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, Available online ,
doi: 10.11884/HPLPB202436.240177
Abstract:
To address the issue of system-level electromagnetic compatibility, a new method of predicting electromagnetic interference of complex systems based on artificial neural network (ANN) reverse model is proposed in this paper. Firstly, the electric field radiated emission (RE) of single equipment is measured. The training data of system-level RE are obtained by simulation based on the equivalence principle of radiated emission. Frequency, RE and coordinate of each single equipment are selected as the input variables, and the system-level RE is the output variable. A reverse model of the three-layer back-propagation (BP) ANN with Levenberg-Marquardt (LM) algorithm is established by exchange the input–output variables. The alternative ANN with minimum validation error is searched as the ultimate ANN. The numerical root-finding algorithm (regular-falsi method and conjugate gradient method) are adopted in this paper to calculate the RE of multi equipments. Results shows that the validation error of this reverse model is significantly improved compared to the traditional three-layer LM-BP ANN. Especially, the ANN reverse model based on conjugate gradient method reduces the validation error from 0.4159% to 0.0997%. This method is independent of complex ANN structures, and improves simulation accuracy with limited training data, which provides a new efficient and feasible solution for electromagnetic compatibility evaluation of electronic information platforms such as ships, satellites, and aircrafts.
To address the issue of system-level electromagnetic compatibility, a new method of predicting electromagnetic interference of complex systems based on artificial neural network (ANN) reverse model is proposed in this paper. Firstly, the electric field radiated emission (RE) of single equipment is measured. The training data of system-level RE are obtained by simulation based on the equivalence principle of radiated emission. Frequency, RE and coordinate of each single equipment are selected as the input variables, and the system-level RE is the output variable. A reverse model of the three-layer back-propagation (BP) ANN with Levenberg-Marquardt (LM) algorithm is established by exchange the input–output variables. The alternative ANN with minimum validation error is searched as the ultimate ANN. The numerical root-finding algorithm (regular-falsi method and conjugate gradient method) are adopted in this paper to calculate the RE of multi equipments. Results shows that the validation error of this reverse model is significantly improved compared to the traditional three-layer LM-BP ANN. Especially, the ANN reverse model based on conjugate gradient method reduces the validation error from 0.4159% to 0.0997%. This method is independent of complex ANN structures, and improves simulation accuracy with limited training data, which provides a new efficient and feasible solution for electromagnetic compatibility evaluation of electronic information platforms such as ships, satellites, and aircrafts.
, Available online ,
doi: 10.11884/HPLPB202436.240117
Abstract:
JMCT3.0 is a large-scale, high-fidelity, three-dimensional general multi-particle transport Monte Carlo (MC) program. Thirteen new functions and eight new algorithms have been developed relative to JMCT2.0. The computing efficiency is enhanced over 30%～600% by optimizing of JCOGIN infrastructure. JMCT can simulate neutron/photon/electron/proton/molecule/light radiation/atmosphere transport problems in any complicated geometry system. It supports the multi-level parallelization in scale of over one hundred thousand cores. At present, JMCT has been widely applied in radiation shielding, critical safe analysis of reactor, nuclear detection and nuclear medicine etc. The methods and simulated functions have been introduced about of proton, low-energy photon/ electron/molecule transport in this paper. The validity of algorithms has been proved by benchmarks. The new functions are mainly used for simulation of image diagnose, flash picture, light radiation and atmosphere transport.
JMCT3.0 is a large-scale, high-fidelity, three-dimensional general multi-particle transport Monte Carlo (MC) program. Thirteen new functions and eight new algorithms have been developed relative to JMCT2.0. The computing efficiency is enhanced over 30%～600% by optimizing of JCOGIN infrastructure. JMCT can simulate neutron/photon/electron/proton/molecule/light radiation/atmosphere transport problems in any complicated geometry system. It supports the multi-level parallelization in scale of over one hundred thousand cores. At present, JMCT has been widely applied in radiation shielding, critical safe analysis of reactor, nuclear detection and nuclear medicine etc. The methods and simulated functions have been introduced about of proton, low-energy photon/ electron/molecule transport in this paper. The validity of algorithms has been proved by benchmarks. The new functions are mainly used for simulation of image diagnose, flash picture, light radiation and atmosphere transport.
, Available online ,
doi: 10.11884/HPLPB202436.240120
Abstract:
Pulse power technology compresses low-power energy in the time domain to achieve high-power output in extremely short durations. In recent years, the trend in pulse power technology has been to replace traditional gas or vacuum switches with a new generation of semiconductor switches. To promote the technical development in the field of pulse power semiconductor devices, this article briefly introduces the development history of voltage-controlled pulse power semiconductor devices and the structure of MOS-controlled thyristors (MCTs). By comparing the pulse performance of MCT with that of commercial IGBT, it illustrates the advantages of high pulse current peak and high di/dt pulse of MCT under the same conditions. However, the conventional MCT cannot be turned off at zero gate voltage, and the carrier injection efficiency and conduction speed need to be further improved. In order to solve the shortcomings of conventional MCT that can not be turned off under zero voltage, this article then summarizes the research progress in device design, technology, and reliability of MCT. It also demonstrates the advantages of MCT devices in typical application scenarios and provides a brief analysis of the development trends of voltage-controlled pulse power semiconductor devices.
Pulse power technology compresses low-power energy in the time domain to achieve high-power output in extremely short durations. In recent years, the trend in pulse power technology has been to replace traditional gas or vacuum switches with a new generation of semiconductor switches. To promote the technical development in the field of pulse power semiconductor devices, this article briefly introduces the development history of voltage-controlled pulse power semiconductor devices and the structure of MOS-controlled thyristors (MCTs). By comparing the pulse performance of MCT with that of commercial IGBT, it illustrates the advantages of high pulse current peak and high di/dt pulse of MCT under the same conditions. However, the conventional MCT cannot be turned off at zero gate voltage, and the carrier injection efficiency and conduction speed need to be further improved. In order to solve the shortcomings of conventional MCT that can not be turned off under zero voltage, this article then summarizes the research progress in device design, technology, and reliability of MCT. It also demonstrates the advantages of MCT devices in typical application scenarios and provides a brief analysis of the development trends of voltage-controlled pulse power semiconductor devices.
, Available online ,
doi: 10.11884/HPLPB202436.240145
Abstract:
Increasing frequency is always an important development direction of high power microwave (HPM). However, as the frequency increases, the volume of an HPM device decreases rapidly and so does the power handling capacity (PHC). For obtaining reasonable PHC, the design of a V-band coaxial transit time oscillator (TTO) based on TM03 mode is carried out to achieve low surface field in this paper. The slow wave structure (SWS) having a large radial width with TM03 mode in such a device designed will lead to low risk of both electric field breakdown and pulse shortening. Firstly, the synchronous effect of velocity between microwave and electron beam is achieved by calculation of dispersion curve and coupling impedance. Then, small group velocity and high coupling impedance are designed to make TM03 a dominant mode in the coaxial V-band TTO. Finally, under the condition of 440 kV and 5kA , an HPM is generated to reach an output power of 440 MW with a low surface electric field of 1.6 MV/cm, a microwave frequency of 62.25 GHz, and a beam-to-wave efficiency of 22% from numerical simulation.
Increasing frequency is always an important development direction of high power microwave (HPM). However, as the frequency increases, the volume of an HPM device decreases rapidly and so does the power handling capacity (PHC). For obtaining reasonable PHC, the design of a V-band coaxial transit time oscillator (TTO) based on TM03 mode is carried out to achieve low surface field in this paper. The slow wave structure (SWS) having a large radial width with TM03 mode in such a device designed will lead to low risk of both electric field breakdown and pulse shortening. Firstly, the synchronous effect of velocity between microwave and electron beam is achieved by calculation of dispersion curve and coupling impedance. Then, small group velocity and high coupling impedance are designed to make TM03 a dominant mode in the coaxial V-band TTO. Finally, under the condition of 440 kV and 5kA , an HPM is generated to reach an output power of 440 MW with a low surface electric field of 1.6 MV/cm, a microwave frequency of 62.25 GHz, and a beam-to-wave efficiency of 22% from numerical simulation.
, Available online ,
doi: 10.11884/HPLPB202436.230403
Abstract:
To improve the reliability and operation life of metallic Bi targets for the production of medical isotope 211At using high current α beam, several beam uniformization methods were simulated and compared. The thermal effect of 500 eμA α beam bombarding a Bi target with wobbler magnet was modeled and analyzed by CFD (Computational Fluid Dynamics) method, which provided key technical support for the design of target system and the improvement of target life time. The results showed that the peak beam thermal effect on the target was obviously reduced by applying beam scanning. In front of the target, a wobbler magnet was used to periodically scan the beam, which could effectively reduce the temperature on Bi target surface. With a scanning frequency of 50 Hz, the highest temperature on Bi target was 189.8 ℃, lower than the melting point of Bi metal (271.3 ℃), which could meet the temperature requirement of Bi target under such a high beam power condition.
To improve the reliability and operation life of metallic Bi targets for the production of medical isotope 211At using high current α beam, several beam uniformization methods were simulated and compared. The thermal effect of 500 eμA α beam bombarding a Bi target with wobbler magnet was modeled and analyzed by CFD (Computational Fluid Dynamics) method, which provided key technical support for the design of target system and the improvement of target life time. The results showed that the peak beam thermal effect on the target was obviously reduced by applying beam scanning. In front of the target, a wobbler magnet was used to periodically scan the beam, which could effectively reduce the temperature on Bi target surface. With a scanning frequency of 50 Hz, the highest temperature on Bi target was 189.8 ℃, lower than the melting point of Bi metal (271.3 ℃), which could meet the temperature requirement of Bi target under such a high beam power condition.
, Available online ,
doi: 10.11884/HPLPB202436.240099
Abstract:
An erbium-doped all-fiber laser model based on dual-peak filter was designed, and the numerical simulation of the dynamic characteristics of asynchronous dual-wavelength pulse mode-locking was carried out. Based on the same noise as the initial condition, the saturation energy of the gain fiber is set to 15 pJ, 40 pJ and 55 pJ, respectively, and the simulation results show that the noise finally evolves into single-wavelength pulse mode-locking, asynchronous dual-wavelength pulse mode-locking, and asynchronous dual-wavelength pulse mode-locking in the form of soliton molecules, in which the evolution process of asynchronous dual-wavelength pulses goes through three stages: noise pulse generation, multi-pulse mode-locking and gain competition, and stable asynchronous dual-wavelength pulse mode-locking. The saturation energy of the gain fiber directly determines the evolution direction of the pulse in the gain competition. The pulse frequency shifts caused by cross-phase modulation during the pulse collision process, resulting in the time domain pulse time jitter.
An erbium-doped all-fiber laser model based on dual-peak filter was designed, and the numerical simulation of the dynamic characteristics of asynchronous dual-wavelength pulse mode-locking was carried out. Based on the same noise as the initial condition, the saturation energy of the gain fiber is set to 15 pJ, 40 pJ and 55 pJ, respectively, and the simulation results show that the noise finally evolves into single-wavelength pulse mode-locking, asynchronous dual-wavelength pulse mode-locking, and asynchronous dual-wavelength pulse mode-locking in the form of soliton molecules, in which the evolution process of asynchronous dual-wavelength pulses goes through three stages: noise pulse generation, multi-pulse mode-locking and gain competition, and stable asynchronous dual-wavelength pulse mode-locking. The saturation energy of the gain fiber directly determines the evolution direction of the pulse in the gain competition. The pulse frequency shifts caused by cross-phase modulation during the pulse collision process, resulting in the time domain pulse time jitter.
, Available online ,
doi: 10.11884/HPLPB202436.240143
Abstract:
Positive underwater discharge can produce abundant physical and chemical effects and is widely used in the fields of energy source exploration and sterilization. However, the physical mechanisms involved in initiation and propagation of streamer are complex and have not been revealed, which limit the efficiency of underwater discharge applications. In this paper, we explore the mode-transition, reillumination and branching characteristics of positive filamentary streamer. The influence of deposited charge and space charge distribution on the propagation of streamer channel is clarified. Our research shows that the positive polarity filamentary streamers can be divided into primary streamer and secondary streamer, and the mode transition of discharges is greatly affected by the gas/liquid interface charge relaxation process. When the applied voltage reaches the accelerating voltage, the primary streamer rapidly transits into secondary streamer. The gas/liquid interface charge density and electric field in primary streamer channel are closely related with initiation, termination and reignition of discharge. The space charge distribution of secondary streamer is greatly affected by the voltage rising edge and the electrode surface structure. Longer voltage rise time leads to lower density of space charge and electric field at the head of streamer channel, which causes the decrease of streamer velocity. With larger radius of the micro-convex structure on the electrode surface, the branching of streamer will take place at the root of the main channel instead of electrode surface. Due to the variation of the spatial charge distribution, the velocity of the branching channel shows a trend of first declining and then increasing when the radius of the micro-convex structure is 5 μm.
Positive underwater discharge can produce abundant physical and chemical effects and is widely used in the fields of energy source exploration and sterilization. However, the physical mechanisms involved in initiation and propagation of streamer are complex and have not been revealed, which limit the efficiency of underwater discharge applications. In this paper, we explore the mode-transition, reillumination and branching characteristics of positive filamentary streamer. The influence of deposited charge and space charge distribution on the propagation of streamer channel is clarified. Our research shows that the positive polarity filamentary streamers can be divided into primary streamer and secondary streamer, and the mode transition of discharges is greatly affected by the gas/liquid interface charge relaxation process. When the applied voltage reaches the accelerating voltage, the primary streamer rapidly transits into secondary streamer. The gas/liquid interface charge density and electric field in primary streamer channel are closely related with initiation, termination and reignition of discharge. The space charge distribution of secondary streamer is greatly affected by the voltage rising edge and the electrode surface structure. Longer voltage rise time leads to lower density of space charge and electric field at the head of streamer channel, which causes the decrease of streamer velocity. With larger radius of the micro-convex structure on the electrode surface, the branching of streamer will take place at the root of the main channel instead of electrode surface. Due to the variation of the spatial charge distribution, the velocity of the branching channel shows a trend of first declining and then increasing when the radius of the micro-convex structure is 5 μm.
, Available online ,
doi: 10.11884/HPLPB202436.240152
Abstract:
Image reconstruction algorithms significantly influence the imaging performance of coded-aperture gamma cameras. However, the widely used Maximum Likelihood Expectation Maximization (MLEM) algorithm falls short in effectively suppressing noise amidst stronger background interference because it relies on the system response matrix under ideal conditions. This paper conducted corresponding research and improvements regarding the “pathological” nature of the MLEM algorithm. Firstly, the Maximum a Posteriori (MAP) algorithm was applied to the image reconstruction of coded aperture imaging, followed by an analysis of the selection methods for key parameters such as the neighborhood size and weight coefficient within the Gibbs prior function of the algorithm.Then, we conducted imaging experiments using the prototype of the coded-aperture gamma camera and compared the image reconstruction results of the MLEM algorithm and the MAP algorithm for the 22Na point source. The results indicate that in the range of 300 to 1200 iterations, the MLEM reconstructed images exhibited noticeable noise spots, with image quality progressively deteriorating as the iterations deepened. In contrast, the MAP reconstructed images did not present any significant noise spots. The average gradient of the reconstructed images was reduced by 26.45% to 49.16% compared to MLEM, and the contrast-to-noise ratio (CNR) was improved by 42.32% to 351.07%. Furthermore, we compared the reconstruction results of multi-point source images with 3 × 3 and 5 × 5 neighborhood sizes. The results indicate that a neighborhood size that is too small leads to a decrease in the brightness of the hotspots in the reconstructed images, consistent with the theoretical analysis. Finally, we compared the imaging results of the MLEM and MAP algorithms in two separate scenarios: one with greater distances and the other with stronger interference. In both scenarios, the MAP algorithm consistently demonstrated better signal-to-noise ratio (SNR) performance.
Image reconstruction algorithms significantly influence the imaging performance of coded-aperture gamma cameras. However, the widely used Maximum Likelihood Expectation Maximization (MLEM) algorithm falls short in effectively suppressing noise amidst stronger background interference because it relies on the system response matrix under ideal conditions. This paper conducted corresponding research and improvements regarding the “pathological” nature of the MLEM algorithm. Firstly, the Maximum a Posteriori (MAP) algorithm was applied to the image reconstruction of coded aperture imaging, followed by an analysis of the selection methods for key parameters such as the neighborhood size and weight coefficient within the Gibbs prior function of the algorithm.Then, we conducted imaging experiments using the prototype of the coded-aperture gamma camera and compared the image reconstruction results of the MLEM algorithm and the MAP algorithm for the 22Na point source. The results indicate that in the range of 300 to 1200 iterations, the MLEM reconstructed images exhibited noticeable noise spots, with image quality progressively deteriorating as the iterations deepened. In contrast, the MAP reconstructed images did not present any significant noise spots. The average gradient of the reconstructed images was reduced by 26.45% to 49.16% compared to MLEM, and the contrast-to-noise ratio (CNR) was improved by 42.32% to 351.07%. Furthermore, we compared the reconstruction results of multi-point source images with 3 × 3 and 5 × 5 neighborhood sizes. The results indicate that a neighborhood size that is too small leads to a decrease in the brightness of the hotspots in the reconstructed images, consistent with the theoretical analysis. Finally, we compared the imaging results of the MLEM and MAP algorithms in two separate scenarios: one with greater distances and the other with stronger interference. In both scenarios, the MAP algorithm consistently demonstrated better signal-to-noise ratio (SNR) performance.
, Available online ,
doi: 10.11884/HPLPB202436.240128
Abstract:
In response to the difficulties posed by traditional microscopy imaging techniques in capturing the structure and thickness of colorless transparent samples, we have designed a miniature three-dimensional reconstruction system for such samples. This innovative system, breaking away from traditional optical structures, performs phase retrieval on transparent samples to achieve three-dimensional reconstruction. It requires only light carrying sample information, which is then bifurcated by a spectroscope and captured by a stereo camera. Constructed using 3D printing technology, the compact system measures just 110 mm×110 mm×60 mm, offering a cost-effective solution that is also compatible with traditional microscopy imaging equipment. It incorporates autofocus and field of view correction algorithms, which, by collecting one over-focused and one under-focused image, solve the transport intensity equation to enable phase retrieval and hence the three-dimensional reconstruction of transparent samples. Test results have shown that the system can achieve an imaging resolution of 2.46μm under a 10x objective lens, and the phase recovery accuracy can also meet the basic requirements. Furthermore, the successful three-dimensional reconstruction of blood cells and scratches on microscope slides validates the system's feasibility and practicality.
In response to the difficulties posed by traditional microscopy imaging techniques in capturing the structure and thickness of colorless transparent samples, we have designed a miniature three-dimensional reconstruction system for such samples. This innovative system, breaking away from traditional optical structures, performs phase retrieval on transparent samples to achieve three-dimensional reconstruction. It requires only light carrying sample information, which is then bifurcated by a spectroscope and captured by a stereo camera. Constructed using 3D printing technology, the compact system measures just 110 mm×110 mm×60 mm, offering a cost-effective solution that is also compatible with traditional microscopy imaging equipment. It incorporates autofocus and field of view correction algorithms, which, by collecting one over-focused and one under-focused image, solve the transport intensity equation to enable phase retrieval and hence the three-dimensional reconstruction of transparent samples. Test results have shown that the system can achieve an imaging resolution of 2.46μm under a 10x objective lens, and the phase recovery accuracy can also meet the basic requirements. Furthermore, the successful three-dimensional reconstruction of blood cells and scratches on microscope slides validates the system's feasibility and practicality.
, Available online ,
doi: 10.11884/HPLPB202436.230386
Abstract:
Aiming at the High Energy Photon Source which needs to calibrate the center of a large number of magnets, a scheme of calibrating the center of magnetic machinery based on coordinate measuring machine (CMM) is proposed, the flow and method of writing automatic measuring program are determined, and the calibration of various types of magnets in the accelerator is completed. The results show that the calibration repeatability of the reference point of collimation is within 0.01 mm by calibrating the mechanical center twice for each magnet. The standard deviation between the measured value and the design value is within 0.015 mm. The calibration efficiency is 2 times higher than that of the laser tracker. This method of magnet calibration with CMM can improve the calibration accuracy, reduce the labor cost, improve the work efficiency, provide reference for the magnet center extraction calibration in the accelerator work, ensure the smooth installation of the accelerator device, and meet the requirements of the accelerator alignment measurement project schedule.
Aiming at the High Energy Photon Source which needs to calibrate the center of a large number of magnets, a scheme of calibrating the center of magnetic machinery based on coordinate measuring machine (CMM) is proposed, the flow and method of writing automatic measuring program are determined, and the calibration of various types of magnets in the accelerator is completed. The results show that the calibration repeatability of the reference point of collimation is within 0.01 mm by calibrating the mechanical center twice for each magnet. The standard deviation between the measured value and the design value is within 0.015 mm. The calibration efficiency is 2 times higher than that of the laser tracker. This method of magnet calibration with CMM can improve the calibration accuracy, reduce the labor cost, improve the work efficiency, provide reference for the magnet center extraction calibration in the accelerator work, ensure the smooth installation of the accelerator device, and meet the requirements of the accelerator alignment measurement project schedule.
, Available online ,
doi: 10.11884/HPLPB202436.240123
Abstract:
In order to improve the muzzle speed and energy utilization of the coil launcher, this article studies the impact of different circuit topology structures of the magnetic resistance electromagnetic coil launcher to improve the performance. Four topology structures, including Silicon controlled rectifier (SCR) type, half-bridge type, Resistor capacitor diode (RCD) absorption type, and Boost-Buck type, were analyzed, and the influence of different topology on the performance is studied by finite element method. The results show that under the same conditions, compared with the SCR circuit, among the three switchable circuits, the Boost-Buck circuit has the least increase in armature muzzle speed, which is 78.77%; the least increase in system energy utilization is the RCD circuit, which is 220.66%. The attenuation rate of the current in the turn-off circuit will affect the acceleration of the armature, and there is an optimal current attenuation rate curve. The most balanced combination of muzzle speed and system energy utilization in the single-stage turn-off circuit is the half-bridge discharge circuit; Boost-Buck discharge circuit is more flexible and suitable for use in multi-stage coil launcher.
In order to improve the muzzle speed and energy utilization of the coil launcher, this article studies the impact of different circuit topology structures of the magnetic resistance electromagnetic coil launcher to improve the performance. Four topology structures, including Silicon controlled rectifier (SCR) type, half-bridge type, Resistor capacitor diode (RCD) absorption type, and Boost-Buck type, were analyzed, and the influence of different topology on the performance is studied by finite element method. The results show that under the same conditions, compared with the SCR circuit, among the three switchable circuits, the Boost-Buck circuit has the least increase in armature muzzle speed, which is 78.77%; the least increase in system energy utilization is the RCD circuit, which is 220.66%. The attenuation rate of the current in the turn-off circuit will affect the acceleration of the armature, and there is an optimal current attenuation rate curve. The most balanced combination of muzzle speed and system energy utilization in the single-stage turn-off circuit is the half-bridge discharge circuit; Boost-Buck discharge circuit is more flexible and suitable for use in multi-stage coil launcher.
, Available online ,
doi: 10.11884/HPLPB202436.230452
Abstract:
Installing an odd number of Siberian Snakes at equally azimuth intervals in a circular collider is a common scheme for obtaining longitudinally polarized beam collisions. In this paper, the solenoid Siberian Snake is selected as the device to preserve beam polarization in the Super Tau-Charm Factory according to its characteristics. The paper introduces in detail how to combine particle swarm optimization algorithm with decoupling and optical matching problem of solenoid snake to design it quickly and optimally, and presents the design results. The results show that the optimization design of solenoid snake based on particle swarm optimization algorithm is effective and efficient.
Installing an odd number of Siberian Snakes at equally azimuth intervals in a circular collider is a common scheme for obtaining longitudinally polarized beam collisions. In this paper, the solenoid Siberian Snake is selected as the device to preserve beam polarization in the Super Tau-Charm Factory according to its characteristics. The paper introduces in detail how to combine particle swarm optimization algorithm with decoupling and optical matching problem of solenoid snake to design it quickly and optimally, and presents the design results. The results show that the optimization design of solenoid snake based on particle swarm optimization algorithm is effective and efficient.
, Available online ,
doi: 10.11884/HPLPB202436.230385
Abstract:
High altitude electromagnetic pulse (HEMP) can produce electromagnetic pulse effects on electronic devices or systems that cannot be ignored. In this paper, a high-speed comparator and a clock driver are selected, and the electromagnetic sensitivity of the power module of these two devices is studied by the experimental method of pulse current injection (PCI). The test results show that the rising edge of the double exponential pulse current is the main cause of the output glitch of the high-speed comparator and clock driver, and the amplitude of the disturbance is affected by the amplitude of the injected pulse current. The electromagnetic sensitivity of the power module of the high-speed comparator is different at different output level. Different operating frequencies of high-speed comparators and clock drivers will show different electromagnetic sensitivity. The results have certain guiding significance for electromagnetic sensitivity analysis and hardening of electronic devices or systems.
High altitude electromagnetic pulse (HEMP) can produce electromagnetic pulse effects on electronic devices or systems that cannot be ignored. In this paper, a high-speed comparator and a clock driver are selected, and the electromagnetic sensitivity of the power module of these two devices is studied by the experimental method of pulse current injection (PCI). The test results show that the rising edge of the double exponential pulse current is the main cause of the output glitch of the high-speed comparator and clock driver, and the amplitude of the disturbance is affected by the amplitude of the injected pulse current. The electromagnetic sensitivity of the power module of the high-speed comparator is different at different output level. Different operating frequencies of high-speed comparators and clock drivers will show different electromagnetic sensitivity. The results have certain guiding significance for electromagnetic sensitivity analysis and hardening of electronic devices or systems.
, Available online ,
doi: 10.11884/HPLPB202436.240072
Abstract:
Aiming at the problem of multiple false alarm signals of radar equipment in complex electromagnetic interference, in order to grasp the influence law of key parameters of radar equipment on false alarm signals, and to reveal the essential reasons for the generation of false alarm signals, taking a type of stepper frequency ranging radar as the test object, theoretically explain the mechanism of false alarm interference and the imaging characteristics of false alarm targets. Combining theoretical and experimental measurements, single-frequency continuous wave is selected as the source of electromagnetic interference, and the test method of injecting equivalent alternative electromagnetic radiation is adopted to summarize and generalize the radar critical parameters of frequency hopping interval and stepping frequency on the false alarm signal role of the law. The results show that the single-frequency electromagnetic interference of the test radar generates false alarm signal. When the frequency stepping of the tested radar is selected as 10 kHz and the frequency hopping time is 0.05ms, the variation of false alarm level with interference frequency offset is relatively stable, and the signal amplitude loss is relatively small. The parameter value can be used as the optimal control parameter, and based on this result, it can provide technical support for subsequent experimental evaluation of radar equipment in multi frequency electromagnetic environments.
Aiming at the problem of multiple false alarm signals of radar equipment in complex electromagnetic interference, in order to grasp the influence law of key parameters of radar equipment on false alarm signals, and to reveal the essential reasons for the generation of false alarm signals, taking a type of stepper frequency ranging radar as the test object, theoretically explain the mechanism of false alarm interference and the imaging characteristics of false alarm targets. Combining theoretical and experimental measurements, single-frequency continuous wave is selected as the source of electromagnetic interference, and the test method of injecting equivalent alternative electromagnetic radiation is adopted to summarize and generalize the radar critical parameters of frequency hopping interval and stepping frequency on the false alarm signal role of the law. The results show that the single-frequency electromagnetic interference of the test radar generates false alarm signal. When the frequency stepping of the tested radar is selected as 10 kHz and the frequency hopping time is 0.05ms, the variation of false alarm level with interference frequency offset is relatively stable, and the signal amplitude loss is relatively small. The parameter value can be used as the optimal control parameter, and based on this result, it can provide technical support for subsequent experimental evaluation of radar equipment in multi frequency electromagnetic environments.
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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, Available online ,
doi: 10.11884/HPLPB202436.240078
Abstract:
To realize multi-channel laser cluster focal spot measurement and give its temporal and spatial resolution characteristics, a focal spot optical measurement platform based on imaging system, photodiode combined with oscilloscope, streak camera and scientific CCD is built. Before the experiment, the sensitivity and dynamic range of the scientific CCD and the performance parameters of the streak camera, such as gain coefficient, slit width and scanning time, were tested and calibrated off-line. The CCD is used to measure the spatial distribution of multi-channel laser cluster focal spot with time integration. By using photodiode combined with oscilloscope and streak camera, the time synchronization of multi-channel laser reaching the target is tested. The time-resolved characteristics of high-quality cluster focal spot are measured, and the fine spatio-temporal evolution image of spectral dispersion smooth beam focal spot is obtained. The test of focal spot shape and time synchronization of multi-beam channel laser cluster provide support for improving focal spot test technology and method of high-power laser device.
To realize multi-channel laser cluster focal spot measurement and give its temporal and spatial resolution characteristics, a focal spot optical measurement platform based on imaging system, photodiode combined with oscilloscope, streak camera and scientific CCD is built. Before the experiment, the sensitivity and dynamic range of the scientific CCD and the performance parameters of the streak camera, such as gain coefficient, slit width and scanning time, were tested and calibrated off-line. The CCD is used to measure the spatial distribution of multi-channel laser cluster focal spot with time integration. By using photodiode combined with oscilloscope and streak camera, the time synchronization of multi-channel laser reaching the target is tested. The time-resolved characteristics of high-quality cluster focal spot are measured, and the fine spatio-temporal evolution image of spectral dispersion smooth beam focal spot is obtained. The test of focal spot shape and time synchronization of multi-beam channel laser cluster provide support for improving focal spot test technology and method of high-power laser device.
, Available online ,
doi: 10.11884/HPLPB202436.240161
Abstract:
Avalanche gallium arsenide photoconductive semiconductor switches (GaAs PCSSs ) have a wide range of applications due to their ultra-fast switching speed, low triggering jitter , optoelectronic isolation , high power capacity, high repetition frequency, and flexible device structure. In this paper, GaAs PCSSs with an anisotropic structure and an electrode gap of 5 mm are fabricated and packaged. The electrical characteristics of the switch in dark-state and on-states under different bias electric fields (36−76 kV/cm) are analyzed, featuring a rising edge in the order of hundred picosecond to nanosecond, low dark-state leakage current (0.15−6.61 μA) and high withstand voltage (18−38 kV). The relationship between the number of switching operations and the peak output voltage is explored. The experimental results show that the output voltage amplitude tends to decrease in a stepwise manner with the increase of the number of operations. The switch lifetime reaches 4.0 × 104 times at 20 kV and 2 Hz.
Avalanche gallium arsenide photoconductive semiconductor switches (GaAs PCSSs ) have a wide range of applications due to their ultra-fast switching speed, low triggering jitter , optoelectronic isolation , high power capacity, high repetition frequency, and flexible device structure. In this paper, GaAs PCSSs with an anisotropic structure and an electrode gap of 5 mm are fabricated and packaged. The electrical characteristics of the switch in dark-state and on-states under different bias electric fields (36−76 kV/cm) are analyzed, featuring a rising edge in the order of hundred picosecond to nanosecond, low dark-state leakage current (0.15−6.61 μA) and high withstand voltage (18−38 kV). The relationship between the number of switching operations and the peak output voltage is explored. The experimental results show that the output voltage amplitude tends to decrease in a stepwise manner with the increase of the number of operations. The switch lifetime reaches 4.0 × 104 times at 20 kV and 2 Hz.
, Available online ,
doi: 10.11884/HPLPB202436.240024
Abstract:
To delve into the impact of nuclear data uncertainty on the effective multiplication factor calculation for the JRR-3M research reactor, this study established a nuclear data uncertainty quantification process based on SANDY. The specific methodology involved perturbing important reaction pathways of the target nuclides with SANDY to generate perturbation files, processing these files with NJOY, and ultimately utilizing OpenMC for Monte Carlo simulations. The influence on the effective multiplication factor due to several key nuclides (such as 235U, 238U, Hf, etc.) data uncertainty was calculated and analysed for three operational conditions of the JRR-3M research reactor. For critical, control rods fully inserted and control rods fully withdrawn conditions, total effective multiplication factor uncertainties are 660.8×10−5, 588.5×10−5 and 708.4×10−5, respectively. In all operational conditions, the impact of the fission release neutron energy distribution of 235U is the most notable. The study reveals that within hafnium control rods only the nuclear data uncertainty of 177Hf plays a major role.
To delve into the impact of nuclear data uncertainty on the effective multiplication factor calculation for the JRR-3M research reactor, this study established a nuclear data uncertainty quantification process based on SANDY. The specific methodology involved perturbing important reaction pathways of the target nuclides with SANDY to generate perturbation files, processing these files with NJOY, and ultimately utilizing OpenMC for Monte Carlo simulations. The influence on the effective multiplication factor due to several key nuclides (such as 235U, 238U, Hf, etc.) data uncertainty was calculated and analysed for three operational conditions of the JRR-3M research reactor. For critical, control rods fully inserted and control rods fully withdrawn conditions, total effective multiplication factor uncertainties are 660.8×10−5, 588.5×10−5 and 708.4×10−5, respectively. In all operational conditions, the impact of the fission release neutron energy distribution of 235U is the most notable. The study reveals that within hafnium control rods only the nuclear data uncertainty of 177Hf plays a major role.
, Available online ,
doi: 10.11884/HPLPB202436.240106
Abstract:
The two-layer magnetized liner target offers an alternative approach to magnetized target fusion implosions by incorporating high atomic number (Z) materials in the innermost layer to mitigate magnetic flux losses caused by Nernst effects and reduce ignition requirements. However, the inclusion of high-Z materials may lead to increased radiation losses due to mixing. This preliminary research on magnetized liner inertial fusion (MagLIF) utilizes germanium (Ge) doped with CH as a high-Z substitute in the liner to isolate the effects of magnetic Nernst advection and mixing. Compared to one-layer targets, the two-layer configuration demonstrates significant increases in temperature and magnetic flux, resulting in a 154% improvement in fusion yield. Different concentrations of CH dopant are introduced into the inner layer of Ge, and the effects of CH concentrations on fusion yield are analyzed. The study shows that using low concentration CH-doped Ge as inner layer of liner can enhance fusion yield.
The two-layer magnetized liner target offers an alternative approach to magnetized target fusion implosions by incorporating high atomic number (Z) materials in the innermost layer to mitigate magnetic flux losses caused by Nernst effects and reduce ignition requirements. However, the inclusion of high-Z materials may lead to increased radiation losses due to mixing. This preliminary research on magnetized liner inertial fusion (MagLIF) utilizes germanium (Ge) doped with CH as a high-Z substitute in the liner to isolate the effects of magnetic Nernst advection and mixing. Compared to one-layer targets, the two-layer configuration demonstrates significant increases in temperature and magnetic flux, resulting in a 154% improvement in fusion yield. Different concentrations of CH dopant are introduced into the inner layer of Ge, and the effects of CH concentrations on fusion yield are analyzed. The study shows that using low concentration CH-doped Ge as inner layer of liner can enhance fusion yield.
, Available online ,
doi: 10.11884/HPLPB202436.230218
Abstract:
Peaking capacitors, due to their compact structure, generally use indirect measurement of the voltage they bear, and direct measurement of their voltage has always been a difficult problem to solve. To solve this problem, we developed a new type of resistance compensation type self-integrating peak capacitor integrated capacitor voltage divider based on peaking capacitors. Secondly, based on the new structure of the voltage divider, the theoretical voltage ratio of the peak capacitance integrated capacitor voltage divider was analyzed. The calculation formula for the theoretical voltage ratio and the analysis of factors affecting low-frequency response were provided, and circuit simulation verification was carried out. At the same time, square wave calibration experiments were conducted, and the partial pressure ratio and response time of the two probes were obtained, and the response time of the probes was less than 6.2 ns. In addition, to obtain a more accurate voltage ratio and verify the stability of the voltage ratio of the integrated capacitor voltage divider under normal working conditions, high-voltage online calibration experiments were conducted, and the voltage ratio of probe 1 was 11071 and probe 2 was 15148. Moreover, at higher voltage levels, the relative measurement error of the capacitive voltage divider probe is relatively small, and the voltage divider ratio has good stability.
Peaking capacitors, due to their compact structure, generally use indirect measurement of the voltage they bear, and direct measurement of their voltage has always been a difficult problem to solve. To solve this problem, we developed a new type of resistance compensation type self-integrating peak capacitor integrated capacitor voltage divider based on peaking capacitors. Secondly, based on the new structure of the voltage divider, the theoretical voltage ratio of the peak capacitance integrated capacitor voltage divider was analyzed. The calculation formula for the theoretical voltage ratio and the analysis of factors affecting low-frequency response were provided, and circuit simulation verification was carried out. At the same time, square wave calibration experiments were conducted, and the partial pressure ratio and response time of the two probes were obtained, and the response time of the probes was less than 6.2 ns. In addition, to obtain a more accurate voltage ratio and verify the stability of the voltage ratio of the integrated capacitor voltage divider under normal working conditions, high-voltage online calibration experiments were conducted, and the voltage ratio of probe 1 was 11071 and probe 2 was 15148. Moreover, at higher voltage levels, the relative measurement error of the capacitive voltage divider probe is relatively small, and the voltage divider ratio has good stability.
, Available online ,
doi: 10.11884/HPLPB202436.230283
Abstract:
Penning ion source has been widely used in associated neutron tube due to its simple structure, small size and low power consumption. Based on the Penning ion source used in the laboratory, the volt-ampere characteristics in the ionization process are analyzed. The distribution of plasma is observed by a CCD camera inside the ion source. The density and temperature of electrons are analyzed by spectroscopy of the hydrogen plasma. Based on the Penning ion source structure used in the laboratory, this paper establishes a global model of collision ionization of H2 molecules and analyzes the influence of working parameters of ion source to the electron temperature and electron density in the plasma. The electron density increases gradually with the increase of discharge power, and it increases first and then decreases when the magnetic field and pressure increase. It is necessary to control the magnetic field within 0.03−0.05 T, and the pressure within (0.2−2)×10−2 Pa. The electron temperature increases with the power and decreases with pressure. The model shows that the electron temperature is less than 10 eV, and the electron density is 1010 cm−3 in the operating range of Penning ion source.
Penning ion source has been widely used in associated neutron tube due to its simple structure, small size and low power consumption. Based on the Penning ion source used in the laboratory, the volt-ampere characteristics in the ionization process are analyzed. The distribution of plasma is observed by a CCD camera inside the ion source. The density and temperature of electrons are analyzed by spectroscopy of the hydrogen plasma. Based on the Penning ion source structure used in the laboratory, this paper establishes a global model of collision ionization of H2 molecules and analyzes the influence of working parameters of ion source to the electron temperature and electron density in the plasma. The electron density increases gradually with the increase of discharge power, and it increases first and then decreases when the magnetic field and pressure increase. It is necessary to control the magnetic field within 0.03−0.05 T, and the pressure within (0.2−2)×10−2 Pa. The electron temperature increases with the power and decreases with pressure. The model shows that the electron temperature is less than 10 eV, and the electron density is 1010 cm−3 in the operating range of Penning ion source.
, Available online ,
doi: 10.11884/HPLPB202436.240147
Abstract:
The high-power microwave source does not satisfy the requirements for deep space communications, wireless power transmission systems and high-power superconducting accelerators because of the real-time power control problems. To break through such limitations, an available power control method based on injection locking is proposed. Theoretical analysis and experiment are carried out to prove the performance of the proposed frequency-controlled microwave source based on dual 20 kW S-band high power magnetrons. The experiment results show that the real-time power control combining via the injecting frequency is achieved, when the injection power or free-running frequency of magnetron is unequal. Simultaneously, the system shows an output power control range of 3.0 dB, a nearly 4.0 MHz injection-locking bandwidth, and a sharp spectrum with an excellent spur suppression ratio of −65.0 dBc@500 kHz. The highest combining power output of 33.9 kW with the system efficiency of 86.6% is also proved. Such researches play an important role in the development of high-power microwave applications.
The high-power microwave source does not satisfy the requirements for deep space communications, wireless power transmission systems and high-power superconducting accelerators because of the real-time power control problems. To break through such limitations, an available power control method based on injection locking is proposed. Theoretical analysis and experiment are carried out to prove the performance of the proposed frequency-controlled microwave source based on dual 20 kW S-band high power magnetrons. The experiment results show that the real-time power control combining via the injecting frequency is achieved, when the injection power or free-running frequency of magnetron is unequal. Simultaneously, the system shows an output power control range of 3.0 dB, a nearly 4.0 MHz injection-locking bandwidth, and a sharp spectrum with an excellent spur suppression ratio of −65.0 dBc@500 kHz. The highest combining power output of 33.9 kW with the system efficiency of 86.6% is also proved. Such researches play an important role in the development of high-power microwave applications.
, Available online ,
doi: 10.11884/HPLPB202436.240068
Abstract:
To address the challenge of establishing a stable removal function for double-sided polishing to predict the finished surface profile, we use the coordinate transformation method to derive the relative velocity distribution equations for the upper and lower surfaces of the component. Subsequently, static pressure distributions on both surfaces are simulated using ANSYS software. The simulation data is then imported into Matlab and fitted with a polynomial method to determine the time-varying pressure distribution formulas for the component's surfaces. Based on the Preston equation, an expression for the correction coefficient K is derived. The value of the correction coefficient K is calculated to be 2.588×10−15 from four sets of polishing experimental data, enabling the construction of a predictive model for the surface pattern in double-sided polishing processes. The predictive model is ultimately validated through machining experiments. The experimental results indicate that the error in predicting the PV (Peak-to-Valley) value accounts for 1.07% to 7.4% of the actual PV value after processing, demonstrating good agreement between the predicted model and the actual post-processing surface pattern.
To address the challenge of establishing a stable removal function for double-sided polishing to predict the finished surface profile, we use the coordinate transformation method to derive the relative velocity distribution equations for the upper and lower surfaces of the component. Subsequently, static pressure distributions on both surfaces are simulated using ANSYS software. The simulation data is then imported into Matlab and fitted with a polynomial method to determine the time-varying pressure distribution formulas for the component's surfaces. Based on the Preston equation, an expression for the correction coefficient K is derived. The value of the correction coefficient K is calculated to be 2.588×10−15 from four sets of polishing experimental data, enabling the construction of a predictive model for the surface pattern in double-sided polishing processes. The predictive model is ultimately validated through machining experiments. The experimental results indicate that the error in predicting the PV (Peak-to-Valley) value accounts for 1.07% to 7.4% of the actual PV value after processing, demonstrating good agreement between the predicted model and the actual post-processing surface pattern.
, Available online ,
doi: 10.11884/HPLPB202436.240086
Abstract:
Currently, the research on pseudospark switches triggered by laser mainly focuses on triggering by ultraviolet laser, and the physical triggering mechanism is generally considered to be photoemission. However, when the weakly focused ultraviolet laser irradiates the photoelectric material (target) in a low electric field environment, the seed electrons generated by the photoemission are very limited. To further reveal the physical mechanism of the switches triggered by the weakly focused ultraviolet laser, we established the test experimental platform for discharge of pseudospark switches triggered by weakly focused 266 nm ultraviolet laser. On this basis, the emission characteristics of seed electrons irradiated by laser were tested. The effects of laser energy, switch voltage, gas pressure, target material and irradiation position on the trigger characteristics of the switch were studied, and the source of seed electrons and their contribution to trigger were analyzed. The results show that when the laser is irradiated on the edge of the hole on the back of the cathode, the prompt electrons generated by the photoemission are not the main source of the seed electrons, and the ultrafast electrons related to the ablation plasma are the main source. Therefore, when the laser is irradiated on the edge of the hole on the back of the cathode, the material with low density and melting boiling point is more suitable as the target material for pseudospark switch triggered by weakly focused ultraviolet laser. According to the testing result, in this case, the operating voltage is −15 kV, and the pressure is 80 Pa (helium), the minimum laser energy of the switch with magnesium as the target can achieve stable trigger conduction is 2 mJ, which is much lower than that of copper (6 mJ) and molybdenum (8 mJ). In addition, under the same conditions, when the laser is irradiated on the inner wall of the cathode hole of the switch, the trigger delay and jitter are 36.9 ns and 1.41 ns, which are much lower than those when the laser is irradiated on the edge of the hole on the back of the cathode (116.4 ns and 5.39 ns).
Currently, the research on pseudospark switches triggered by laser mainly focuses on triggering by ultraviolet laser, and the physical triggering mechanism is generally considered to be photoemission. However, when the weakly focused ultraviolet laser irradiates the photoelectric material (target) in a low electric field environment, the seed electrons generated by the photoemission are very limited. To further reveal the physical mechanism of the switches triggered by the weakly focused ultraviolet laser, we established the test experimental platform for discharge of pseudospark switches triggered by weakly focused 266 nm ultraviolet laser. On this basis, the emission characteristics of seed electrons irradiated by laser were tested. The effects of laser energy, switch voltage, gas pressure, target material and irradiation position on the trigger characteristics of the switch were studied, and the source of seed electrons and their contribution to trigger were analyzed. The results show that when the laser is irradiated on the edge of the hole on the back of the cathode, the prompt electrons generated by the photoemission are not the main source of the seed electrons, and the ultrafast electrons related to the ablation plasma are the main source. Therefore, when the laser is irradiated on the edge of the hole on the back of the cathode, the material with low density and melting boiling point is more suitable as the target material for pseudospark switch triggered by weakly focused ultraviolet laser. According to the testing result, in this case, the operating voltage is −15 kV, and the pressure is 80 Pa (helium), the minimum laser energy of the switch with magnesium as the target can achieve stable trigger conduction is 2 mJ, which is much lower than that of copper (6 mJ) and molybdenum (8 mJ). In addition, under the same conditions, when the laser is irradiated on the inner wall of the cathode hole of the switch, the trigger delay and jitter are 36.9 ns and 1.41 ns, which are much lower than those when the laser is irradiated on the edge of the hole on the back of the cathode (116.4 ns and 5.39 ns).
, Available online ,
doi: 10.11884/HPLPB202436.240144
Abstract:
To enhance the performance of laser-induced breakdown spectroscopy (LIBS) for the analysis of element Cr in solutions, a surface-enhanced LIBS technique combining metallic microstructures is proposed. Initially, using femtosecond laser surface texturing technology, various shapes and cycles of microstructures including rectangles, circles, triangles, and hexagons were etched on the surface of metallic aluminum. Through comparative analysis, the effects of different microstructures on the surface-enhanced LIBS spectral intensity and stability of Cr-element aqueous solutions deposited on them were investigated. The results indicate that smaller microstructure cycles result in more significant spectral enhancement, with rectangular microstructures demonstrating the optimal spectral enhancement at the same period, increasing the spectral intensity by approximately four times compared to untreated metallic aluminum. Furthermore, hexagonal microstructures exhibit the best spectral stability and repeatability. These findings provide a viable method for substrate preparation for applying surface-enhanced LIBS techniques to the detection of heavy metal elements in aqueous solutions.
To enhance the performance of laser-induced breakdown spectroscopy (LIBS) for the analysis of element Cr in solutions, a surface-enhanced LIBS technique combining metallic microstructures is proposed. Initially, using femtosecond laser surface texturing technology, various shapes and cycles of microstructures including rectangles, circles, triangles, and hexagons were etched on the surface of metallic aluminum. Through comparative analysis, the effects of different microstructures on the surface-enhanced LIBS spectral intensity and stability of Cr-element aqueous solutions deposited on them were investigated. The results indicate that smaller microstructure cycles result in more significant spectral enhancement, with rectangular microstructures demonstrating the optimal spectral enhancement at the same period, increasing the spectral intensity by approximately four times compared to untreated metallic aluminum. Furthermore, hexagonal microstructures exhibit the best spectral stability and repeatability. These findings provide a viable method for substrate preparation for applying surface-enhanced LIBS techniques to the detection of heavy metal elements in aqueous solutions.
, Available online ,
doi: 10.11884/HPLPB202436.240079
Abstract:
In view of the adverse effect of noise on frequency hopping signal parameter estimation, a frequency hopping signal parameter estimation method based on time-frequency transform and waveform shaping is proposed. The time-frequency ridge is calculated by the short-time Fourier transform of the frequency hopping signal, the waveform shaping of the time-frequency ridge is processed to eliminate the false time-hopping interference caused by noise, and the hopping period sequence is obtained through the time-hopping sequence. The histogram of the hopping period sequence is calculated, and the value with the most occurrence times is selected to calculate the hopping speed of the frequency hopping signal. According to the hopping period sequence, signal of each hop is extracted respectively, and then the frequency is estimated. The effectiveness of the proposed method is verified by experiments, and the ideal estimation results of hopping time, hopping speed and frequency of frequency hopping signal under low signal-to-noise ratio are guaranteed by comprehensive use of time-frequency transformation and waveform shaping technology.
In view of the adverse effect of noise on frequency hopping signal parameter estimation, a frequency hopping signal parameter estimation method based on time-frequency transform and waveform shaping is proposed. The time-frequency ridge is calculated by the short-time Fourier transform of the frequency hopping signal, the waveform shaping of the time-frequency ridge is processed to eliminate the false time-hopping interference caused by noise, and the hopping period sequence is obtained through the time-hopping sequence. The histogram of the hopping period sequence is calculated, and the value with the most occurrence times is selected to calculate the hopping speed of the frequency hopping signal. According to the hopping period sequence, signal of each hop is extracted respectively, and then the frequency is estimated. The effectiveness of the proposed method is verified by experiments, and the ideal estimation results of hopping time, hopping speed and frequency of frequency hopping signal under low signal-to-noise ratio are guaranteed by comprehensive use of time-frequency transformation and waveform shaping technology.
Column
- Cover and Contents
- High Power Laser Physics and Technology
- Inertial Confinement Fusion Physics and Technology
- High Power Microwave Technology
- Particle Beams and Accelerator Technology
- Pulsed Power Technology
- Nuclear Science and Engineering
- Advanced Interdisciplinary Science
- Special Column of 4th Symposium on Frontier of HPLPB
Display Method:
2024, 36: 081001.
doi: 10.11884/HPLPB202436.240081
Abstract:
Aiming at the difficulty of fabricating large-area nanograting structures with femtosecond laser in one step, the direct writing method of femtosecond laser pulse using slit-spatial shaping is proposed in this paper. By conducting a study on the parameter dependence of nanograting structures on the single-crystal silicon surface with the processing system, the optimized conditions of incident shaping femtosecond laser—energy density of 8.00 μJ/cm2, scanning speed of 9 mm/s, and slit width of 0.40 mm—are obtained. By using SEM, AFM and other microscopic characterization methods, it is indicated that the fabricated nanograting structure has an extremely high width (41.20 μm), greatly improving the fabrication efficiency of large-area nanograting structures in one step. This study provides a certain reference for the current research on efficiency optimizing and performance enhancing of femtosecond laser direct writing systems.
Aiming at the difficulty of fabricating large-area nanograting structures with femtosecond laser in one step, the direct writing method of femtosecond laser pulse using slit-spatial shaping is proposed in this paper. By conducting a study on the parameter dependence of nanograting structures on the single-crystal silicon surface with the processing system, the optimized conditions of incident shaping femtosecond laser—energy density of 8.00 μJ/cm2, scanning speed of 9 mm/s, and slit width of 0.40 mm—are obtained. By using SEM, AFM and other microscopic characterization methods, it is indicated that the fabricated nanograting structure has an extremely high width (41.20 μm), greatly improving the fabrication efficiency of large-area nanograting structures in one step. This study provides a certain reference for the current research on efficiency optimizing and performance enhancing of femtosecond laser direct writing systems.
2024, 36: 081002.
doi: 10.11884/HPLPB202436.240125
Abstract:
In semiconductor laser self-mixing interferometry (SMI) for micro-displacement measurement, the precise extraction of phase information is essential for high-accuracy displacement reconstruction. However, measurement noise induces phase errors in the SMI signal, leading to suboptimal displacement reconstruction accuracy. To tackle the challenge of signal denoising, wavelet thresholding denoising algorithms can effectively filter out most of the noise. However, they suffer from local oscillation issues when applied to SMI signal denoising. This results in the appearance of new interference peaks in the denoised self-mixing interference signal, thereby causing erroneous displacement reconstruction. This paper proposes an SMI signal processing algorithm that synergistically combines wavelet thresholding and Savitzky-Golay (S-G) filtering. By incorporating the S-G filtering algorithm, the algorithm smooths out noise at phase jump points on a global scale, thus mitigating the local oscillation issues inherent in wavelet-only denoising. Experimental results of displacement reconstruction indicate that the proposed method successfully eliminates high-frequency noise at both amplitude and phase jump points. Consequently, the reconstructed displacement curve retains the original waveform characteristics of the vibrating object.
In semiconductor laser self-mixing interferometry (SMI) for micro-displacement measurement, the precise extraction of phase information is essential for high-accuracy displacement reconstruction. However, measurement noise induces phase errors in the SMI signal, leading to suboptimal displacement reconstruction accuracy. To tackle the challenge of signal denoising, wavelet thresholding denoising algorithms can effectively filter out most of the noise. However, they suffer from local oscillation issues when applied to SMI signal denoising. This results in the appearance of new interference peaks in the denoised self-mixing interference signal, thereby causing erroneous displacement reconstruction. This paper proposes an SMI signal processing algorithm that synergistically combines wavelet thresholding and Savitzky-Golay (S-G) filtering. By incorporating the S-G filtering algorithm, the algorithm smooths out noise at phase jump points on a global scale, thus mitigating the local oscillation issues inherent in wavelet-only denoising. Experimental results of displacement reconstruction indicate that the proposed method successfully eliminates high-frequency noise at both amplitude and phase jump points. Consequently, the reconstructed displacement curve retains the original waveform characteristics of the vibrating object.
2024, 36: 082001.
doi: 10.11884/HPLPB202436.240098
Abstract:
This study presents a conceptual design of a 200 MW laser Inertial Confinement Fusion (ICF) reactor blanket, referring to fusion reactor technologies. The blanket employs a dual-coolant structure consisting of supercritical CO2 (S-CO2) and liquid lead-lithium (PbLi). Transient and steady-state coupled models are established to calculate the temperature distribution and variations within the blanket. The implosion of the pellets is computed using MULTI-IFE. The nuclear heat coupling part is based on the Monte Carlo program OpenMC and self-programmed heat transfer models to calculate the blanket’s structure, cooling, and tritium production. The research findings indicate that the nuclear heat coupling model can complete preliminary calculations and analysis of the blanket. Periodic transient loads cause oscillations in the temperature of the first wall surface, but the temperature inside the blanket eventually converges to the steady-state calculation results. The reactor size significantly affects temperature reduction and oscillation effects, but it still requires xenon to flat radiation power peak. Both tritium production and energy export from the blanket are influenced by the reactor cavity size and the size of the breeding zone. Under the 200 MW operating conditions, it shows that a 3 m radius and a 0.25 m breeding zone size best meet the requirements.
This study presents a conceptual design of a 200 MW laser Inertial Confinement Fusion (ICF) reactor blanket, referring to fusion reactor technologies. The blanket employs a dual-coolant structure consisting of supercritical CO2 (S-CO2) and liquid lead-lithium (PbLi). Transient and steady-state coupled models are established to calculate the temperature distribution and variations within the blanket. The implosion of the pellets is computed using MULTI-IFE. The nuclear heat coupling part is based on the Monte Carlo program OpenMC and self-programmed heat transfer models to calculate the blanket’s structure, cooling, and tritium production. The research findings indicate that the nuclear heat coupling model can complete preliminary calculations and analysis of the blanket. Periodic transient loads cause oscillations in the temperature of the first wall surface, but the temperature inside the blanket eventually converges to the steady-state calculation results. The reactor size significantly affects temperature reduction and oscillation effects, but it still requires xenon to flat radiation power peak. Both tritium production and energy export from the blanket are influenced by the reactor cavity size and the size of the breeding zone. Under the 200 MW operating conditions, it shows that a 3 m radius and a 0.25 m breeding zone size best meet the requirements.
2024, 36: 082002.
doi: 10.11884/HPLPB202436.240059
Abstract:
It is significant for the design and production of detonators and other initiating explosive devices to study the variation law between high-pressure spark discharge characteristics and loading high pressure and spark gap. Taking the picosecond time-resolved streak camera and spectrometer as the core and the spark plasma generated by the high-voltage pulse power supply as the research object, a set of transient spectrum and scanning pyrometer systems was built. In the experiment, the two influencing factors of the tip gap and the two-pole voltage are considered. By collecting the transient spectrum of the spark generated by the high-voltage breakdown of the air at the tip, after processing and calibrating the data, combined with Plank’s blackbody radiation theory, the diagnosis of the transient spectrum and temperature of the discharge plasma is realized. The results show that under the same tip gap, with the increase of voltage, the emission spectrum of discharge plasma increases and reaches saturation in a specific voltage range. The transient temperature generated by the discharge shows an overall upward trend and usually gets a peak between 1.02−1.16 μs. When the tip voltage is 10 kV, the temperature can reach up to 16 617 K. In the case of the same voltage, as the gap increases, the emission spectrum of the discharge plasma first increases and then decreases, and the discharge temperature gradually drops in the overall trend.
It is significant for the design and production of detonators and other initiating explosive devices to study the variation law between high-pressure spark discharge characteristics and loading high pressure and spark gap. Taking the picosecond time-resolved streak camera and spectrometer as the core and the spark plasma generated by the high-voltage pulse power supply as the research object, a set of transient spectrum and scanning pyrometer systems was built. In the experiment, the two influencing factors of the tip gap and the two-pole voltage are considered. By collecting the transient spectrum of the spark generated by the high-voltage breakdown of the air at the tip, after processing and calibrating the data, combined with Plank’s blackbody radiation theory, the diagnosis of the transient spectrum and temperature of the discharge plasma is realized. The results show that under the same tip gap, with the increase of voltage, the emission spectrum of discharge plasma increases and reaches saturation in a specific voltage range. The transient temperature generated by the discharge shows an overall upward trend and usually gets a peak between 1.02−1.16 μs. When the tip voltage is 10 kV, the temperature can reach up to 16 617 K. In the case of the same voltage, as the gap increases, the emission spectrum of the discharge plasma first increases and then decreases, and the discharge temperature gradually drops in the overall trend.
2024, 36: 083001.
doi: 10.11884/HPLPB202436.240065
Abstract:
As a suspension for military aircraft, missile has potential for being struck by lightning in special thunderstorm environments. To improve the lightning protection of airborne missiles, a simulation environment of military aircraft with missiles is built in CST software according to the testing methods in SAE ARP5416 standard. The lightning 1A zones are classified through electrostatic field simulation, and the indirect effects of lightning striking on this model are simulated under injection current method. Simulation results show that the head rear edge of missile (metal parts) and tail wing tip of missile are susceptible to initial attachment from lightning. When the head rear edge of the missile is attached by lightning, extremely harsh electromagnetic environment occurs at the radome, and the equipment in the cabin of carbon fiber reinforced plastic (CFRP) can be damaged owing to the strong electric field and the high voltage induced on cables. However, the electric field strength and induced voltage amplitudes on cables can be dropped in two orders of magnitude separately in the condition of aluminum plating inside the CFRP cabin.
As a suspension for military aircraft, missile has potential for being struck by lightning in special thunderstorm environments. To improve the lightning protection of airborne missiles, a simulation environment of military aircraft with missiles is built in CST software according to the testing methods in SAE ARP5416 standard. The lightning 1A zones are classified through electrostatic field simulation, and the indirect effects of lightning striking on this model are simulated under injection current method. Simulation results show that the head rear edge of missile (metal parts) and tail wing tip of missile are susceptible to initial attachment from lightning. When the head rear edge of the missile is attached by lightning, extremely harsh electromagnetic environment occurs at the radome, and the equipment in the cabin of carbon fiber reinforced plastic (CFRP) can be damaged owing to the strong electric field and the high voltage induced on cables. However, the electric field strength and induced voltage amplitudes on cables can be dropped in two orders of magnitude separately in the condition of aluminum plating inside the CFRP cabin.
2024, 36: 083002.
doi: 10.11884/HPLPB202436.240119
Abstract:
Schottky mixer is the key component of terahertz receiving system. Compared with the receiver based on SIS (superconductor-insulator-superconductor) mixer and HEB (hot-electron bolometer) mixer, the terahertz receiver system constructed on the basis of Schottky diode mixer does not rely on low-temperature accessory equipment, and it has the advantages of low cost, light weight, small volume and low power consumption. At present, the structure of terahertz receiver front-end based on Schottky diode mixer is relatively complex. To solve the problems of complex structure, low integration and high loss of terahertz receiver front-end, a 288−318 GHz sub-harmonic mixer based on Schottky diode and its local oscillation channel is proposed. Accordingly, a terahertz receiver system based on this mixer is constructed. The terahertz receiver’s local oscillation channel consists of a 75 GHz sextupler, a power amplifier integrated module and a 150 GHz frequency doubler. The integrated design of the local oscillator channel makes the receiver integration greatly improved. The overall size of the integrated module is 20 mm×20 mm×43 mm. The final test of the receiver shows that: in the bandwidth of 288−318 GHz, the double sideband conversion loss of the receiver is 5.8−9.4 dB, and the noise temperature is 1 055−1 722 K, which has good RF performance.
Schottky mixer is the key component of terahertz receiving system. Compared with the receiver based on SIS (superconductor-insulator-superconductor) mixer and HEB (hot-electron bolometer) mixer, the terahertz receiver system constructed on the basis of Schottky diode mixer does not rely on low-temperature accessory equipment, and it has the advantages of low cost, light weight, small volume and low power consumption. At present, the structure of terahertz receiver front-end based on Schottky diode mixer is relatively complex. To solve the problems of complex structure, low integration and high loss of terahertz receiver front-end, a 288−318 GHz sub-harmonic mixer based on Schottky diode and its local oscillation channel is proposed. Accordingly, a terahertz receiver system based on this mixer is constructed. The terahertz receiver’s local oscillation channel consists of a 75 GHz sextupler, a power amplifier integrated module and a 150 GHz frequency doubler. The integrated design of the local oscillator channel makes the receiver integration greatly improved. The overall size of the integrated module is 20 mm×20 mm×43 mm. The final test of the receiver shows that: in the bandwidth of 288−318 GHz, the double sideband conversion loss of the receiver is 5.8−9.4 dB, and the noise temperature is 1 055−1 722 K, which has good RF performance.
2024, 36: 083003.
doi: 10.11884/HPLPB202436.230448
Abstract:
A slotted waveguide array antenna operating at S band for transmitting high power microwave is developed in this paper. The profile height is reduced by arranging the coupling waveguide and feeding waveguide on same layout. The coupling slots with same offsets direction and the radiating slots arranged regularly compensate phase, which achieves in-phase superposition of pattern of slot units. The influence of different slot parameters and types of divider on power capacity of the antenna are simulated. 0.1 MPa SF6 gas is filled in the sealed antenna to enhance power-handling capability. The simulated and test results show that the antenna has a 6.7% bandwidth with VSWR less than 1.5 and a gain up to 27 dBi. Hot test of this antenna is carried out fed by narrow-band high power microwave source. The transmitted waveform and the output one agree well. The measured output power of the source is 2.67 MW.
A slotted waveguide array antenna operating at S band for transmitting high power microwave is developed in this paper. The profile height is reduced by arranging the coupling waveguide and feeding waveguide on same layout. The coupling slots with same offsets direction and the radiating slots arranged regularly compensate phase, which achieves in-phase superposition of pattern of slot units. The influence of different slot parameters and types of divider on power capacity of the antenna are simulated. 0.1 MPa SF6 gas is filled in the sealed antenna to enhance power-handling capability. The simulated and test results show that the antenna has a 6.7% bandwidth with VSWR less than 1.5 and a gain up to 27 dBi. Hot test of this antenna is carried out fed by narrow-band high power microwave source. The transmitted waveform and the output one agree well. The measured output power of the source is 2.67 MW.
2024, 36: 083004.
doi: 10.11884/HPLPB202436.240090
Abstract:
Baluns with lumped parameters are compact and easily integrated, but they have limitations in terms of power handling and bandwidth. On the other hand, baluns with distributed parameters, such as coaxial baluns, are extensively utilized in the design of high-power irradiation antennas for differential feeding and impedance matching, owing to their wide bandwidth, low loss, and high power capacity. To address the engineering requirements of wideband high-power irradiation antennas in a specific experimental system, a coaxial balun with an impedance transformation ratio of 1∶2.25 loaded with a ferrite magnetic ring is designed and realised based on the coaxial balun design method with any non-integer impedance transformation ratio. Simulation and measurement results demonstrate that the balun operates within the frequency range of 0.01−1.30 GHz, with a phase imbalance within ±5° of 180° and an amplitude imbalance within ±1 dB. The insertion losses of both paths are below 1.5 dB. The electrical performance of the balun at 500 W power feed is simulated and analysed to verify its power capacity.
Baluns with lumped parameters are compact and easily integrated, but they have limitations in terms of power handling and bandwidth. On the other hand, baluns with distributed parameters, such as coaxial baluns, are extensively utilized in the design of high-power irradiation antennas for differential feeding and impedance matching, owing to their wide bandwidth, low loss, and high power capacity. To address the engineering requirements of wideband high-power irradiation antennas in a specific experimental system, a coaxial balun with an impedance transformation ratio of 1∶2.25 loaded with a ferrite magnetic ring is designed and realised based on the coaxial balun design method with any non-integer impedance transformation ratio. Simulation and measurement results demonstrate that the balun operates within the frequency range of 0.01−1.30 GHz, with a phase imbalance within ±5° of 180° and an amplitude imbalance within ±1 dB. The insertion losses of both paths are below 1.5 dB. The electrical performance of the balun at 500 W power feed is simulated and analysed to verify its power capacity.
2024, 36: 083005.
doi: 10.11884/HPLPB202436.240118
Abstract:
A 320 GHz balanced frequency tripler based on face-to-face differential configuration has been demonstrated without any on-chip capacitor. The proposed circuit could increase the power handling by a factor of two compared to the traditional balanced ones without any decline in efficiency. To improve the simulation accuracy under high dissipated power level, an accurate self-consistent electro-thermal model has been implemented using the symbolically defined device (SDD) component during the harmonic balance simulation. The fabricated tripler has proved that driven by powers ranging from 123 to 200 mW, the maximum output power and conversion efficiency can be 17.27 mW and 8.8% at 309.6 GHz, respectively. Moreover, the tripler reaches a peak output power of 27.33 mW with 7.2% conversion efficiency when driven from 305 to 384 mW. This configuration manifests a prospective solution for high-power multipliers, facilitating the application in various fields such as terahertz high-speed communication, radar imaging, and astronomical observation in the future.
A 320 GHz balanced frequency tripler based on face-to-face differential configuration has been demonstrated without any on-chip capacitor. The proposed circuit could increase the power handling by a factor of two compared to the traditional balanced ones without any decline in efficiency. To improve the simulation accuracy under high dissipated power level, an accurate self-consistent electro-thermal model has been implemented using the symbolically defined device (SDD) component during the harmonic balance simulation. The fabricated tripler has proved that driven by powers ranging from 123 to 200 mW, the maximum output power and conversion efficiency can be 17.27 mW and 8.8% at 309.6 GHz, respectively. Moreover, the tripler reaches a peak output power of 27.33 mW with 7.2% conversion efficiency when driven from 305 to 384 mW. This configuration manifests a prospective solution for high-power multipliers, facilitating the application in various fields such as terahertz high-speed communication, radar imaging, and astronomical observation in the future.
2024, 36: 083006.
doi: 10.11884/HPLPB202436.230401
Abstract:
This paper presents a cascaded broadband choke device, which can prevent microwave leakage by a transmission shaft in the waveguide. Utilizing the principle of impedance transformation, the bandwidth attributes of the cascaded broadband choke device are examined. It is discerned that augmenting the quantity of dielectric slices can enhance the bandwidth of the choke device. Furthermore, based on the principle of equivalent wavelength, escalating the dielectric constant of the dielectric slice can effectively reduce the choke device’s volume. An electromagnetic simulation software is employed to establish a model of a double-layer choke structure. This model is then used to simulate and analyze the impact of variables such as the number of dielectric slices, dielectric constant, and size on the choke structure’s performance. The simulation outcomes indicate that at a working frequency of 10 GHz, the leakage loss of the double-layer choke structure is less than −40 dB within a bandwidth range of 9.70−10.82 GHz, achieving a relative bandwidth of 8.2%. A simplified simulation model is subsequently utilized for physical fabrication and testing. The experimental findings not only corroborate the accuracy of the simulation results but also affirm the low-loss and wide-bandwidth characteristics of the proposed choke structure.
This paper presents a cascaded broadband choke device, which can prevent microwave leakage by a transmission shaft in the waveguide. Utilizing the principle of impedance transformation, the bandwidth attributes of the cascaded broadband choke device are examined. It is discerned that augmenting the quantity of dielectric slices can enhance the bandwidth of the choke device. Furthermore, based on the principle of equivalent wavelength, escalating the dielectric constant of the dielectric slice can effectively reduce the choke device’s volume. An electromagnetic simulation software is employed to establish a model of a double-layer choke structure. This model is then used to simulate and analyze the impact of variables such as the number of dielectric slices, dielectric constant, and size on the choke structure’s performance. The simulation outcomes indicate that at a working frequency of 10 GHz, the leakage loss of the double-layer choke structure is less than −40 dB within a bandwidth range of 9.70−10.82 GHz, achieving a relative bandwidth of 8.2%. A simplified simulation model is subsequently utilized for physical fabrication and testing. The experimental findings not only corroborate the accuracy of the simulation results but also affirm the low-loss and wide-bandwidth characteristics of the proposed choke structure.
2024, 36: 084001.
doi: 10.11884/HPLPB202436.240071
Abstract:
Scintillator array is composed of a large number of independent crystal columns, which limit the diffusion of visible light in the conversion screen, can improve the X-ray conversion efficiency while ensuring the radiography system to have higher spatial resolution, thus it is an important device in high-energy flash radiography system. There are inconsistency response in the received image due to the different conversion coefficients among the crystal columns of the scintillator array. Only by correcting the inconsistency response can the image be interpreted effectively. In this paper, the correction method of inconsistency response in experimental images is studied. Firstly, the empty field image is obtained by flat plate radiography, then the dark current background and impulse noise are deducted from the experimental image and the empty field image, and finally the pixel division operation is carried out between the experimental image and the empty field image. Aiming at the mismatch between the empty field image and the experimental image in strong vibration environment, a method of shifting the empty field image is proposed to realize the re-matching between the empty field image and the experimental image, and the standard deviation data of the corrected image is used to judge the matching between the two images. Experimental results show that the shifted empty field image can correct the inconsistency response of array screen image in strong vibration environment.
Scintillator array is composed of a large number of independent crystal columns, which limit the diffusion of visible light in the conversion screen, can improve the X-ray conversion efficiency while ensuring the radiography system to have higher spatial resolution, thus it is an important device in high-energy flash radiography system. There are inconsistency response in the received image due to the different conversion coefficients among the crystal columns of the scintillator array. Only by correcting the inconsistency response can the image be interpreted effectively. In this paper, the correction method of inconsistency response in experimental images is studied. Firstly, the empty field image is obtained by flat plate radiography, then the dark current background and impulse noise are deducted from the experimental image and the empty field image, and finally the pixel division operation is carried out between the experimental image and the empty field image. Aiming at the mismatch between the empty field image and the experimental image in strong vibration environment, a method of shifting the empty field image is proposed to realize the re-matching between the empty field image and the experimental image, and the standard deviation data of the corrected image is used to judge the matching between the two images. Experimental results show that the shifted empty field image can correct the inconsistency response of array screen image in strong vibration environment.
2024, 36: 084002.
doi: 10.11884/HPLPB202436.230407
Abstract:
This paper presents the development of superconducting longitudinal gradient bend prototype for Hefei Advanced Light Facility storage ring. The magnet structure parameters were optimized using a developed method that considered the requirements of spatial magnetic field distribution and magnet operating load. To verify the magnet design, a prototype magnet with a longitudinal length of 0.30 m and a pole gap of 46 mm was fabricated using a rectangular niobium-titanium wire and DT4C material. A simple low-temperature test device was built to measure the magnetizing characteristics of the magnet, and after more than 10 times of quench, the maximum operating current of the magnet was measured to be more than 275 A. The longitudinal magnetic field distribution of the magnet was measured, revealing an integral field of 0.4 T·m and a peak magnetic field of approximately 4.5 T at an operating current of about 196 A. The test results are basically consistent with the theoretical design, indicating that the design is reliable.
This paper presents the development of superconducting longitudinal gradient bend prototype for Hefei Advanced Light Facility storage ring. The magnet structure parameters were optimized using a developed method that considered the requirements of spatial magnetic field distribution and magnet operating load. To verify the magnet design, a prototype magnet with a longitudinal length of 0.30 m and a pole gap of 46 mm was fabricated using a rectangular niobium-titanium wire and DT4C material. A simple low-temperature test device was built to measure the magnetizing characteristics of the magnet, and after more than 10 times of quench, the maximum operating current of the magnet was measured to be more than 275 A. The longitudinal magnetic field distribution of the magnet was measured, revealing an integral field of 0.4 T·m and a peak magnetic field of approximately 4.5 T at an operating current of about 196 A. The test results are basically consistent with the theoretical design, indicating that the design is reliable.
2024, 36: 084003.
doi: 10.11884/HPLPB202436.240041
Abstract:
A linear timing system was designed for the linear injector of harbin institution of Technology’s space environment simulation and research infrastructure (SESRI) -300 MeV proton and heavy ion accelerator. The linear timing system provides precise timing trigger signals for linear accelerator chopper system with pulse operation mode, low-level RF control system, beam current diagnostic and feedback system to meet the demands of physical beam tuning. The system hardware, based on Field Programmable Gate Array (FPGA), realizes precise timing control of related equipment of linear timing system in internal trigger mode and external trigger mode, as well as the control and safety interlock of chopper. The hardware can realize optical signal communication, W5300 Ethernet communication, multiple relay outputs and multiple synchronized trigger signals with precise timing outputs. At the same time, the use of optical signal communication module will facilitate the cascade of systems and system scalability, which can meet the large-scale needs of linear gas pedal timing system. The user high level software is developed based on the distributed architecture of EPICS (Experimental Physics and Industrial Control System). The linear timing system has been successfully used in SESRI-300 MeV and SSC-LINAC of Institute of Modern Physics (IMP), and has operated stably and reliably for a long period of time without any failure.
A linear timing system was designed for the linear injector of harbin institution of Technology’s space environment simulation and research infrastructure (SESRI) -300 MeV proton and heavy ion accelerator. The linear timing system provides precise timing trigger signals for linear accelerator chopper system with pulse operation mode, low-level RF control system, beam current diagnostic and feedback system to meet the demands of physical beam tuning. The system hardware, based on Field Programmable Gate Array (FPGA), realizes precise timing control of related equipment of linear timing system in internal trigger mode and external trigger mode, as well as the control and safety interlock of chopper. The hardware can realize optical signal communication, W5300 Ethernet communication, multiple relay outputs and multiple synchronized trigger signals with precise timing outputs. At the same time, the use of optical signal communication module will facilitate the cascade of systems and system scalability, which can meet the large-scale needs of linear gas pedal timing system. The user high level software is developed based on the distributed architecture of EPICS (Experimental Physics and Industrial Control System). The linear timing system has been successfully used in SESRI-300 MeV and SSC-LINAC of Institute of Modern Physics (IMP), and has operated stably and reliably for a long period of time without any failure.
2024, 36: 084004.
doi: 10.11884/HPLPB202436.230323
Abstract:
For particle accelerators, ground deformation can cause beam distortion or even loss, thus it is necessary to study ground deformation in particle accelerator field. After constructing two parallelly distributed hydrostatic leveling systems consisting of 7 static leveling sensors spaced 10 m apart in the Hefei Light Source’s linear accelerator tunnel successively, we analyzed a total of three periods’ monitoring data collected by the two systems for a period length of half a month. We found the linear relationship in the ATL model and obtained the constant values of the ATL model separately, and discover the correlation between the model constant and seasons’ temperature. Finally, through data comparison, it was found that the periodic components in the relative motion of ground points were mainly affected by the Earth tide.
For particle accelerators, ground deformation can cause beam distortion or even loss, thus it is necessary to study ground deformation in particle accelerator field. After constructing two parallelly distributed hydrostatic leveling systems consisting of 7 static leveling sensors spaced 10 m apart in the Hefei Light Source’s linear accelerator tunnel successively, we analyzed a total of three periods’ monitoring data collected by the two systems for a period length of half a month. We found the linear relationship in the ATL model and obtained the constant values of the ATL model separately, and discover the correlation between the model constant and seasons’ temperature. Finally, through data comparison, it was found that the periodic components in the relative motion of ground points were mainly affected by the Earth tide.
2024, 36: 084005.
doi: 10.11884/HPLPB202436.230325
Abstract:
A highly precise low-level radio-frequency (LLRF) system for a 1.3 GHz continuous-wave (CW) superconducting radio-frequency (RF) cavity is required to stabilize the electromagnetic field of cavities. However, because of the high loaded quality factor and wide electromagnetic frequency band of the 1.3 GHz CW RF cavity, the RF cavity has a small electromagnetic bandwidth in the frequency domain. The small electromagnetic frequency mismatch between the RF power source and RF cavity can easily cause ponderomotive instabilities in the generator driven resonator control system, eventually resulting in variations in the electromagnetic field of the cavity. In this study, a self-excited loop (SEL) control system was developed to prevent the occurrence of ponderomotive instabilities and compensate for the effects of microphonics noise. In addition, a digital 1.3 GHz RF cavity simulator, which can easily verify the designed algorithms of the LLRF system, was developed. The recorded measurements show that the SEL control system can ensure stability of the cavity field even when the RF cavity is detuned by 5 Hz. The comparison and validation have verified that the cavity simulator is a reliable platform to test the new algorithms.
2024, 36: 085001.
doi: 10.11884/HPLPB202436.230349
Abstract:
In this paper, the photovoltaic (PV) power prediction model is optimized according to the characteristics of PV output units in distributed energy industrial parks to provide data support for the subsequent dispatching strategy. The EMD-SARIMA forecasting model is a combination of Empirical Mode Decomposition (EMD) and Seasonal Autoregressive Integrated Moving Average (SARIMA). In the model, the problem of determining the period of each IMF component of the signal component is proposed, the period T calculation method incorporating fast Fourier transform (FFT) is proposed, and the obtained period is fed into SARIMA as an input parameter together with the IMF sequence for prediction, which constitutes the EMD-FFT-SARIMA prediction model. Then, the prediction results corresponding to each IMF are superimposed and reconstructed to obtain the final prediction results. The error calculation of the prediction results reveals that the root mean square error (RMSE) decreases from 120.6 MW to 19.3 MW, and the mean absolute error (MAE) decreases from 52.87 MW to 12.3 MW.
In this paper, the photovoltaic (PV) power prediction model is optimized according to the characteristics of PV output units in distributed energy industrial parks to provide data support for the subsequent dispatching strategy. The EMD-SARIMA forecasting model is a combination of Empirical Mode Decomposition (EMD) and Seasonal Autoregressive Integrated Moving Average (SARIMA). In the model, the problem of determining the period of each IMF component of the signal component is proposed, the period T calculation method incorporating fast Fourier transform (FFT) is proposed, and the obtained period is fed into SARIMA as an input parameter together with the IMF sequence for prediction, which constitutes the EMD-FFT-SARIMA prediction model. Then, the prediction results corresponding to each IMF are superimposed and reconstructed to obtain the final prediction results. The error calculation of the prediction results reveals that the root mean square error (RMSE) decreases from 120.6 MW to 19.3 MW, and the mean absolute error (MAE) decreases from 52.87 MW to 12.3 MW.
2024, 36: 085002.
doi: 10.11884/HPLPB202436.240047
Abstract:
A drive circuit for solid-state high-voltage Marx pulser generator is designed, and the output side of the drive circuit adopts energy storage capacitor and P-N-MOS structure, which can complete the synchronization, fast turning on and turnin off control of the power MOSFET in the power circuit of the solid-state pulse generator, and has the functions of dead-time adjustment and negative voltage bias. In addition, the drive circuit is combined with the scheme of reverse wiring on the secondary side of the core-piercing magnetic ring to realize the control of two power MOSFETs of charging and discharging in the power loop using the same signal. Experiments show that the solid-state Marx pulse generator using this drive circuit can output a pulse square wave with a stable amplitude of 24 kV, and the output pulse width can be freely adjusted between 300 ns and 10 μs, and the rising and falling edges are within 40 ns.
A drive circuit for solid-state high-voltage Marx pulser generator is designed, and the output side of the drive circuit adopts energy storage capacitor and P-N-MOS structure, which can complete the synchronization, fast turning on and turnin off control of the power MOSFET in the power circuit of the solid-state pulse generator, and has the functions of dead-time adjustment and negative voltage bias. In addition, the drive circuit is combined with the scheme of reverse wiring on the secondary side of the core-piercing magnetic ring to realize the control of two power MOSFETs of charging and discharging in the power loop using the same signal. Experiments show that the solid-state Marx pulse generator using this drive circuit can output a pulse square wave with a stable amplitude of 24 kV, and the output pulse width can be freely adjusted between 300 ns and 10 μs, and the rising and falling edges are within 40 ns.
2024, 36: 086001.
doi: 10.11884/HPLPB202436.230368
Abstract:
To determine the alarm threshold for criticality accident alarm systems (CAASs) used in facility monitoring, it is necessary to select appropriate benchmark experiments for validation. This paper constructs a simplified model and a representative virtual equipment room model, taking into consideration the characteristics of CAASs in the equipment room. The functionality of calculating sensitivity coefficients using the differential operator sampling approach in the Monte Carlo code RMC was implemented to solve the fixed source problem. Following that, a sensitivity and uncertainty analysis was conducted to examine the similarities between systems and explore the factors influencing them. The results indicate that the neutron source term spectrum and the concrete material significantly affect the similarity between systems. Additionally, the thickness of the concrete between the detector and the inner wall has a moderate influence on similarity, whereas the geometric position of the source term has a negligible impact. The impact of the spent fuel composition on similarity can be neglected. Based on the similarity analysis procedure proposed in this study, it is concluded that the simplified model exhibits a relatively high similarity to the virtual equipment room model. Hence, the research conclusions based on the simplified model are applicable to the virtual equipment room model, offering valuable insights for similarity studies of CAASs in engineering.
To determine the alarm threshold for criticality accident alarm systems (CAASs) used in facility monitoring, it is necessary to select appropriate benchmark experiments for validation. This paper constructs a simplified model and a representative virtual equipment room model, taking into consideration the characteristics of CAASs in the equipment room. The functionality of calculating sensitivity coefficients using the differential operator sampling approach in the Monte Carlo code RMC was implemented to solve the fixed source problem. Following that, a sensitivity and uncertainty analysis was conducted to examine the similarities between systems and explore the factors influencing them. The results indicate that the neutron source term spectrum and the concrete material significantly affect the similarity between systems. Additionally, the thickness of the concrete between the detector and the inner wall has a moderate influence on similarity, whereas the geometric position of the source term has a negligible impact. The impact of the spent fuel composition on similarity can be neglected. Based on the similarity analysis procedure proposed in this study, it is concluded that the simplified model exhibits a relatively high similarity to the virtual equipment room model. Hence, the research conclusions based on the simplified model are applicable to the virtual equipment room model, offering valuable insights for similarity studies of CAASs in engineering.
2024, 36: 089001.
doi: 10.11884/HPLPB202436.240130
Abstract:
In this paper, to address the problem that the single-object tracking algorithm of Siamese fully convolutional networks cannot extract the high-level semantic features of the object and cannot focus on and learn the channel, spatial and coordinate features of the object at one time, which leads to degradation of the tracking performance and tracking failures when faced with the challenges of the object's deformation, attitude changes, and background interference in a complex scenario, we propose a single-object tracking algorithm for Siamese networks based on the multiple-attention mechanism and response fusion. In this algorithm, three modules, namely, the backbone feature extraction network with small convolutional kernel fused with jump-layer connected features, the improved attention mechanism, and the response fusion operation after convolutional inter-correlation are designed to enhance the tracking performance of this algorithm, and the effectiveness of these three modules is verified by ablation experiments. Finally, after testing on the OTB100 benchmark dataset, the tracking accuracy reaches 0.825, and the tracking success rate reaches 0.618. Meanwhile, compared with other advanced algorithms, it shows that the algorithm not only can effectively cope with the problem of decreasing performance of object tracking algorithms in complex scenarios, but also can further improve the tracking accuracy under the premise of guaranteeing the tracking speed.
In this paper, to address the problem that the single-object tracking algorithm of Siamese fully convolutional networks cannot extract the high-level semantic features of the object and cannot focus on and learn the channel, spatial and coordinate features of the object at one time, which leads to degradation of the tracking performance and tracking failures when faced with the challenges of the object's deformation, attitude changes, and background interference in a complex scenario, we propose a single-object tracking algorithm for Siamese networks based on the multiple-attention mechanism and response fusion. In this algorithm, three modules, namely, the backbone feature extraction network with small convolutional kernel fused with jump-layer connected features, the improved attention mechanism, and the response fusion operation after convolutional inter-correlation are designed to enhance the tracking performance of this algorithm, and the effectiveness of these three modules is verified by ablation experiments. Finally, after testing on the OTB100 benchmark dataset, the tracking accuracy reaches 0.825, and the tracking success rate reaches 0.618. Meanwhile, compared with other advanced algorithms, it shows that the algorithm not only can effectively cope with the problem of decreasing performance of object tracking algorithms in complex scenarios, but also can further improve the tracking accuracy under the premise of guaranteeing the tracking speed.
2024, 36: 089002.
doi: 10.11884/HPLPB202436.240067
Abstract:
Ion thruster is one of the widely used electric thrusters in space and space missions. The grid plays the role in extracting ions and accelerating them to achieve thrust, directly affecting the performance and lifespan of the thruster. Compared to traditional molybdenum grids, carbon based grids have advantages such as low thermal expansion coefficient and resistance to ion sputtering, making them ideal candidate materials for high specific impulse, high thrust, and long-life ion thruster. They have been successfully applied in orbit by some advanced ion thrusters abroad. This review analyzes and compares the characteristics of different grid materials, investigates and summarizes the development process and technical characteristics of carbon based grids at home and abroad, and reports the authors' recent progress in the development of small caliber, different configurations C/C grids, and integrated C/C grids. Finally, based on the development trend of ion propulsion in China, the review summarizes experiences and puts forward suggestions for subsequent carbon based grid research.
Ion thruster is one of the widely used electric thrusters in space and space missions. The grid plays the role in extracting ions and accelerating them to achieve thrust, directly affecting the performance and lifespan of the thruster. Compared to traditional molybdenum grids, carbon based grids have advantages such as low thermal expansion coefficient and resistance to ion sputtering, making them ideal candidate materials for high specific impulse, high thrust, and long-life ion thruster. They have been successfully applied in orbit by some advanced ion thrusters abroad. This review analyzes and compares the characteristics of different grid materials, investigates and summarizes the development process and technical characteristics of carbon based grids at home and abroad, and reports the authors' recent progress in the development of small caliber, different configurations C/C grids, and integrated C/C grids. Finally, based on the development trend of ion propulsion in China, the review summarizes experiences and puts forward suggestions for subsequent carbon based grid research.
2024, 36: 089003.
doi: 10.11884/HPLPB202436.230351
Abstract:
Aiming at the displacement measurement problem of two-dimensional high-frequency motion of two-axis piezoelectric shear stacks driven by high-frequency voltage, a method for measuring the displacement of piezoelectric shear stacks by using the machining trajectories of atomic force microscope (AFM) probe in tapping mode was proposed. Firstly, the thermoplastic polymer polymethyl methacrylate (PMMA) film was prepared, and then the AFM probe tapping experiment was carried out. By scanning the processing trajectory of the AFM probe and post-processing it, the two-dimensional high-frequency motion displacement of the piezoelectric shear stack was successfully obtained. Accurate detection of two-dimensional high-frequency complex motion of piezoelectric shear stacks in a semi-contact manner is realized. Based on the experimental data, the variation of the two-dimensional motion displacement of the piezoelectric shear stack with the voltage amplitude and frequency is analyzed.
Aiming at the displacement measurement problem of two-dimensional high-frequency motion of two-axis piezoelectric shear stacks driven by high-frequency voltage, a method for measuring the displacement of piezoelectric shear stacks by using the machining trajectories of atomic force microscope (AFM) probe in tapping mode was proposed. Firstly, the thermoplastic polymer polymethyl methacrylate (PMMA) film was prepared, and then the AFM probe tapping experiment was carried out. By scanning the processing trajectory of the AFM probe and post-processing it, the two-dimensional high-frequency motion displacement of the piezoelectric shear stack was successfully obtained. Accurate detection of two-dimensional high-frequency complex motion of piezoelectric shear stacks in a semi-contact manner is realized. Based on the experimental data, the variation of the two-dimensional motion displacement of the piezoelectric shear stack with the voltage amplitude and frequency is analyzed.
2024, 36: 083007.
doi: 10.11884/HPLPB202436.240109
Abstract:
The high-efficiency mutual coupling phase locking of magnetron provides an effective technical solution for high-efficiency and high-power arrays based on electric vacuum oscillators. The introduction of the mutual coupling structure makes the mutual coupling magnetron establish a new resonant mode sequence, in which the mode satisfying the high-efficiency phase-locking of the mutual coupling magnetron is the desired phase-locking mode. However, the phase-locked mode is susceptible to the interference of adjacent modes in the mode sequence, resulting in unstable operation. In this paper, a method of regulating the mode distribution by combining the equivalent circuit with the eigenmode analysis is proposed. By regulating the frequency separation of the mode, the phase-locked mode can work in a single mode. At the same time, the matching resonance conditions of the magnetron working mode and the coupling field of the mutual coupling structure are established to realize efficient mutual coupling phase locking of the magnetron. To verify the effectiveness of the method, an efficient mutual coupling model based on S-band MW-level magnetron is designed, and the particle simulation of the phase-locked mode operating characteristics is carried out. The simulation results show that the mutual coupling model can work stably in the high-efficiency phase-locking modes: 0 phase difference mode and π phase difference mode. The locking frequency is about 2.545 GHz, which is close to the free oscillation frequency of the magnetron single tube. The output power of each magnetron is close to the output power of a single tube in free operation. The electronic efficiency is almost the same as that of a single tube, and the mutual coupling phase-locking efficiency reaches 99%, achieving high-efficiency phase-locking.
The high-efficiency mutual coupling phase locking of magnetron provides an effective technical solution for high-efficiency and high-power arrays based on electric vacuum oscillators. The introduction of the mutual coupling structure makes the mutual coupling magnetron establish a new resonant mode sequence, in which the mode satisfying the high-efficiency phase-locking of the mutual coupling magnetron is the desired phase-locking mode. However, the phase-locked mode is susceptible to the interference of adjacent modes in the mode sequence, resulting in unstable operation. In this paper, a method of regulating the mode distribution by combining the equivalent circuit with the eigenmode analysis is proposed. By regulating the frequency separation of the mode, the phase-locked mode can work in a single mode. At the same time, the matching resonance conditions of the magnetron working mode and the coupling field of the mutual coupling structure are established to realize efficient mutual coupling phase locking of the magnetron. To verify the effectiveness of the method, an efficient mutual coupling model based on S-band MW-level magnetron is designed, and the particle simulation of the phase-locked mode operating characteristics is carried out. The simulation results show that the mutual coupling model can work stably in the high-efficiency phase-locking modes: 0 phase difference mode and π phase difference mode. The locking frequency is about 2.545 GHz, which is close to the free oscillation frequency of the magnetron single tube. The output power of each magnetron is close to the output power of a single tube in free operation. The electronic efficiency is almost the same as that of a single tube, and the mutual coupling phase-locking efficiency reaches 99%, achieving high-efficiency phase-locking.
2024, 36: 085003.
doi: 10.11884/HPLPB202436.240092
Abstract:
For requirement of quantity transmission in broadband measurement system, a unipolar rectangular pulse source is designed to realize 10 kV rectangular wave pulse output with MOSFET as the core component based on Marx circuit. The modular and miniaturization of the pulse generator is realized by using the stack structure to build the 12-stage prototype. The experimental results show that when the input voltage is 850 V, the proposed pulse source can generate a fast output pulse with 10 kV maximum voltage, rise time less than 100 ns, 200 μs pulse width under the capacitive load below 300 pF. The power supply can be used in rectangular wave response performance test of broadband measuring equipment or pulse power related applications.
For requirement of quantity transmission in broadband measurement system, a unipolar rectangular pulse source is designed to realize 10 kV rectangular wave pulse output with MOSFET as the core component based on Marx circuit. The modular and miniaturization of the pulse generator is realized by using the stack structure to build the 12-stage prototype. The experimental results show that when the input voltage is 850 V, the proposed pulse source can generate a fast output pulse with 10 kV maximum voltage, rise time less than 100 ns, 200 μs pulse width under the capacitive load below 300 pF. The power supply can be used in rectangular wave response performance test of broadband measuring equipment or pulse power related applications.
