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, Available online , doi: 10.11884/HPLPB202537.250011
Abstract:
The geoelectric fields induced by late-time high altitude electromagnetic pulse (HEMP E3) and geomagnetic storms lead to low frequency geomagnetically induced currents in the transmission grids, and the resulting half-cycle saturation of a large number of transformers could potentially threaten the power system voltage stability. However, in the existing study on HEMP E3 effect evaluation, it is typically assuming a uniform or 1D layered earth structure, without adequately considering the influence of lateral variations in earth conductivity on the induced geoelectric fields. Thus, it is difficult to rigorously assess the electromagnetic security of power systems under complex geological conditions such as coasts. This paper establishes a 3D computational model for HEMP E3 geoelectric fields based on finite element method, then studies the influence of complex earth conductivity structure on the spatiotemporal distribution of HEMP E3 geoelectric fields, and finally evaluates the power system voltage stability via electromagnetic transient simulation method. The results uncover substantial changes in the amplitude and duration of HEMP E3 geoelectric fields near the conductivity interface, which may lead to significant deviation in the voltage stability results of the power system. The method developed in this paper provides an important basis for the HEMP effect evaluation and protection of infrastructure located in complex geological areas.
The geoelectric fields induced by late-time high altitude electromagnetic pulse (HEMP E3) and geomagnetic storms lead to low frequency geomagnetically induced currents in the transmission grids, and the resulting half-cycle saturation of a large number of transformers could potentially threaten the power system voltage stability. However, in the existing study on HEMP E3 effect evaluation, it is typically assuming a uniform or 1D layered earth structure, without adequately considering the influence of lateral variations in earth conductivity on the induced geoelectric fields. Thus, it is difficult to rigorously assess the electromagnetic security of power systems under complex geological conditions such as coasts. This paper establishes a 3D computational model for HEMP E3 geoelectric fields based on finite element method, then studies the influence of complex earth conductivity structure on the spatiotemporal distribution of HEMP E3 geoelectric fields, and finally evaluates the power system voltage stability via electromagnetic transient simulation method. The results uncover substantial changes in the amplitude and duration of HEMP E3 geoelectric fields near the conductivity interface, which may lead to significant deviation in the voltage stability results of the power system. The method developed in this paper provides an important basis for the HEMP effect evaluation and protection of infrastructure located in complex geological areas.
, Available online , doi: 10.11884/HPLPB202537.240426
Abstract:
This study focuses on the performance of vertical photoconductive semiconductor switch (PCSS) based on Fe: β-Ga2O3 under high voltage. The results show that deep levels in Fe: β-Ga2O3 can provide carriers of non-intrinsic excitation. The device did not exhibit breakdown tendencies when subjected to a 20 kV input voltage with single-shot laser triggering. After more than5000 trigger cycles at 15 kV by a 10 Hz laser, the switch eventually failed. Nevertheless, pulse performance remained stable throughout the effective data collection period, preliminarily demonstrating the potential of Ga2O3 PCSS for applications in extreme conditions such as high power and high frequency. Failure analysis indicates that a wide bandgap is not the sole determinant of high breakdown voltage. In addition to employing precise doping techniques to introduce specific defects and modify material properties, further improvements in existing material growth methods and device packaging structures can also contribute to enhancing the output and lifetime of PCSS.
This study focuses on the performance of vertical photoconductive semiconductor switch (PCSS) based on Fe: β-Ga2O3 under high voltage. The results show that deep levels in Fe: β-Ga2O3 can provide carriers of non-intrinsic excitation. The device did not exhibit breakdown tendencies when subjected to a 20 kV input voltage with single-shot laser triggering. After more than
, Available online , doi: 10.11884/HPLPB202537.240412
Abstract:
With the continuous development of photoconductive microwave technology towards high-frequency, high-power, long-life, and high-efficiency directions, lateral photoconductive devices have the potential to achieve high photoelectric gain and high main frequency response due to intrinsic light triggering and low parasitic capacitance. We investigated the photocurrent response of intrinsic light back-illuminated lateral silicon carbide (SiC) photoconductive switches. Based on semiconductor numerical simulation, the output photocurrent of the device under intrinsic light triggering with different substrate thicknesses and different light powers was compared for front and back illumination. The internal current and electric field distribution of the device were analyzed and compared. Finally, experimental tests were conducted on the front and back triggering of a 50 μm lateral SiC photoconductive switch. The experimental results show that under a 40 kW peak light power, the on-resistance of the back-triggered device is reduced by 40% compared to the front-triggered device, confirming the high photoelectric conversion efficiency of the back-illuminated device, and the internal electric field and current of the back-triggered device are more uniform, which is more conducive to improving the device’s high-power capacity. The results provide simulation and experimental references for the intrinsic triggering of planar photoconductive switches.
With the continuous development of photoconductive microwave technology towards high-frequency, high-power, long-life, and high-efficiency directions, lateral photoconductive devices have the potential to achieve high photoelectric gain and high main frequency response due to intrinsic light triggering and low parasitic capacitance. We investigated the photocurrent response of intrinsic light back-illuminated lateral silicon carbide (SiC) photoconductive switches. Based on semiconductor numerical simulation, the output photocurrent of the device under intrinsic light triggering with different substrate thicknesses and different light powers was compared for front and back illumination. The internal current and electric field distribution of the device were analyzed and compared. Finally, experimental tests were conducted on the front and back triggering of a 50 μm lateral SiC photoconductive switch. The experimental results show that under a 40 kW peak light power, the on-resistance of the back-triggered device is reduced by 40% compared to the front-triggered device, confirming the high photoelectric conversion efficiency of the back-illuminated device, and the internal electric field and current of the back-triggered device are more uniform, which is more conducive to improving the device’s high-power capacity. The results provide simulation and experimental references for the intrinsic triggering of planar photoconductive switches.
, Available online , doi: 10.11884/HPLPB202537.240383
Abstract:
The insulating property of water medium affects the operation status of pulse power device, and air bubbles in water are the main factor causing breakdown of water medium. In order to remove air bubbles and dissolved gases in the water medium, the causes of air bubbles in the water medium are analyzed, and for the removal of body-phase air bubbles and surface adsorption air bubbles in the water medium, the methods of removing air bubbles by using vortex separators and reverse osmosis membranes are compared, and experimental research is carried out to study the performance of their air bubble removal. The results show that the vortex separator's low cyclonic strength leads to low separation efficiency, and the reverse osmosis membrane degassing makes the surface adsorbed bubbles re-dissolve by reducing the solubility of the gas in the water, and the separation efficiency is high, which can remove the gas bubbles and dissolved gases in the water, and it is of great significance for the stable operation of the pulsed power device.
The insulating property of water medium affects the operation status of pulse power device, and air bubbles in water are the main factor causing breakdown of water medium. In order to remove air bubbles and dissolved gases in the water medium, the causes of air bubbles in the water medium are analyzed, and for the removal of body-phase air bubbles and surface adsorption air bubbles in the water medium, the methods of removing air bubbles by using vortex separators and reverse osmosis membranes are compared, and experimental research is carried out to study the performance of their air bubble removal. The results show that the vortex separator's low cyclonic strength leads to low separation efficiency, and the reverse osmosis membrane degassing makes the surface adsorbed bubbles re-dissolve by reducing the solubility of the gas in the water, and the separation efficiency is high, which can remove the gas bubbles and dissolved gases in the water, and it is of great significance for the stable operation of the pulsed power device.
, Available online , doi: 10.11884/HPLPB202537.250028
Abstract:
The signal compensation method based on Wiener filtering has been demonstrated to have excellent compensation performance towards the signal distortion induced by the long-distance transmission in coaxial cable. However, how the parameters of this compensation method affect the compensation performance has not yet been investigated and analyzed, which may in turn bring some obstacles in the practical utilization of this modified method. Herein, we carried out a systematic study on the effect of the parameters on the signal compensation performance of this modified method. The results show that: for the signal-to-noise ratio (SNR), When the SNR is less than 25 dB, the compensation performance is continuously improved as the SNR increases. Once the SNR attains～25 dB, the relative error (δ) in between the compensated signal and input signal nearly keeps unchanged. For the sampling frequency interval Δf in S21 parameter measurement, the compensation performance keeps unchanged when Δf is small, and the compensation performance slowly deteriorates as Δf exceeds a certain value. As for the power estimation method, it is proved that among the traditional power estimation methods, the Burg method can obtain better compensation performance. This study can provide a beneficial reference for the application of the signal compensation method based on Wiener filtering.
The signal compensation method based on Wiener filtering has been demonstrated to have excellent compensation performance towards the signal distortion induced by the long-distance transmission in coaxial cable. However, how the parameters of this compensation method affect the compensation performance has not yet been investigated and analyzed, which may in turn bring some obstacles in the practical utilization of this modified method. Herein, we carried out a systematic study on the effect of the parameters on the signal compensation performance of this modified method. The results show that: for the signal-to-noise ratio (SNR), When the SNR is less than 25 dB, the compensation performance is continuously improved as the SNR increases. Once the SNR attains～25 dB, the relative error (δ) in between the compensated signal and input signal nearly keeps unchanged. For the sampling frequency interval Δf in S21 parameter measurement, the compensation performance keeps unchanged when Δf is small, and the compensation performance slowly deteriorates as Δf exceeds a certain value. As for the power estimation method, it is proved that among the traditional power estimation methods, the Burg method can obtain better compensation performance. This study can provide a beneficial reference for the application of the signal compensation method based on Wiener filtering.
, Available online , doi: 10.11884/HPLPB202537.240240
Abstract:
In response to the timing requirements for the commissioning and offline operation of many pre-research equipments at the China Spallation Neutron Source Phase II (CSNS-II), a synchronous timing system has been designed and developed independently based on “high-precision timing generator + low-jitter fiber optical transmission link”, which provides accurate triggers for the pre-research equipments in accordance with the physical design requirements. The hardware mainly consists of with cost-effective master boards and terminal boards, which realize strict synchronization and low-jitter transmission. Meanwhile, the master board has the ability to expand the number of output channels by using multimode optical fiber to realize the cascade connection of the hardware boards through high-speed serial transmission links; the upper software adopts adopts the method of "Serial Server + PC soft IOC" to realise the data interaction mechanism between the master board and Experimental Physics and Industrial Control System (EPICS), which can accurately configure the frequency, delay, pulse width and other parameters remotely. The synchronous timing system has been successfully used in the commissioning and operation of key pre-research equipments such as the radio frequency ion source of the CSNS-II, which has been operated stably and reliably for a long period of time. In addition, compared with commercial products, the synchronous timing system has the advantages of flexible design, strong anti-interference capability, and high versatility, which can provide a practical technical reference for the design and realisation of synchronous timing system for particle accelerator equipment at home and abroad.
In response to the timing requirements for the commissioning and offline operation of many pre-research equipments at the China Spallation Neutron Source Phase II (CSNS-II), a synchronous timing system has been designed and developed independently based on “high-precision timing generator + low-jitter fiber optical transmission link”, which provides accurate triggers for the pre-research equipments in accordance with the physical design requirements. The hardware mainly consists of with cost-effective master boards and terminal boards, which realize strict synchronization and low-jitter transmission. Meanwhile, the master board has the ability to expand the number of output channels by using multimode optical fiber to realize the cascade connection of the hardware boards through high-speed serial transmission links; the upper software adopts adopts the method of "Serial Server + PC soft IOC" to realise the data interaction mechanism between the master board and Experimental Physics and Industrial Control System (EPICS), which can accurately configure the frequency, delay, pulse width and other parameters remotely. The synchronous timing system has been successfully used in the commissioning and operation of key pre-research equipments such as the radio frequency ion source of the CSNS-II, which has been operated stably and reliably for a long period of time. In addition, compared with commercial products, the synchronous timing system has the advantages of flexible design, strong anti-interference capability, and high versatility, which can provide a practical technical reference for the design and realisation of synchronous timing system for particle accelerator equipment at home and abroad.
, Available online , doi: 10.11884/HPLPB202537.250004
Abstract:
Laser wireless energy transmission technology has the advantages of high power, long transmission distance, non-contact operation, and simultaneous energy and information transmission, and is expected to become a revolutionary energy transmission method, showing great application potential in consumer electronics, drones, aerospace and other fields. In this paper, the core module of laser wireless energy transmission technology and its development status in the fields of ground, aerospace and underwater at home and abroad are analyzed, and the technical challenges are summarized. Finally, the future development trend of laser wireless energy transmission system is discussed.
Laser wireless energy transmission technology has the advantages of high power, long transmission distance, non-contact operation, and simultaneous energy and information transmission, and is expected to become a revolutionary energy transmission method, showing great application potential in consumer electronics, drones, aerospace and other fields. In this paper, the core module of laser wireless energy transmission technology and its development status in the fields of ground, aerospace and underwater at home and abroad are analyzed, and the technical challenges are summarized. Finally, the future development trend of laser wireless energy transmission system is discussed.
, Available online , doi: 10.11884/HPLPB202436.240163
Abstract:
The quantitative study of combat effectiveness index is crucial for the informatization construction of the armed forces. To solve the problems of limits of quantitative research, low method accuracy, and weak robustness in the study of combat effectiveness index, and to break through the limitations of dominating complex rules, multivariate mathematical models, and strong coupling of influencing factors in the combat effectiveness index function, inspired by the mathematical analysis methods of rules in fuzzy logic theory, we proposed a local approximation based method for fitting combat effectiveness index function. Combining the powerful self-learning and self-deduction capabilities of neural networks, we constructed a corresponding quantitative calculation model based on radial basis function (RBF). Simulation comparative experiments show that the proposed method has an error rate of about 2% and 6% lower than the current best performing method using global approximation, and exhibits stronger robustness. Our method has strong practicality, can be migrated to other military fields, and has good engineering application prospects.
The quantitative study of combat effectiveness index is crucial for the informatization construction of the armed forces. To solve the problems of limits of quantitative research, low method accuracy, and weak robustness in the study of combat effectiveness index, and to break through the limitations of dominating complex rules, multivariate mathematical models, and strong coupling of influencing factors in the combat effectiveness index function, inspired by the mathematical analysis methods of rules in fuzzy logic theory, we proposed a local approximation based method for fitting combat effectiveness index function. Combining the powerful self-learning and self-deduction capabilities of neural networks, we constructed a corresponding quantitative calculation model based on radial basis function (RBF). Simulation comparative experiments show that the proposed method has an error rate of about 2% and 6% lower than the current best performing method using global approximation, and exhibits stronger robustness. Our method has strong practicality, can be migrated to other military fields, and has good engineering application prospects.
