital angular momentum, which may own the application prospect going from optical communications, bio-photonics, optical micromanipulations to ion accelerations.
Vortex beams with ultra-high brilliance can greatly enrich the light and matter interaction process and even shed light on the unexpected information in relativistic nonlinear optics. Thus, we propose a scheme for relativistic intense vortex harmonic radiation by use of bi-circular Laguerre-Gaussian lasers irradiating relativistic plasmas. According to the law of conservation of photon energy and angular momentum during the generation of higher-order harmonics, the emitted harmonics own controllable spin and orbital angular momentum simultaneously, as the three-dimensional particle-in-cell simulation results shown. Based on this discussion, the methods of adjusting harmonic order, polarization state (spin angular momentum) and topological charge number (orbital angular momentum) are proposed. It is found that if frequency ratio and circular polarization state of the bi-chromatic Laguerre-Gaussian laser are changed, such as with the same right-handed or left-handed circular polarization. The harmonic characteristics, including the harmonic order, the polarization state and the vortex order are flexibly controlled. Therefore, this work provides an efficient and practical approach to produce bright, spectral tunable harmonic radiation with designable spin and orbital angular momentum, which may own the application prospect going from optical communications, bio-photonics, optical micromanipulations to ion accelerations.
2023,
35: 052001.
doi: 10.11884/HPLPB202335.220153
Abstract:
Low-coherent light pulses with precise time-shaping capability have the potential to suppress the instability of laser-plasma interactions in laser inertial confinement fusion, but related research is currently lacking. In this paper, the law of the influence of the amplitude modulator on the time-frequency characteristics of broadband low-coherent light was studied, and the intensity of the light pulse was modulated by changing the RF coefficient and bias voltage of the Mach-Zehnder interferometric amplitude modulator. The time domain waveform distribution, spectrum and complex coherence modulus curve of the modulated light pulse were analyzed. The research shows that the RF coefficient has no obvious modulation on the spectral composition and temporal coherence of the light pulse, and the RF coefficient has an optimal working range, which makes the waveform fidelity of the output light pulse the best. When the bias voltage is at half-wave voltage, the time domain waveform fidelity of the optical pulse is the best, and the temporal coherence is the lowest, but the spectral components are missing. The arm length difference of the modulator is calculated from the measured spectrum, and the influence of the arm length difference and bias voltage on the frequency domain characteristics of the broadband low-coherent light is simulated theoretically, the results are in good agreement with the experimental results. As the actual electro-optic overlap integration factor changes with the voltage, there is an error between the simulation and the actual measurement results. However, the laws obtained from the research will provide a more clear direction for low coherent pulse precision shaping system development.
Low-coherent light pulses with precise time-shaping capability have the potential to suppress the instability of laser-plasma interactions in laser inertial confinement fusion, but related research is currently lacking. In this paper, the law of the influence of the amplitude modulator on the time-frequency characteristics of broadband low-coherent light was studied, and the intensity of the light pulse was modulated by changing the RF coefficient and bias voltage of the Mach-Zehnder interferometric amplitude modulator. The time domain waveform distribution, spectrum and complex coherence modulus curve of the modulated light pulse were analyzed. The research shows that the RF coefficient has no obvious modulation on the spectral composition and temporal coherence of the light pulse, and the RF coefficient has an optimal working range, which makes the waveform fidelity of the output light pulse the best. When the bias voltage is at half-wave voltage, the time domain waveform fidelity of the optical pulse is the best, and the temporal coherence is the lowest, but the spectral components are missing. The arm length difference of the modulator is calculated from the measured spectrum, and the influence of the arm length difference and bias voltage on the frequency domain characteristics of the broadband low-coherent light is simulated theoretically, the results are in good agreement with the experimental results. As the actual electro-optic overlap integration factor changes with the voltage, there is an error between the simulation and the actual measurement results. However, the laws obtained from the research will provide a more clear direction for low coherent pulse precision shaping system development.
2023,
35: 052002.
doi: 10.11884/HPLPB202335.220280
Abstract:
The dynamic process of load plasma impacting on the foam cylinder was studied by two-dimensional radiation hydrodynamics simulation, and the influence of the shape of load plasma with disturbance on the radiation temperature in dynamic hohlraum was explored. The results show that Rayleigh-Taylor fluid instability will be generated after the disturbed load plasma impacting on the foam, and the development of RT instability will lead to the radiation leakage in the light-thin region of the load plasma, which will reduce the radiation temperature in the dynamic hohlraum. The larger the amplitude and the wavelength of disturbance in the load plasma, the more serious radiation leakage occurs, and the lower the radiation temperature will be in the dynamic hohlraum under the same kinetic energy loading condition.
The dynamic process of load plasma impacting on the foam cylinder was studied by two-dimensional radiation hydrodynamics simulation, and the influence of the shape of load plasma with disturbance on the radiation temperature in dynamic hohlraum was explored. The results show that Rayleigh-Taylor fluid instability will be generated after the disturbed load plasma impacting on the foam, and the development of RT instability will lead to the radiation leakage in the light-thin region of the load plasma, which will reduce the radiation temperature in the dynamic hohlraum. The larger the amplitude and the wavelength of disturbance in the load plasma, the more serious radiation leakage occurs, and the lower the radiation temperature will be in the dynamic hohlraum under the same kinetic energy loading condition.
2023,
35: 053001.
doi: 10.11884/HPLPB202335.220352
Abstract:
Power distribution network is the basic unit of unmanned aerial vehicle (UAV) positioning system, but also the weak link of electromagnetic interference (EMI). The conduction coupling interference effect of power distribution network (PDN) is the main cause of positioning system failure. To improve the accuracy of positioning system sensitivity of electromagnetic interference prediction model, based on the Taylor series description method for nonlinear systems, the Taylor series behavior level model coefficient is characterized as interference frequency related function, thus a UAV positioning system PDN electromagnetic interference response prediction model is established, which analyzes and predicts PDN’s nonlinear dc bias voltage under the circumstance of interference. The results show that the Taylor series based PDN EMI response prediction model can accurately predict the nonlinear DC bias of PDN under 250−400 MHz EMI, and the prediction error is within 3%.
Power distribution network is the basic unit of unmanned aerial vehicle (UAV) positioning system, but also the weak link of electromagnetic interference (EMI). The conduction coupling interference effect of power distribution network (PDN) is the main cause of positioning system failure. To improve the accuracy of positioning system sensitivity of electromagnetic interference prediction model, based on the Taylor series description method for nonlinear systems, the Taylor series behavior level model coefficient is characterized as interference frequency related function, thus a UAV positioning system PDN electromagnetic interference response prediction model is established, which analyzes and predicts PDN’s nonlinear dc bias voltage under the circumstance of interference. The results show that the Taylor series based PDN EMI response prediction model can accurately predict the nonlinear DC bias of PDN under 250−400 MHz EMI, and the prediction error is within 3%.
2023,
35: 053002.
doi: 10.11884/HPLPB202335.220401
Abstract:
A 13×14 planar split ring resonator (SRR) antenna array with the Chebyshev feed network is proposed. This antenna array consists of antenna elements and a Chebyshev feed network. Based on the principle of the Yagi antenna, the radiating patch is designed as an antenna element of the director with the metal ground being the reflector. The radiating patch is composed of three SRRs, an I-shaped resonator and two circular monopoles to enhance the radiation capability of the antenna element and improves the antenna gain. The feed of the antenna element is composed of arc monopoles, which improves the flexibility of adjusting the impedance matching. Furthermore, the calculation of the current matrix is used to guide the design of the Chebyshev feed network, and the non-uniform current distribution is used to reduce the side lobes. Moreover, the antenna element substrate is vertically erected on the substrate of the feed network to reduce the aperture size of the array with the feed network. Finally, the antenna array achieves a high gain of 22.3 dBi and low sidelobe level of −16 dB and −17.66 dB in E-plane and H-respectively.
A 13×14 planar split ring resonator (SRR) antenna array with the Chebyshev feed network is proposed. This antenna array consists of antenna elements and a Chebyshev feed network. Based on the principle of the Yagi antenna, the radiating patch is designed as an antenna element of the director with the metal ground being the reflector. The radiating patch is composed of three SRRs, an I-shaped resonator and two circular monopoles to enhance the radiation capability of the antenna element and improves the antenna gain. The feed of the antenna element is composed of arc monopoles, which improves the flexibility of adjusting the impedance matching. Furthermore, the calculation of the current matrix is used to guide the design of the Chebyshev feed network, and the non-uniform current distribution is used to reduce the side lobes. Moreover, the antenna element substrate is vertically erected on the substrate of the feed network to reduce the aperture size of the array with the feed network. Finally, the antenna array achieves a high gain of 22.3 dBi and low sidelobe level of −16 dB and −17.66 dB in E-plane and H-respectively.
2023,
35: 053003.
doi: 10.11884/HPLPB202335.220338
Abstract:
Fast leading-edge RF pulse emission is an advantageous function of solid-state active phased arrays. In this paper, the conditions of realizing fast leading-edge RF pulse emission are analyzed, including influences and design points of RF excitation transmission, power amplification, timing synchronization and aperture fill time. The conclusions are applied to a prototype design of an X-band solid-state active phased array, followed by validation test. RF pulses emitted by thousands of solid-state active channels are spatially combined into one, with the leading-edge shorter than 5 ns, which validates the analysis.
Fast leading-edge RF pulse emission is an advantageous function of solid-state active phased arrays. In this paper, the conditions of realizing fast leading-edge RF pulse emission are analyzed, including influences and design points of RF excitation transmission, power amplification, timing synchronization and aperture fill time. The conclusions are applied to a prototype design of an X-band solid-state active phased array, followed by validation test. RF pulses emitted by thousands of solid-state active channels are spatially combined into one, with the leading-edge shorter than 5 ns, which validates the analysis.
2023,
35: 053004.
doi: 10.11884/HPLPB202335.220370
Abstract:
To realize the on-line measurement of power, frequency and phase of modular relativistic triaxial klystron amplifier, a compact directional coupler with high directivity and bandwidth is simulated and experimentally studied. Based on the theoretical analysis of the pinhole coupling theory and the phase superposition principle, a dual-hole compact directional coupler is designed. On this basis, the main and auxiliary waveguides are connected orthogonally, and the coupling holes are distributed along the axial and angular directions, which further shortens the length of the coupler. The parameters of the coupler are optimized by electromagnetic simulation. The simulation results show that when the center frequency is 10 GHz, the coupling degree of the ordinary dual-hole directional coupler to the TM01 mode is −60.68 dB, and the directivity is greater than 20 dB in the bandwidth of 250 MHz, and the coupling area length is 3.49 cm. The coupling degree of the improved directional coupler to the TM01 mode is −58.1 dB, and the directivity is greater than 20 dB in the bandwidth of 300 MHz. At this time, the length of the coupling zone is only 1.8 cm (about 0.6λ）. The cold cavity experimental results of the coupler are in good agreement with the simulation results.
To realize the on-line measurement of power, frequency and phase of modular relativistic triaxial klystron amplifier, a compact directional coupler with high directivity and bandwidth is simulated and experimentally studied. Based on the theoretical analysis of the pinhole coupling theory and the phase superposition principle, a dual-hole compact directional coupler is designed. On this basis, the main and auxiliary waveguides are connected orthogonally, and the coupling holes are distributed along the axial and angular directions, which further shortens the length of the coupler. The parameters of the coupler are optimized by electromagnetic simulation. The simulation results show that when the center frequency is 10 GHz, the coupling degree of the ordinary dual-hole directional coupler to the TM01 mode is −60.68 dB, and the directivity is greater than 20 dB in the bandwidth of 250 MHz, and the coupling area length is 3.49 cm. The coupling degree of the improved directional coupler to the TM01 mode is −58.1 dB, and the directivity is greater than 20 dB in the bandwidth of 300 MHz. At this time, the length of the coupling zone is only 1.8 cm (about 0.6λ）. The cold cavity experimental results of the coupler are in good agreement with the simulation results.
2023,
35: 053005.
doi: 10.11884/HPLPB202335.220211
Abstract:
For examining effects of atmosphere on system generated electromagnetic pulse (SGEMP), the external SGEMP are simulated by the 3D PIC code in pre-ionized plasma and by the PIC-MCC code in low pressure air respectively in the X-ray energy deposition region (50 km to 100 km). For three fluences of X-ray (4×10−3 J/cm2、4×10−2 J/cm2、0.4 J/cm2), the simulations are done in pre-ionized plasma corresponding to two different altitudes (70 km and 80−90 km) and low pressure air corresponding to 56 km altitude each other, and the results are compared with those in vacuum. The variation laws of external SGEMP in pre-ionized plasma and low pressure air are received : the effects have relation to fluence of X-ray, when the fluence of X-ray is low, the magnetic field increases and the electric field decreases in the plasma environment, while the variations of external SGEMP are not obvious in low pressure air; with the fluence of X-ray increasing, the space charge nonlinear effects become more and more obvious, the electric field and magnetic field are enhanced together in both pre-ionized plasma and low pressure air, and the enhancement effects are more significant in low pressure air.
For examining effects of atmosphere on system generated electromagnetic pulse (SGEMP), the external SGEMP are simulated by the 3D PIC code in pre-ionized plasma and by the PIC-MCC code in low pressure air respectively in the X-ray energy deposition region (50 km to 100 km). For three fluences of X-ray (4×10−3 J/cm2、4×10−2 J/cm2、0.4 J/cm2), the simulations are done in pre-ionized plasma corresponding to two different altitudes (70 km and 80−90 km) and low pressure air corresponding to 56 km altitude each other, and the results are compared with those in vacuum. The variation laws of external SGEMP in pre-ionized plasma and low pressure air are received : the effects have relation to fluence of X-ray, when the fluence of X-ray is low, the magnetic field increases and the electric field decreases in the plasma environment, while the variations of external SGEMP are not obvious in low pressure air; with the fluence of X-ray increasing, the space charge nonlinear effects become more and more obvious, the electric field and magnetic field are enhanced together in both pre-ionized plasma and low pressure air, and the enhancement effects are more significant in low pressure air.
2023,
35: 053006.
doi: 10.11884/HPLPB202335.230006
Abstract:
The electromagnetic waves radiating inside a building can cause reverberation effect, which can be evaluated using power balance method (PWB) to quickly determine the field level of indoor electromagnetic environment. However, the current calculation models of wall coupling cross section (CCS) in PWB method for electricallally large enclosure are based on the assumption that electromagnetic waves cannot penetrate through the enclosure walls. As a result, these models are not applicable for calculating the CCS of penetrable indoor building walls. To address this issue, a novel CCS model applicable for building walls with finite thickness is presented. The proposed CCS model considers the thickness and electromagnetic characteristics of building walls and can effectively reflect the effects of electromagnetic wave’s multiple reflections inside the walls on the indoor electromagnetic environment. The proposed model has been employed to estimate the indoor electric field level. The predicted results agree with the measurements, which validates the proposed CCS model for building walls with finite thickness.
The electromagnetic waves radiating inside a building can cause reverberation effect, which can be evaluated using power balance method (PWB) to quickly determine the field level of indoor electromagnetic environment. However, the current calculation models of wall coupling cross section (CCS) in PWB method for electricallally large enclosure are based on the assumption that electromagnetic waves cannot penetrate through the enclosure walls. As a result, these models are not applicable for calculating the CCS of penetrable indoor building walls. To address this issue, a novel CCS model applicable for building walls with finite thickness is presented. The proposed CCS model considers the thickness and electromagnetic characteristics of building walls and can effectively reflect the effects of electromagnetic wave’s multiple reflections inside the walls on the indoor electromagnetic environment. The proposed model has been employed to estimate the indoor electric field level. The predicted results agree with the measurements, which validates the proposed CCS model for building walls with finite thickness.
2023,
35: 054001.
doi: 10.11884/HPLPB202335.230061
Abstract:
The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron radiation source that will operate in high energy region in China. The HEPS accelerator consists of a linear accelerator, a booster, a storage ring and three transfer lines. This paper presents important progress on the HEPS Linac. The 500 MeV Linac has been constructed using S-band normal conducting structures, including a thermionic cathode electron gun, beam bunching system, and main accelerating section. After completing the equipment installation and high-power RF conditioning, the beam commissioning was started on March 9, 2023. The beam was successfully transferred to the end of the Linac on the same day, and a beam with 500 MeV of energy and 2.5 nC of pulse charge was achieved within 5 days. As measured up to date at the Linac exit, the beam energy spread and energy stability are 0.4% and 0.06% respectively, and the horizontal and vertical geometric emittances are 233 nm and 145 nm, respectively. The maximum bunch charge reaches up to 7.0 nC. Further beam commissioning will be implemented to gain full performance of the Linac.
2023,
35: 054002.
doi: 10.11884/HPLPB202335.220364
Abstract:
Circular electron-positron collider (CEPC) is a double ring collider with a circumference of 100 km and a maximum energy of 120 GeV. To meet the needs of different energy particles injected from the booster to the collision ring, an off-axis injection system of the collision ring is designed for the W and Z energy modes to realize the accumulation of beam. To improve the injection efficiency, also be compatible with different injection energy, and different beam filling modes, and at the same time reduce the disturbance of other bucket by the kicker magnet during the injection process as much as possible, the off-axis injection kicker magnet system of the collision ring is required to be a trapezoidal wave pulse discharge system with a rise time and falling time of less than 200 ns and a pulse bottom width adjustment range of 440−2420 ns. Compared with the common lumped-inductance kicker magnet, the delay-line kicker magnet has better dynamic response characteristics and is suitable for producing a trapezoidal pulse with steeper front and more ideal waveform. In this paper, according to the physical requirements of beam injection of CEPC, the physical design and structure design of a delay-line kicker magnet are completed, and the PSpice and Opera programs are used for simulation. The design results show that the delay-line kicker magnet is composed of 26 LC units superimposed. The total length of the kicker magnet is 1018 mm, and the magnetic effective length is 942 mm. In [−20, 20] mm magnet aperture, the magnetic field strength is 0.042 1 T, the magnetic field uniformity is better than ±0.2%; the total rise time (10%−90%) of the kicker magnet system is 193 ns, and the fall time (90%−10%) is 191 ns. Theoretical analysis, PSpice program and Opera program simulation all verify the feasibility of the magnet design scheme.
Circular electron-positron collider (CEPC) is a double ring collider with a circumference of 100 km and a maximum energy of 120 GeV. To meet the needs of different energy particles injected from the booster to the collision ring, an off-axis injection system of the collision ring is designed for the W and Z energy modes to realize the accumulation of beam. To improve the injection efficiency, also be compatible with different injection energy, and different beam filling modes, and at the same time reduce the disturbance of other bucket by the kicker magnet during the injection process as much as possible, the off-axis injection kicker magnet system of the collision ring is required to be a trapezoidal wave pulse discharge system with a rise time and falling time of less than 200 ns and a pulse bottom width adjustment range of 440−2420 ns. Compared with the common lumped-inductance kicker magnet, the delay-line kicker magnet has better dynamic response characteristics and is suitable for producing a trapezoidal pulse with steeper front and more ideal waveform. In this paper, according to the physical requirements of beam injection of CEPC, the physical design and structure design of a delay-line kicker magnet are completed, and the PSpice and Opera programs are used for simulation. The design results show that the delay-line kicker magnet is composed of 26 LC units superimposed. The total length of the kicker magnet is 1018 mm, and the magnetic effective length is 942 mm. In [−20, 20] mm magnet aperture, the magnetic field strength is 0.042 1 T, the magnetic field uniformity is better than ±0.2%; the total rise time (10%−90%) of the kicker magnet system is 193 ns, and the fall time (90%−10%) is 191 ns. Theoretical analysis, PSpice program and Opera program simulation all verify the feasibility of the magnet design scheme.
2023,
35: 055001.
doi: 10.11884/HPLPB202335.220310
Abstract:
The scheme of a dual short pulse output structure is proposed, according to the concept that two microwave device driven by the same pulsed accelerator can produced stable dual-frequency high power microwave (HPM) simultaneously. Structure model of a dual short pulse output structure is designed, which is connected to the main switch and can transmit the high voltage nanosecond pulse generated by the switch to the HPM generator. The two-channel pulse is produced by the same pulse source and has good consistency. In this paper, the pulse transmission process of the dual short pulse transmission structure is modeled and simulated, and the influence of electrical parameters such as transmission line impedance and input pulse front on output waveform quality is studied. The risk analysis about insulation and structural optimization are completed. It is estimated that the output pulse quality of the simultaneous output line is equal to that of the single transmission line under 4−8 ns quasi-square wave input pulse, and the overshoot oscillation is less than 20%, the flat top oscillation is less than 1%, and it can meet the insulation requirement.
The scheme of a dual short pulse output structure is proposed, according to the concept that two microwave device driven by the same pulsed accelerator can produced stable dual-frequency high power microwave (HPM) simultaneously. Structure model of a dual short pulse output structure is designed, which is connected to the main switch and can transmit the high voltage nanosecond pulse generated by the switch to the HPM generator. The two-channel pulse is produced by the same pulse source and has good consistency. In this paper, the pulse transmission process of the dual short pulse transmission structure is modeled and simulated, and the influence of electrical parameters such as transmission line impedance and input pulse front on output waveform quality is studied. The risk analysis about insulation and structural optimization are completed. It is estimated that the output pulse quality of the simultaneous output line is equal to that of the single transmission line under 4−8 ns quasi-square wave input pulse, and the overshoot oscillation is less than 20%, the flat top oscillation is less than 1%, and it can meet the insulation requirement.
2023,
35: 055002.
doi: 10.11884/HPLPB202335.220291
Abstract:
With the development of pulsed power technology, nanosecond pulsed electric field has been gradually applied to plasma water treatment, irreversible electroporation for tumor ablation and other technologies. To meet the application requirements of nanosecond pulses, the power supply is required to output high voltage exceeding 10 kV, with narrow nanosecond pulse width and fast rising edge. At the same time, it is required to reduce the size and the cost. The nanosecond pulse power supply is an inductor-isolated Marx generator, whose circuit can realize modular superposition. Inductive isolation can reduce the number of switches and raise the charging voltage to obtain a higher voltage output. The driving circuit has only one control signal and one DC power supply module, which can control all discharge tubes at the same time after power amplification and magnetic isolation. The driving circuit has the advantages of simple structure, low cost, small volume and high voltage resistance. The power supply has 24 stages. Under the condition of 50 kΩ resistive load, high voltage pulses with 500 ns pulse width, amplitude of 0−14 kV and adjustable frequency of 0.5−1 kHz are generated. The size of the main circuit is only 23 cm×10 cm×12 cm.
With the development of pulsed power technology, nanosecond pulsed electric field has been gradually applied to plasma water treatment, irreversible electroporation for tumor ablation and other technologies. To meet the application requirements of nanosecond pulses, the power supply is required to output high voltage exceeding 10 kV, with narrow nanosecond pulse width and fast rising edge. At the same time, it is required to reduce the size and the cost. The nanosecond pulse power supply is an inductor-isolated Marx generator, whose circuit can realize modular superposition. Inductive isolation can reduce the number of switches and raise the charging voltage to obtain a higher voltage output. The driving circuit has only one control signal and one DC power supply module, which can control all discharge tubes at the same time after power amplification and magnetic isolation. The driving circuit has the advantages of simple structure, low cost, small volume and high voltage resistance. The power supply has 24 stages. Under the condition of 50 kΩ resistive load, high voltage pulses with 500 ns pulse width, amplitude of 0−14 kV and adjustable frequency of 0.5−1 kHz are generated. The size of the main circuit is only 23 cm×10 cm×12 cm.
2023,
35: 055003.
doi: 10.11884/HPLPB202335.220281
Abstract:
Aiming at the electromagnetic flanging process for small aluminum alloy tube fittings, the driving coil is placed on the outside of the end of the tube, and the dual-frequency discharge current method is used to generate the attractive electromagnetic force to realize flanging in the existing method. However, its flanging ability is not strong, under this background, an attractive electromagnetic force flanging method with a magnetic field shaper is proposed. On the basis of the existing method, a magnetic field shaper is introduced, which can change the magnetic field configuration, optimize the electromagnetic force distribution and increase the axial electromagnetic force, so as to achieve the purpose of enhancing the flanging effect. To verify the feasibility of this method, firstly, the electromagnetic-structural fully coupled finite element simulation model of the tube flanging process was built, and the flanging effects after introducing different magnetic field shaper were compared, and it is concluded that the stepped magnetic field shaper has the best effect. The flanging process were analyzed under the working conditions with stepped magnetic field shaper and without magnetic field shaper. The results show that the flanging angle of the tube fittings is increased from 38° to 90° compared with the case without the magnetic field shaper. Further analysis shows that the radial component of the magnetic flux density and the annular component of the eddy current density increase to 164% and 135%, respectively. The distribution of the electromagnetic force acting on the pipe fittings changes, and the density of the axial electromagnetic force increases significantly at the peak time, increasing to 211%. The method further improves the electromagnetic flanging forming of small aluminum alloy tube fittings, and it has a certain significance for expanding the application of electromagnetic forming technology in aluminum alloy tube flanging.
Aiming at the electromagnetic flanging process for small aluminum alloy tube fittings, the driving coil is placed on the outside of the end of the tube, and the dual-frequency discharge current method is used to generate the attractive electromagnetic force to realize flanging in the existing method. However, its flanging ability is not strong, under this background, an attractive electromagnetic force flanging method with a magnetic field shaper is proposed. On the basis of the existing method, a magnetic field shaper is introduced, which can change the magnetic field configuration, optimize the electromagnetic force distribution and increase the axial electromagnetic force, so as to achieve the purpose of enhancing the flanging effect. To verify the feasibility of this method, firstly, the electromagnetic-structural fully coupled finite element simulation model of the tube flanging process was built, and the flanging effects after introducing different magnetic field shaper were compared, and it is concluded that the stepped magnetic field shaper has the best effect. The flanging process were analyzed under the working conditions with stepped magnetic field shaper and without magnetic field shaper. The results show that the flanging angle of the tube fittings is increased from 38° to 90° compared with the case without the magnetic field shaper. Further analysis shows that the radial component of the magnetic flux density and the annular component of the eddy current density increase to 164% and 135%, respectively. The distribution of the electromagnetic force acting on the pipe fittings changes, and the density of the axial electromagnetic force increases significantly at the peak time, increasing to 211%. The method further improves the electromagnetic flanging forming of small aluminum alloy tube fittings, and it has a certain significance for expanding the application of electromagnetic forming technology in aluminum alloy tube flanging.
2023,
35: 055004.
doi: 10.11884/HPLPB202335.220304
Abstract:
The magnetic switch is one of the switching devices with excellent performance that can be selected for the repetitive frequency pulse power system. At present, the simulation model of the magnetic switch is a pure circuit model established based on the macroscopic characteristics of the volt-second integral, without considering the change of the magnetic core characteristics during the core saturation process, it is difficult to accurately predict the pre-pulse on the magnetic switch load, and the front error of the waveform is also larger. In this paper, the hysteresis loop and initial magnetization curve of the Fe-based nanocrystalline magnetic core under fast pulse excitation are tested and obtained. Using the key parameters of the magnetic core hysteresis loop, the J-A parameter of the magnetic core under pulse excitation is extracted, which is used to define Magnetic core properties for a magnetic switch model in multi-physics field. For the magnetic switch pulse compression circuit, the field-circuit coupling simulation model was established by using the multi-physics simulation software COMSOL, and the output waveform was simulated. Compared with the experimental results, the pre-pulse amplitude error is 2%, the peak error is 2%, and the front error is 5%, which proves the validity and accuracy of the established field-circuit coupling simulation model.
The magnetic switch is one of the switching devices with excellent performance that can be selected for the repetitive frequency pulse power system. At present, the simulation model of the magnetic switch is a pure circuit model established based on the macroscopic characteristics of the volt-second integral, without considering the change of the magnetic core characteristics during the core saturation process, it is difficult to accurately predict the pre-pulse on the magnetic switch load, and the front error of the waveform is also larger. In this paper, the hysteresis loop and initial magnetization curve of the Fe-based nanocrystalline magnetic core under fast pulse excitation are tested and obtained. Using the key parameters of the magnetic core hysteresis loop, the J-A parameter of the magnetic core under pulse excitation is extracted, which is used to define Magnetic core properties for a magnetic switch model in multi-physics field. For the magnetic switch pulse compression circuit, the field-circuit coupling simulation model was established by using the multi-physics simulation software COMSOL, and the output waveform was simulated. Compared with the experimental results, the pre-pulse amplitude error is 2%, the peak error is 2%, and the front error is 5%, which proves the validity and accuracy of the established field-circuit coupling simulation model.
2023,
35: 055005.
doi: 10.11884/HPLPB202335.220333
Abstract:
Microfluidic plasma is a new process intensification strategy that combines the advantages of both microfluidic and plasma techniques. It can improve the uniformity and stability of the reaction process, control the reaction contact interface, and avoid rapid quenching of the species while increasing density of the active substances. This work summarizes representative radicals existed in microfluidic plasma and the relevant characterization techniques. Then, the microfluidic plasmas are classified into three categories based on the characteristic structure of the reactors. Afterwards, selective examples are given to demonstrate typical applications of the microfluidic plasma process intensification strategy, such as chemical synthesis, surface modification, nanomaterials preparation, contaminant detection, and biomedical purpose. Finally, the development trend of this technique is prospected.
2023,
35: 056001.
doi: 10.11884/HPLPB202335.220398
Abstract:
The lead-bismuth eutectic (LBE) is one of the most promising coolants for the lead-cooled fast reactor (LFR) and the accelerator driven sub-critical system (ADS). The liquid metal corrosion (LMC) and stress corrosion in liquid LBE environments are inevitable critical issues for structural materials such as ferritic/martensitic steel, austenitic stainless steel, which are potential safety hazards for the service of structural materials. In this work, the corrosion types and liquid metal embrittlement (LME) mechanism of steel are illustrated, the influences of material design and processing (chemical composition, heat treatment, processing and manufacturing and surface treatment) and corrosion conditions (temperature, mass fraction of oxygen and time) on the corrosion behavior and of steels are summarized. In addition, stress corrosion and LME in liquid LBE is clarified, and the effects of internal and external factors (types, surface defect, heat treatment, mass fraction of oxygen, corrosion temperature and tensile rates) on the mechanical properties of steels are analyzed. In the end, the future research interests of steels in LBE are prospected. The future steel used in liquid LBE is proposed to optimize the material design and treatment (appropriately increasing the content of Si and Al, surface coating and heat treatment) and control the environmental parameters (temperature, mass fraction of oxygen and corrosion time) in LBE to improve its corrosion resistance.
2023,
35: 056002.
doi: 10.11884/HPLPB202335.230010
Abstract:
Burnup credit has an important impact on improving the efficiency of spent fuel storage. In the burnup credit, the burnup calculation model can affect the nuclide composition deviation, and the more accurate the nuclide composition, the lower the critical safety margin for spent fuel storage. To improve the accuracy of the burnup calculation, a multi-assembly burnup calculation model loaded with different fuel enrichment is proposed in this paper. Six samples of TMI-1 reactor NJ07OG assemblies were calculated, compared and analyzed by using different burnup calculation models. The results show that the average relative deviations of 235U, 238U and 239Pu obtained from the multi-assembly burnup model with different fuel enrichment are closer to zero and the relative deviations are more evenly distributed among the six samples than that of other models.
Burnup credit has an important impact on improving the efficiency of spent fuel storage. In the burnup credit, the burnup calculation model can affect the nuclide composition deviation, and the more accurate the nuclide composition, the lower the critical safety margin for spent fuel storage. To improve the accuracy of the burnup calculation, a multi-assembly burnup calculation model loaded with different fuel enrichment is proposed in this paper. Six samples of TMI-1 reactor NJ07OG assemblies were calculated, compared and analyzed by using different burnup calculation models. The results show that the average relative deviations of 235U, 238U and 239Pu obtained from the multi-assembly burnup model with different fuel enrichment are closer to zero and the relative deviations are more evenly distributed among the six samples than that of other models.
2023,
35: 059001.
doi: 10.11884/HPLPB202335.220353
Abstract:
Atmospheric neutrons can cause the single event effect (SEE) of integrated circuits, resulting in data loss or functional interrupt. The SEE failure rate caused by atmospheric neutrons depends on its flux, thus obtaining the atmospheric neutron flux is the premise of SEE failure rate assessment. In this paper, the atmospheric neutron energy spectra and fluxes in Guangzhou, Lanzhou and Lhasa are measured using the Bonner sphere spectrometers (BSS). Typical characteristics of atmospheric neutron spectrum are obtained. The measured results show that the atmospheric neutron flux in different areas is affected by the altitude, and the terrestrial atmospheric neutron flux increases with the altitude. In addition, the nuclear reaction process of primary cosmic ray particles in the earth’s atmosphere can also be simulated based on the Monte Carlo simulation tools, so as to calculate the atmospheric neutron spectrum. It shows that the measured data of atmospheric neutron spectra are in good agreement with the simulation data. These data can be used in quantitative evaluation of atmospheric neutron-induced SEE of integrated circuits.
Atmospheric neutrons can cause the single event effect (SEE) of integrated circuits, resulting in data loss or functional interrupt. The SEE failure rate caused by atmospheric neutrons depends on its flux, thus obtaining the atmospheric neutron flux is the premise of SEE failure rate assessment. In this paper, the atmospheric neutron energy spectra and fluxes in Guangzhou, Lanzhou and Lhasa are measured using the Bonner sphere spectrometers (BSS). Typical characteristics of atmospheric neutron spectrum are obtained. The measured results show that the atmospheric neutron flux in different areas is affected by the altitude, and the terrestrial atmospheric neutron flux increases with the altitude. In addition, the nuclear reaction process of primary cosmic ray particles in the earth’s atmosphere can also be simulated based on the Monte Carlo simulation tools, so as to calculate the atmospheric neutron spectrum. It shows that the measured data of atmospheric neutron spectra are in good agreement with the simulation data. These data can be used in quantitative evaluation of atmospheric neutron-induced SEE of integrated circuits.
2023,
35: 059002.
doi: 10.11884/HPLPB202335.220396
Abstract:
The phase information of the transmitted object, also known as digital holography, can be obtained by the element interference based on prism pair. This method has the advantages of compact structure, stable interference fringe and high measurement accuracy. In this paper, the ray tracing method is used to establish the equivalent model of ray tracing, considering the azimuth rotation of the prism pair and the eccentricity of the inclined plane. The equivalent model is used to simulate the digital holographic interference fringes, and give the analytic expressions of fringe density change and tilt. The interference digital holograms are obtained and the refractive index distribution is inversed for the micro structure optical elements such as single-mode and multimode fibers. The experimental device of micro imaging unit interference is built, and the actual measurement interference pattern is obtained. The experimental results are consistent with the simulation results, which proves the effectiveness of this model.
The phase information of the transmitted object, also known as digital holography, can be obtained by the element interference based on prism pair. This method has the advantages of compact structure, stable interference fringe and high measurement accuracy. In this paper, the ray tracing method is used to establish the equivalent model of ray tracing, considering the azimuth rotation of the prism pair and the eccentricity of the inclined plane. The equivalent model is used to simulate the digital holographic interference fringes, and give the analytic expressions of fringe density change and tilt. The interference digital holograms are obtained and the refractive index distribution is inversed for the micro structure optical elements such as single-mode and multimode fibers. The experimental device of micro imaging unit interference is built, and the actual measurement interference pattern is obtained. The experimental results are consistent with the simulation results, which proves the effectiveness of this model.
