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, Available online , doi: 10.11884/HPLPB202537.250065
Abstract:
As a new type of laser driver to suppress laser plasma instability, the low-coherence laser driver holds significant research value in the field of laser inertial confinement fusion. To achieve large-bandwidth and high-power low-coherence pulse parametric amplification, this study provides a detailed analysis of the parametric matching characteristics of DKDP crystals with varying deuteration rates under Type-I colinear phase matching conditions. The fundamental parameters, including phase-matching angles, walk-off angles, and parametric bandwidths, are determined. The theoretical parameter bandwidth of the 58% deuterium-doped DKDP crystal is 180 nm. On this basis, a design for broadband low-temporal-coherence optical parametric amplification based on 58%DKDP crystals is proposed, and the theoretical model and the corresponding numerical model are established by the three-wave coupled equations. Furthermore, an experimental investigation of parametric amplification based on 58%-deuterium-doped DKDP crystals is conducted. The center wavelength of the broadband low-coherence signal light is set at1053 nm, while the pump wavelength is fixed at 532 nm. The spectral width is 40 nm with a gain factor of 2.1. The results show that 58% DKDP crystal has a large gain bandwidth, and combined with the colinear phase-matching method, such crystals are expected to enable large-bandwidth and high-gain amplification of low-coherence light.
As a new type of laser driver to suppress laser plasma instability, the low-coherence laser driver holds significant research value in the field of laser inertial confinement fusion. To achieve large-bandwidth and high-power low-coherence pulse parametric amplification, this study provides a detailed analysis of the parametric matching characteristics of DKDP crystals with varying deuteration rates under Type-I colinear phase matching conditions. The fundamental parameters, including phase-matching angles, walk-off angles, and parametric bandwidths, are determined. The theoretical parameter bandwidth of the 58% deuterium-doped DKDP crystal is 180 nm. On this basis, a design for broadband low-temporal-coherence optical parametric amplification based on 58%DKDP crystals is proposed, and the theoretical model and the corresponding numerical model are established by the three-wave coupled equations. Furthermore, an experimental investigation of parametric amplification based on 58%-deuterium-doped DKDP crystals is conducted. The center wavelength of the broadband low-coherence signal light is set at
, Available online , doi: 10.11884/HPLPB202537.250034
Abstract:
Ross pair and filters stack spectrometers are commonly used to detect hard X-ray spectrum. The results of filters stack spectrometer are highly sensitive to the profile of pre-estimated spectrum, while Ross pair is limited to discrete spectrum. Here we provide a Ross pair- filters stack mixed spectrometer, which combining the advantages of traditional filter stack spectrometers and Ross pairs. Each layer of the filter in the traditional filters stack spectrometer has been replaced with a Ross filters pair. Thus the discrete spectrum given by Ross pair can be used as the pre-estimated spectrum for the filters stack to solve the entire x-ray spectrum. Numerical and physical experiments using x-ray tube confirm that the present mixed spectrometer can provide more accurate spectral structures compared to traditional filter stack spectrometers. The compact and lightweight advantages make it widely applicable in hard x-ray spectral measurements.
Ross pair and filters stack spectrometers are commonly used to detect hard X-ray spectrum. The results of filters stack spectrometer are highly sensitive to the profile of pre-estimated spectrum, while Ross pair is limited to discrete spectrum. Here we provide a Ross pair- filters stack mixed spectrometer, which combining the advantages of traditional filter stack spectrometers and Ross pairs. Each layer of the filter in the traditional filters stack spectrometer has been replaced with a Ross filters pair. Thus the discrete spectrum given by Ross pair can be used as the pre-estimated spectrum for the filters stack to solve the entire x-ray spectrum. Numerical and physical experiments using x-ray tube confirm that the present mixed spectrometer can provide more accurate spectral structures compared to traditional filter stack spectrometers. The compact and lightweight advantages make it widely applicable in hard x-ray spectral measurements.
, Available online , doi: 10.11884/HPLPB202537.250063
Abstract:
With the rapid development of science and technology, the application of high-speed optical imaging and ultrafast diagnostic technologies in fields such as science, industry, national defense and medicine is becoming increasingly important. The synchroscan streak camera, as an ultrafast optical phenomenon detection instrument, is used in conjunction with high-repetition-frequency lasers to achieve high-precision time-synchronized pump detection. It realizes high signal-to-noise ratio detection by accumulating and amplifying weak optical signals. However, in the long-term working mode of the existing synchronous scanning circuit, the cumulative high-frequency noise of the signal source device increases accordingly. At the same time, there is a problem of lacking a specific impedance matching design method, which affects the improvement of the time resolution performance of the streak camera. This paper comprehensively considers various transformer structures and design schemes, conducts resonant matching design based on helical resonators, and carries out relevant simulation studies using finite element simulation. Through the adjustment of the parameters of the primary coil of the resonator, the matching between the output impedance of the RF power amplifier and the capacitive load is achieved. The research on resonant coupling boost of the design model shows that it can output peak voltage under a certain power input, verifying the effectiveness of the helical resonance method. Through the comparative analysis of noise response and time jitter, it is indicated that the design method in this paper can further improve the time resolution performance of synchronous scanning.
With the rapid development of science and technology, the application of high-speed optical imaging and ultrafast diagnostic technologies in fields such as science, industry, national defense and medicine is becoming increasingly important. The synchroscan streak camera, as an ultrafast optical phenomenon detection instrument, is used in conjunction with high-repetition-frequency lasers to achieve high-precision time-synchronized pump detection. It realizes high signal-to-noise ratio detection by accumulating and amplifying weak optical signals. However, in the long-term working mode of the existing synchronous scanning circuit, the cumulative high-frequency noise of the signal source device increases accordingly. At the same time, there is a problem of lacking a specific impedance matching design method, which affects the improvement of the time resolution performance of the streak camera. This paper comprehensively considers various transformer structures and design schemes, conducts resonant matching design based on helical resonators, and carries out relevant simulation studies using finite element simulation. Through the adjustment of the parameters of the primary coil of the resonator, the matching between the output impedance of the RF power amplifier and the capacitive load is achieved. The research on resonant coupling boost of the design model shows that it can output peak voltage under a certain power input, verifying the effectiveness of the helical resonance method. Through the comparative analysis of noise response and time jitter, it is indicated that the design method in this paper can further improve the time resolution performance of synchronous scanning.
, Available online , doi: 10.11884/HPLPB202537.250094
Abstract:
This paper employs a Transformer model to address the challenge of real-time temperature prediction for optical elements under multi-physical field coupling. Experimental results demonstrate that compared to empirical model methods, the Transformer model achieves reductions of 70% and 32% in root mean square error (RMSE) and mean absolute error (MAE), respectively. When compared to LSTM-based methods, the Transformer model reduces RMSE and MAE by 66% and 23%, respectively. Additionally, the coefficient of determination (R2) of the Transformer model approaches 1 more closely, indicating higher consistency between predicted and actual values.
This paper employs a Transformer model to address the challenge of real-time temperature prediction for optical elements under multi-physical field coupling. Experimental results demonstrate that compared to empirical model methods, the Transformer model achieves reductions of 70% and 32% in root mean square error (RMSE) and mean absolute error (MAE), respectively. When compared to LSTM-based methods, the Transformer model reduces RMSE and MAE by 66% and 23%, respectively. Additionally, the coefficient of determination (R2) of the Transformer model approaches 1 more closely, indicating higher consistency between predicted and actual values.
, Available online , doi: 10.11884/HPLPB202537.250045
Abstract:
In view of the limitations associated with traditional single-spot laser solid-state phase transformation temperature control methods in complex curved workpieces, this paper proposes a Multi-input Multi-output (MIMO) temperature decoupling control strategy based on Active Disturbance Rejection Control (ADRC). Firstly, a finite element model of multi-spot laser-induced solid-state phase transformation was developed, and a model-order reduction method was applied to extract the key dynamic characteristics of the system, significantly reducing computational complexity and laying a foundation for effective control. Subsequently, to address the high-frequency jitter problem encountered by the conventional fal function within small-error regions, an improved bfal function based on Bernstein polynomials was proposed, thereby enhancing system observation accuracy and disturbance rejection capability. Moreover, an improved Particle Swarm Optimization (PSO) algorithm was utilized for the parameter tuning of ADRC controllers, effectively accelerating the optimization process. Finally, co-simulations conducted on the MATLAB/Simulink and COMSOL platforms demonstrated that the proposed PSO-ADRC controller achieves superior performance in terms of response speed, overshoot reduction, and steady-state accuracy compared to the conventional PID and standard ADRC methods. The method thus provides an efficient and precise solution for multi-spot laser solid-state phase transformation temperature control in complex curved workpieces.
In view of the limitations associated with traditional single-spot laser solid-state phase transformation temperature control methods in complex curved workpieces, this paper proposes a Multi-input Multi-output (MIMO) temperature decoupling control strategy based on Active Disturbance Rejection Control (ADRC). Firstly, a finite element model of multi-spot laser-induced solid-state phase transformation was developed, and a model-order reduction method was applied to extract the key dynamic characteristics of the system, significantly reducing computational complexity and laying a foundation for effective control. Subsequently, to address the high-frequency jitter problem encountered by the conventional fal function within small-error regions, an improved bfal function based on Bernstein polynomials was proposed, thereby enhancing system observation accuracy and disturbance rejection capability. Moreover, an improved Particle Swarm Optimization (PSO) algorithm was utilized for the parameter tuning of ADRC controllers, effectively accelerating the optimization process. Finally, co-simulations conducted on the MATLAB/Simulink and COMSOL platforms demonstrated that the proposed PSO-ADRC controller achieves superior performance in terms of response speed, overshoot reduction, and steady-state accuracy compared to the conventional PID and standard ADRC methods. The method thus provides an efficient and precise solution for multi-spot laser solid-state phase transformation temperature control in complex curved workpieces.
, Available online , doi: 10.11884/HPLPB202537.250072
Abstract:
To achieve stable transmission of laser with lower loss, single mode, and single polarization in the mid-infrared band, a bend-resistant hollow-core anti-resonant fiber configuration with a double-cladding nested structure is designed in this paper. The finite element method is used to optimize the structural parameters, and the transmission characteristics of broadband low-loss single polarization of the fiber are proved in simulation. The confinement loss of this fiber is less than 0.01 dB/km within the wavelength range of 2.9−3.3 μm, the high-order mode extinction ratio is greater than 1,000, and the confinement loss is as low as0.0014 dB/km at 3 μm wavelength. The symmetry of the fiber structure is destroyed by using different nested tube thicknesses, and the single-polarization characteristic of the fiber is theoretically investigated. Within the wavelength range of 2.996−3.004 μm, the polarization extinction ratio is greater than 10 000, which has an extremely stable single polarization effect. In addition, theoretical analysis indicates that this fiber also has excellent bending resistance performance. When the bending radius in the y-direction is greater than 5 cm, it can still ensure single-polarization laser transmission, and the bending loss is less than 3.11 dB/km. The designed hollow-core anti-resonant fiber configuration has great potential for application in the mid-infrared fiber laser and other fields.
To achieve stable transmission of laser with lower loss, single mode, and single polarization in the mid-infrared band, a bend-resistant hollow-core anti-resonant fiber configuration with a double-cladding nested structure is designed in this paper. The finite element method is used to optimize the structural parameters, and the transmission characteristics of broadband low-loss single polarization of the fiber are proved in simulation. The confinement loss of this fiber is less than 0.01 dB/km within the wavelength range of 2.9−3.3 μm, the high-order mode extinction ratio is greater than 1,000, and the confinement loss is as low as
, Available online , doi: 10.11884/HPLPB202537.240429
Abstract:
In experimental studies of indirect drive inertial confinement fusion, both flat-response X-ray detector (FXRD) and space-resolving flux detector (SRFD) are commonly used to measure the radiation flux. The SRFD can measure radiation flux in localized spatial regions, thus avoiding signal disruption from non-targeted regions. However, direct experimental evidence has long been lacking to determine the consistency between SRFD and FXRD. In this paper, we introduce the experimental design of consistency measurement of the SRFD detector and FXRD detector at Shenguang 100 kJ facility, based on a small-plane target, which considers the field-of-view and signal amplitude of the two detectors. The experimental results show that the average difference in the radiation flux obtained by the two detectors is approximately 4.6%, which shows good consistency. Finally, the radiation flux given by the radiation hydrodynamic simulation is reasonably close to the experiment, with some differences in the behavior at the rising edge and decreasing edge. It is possibly related to the details of the simulation model. This work provides a good foundation for experimental studies related to the precision measurement of X-ray radiation flux in a local spatial region.
In experimental studies of indirect drive inertial confinement fusion, both flat-response X-ray detector (FXRD) and space-resolving flux detector (SRFD) are commonly used to measure the radiation flux. The SRFD can measure radiation flux in localized spatial regions, thus avoiding signal disruption from non-targeted regions. However, direct experimental evidence has long been lacking to determine the consistency between SRFD and FXRD. In this paper, we introduce the experimental design of consistency measurement of the SRFD detector and FXRD detector at Shenguang 100 kJ facility, based on a small-plane target, which considers the field-of-view and signal amplitude of the two detectors. The experimental results show that the average difference in the radiation flux obtained by the two detectors is approximately 4.6%, which shows good consistency. Finally, the radiation flux given by the radiation hydrodynamic simulation is reasonably close to the experiment, with some differences in the behavior at the rising edge and decreasing edge. It is possibly related to the details of the simulation model. This work provides a good foundation for experimental studies related to the precision measurement of X-ray radiation flux in a local spatial region.
, Available online , doi: 10.11884/HPLPB202537.250027
Abstract:
In order to achieve four-phase images registration, an image registration method based on SIFT (Scale Invariant Features Transform) algorithm is proposed in this paper. The method is divided into four steps. Firstly, the feature points of the reference image and the misregistration images are extracted respectively. In this step, the characteristics of 2D-VISAR images are fully considered and homologous non-fringe images are introduced to obtain more accurate results. The second step is feature points matching. After roughly matching, the two-step-filtering method composed by angle histograms and feature point distance is designed to achieve accurate matching. The third step involves calculating the transformation parameters based on the final matching results. Finally, the transformation parameters are applied to misregistration images for interpolation transformation to achieve image registration. One of the four-phase images is used as the reference image to register the remaining three images. For nonfringe images, experimental results show that the correlation coefficient between registered images and the reference image increases from 0.5 to above 0.9. For fringe images , the calculation accuracy of wrapped phase improves significantly. Therefore, the algorithm in this paper effectively solves the registration problem of 2D-VISAR four-phase images, laying a foundation for further data processing in the future.
In order to achieve four-phase images registration, an image registration method based on SIFT (Scale Invariant Features Transform) algorithm is proposed in this paper. The method is divided into four steps. Firstly, the feature points of the reference image and the misregistration images are extracted respectively. In this step, the characteristics of 2D-VISAR images are fully considered and homologous non-fringe images are introduced to obtain more accurate results. The second step is feature points matching. After roughly matching, the two-step-filtering method composed by angle histograms and feature point distance is designed to achieve accurate matching. The third step involves calculating the transformation parameters based on the final matching results. Finally, the transformation parameters are applied to misregistration images for interpolation transformation to achieve image registration. One of the four-phase images is used as the reference image to register the remaining three images. For nonfringe images, experimental results show that the correlation coefficient between registered images and the reference image increases from 0.5 to above 0.9. For fringe images , the calculation accuracy of wrapped phase improves significantly. Therefore, the algorithm in this paper effectively solves the registration problem of 2D-VISAR four-phase images, laying a foundation for further data processing in the future.
, Available online , doi: 10.11884/HPLPB202537.250010
Abstract:
Microstrip Traveling Wave Tubes (TWTs) have garnered significant attention due to their potential applications in communication, defense, and industrial systems. This paper presents a compact W-band dual-channel TWT, utilizing a U-shaped microstrip meander line slow wave structure (SWS). High-frequency characteristics are analyzed through simulation and cold tests. The results demonstrate that adjusting structural parameters effectively optimizes the S-parameters. Particle-in-cell (PIC) simulations with an 18.8 kV, 0.1 A electron beam predict an output power of 18 W with a gain of 14 dB. Experimental measurements of S-parameters are conducted using three substrate materials: Rogers5880 , quartz, and diamond. The quartz substrate exhibits the closest agreement with simulation results. The results advance the development of the microstrip TWTs for high-data-rate communication systems.
Microstrip Traveling Wave Tubes (TWTs) have garnered significant attention due to their potential applications in communication, defense, and industrial systems. This paper presents a compact W-band dual-channel TWT, utilizing a U-shaped microstrip meander line slow wave structure (SWS). High-frequency characteristics are analyzed through simulation and cold tests. The results demonstrate that adjusting structural parameters effectively optimizes the S-parameters. Particle-in-cell (PIC) simulations with an 18.8 kV, 0.1 A electron beam predict an output power of 18 W with a gain of 14 dB. Experimental measurements of S-parameters are conducted using three substrate materials: Rogers
, Available online , doi: 10.11884/HPLPB202537.250030
Abstract:
In order to solve the problem of microwave ignition of solid energetic materials under low power conditions, this paper proposes a low-power high-field microwave ignition technology based on dual-focusing optimization design of rectangular resonant cavity. The developed microwave ignition device consists of a solid-state microwave source, a rectangular resonant cavity, a microwave probe and other parts. Among them, the rectangular resonant cavity is fed by a probe, and the energy is focused once by resonance. Combined with the distortion effect of the probe tip on the electric field and the compression effect of the metal stage on the electric field distribution space, the secondary focusing of the energy in the cavity during resonance is realized, and the electromagnetic compatibility design is used to prevent electromagnetic wave leakage. The simulation and experiment show that the microwave ignition device has multiple operating frequency points in the range of 2−3 GHz and the frequency is adjustable. The maximum field strength can reach MV/m level at 22 W power, and can realize the effective ignition of small black powder. Compared with the existing device, the ignition power is greatly reduced. The developed low-power and high-field microwave ignition technology can provide a platform for the study of microwave ignition of solid energetic materials.
In order to solve the problem of microwave ignition of solid energetic materials under low power conditions, this paper proposes a low-power high-field microwave ignition technology based on dual-focusing optimization design of rectangular resonant cavity. The developed microwave ignition device consists of a solid-state microwave source, a rectangular resonant cavity, a microwave probe and other parts. Among them, the rectangular resonant cavity is fed by a probe, and the energy is focused once by resonance. Combined with the distortion effect of the probe tip on the electric field and the compression effect of the metal stage on the electric field distribution space, the secondary focusing of the energy in the cavity during resonance is realized, and the electromagnetic compatibility design is used to prevent electromagnetic wave leakage. The simulation and experiment show that the microwave ignition device has multiple operating frequency points in the range of 2−3 GHz and the frequency is adjustable. The maximum field strength can reach MV/m level at 22 W power, and can realize the effective ignition of small black powder. Compared with the existing device, the ignition power is greatly reduced. The developed low-power and high-field microwave ignition technology can provide a platform for the study of microwave ignition of solid energetic materials.
, Available online , doi: 10.11884/HPLPB202537.250089
Abstract:
This paper proposes a compact Q-band relativistic backward wave oscillator (RBWO) operating at low magnetic fields, aiming to advance the miniaturization of high-power microwave (HPM) sources. The device consists of a resonant cavity reflector and two sections of periodic slow-wave structures (SWS), designed in a coaxial configuration. By exploiting the inherent characteristics of the coaxial structure, an optimal inner diameter was selected to enhance power handling capacity while mitigating space charge effects induced by the reduced device size. Through comprehensive simulation and optimization, the device achieved a microwave output power of 470 MW with an efficiency of 39.1% under operational conditions of a guiding magnetic field (B = 0.9 T), a diode voltage of 400 kV, and a beam current of 3 kA. The generated microwave signal exhibited a central frequency of 45 GHz.
This paper proposes a compact Q-band relativistic backward wave oscillator (RBWO) operating at low magnetic fields, aiming to advance the miniaturization of high-power microwave (HPM) sources. The device consists of a resonant cavity reflector and two sections of periodic slow-wave structures (SWS), designed in a coaxial configuration. By exploiting the inherent characteristics of the coaxial structure, an optimal inner diameter was selected to enhance power handling capacity while mitigating space charge effects induced by the reduced device size. Through comprehensive simulation and optimization, the device achieved a microwave output power of 470 MW with an efficiency of 39.1% under operational conditions of a guiding magnetic field (B = 0.9 T), a diode voltage of 400 kV, and a beam current of 3 kA. The generated microwave signal exhibited a central frequency of 45 GHz.
, Available online , doi: 10.11884/HPLPB202537.240430
Abstract:
X-ray beam position Monitor (XBPM) can be used to measure the position of synchrotron radiation. The front-end acquisition circuit is mainly used for analog signal acquisition and processing. In this paper, an XBPM electronic analog front-end board (XBPM-AFE) suitable for the front end area of High Energy Photo Source (HEPS) beamline is developed. The functions of current-voltage conversion, range switching, gain control and ADC sampling of the signal of XBPM are designed and implemented. The hardware circuit design and the test results of XBPM-AFE are given.
X-ray beam position Monitor (XBPM) can be used to measure the position of synchrotron radiation. The front-end acquisition circuit is mainly used for analog signal acquisition and processing. In this paper, an XBPM electronic analog front-end board (XBPM-AFE) suitable for the front end area of High Energy Photo Source (HEPS) beamline is developed. The functions of current-voltage conversion, range switching, gain control and ADC sampling of the signal of XBPM are designed and implemented. The hardware circuit design and the test results of XBPM-AFE are given.
, Available online , doi: 10.11884/HPLPB202537.250100
Abstract:
This study establishes a thermal radiation pulse transport model to quantify the energy release rate and cumulative energy of thermal radiation across temporal variations, spectral bands, and propagation distances through dimensionless processing and numerical simulations. Special emphasis is placed on analyzing the influence of atmospheric transmittance and air density ratios on the spatial distribution of thermal radiation energy, revealing the propagation characteristics of strong explosion-induced thermal radiation in spatial transmission and its wavelength dependence. The results demonstrate that temporally, the cumulative thermal radiation energy increases with time while exhibiting a gradually decreasing growth rate. During the fireball re-ignition phase, the visible band contributes a marginally higher proportion to cumulative energy, whereas the infrared band dominates during the cooling phase. Spatially, the thermal radiation energy decreases with lower altitude as propagation distance extends, until reaching a stabilization threshold where the spatial distribution becomes relatively constant. The developed model enables prediction of thermal radiation energy distribution at specific locations under arbitrary explosion conditions, providing theoretical support for protective design of wavelength-sensitive materials.
This study establishes a thermal radiation pulse transport model to quantify the energy release rate and cumulative energy of thermal radiation across temporal variations, spectral bands, and propagation distances through dimensionless processing and numerical simulations. Special emphasis is placed on analyzing the influence of atmospheric transmittance and air density ratios on the spatial distribution of thermal radiation energy, revealing the propagation characteristics of strong explosion-induced thermal radiation in spatial transmission and its wavelength dependence. The results demonstrate that temporally, the cumulative thermal radiation energy increases with time while exhibiting a gradually decreasing growth rate. During the fireball re-ignition phase, the visible band contributes a marginally higher proportion to cumulative energy, whereas the infrared band dominates during the cooling phase. Spatially, the thermal radiation energy decreases with lower altitude as propagation distance extends, until reaching a stabilization threshold where the spatial distribution becomes relatively constant. The developed model enables prediction of thermal radiation energy distribution at specific locations under arbitrary explosion conditions, providing theoretical support for protective design of wavelength-sensitive materials.
, Available online , doi: 10.11884/HPLPB202537.250020
Abstract:
The beam quality of the accelerator directly affects its application performance, and the structure of the electron gun determines the initial beam state of the accelerator. Optimizing the RF grid-controlled electron gun suitable for rhodotron and reducing its emittance can obtain higher CT imaging resolution. The Particle Tracking solver based on CST is simulated and analyzed to obtain a beam with a normalized rms emittance of0.4918 mm·mrad and a peak current of 35 mA. And discussed the influence of changes in electron gun structure on the emittance of and TWISS parameters.The results show that when the focus Angle changes, the normalized rms emittance is greatly affected. And in 67.5°, 60° and 45°, the minimum normalized rms emittance is 0.2617 mm·mrad when the focus Angle is 60°.
The beam quality of the accelerator directly affects its application performance, and the structure of the electron gun determines the initial beam state of the accelerator. Optimizing the RF grid-controlled electron gun suitable for rhodotron and reducing its emittance can obtain higher CT imaging resolution. The Particle Tracking solver based on CST is simulated and analyzed to obtain a beam with a normalized rms emittance of
, Available online , doi: 10.11884/HPLPB202537.240387
Abstract:
The next generation of synchrotron radiation light sources features extremely low emittance, enabling the generation of synchrotron radiation with significantly higher brilliance, which facilitates the exploration of matter at smaller scales. However, the extremely low emittance results in stronger sextupole magnet strengths, leading to high natural chromaticity. This necessitates the use of sextupole magnets to correct the natural chromaticity. For the Shanghai Synchrotron Radiation Facility Upgrade (SSRF-U), a lattice was designed for the storage ring that can achieve an ultra-low natural emittance of 72.2 pm·rad on the beam energy of 3.5 GeV. However, the significant detuning effects, led by high second-order resonant driving terms due to strong sextupoles, will degrade performance of the facility. To resolve this issue, installation of octupoles in the SSRF-U storage ring has been planned. This paper presents the study results about configuration choosing and optimization method for the octupoles. An optimal solution for the SSRF-U storage ring was obtained to effectively mitigate the amplitude-dependent tune shift and the second-order chromaticity, consequently leading an increased dynamic aperture (DA), momentum acceptance (MA), and reduced sensitivity to magnetic errors.
The next generation of synchrotron radiation light sources features extremely low emittance, enabling the generation of synchrotron radiation with significantly higher brilliance, which facilitates the exploration of matter at smaller scales. However, the extremely low emittance results in stronger sextupole magnet strengths, leading to high natural chromaticity. This necessitates the use of sextupole magnets to correct the natural chromaticity. For the Shanghai Synchrotron Radiation Facility Upgrade (SSRF-U), a lattice was designed for the storage ring that can achieve an ultra-low natural emittance of 72.2 pm·rad on the beam energy of 3.5 GeV. However, the significant detuning effects, led by high second-order resonant driving terms due to strong sextupoles, will degrade performance of the facility. To resolve this issue, installation of octupoles in the SSRF-U storage ring has been planned. This paper presents the study results about configuration choosing and optimization method for the octupoles. An optimal solution for the SSRF-U storage ring was obtained to effectively mitigate the amplitude-dependent tune shift and the second-order chromaticity, consequently leading an increased dynamic aperture (DA), momentum acceptance (MA), and reduced sensitivity to magnetic errors.
Design and validation of a proton beam line based on a rapid-cycling synchrotron for Flash radiation
, Available online , doi: 10.11884/HPLPB202537.250003
Abstract:
We design a proton beamline based on a rapid-cycling synchrotron for Flash radiation with ultra-high dose rate. Because proton beams can be extracted within hundreds of nanoseconds in the rapid-cycling synchrotron, its energy may be altered from one cycle to the next with different extraction time. The intended beamline system can realize layer stacking irradiation at an instantaneous dose rate of 107 Gy/s. Each of longitudinal layer requires a different beam intensity. The target is divided longitudinally into different layers, each of which needs a different beam energy, in order to produce a uniform irradiation field. The system, including a double scatter system, a range compensator, a ripple filter, and a multi-leaf collimator to maximize proton fluence into the target, is simulated using the Monte Carlo software FLUKA. Three different kinds of ripple filters are built in the low, medium, and high energy zones based on the original Bragg peaks in order to decrease the number of energy layers and shorten the total irradiation duration. These filters transform the spike region into a Gaussian distribution with flat expansion areas of 2 cm, 6 cm, and 20 cm, respectively. Combining the rapid-cycling synchrotron with the layer stacking irradiation provides a novel method for realizing Flash proton irradiation, which delivers an ultra-high dose rate to the target.
We design a proton beamline based on a rapid-cycling synchrotron for Flash radiation with ultra-high dose rate. Because proton beams can be extracted within hundreds of nanoseconds in the rapid-cycling synchrotron, its energy may be altered from one cycle to the next with different extraction time. The intended beamline system can realize layer stacking irradiation at an instantaneous dose rate of 107 Gy/s. Each of longitudinal layer requires a different beam intensity. The target is divided longitudinally into different layers, each of which needs a different beam energy, in order to produce a uniform irradiation field. The system, including a double scatter system, a range compensator, a ripple filter, and a multi-leaf collimator to maximize proton fluence into the target, is simulated using the Monte Carlo software FLUKA. Three different kinds of ripple filters are built in the low, medium, and high energy zones based on the original Bragg peaks in order to decrease the number of energy layers and shorten the total irradiation duration. These filters transform the spike region into a Gaussian distribution with flat expansion areas of 2 cm, 6 cm, and 20 cm, respectively. Combining the rapid-cycling synchrotron with the layer stacking irradiation provides a novel method for realizing Flash proton irradiation, which delivers an ultra-high dose rate to the target.
, Available online , doi: 10.11884/HPLPB202537.250062
Abstract:
Aiming at the electromagnetic pulse protection requirements of RF front-end in complex electromagnetic environment, a strong electromagnetic pulse protection circuit working in L-band is designed. This circuit takes PIN diode as the core device, adopts a multi-level PIN diode cascade protection structure, connects each stage through microstrip transmission lines and optimizes the design. The performance of the circuit under different working conditions is verified by simulation, and its physical test is carried out. The test results show that in the L-band, its insertion loss is less than 0.6 dB, return loss is less than 11.93 dB, and standing wave ratio is less than 1.68. It has good signal transmission performance; Under the injection of 4 kV square wave pulse, the circuit can respond quickly within 1 ns, and the peak leakage voltage generated by the circuit is 69.636 V. After 2 ns, the stable output voltage of the circuit is less than 20 V, indicating that the circuit has good transient protection capability against fast edge pulse. Combined with the low loss characteristics in L-band, the circuit can provide effective electromagnetic pulse protection support for equipment working in L-band.
Aiming at the electromagnetic pulse protection requirements of RF front-end in complex electromagnetic environment, a strong electromagnetic pulse protection circuit working in L-band is designed. This circuit takes PIN diode as the core device, adopts a multi-level PIN diode cascade protection structure, connects each stage through microstrip transmission lines and optimizes the design. The performance of the circuit under different working conditions is verified by simulation, and its physical test is carried out. The test results show that in the L-band, its insertion loss is less than 0.6 dB, return loss is less than 11.93 dB, and standing wave ratio is less than 1.68. It has good signal transmission performance; Under the injection of 4 kV square wave pulse, the circuit can respond quickly within 1 ns, and the peak leakage voltage generated by the circuit is 69.636 V. After 2 ns, the stable output voltage of the circuit is less than 20 V, indicating that the circuit has good transient protection capability against fast edge pulse. Combined with the low loss characteristics in L-band, the circuit can provide effective electromagnetic pulse protection support for equipment working in L-band.
Measurement method for areal density of pulsed X-ray photographic images in metal ejection diagnosis
, Available online , doi: 10.11884/HPLPB202537.250025
Abstract:
The ejection phenomenon generated by metal materials under strong impact is an important issue in the field of impact compression research. Pulse X-ray photography is an important diagnostic testing method for micro jet processes. The use of X-ray images to obtain the surface density of metal material experimental objects and jets under strong impact is an important objective of this type of experiment. A method for measuring the areal density data of ejection X-ray images based on stepped wedges is proposed. The method reduces the influence of white spot noise by median filtering, corrects the unevenness of light field distribution and detector response by using empty field images, obtains the system point spread function by imaging the Roll-Bar object, and uses the imaging system point spread function and an improved Tikhonov regularization based image restoration method to reduce the impact of blur on X-ray images. The processing flow for obtaining the areal density information of ejection X-ray images is provided. The verification of the inversion of areal density in static object experimental images shows that the proposed areal density measurement method can accurately obtain the areal density information of metal ejection experimental X-ray images.
The ejection phenomenon generated by metal materials under strong impact is an important issue in the field of impact compression research. Pulse X-ray photography is an important diagnostic testing method for micro jet processes. The use of X-ray images to obtain the surface density of metal material experimental objects and jets under strong impact is an important objective of this type of experiment. A method for measuring the areal density data of ejection X-ray images based on stepped wedges is proposed. The method reduces the influence of white spot noise by median filtering, corrects the unevenness of light field distribution and detector response by using empty field images, obtains the system point spread function by imaging the Roll-Bar object, and uses the imaging system point spread function and an improved Tikhonov regularization based image restoration method to reduce the impact of blur on X-ray images. The processing flow for obtaining the areal density information of ejection X-ray images is provided. The verification of the inversion of areal density in static object experimental images shows that the proposed areal density measurement method can accurately obtain the areal density information of metal ejection experimental X-ray images.
, Available online , doi: 10.11884/HPLPB202537.250021
Abstract:
Common power equipment in the factory and maintenance needs lightning impact voltage testing to detect the level of insulation equipment. This paper proposes a miniaturized impulse voltage generator different from the traditional gas ball gap. It adopts a modular multi-stage structure, uses the Marx topology as the main circuit, and uses MOSFET as the main switch. MATLAB is used to fit and modulate lightning impulses or chopped lightning impulses through the nearest-level forced modulation algorithm (NLM). FPGA controls the modular impulse voltage generator to generate impulse voltage waveforms such as charging voltage, wavefront time, wave tail time, and truncation time, which the host computer can flexibly adjust. The test results show that the maximum output voltage of a single impulse voltage module is 24 kV, with a total of 30 stages of voltage output; when 5 impulse voltage modules are operated in series, a maximum of 150 stages of different voltages can be generated, and the peak voltage can reach −100 kV lightning impulses or chopped lightning impulses.
Common power equipment in the factory and maintenance needs lightning impact voltage testing to detect the level of insulation equipment. This paper proposes a miniaturized impulse voltage generator different from the traditional gas ball gap. It adopts a modular multi-stage structure, uses the Marx topology as the main circuit, and uses MOSFET as the main switch. MATLAB is used to fit and modulate lightning impulses or chopped lightning impulses through the nearest-level forced modulation algorithm (NLM). FPGA controls the modular impulse voltage generator to generate impulse voltage waveforms such as charging voltage, wavefront time, wave tail time, and truncation time, which the host computer can flexibly adjust. The test results show that the maximum output voltage of a single impulse voltage module is 24 kV, with a total of 30 stages of voltage output; when 5 impulse voltage modules are operated in series, a maximum of 150 stages of different voltages can be generated, and the peak voltage can reach −100 kV lightning impulses or chopped lightning impulses.
