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, Available online ,
doi: 10.11884/HPLPB202537.240360
Abstract:
A simple and effective improved A* algorithm is proposed to solve the problem of robot path planning in the integrated installation of large-scale laser devices. Compared with the traditional A* algorithm, the algorithm has been improved in three steps. Firstly, the walking direction is limited, which avoids the phenomenon of crossing obstacles occurred in the traditional A* algorithm; Secondly, the heuristic function is optimized as a weighted Manhattan distance function, which accelerates the expansion of nodes in the x direction or y direction, and reduces the surge of traversal nodes caused by limiting the walking direction. Thirdly, the turning penalty term is introduced to reduce the number of turns in the path planning process, and improve the search efficiency and quality. The performance of the three-step improved A* algorithm is verified in different size raster maps, and compared with the traditional A* algorithm. Experimental results show that in simple maps, the number of nodes traversed by the three-step improved A* algorithm is slightly higher than that of the traditional A* algorithm, and the number of turns is equivalent to that of the traditional A* algorithm, but the obstacle avoidance performance is obviously better than that of the traditional A* algorithm, which is more conducive to the safe walking of robots. In complex maps, considering the priority relationship of traversal nodes, turn times and path length, the parameters of the three-step improved A* algorithm can be adjusted to obtain the optimal path planning result.
A simple and effective improved A* algorithm is proposed to solve the problem of robot path planning in the integrated installation of large-scale laser devices. Compared with the traditional A* algorithm, the algorithm has been improved in three steps. Firstly, the walking direction is limited, which avoids the phenomenon of crossing obstacles occurred in the traditional A* algorithm; Secondly, the heuristic function is optimized as a weighted Manhattan distance function, which accelerates the expansion of nodes in the x direction or y direction, and reduces the surge of traversal nodes caused by limiting the walking direction. Thirdly, the turning penalty term is introduced to reduce the number of turns in the path planning process, and improve the search efficiency and quality. The performance of the three-step improved A* algorithm is verified in different size raster maps, and compared with the traditional A* algorithm. Experimental results show that in simple maps, the number of nodes traversed by the three-step improved A* algorithm is slightly higher than that of the traditional A* algorithm, and the number of turns is equivalent to that of the traditional A* algorithm, but the obstacle avoidance performance is obviously better than that of the traditional A* algorithm, which is more conducive to the safe walking of robots. In complex maps, considering the priority relationship of traversal nodes, turn times and path length, the parameters of the three-step improved A* algorithm can be adjusted to obtain the optimal path planning result.
, Available online ,
doi: 10.11884/HPLPB202537.240397
Abstract:
The deterministic calculation method based on multi-group cross section has always been an important approach in the design of nuclear reactors. The accuracy of multi-group cross section directly affects the precision of nuclear reactor physics calculations. In order to generate high-precision cross section data for fast reactors, North China Electric Power University has developed the high-precision cross section processing code MGGC2.0. This paper conducts benchmark verification and validation of the code. The infinite homogeneous mixed media UO2, MOX, and U-TRU-Zr fuels are calculated based on the ENDF/B-VII.1 library, and the macroscopic cross section generated by MGGC2.0 are compared with those produced by MCNP to verify the accuracy of the program in generating multi-group cross section. The relative deviation of the macroscopic multi-group total cross section from the reference solution of MCNP is generally within 5%. Subsequently, calculations are performed for the Russian fast reactor experiment BFS97-1, and a homogenization method of the fuel few-group cross section for various fuel arrangement forms is proposed. The collision probability method in MGGC2.0 was used to calculate the few-group cross section data for the fuel, and DIF3D program was employed for core calculations. Additionally, this study compared the results obtained using different cross section homogenization methods. The research findings indicate that for BFS97-1, if the cross section generated directly by critical search are used, the absolute deviation of the keff calculated by DIF3D from the keff calculated by MCNP is 2.541×10−2. This paper improves the calculation method of axial fuel inhomogeneity, reducing the deviation to below 5.0×10−4. The deviations between the calculated results for BFS97-1, BFS97-2, BFS97-5, and BFS97-6 and the MCNP results are all within3.0×10−3, validating the high accuracy of the code in generating multi-group and few-group cross section, which meets the requirements of engineering design.
The deterministic calculation method based on multi-group cross section has always been an important approach in the design of nuclear reactors. The accuracy of multi-group cross section directly affects the precision of nuclear reactor physics calculations. In order to generate high-precision cross section data for fast reactors, North China Electric Power University has developed the high-precision cross section processing code MGGC2.0. This paper conducts benchmark verification and validation of the code. The infinite homogeneous mixed media UO2, MOX, and U-TRU-Zr fuels are calculated based on the ENDF/B-VII.1 library, and the macroscopic cross section generated by MGGC2.0 are compared with those produced by MCNP to verify the accuracy of the program in generating multi-group cross section. The relative deviation of the macroscopic multi-group total cross section from the reference solution of MCNP is generally within 5%. Subsequently, calculations are performed for the Russian fast reactor experiment BFS97-1, and a homogenization method of the fuel few-group cross section for various fuel arrangement forms is proposed. The collision probability method in MGGC2.0 was used to calculate the few-group cross section data for the fuel, and DIF3D program was employed for core calculations. Additionally, this study compared the results obtained using different cross section homogenization methods. The research findings indicate that for BFS97-1, if the cross section generated directly by critical search are used, the absolute deviation of the keff calculated by DIF3D from the keff calculated by MCNP is 2.541×10−2. This paper improves the calculation method of axial fuel inhomogeneity, reducing the deviation to below 5.0×10−4. The deviations between the calculated results for BFS97-1, BFS97-2, BFS97-5, and BFS97-6 and the MCNP results are all within3.0×10−3, validating the high accuracy of the code in generating multi-group and few-group cross section, which meets the requirements of engineering design.
, Available online ,
doi: 10.11884/HPLPB202537.240413
Abstract:
In high-energy laser systems, the performance parameters of large-aperture sampling optics determine the accuracy of beam testing and evaluation, as well as the precision of overall system performance control. This paper focuses on the performance testing requirements of sampling optics with high-reflectivity (HR) on the front surface and anti-reflectivity (AR) on the back surface. Utilizing the cavity ring-down (CRD) based reflectivity uniformity testing of large-aperture sampling optics, the reflectivity distribution, optical loss, and high-resolution scanning imaging of defects of sampling optics are obtained by scanning measuring the incident light form both the reflective film surface and the anti-reflective film surface, respectively. Furthermore, by comparing and analyzing the defect distribution maps, the classification of defects in the reflective film, transmissive film, and substrate of the sampling optics can be achieved. Finally, by establishing a dual channel CRD system, the residual reflectance distribution of anti-reflective film and the types of defects in the transmissive film were obtained. The testing and analysis method proposed in this paper provides a systematic and comprehensive characterization tool for the performance evaluation and defect analysis of sampling optics.
In high-energy laser systems, the performance parameters of large-aperture sampling optics determine the accuracy of beam testing and evaluation, as well as the precision of overall system performance control. This paper focuses on the performance testing requirements of sampling optics with high-reflectivity (HR) on the front surface and anti-reflectivity (AR) on the back surface. Utilizing the cavity ring-down (CRD) based reflectivity uniformity testing of large-aperture sampling optics, the reflectivity distribution, optical loss, and high-resolution scanning imaging of defects of sampling optics are obtained by scanning measuring the incident light form both the reflective film surface and the anti-reflective film surface, respectively. Furthermore, by comparing and analyzing the defect distribution maps, the classification of defects in the reflective film, transmissive film, and substrate of the sampling optics can be achieved. Finally, by establishing a dual channel CRD system, the residual reflectance distribution of anti-reflective film and the types of defects in the transmissive film were obtained. The testing and analysis method proposed in this paper provides a systematic and comprehensive characterization tool for the performance evaluation and defect analysis of sampling optics.
, Available online ,
doi: 10.11884/HPLPB202537.240400
Abstract:
In order to effectively solve the problem of strong electromagnetic pulse power required to drive particle reactions, a new pulse power synchronous amplification technology based on hydrogen plasma loading and wave-particle resonance mechanism is studied on the basis of piezoelectric ceramic stack pulse source. The amplification mechanism is as follows: first, the energy of hydrogen molecule bonding orbitals is lower than that of antibonding orbitals, and internal energy will be released during the ionization process to promote the efficient occurrence of the ionization process driven by pulse power; Second, after the ionization of hydrogen atoms, the electromagnetic field and electrons undergo wave-particle resonance, and the electron energy is synchronously converted into electromagnetic field energy. After the amplification of wave-particle resonance, a stronger electromagnetic pulse is obtained, which can form a spherical electromagnetic field when applied to the spiral electrode, and has an extremely high acceleration gradient, which can accelerate a large number of protons produced after efficient ionization of hydrogen atoms. In this paper, the above theory is effectively proved through experimental tests and simulation analysis, and this research is expected to lay a foundation for a miniaturized and low-cost proton generator driven by strong electromagnetic pulses.
In order to effectively solve the problem of strong electromagnetic pulse power required to drive particle reactions, a new pulse power synchronous amplification technology based on hydrogen plasma loading and wave-particle resonance mechanism is studied on the basis of piezoelectric ceramic stack pulse source. The amplification mechanism is as follows: first, the energy of hydrogen molecule bonding orbitals is lower than that of antibonding orbitals, and internal energy will be released during the ionization process to promote the efficient occurrence of the ionization process driven by pulse power; Second, after the ionization of hydrogen atoms, the electromagnetic field and electrons undergo wave-particle resonance, and the electron energy is synchronously converted into electromagnetic field energy. After the amplification of wave-particle resonance, a stronger electromagnetic pulse is obtained, which can form a spherical electromagnetic field when applied to the spiral electrode, and has an extremely high acceleration gradient, which can accelerate a large number of protons produced after efficient ionization of hydrogen atoms. In this paper, the above theory is effectively proved through experimental tests and simulation analysis, and this research is expected to lay a foundation for a miniaturized and low-cost proton generator driven by strong electromagnetic pulses.
, Available online ,
doi: 10.11884/HPLPB202537.240401
Abstract:
In this paper, the working principle, composition and configuration of a miniaturized high-throughput neutron source system are introduced. This paper systematically introduces the piezoelectric pulse power source technology, nuclear reaction design technology, spherical electromagnetic field generation technology, particle proximity acceleration technology, particle polarization and resonance collision technology required for the development of this neutron source system. A complete neutron source physical system was developed and tested for energy spectrum and flux. The expected physical phenomena were observed in the experiments, and the occurrence of nuclear reactions was proved by online and offline neutron measurement methods, and the test results showed that the neutron radiation flux of the new miniature neutron source with a diameter of 2 cm and a length of 4 cm reached the level of 1010 n/(cm2·s), which belongs to strong neutron radiation source.
In this paper, the working principle, composition and configuration of a miniaturized high-throughput neutron source system are introduced. This paper systematically introduces the piezoelectric pulse power source technology, nuclear reaction design technology, spherical electromagnetic field generation technology, particle proximity acceleration technology, particle polarization and resonance collision technology required for the development of this neutron source system. A complete neutron source physical system was developed and tested for energy spectrum and flux. The expected physical phenomena were observed in the experiments, and the occurrence of nuclear reactions was proved by online and offline neutron measurement methods, and the test results showed that the neutron radiation flux of the new miniature neutron source with a diameter of 2 cm and a length of 4 cm reached the level of 1010 n/(cm2·s), which belongs to strong neutron radiation source.
, Available online ,
doi: 10.11884/HPLPB202537.240131
Abstract:
The Peking University (petawatt) laser proton accelerator develops a laser proton radiotherapy system in response to the needs of proton radiation tumor treatment. The common collection section of its horizontal and vertical beam lines mainly consists of three superconducting solenoids (S1-S3). Large stresses are generated in the solenoids during the cooling down and excitation process, in addition, the superconducting solenoids are operated by fast ramping, and the AC loss in the process will have an important impact on the solenoid excitation speed and stable operation. In this paper, the highest field strength and the most complex structure of 7.8T-120 mm solenoid S1 is taken as the research object, and COMSOL Multiphysics software is used to carry out the stress analysis of superconducting solenoids under multi-field conditions, and at the same time, the simulation of the AC loss due to the rapid change of the current is carried out. Subsequently, corresponding experimental studies were carried out to obtain the variation curves of strain with temperature, correlations betweencurrent, magnetic field and strain correspondingly. According to the experiment data, there is a significant positive correlation between the measured values of magnetic field and strain and the change of current, which verifies the rationality of the superconducting solenoid design. It provides experience and reference for the subsequent design and development of similar superconducting magnets.
The Peking University (petawatt) laser proton accelerator develops a laser proton radiotherapy system in response to the needs of proton radiation tumor treatment. The common collection section of its horizontal and vertical beam lines mainly consists of three superconducting solenoids (S1-S3). Large stresses are generated in the solenoids during the cooling down and excitation process, in addition, the superconducting solenoids are operated by fast ramping, and the AC loss in the process will have an important impact on the solenoid excitation speed and stable operation. In this paper, the highest field strength and the most complex structure of 7.8T-120 mm solenoid S1 is taken as the research object, and COMSOL Multiphysics software is used to carry out the stress analysis of superconducting solenoids under multi-field conditions, and at the same time, the simulation of the AC loss due to the rapid change of the current is carried out. Subsequently, corresponding experimental studies were carried out to obtain the variation curves of strain with temperature, correlations betweencurrent, magnetic field and strain correspondingly. According to the experiment data, there is a significant positive correlation between the measured values of magnetic field and strain and the change of current, which verifies the rationality of the superconducting solenoid design. It provides experience and reference for the subsequent design and development of similar superconducting magnets.
, Available online ,
doi: 10.11884/HPLPB202537.240407
Abstract:
This paper conducts a detailed study on the influence of second-harmonic parasitic effects in non-collinear ultra-broadband degenerate optical parametric amplification (OPA), which is pumped by frequency-doubled Ti:sapphire lasers. We consider both walk-off compensation and non-walk-off compensation scenarios. The study reveals that, under the non-walk-off compensation method, by appropriately increasing the non-collinear angle between the pump and signal beams, the impact of second-harmonic parasitic effects on the signal's output spectrum can be effectively reduced while ensuring broad-spectrum amplification of the signal. The evolution of the signal's output spectrum and output flux is investigated for different pump spectral bandwidths, clarifying the requirements for the pump spectral bandwidth given a specific signal output spectral bandwidth. The research findings provide design guidelines for generating ultra-broadband, high-temporal contrast femtosecond seed based on degenerate OPA.
This paper conducts a detailed study on the influence of second-harmonic parasitic effects in non-collinear ultra-broadband degenerate optical parametric amplification (OPA), which is pumped by frequency-doubled Ti:sapphire lasers. We consider both walk-off compensation and non-walk-off compensation scenarios. The study reveals that, under the non-walk-off compensation method, by appropriately increasing the non-collinear angle between the pump and signal beams, the impact of second-harmonic parasitic effects on the signal's output spectrum can be effectively reduced while ensuring broad-spectrum amplification of the signal. The evolution of the signal's output spectrum and output flux is investigated for different pump spectral bandwidths, clarifying the requirements for the pump spectral bandwidth given a specific signal output spectral bandwidth. The research findings provide design guidelines for generating ultra-broadband, high-temporal contrast femtosecond seed based on degenerate OPA.
, Available online ,
doi: 10.11884/HPLPB202537.240257
Abstract:
To facilitate online replacement and maintenance of solid-state power sources in particle accelerators, a cavity power combiner with online decoupling capability is required. While cavity combiners offer high power capacity, adjustable input coupling has not been achievable online. Therefore, we designed a 650 MHz eight-in-one cavity power combiner with a rotatable decoupling system. By integrating non-contact open-circuit slits at the RF input port and separating the coupling loop from the cavity, we enabled online rotation adjustment of the magnetic coupling loop. This adjustment allows real-time tuning of input coupling according to the operational status of solid-state power sources, facilitating hot-swapping and efficiency optimization. Simulation results demonstrate high synthesis efficiency and minimal power loss, with excellent amplitude consistency between input and output ports (deviations within 0.25 dB). The ability to adjust coupling online enhances RF isolation at input ports, enabling seamless hot-swappable replacement of power amplifier modules and significantly improving maintainability and flexibility.
To facilitate online replacement and maintenance of solid-state power sources in particle accelerators, a cavity power combiner with online decoupling capability is required. While cavity combiners offer high power capacity, adjustable input coupling has not been achievable online. Therefore, we designed a 650 MHz eight-in-one cavity power combiner with a rotatable decoupling system. By integrating non-contact open-circuit slits at the RF input port and separating the coupling loop from the cavity, we enabled online rotation adjustment of the magnetic coupling loop. This adjustment allows real-time tuning of input coupling according to the operational status of solid-state power sources, facilitating hot-swapping and efficiency optimization. Simulation results demonstrate high synthesis efficiency and minimal power loss, with excellent amplitude consistency between input and output ports (deviations within 0.25 dB). The ability to adjust coupling online enhances RF isolation at input ports, enabling seamless hot-swappable replacement of power amplifier modules and significantly improving maintainability and flexibility.
, Available online ,
doi: 10.11884/HPLPB202537.240386
Abstract:
During the integration of High Power Microwave (HPM) systems, the docking condition of the microwave source and the transmission-emission subsystem affects the HPM system performance directly. Poor docking conditions may cause radio frequency breakdown at the connection surface, which will result in the reduction of the entire system’s output power. Therefore, diagnosing the docking state of the system is of great engineering significance. For this reason, a non-contact high-power microwave transmission technology is investigated in this paper, and an injection power measurement method is proposed for a Ku-band GW-level HPM system using a conical horn as the feed source. Based on simulation designs, key subassembly of the technology was developed. In addition, the small signal test and power handling capacity assessment of the subassembly were carried out. The experimental outcomes demonstrated that the reflection coefficient was consistently below −26 dB, the coupling coefficient was (−0.31±0.07) dB within the frequency band of (15±0.15) GHz, and the power handling capacity exceeded 900 MW. The experimental and simulation results show that not only the proposed measurement technology has the characteristics of stable coupling coefficient and low test errors, but also can effectively measure the microwave power injected by HPM source through the feed-horn and diagnose the docking state of the HPM system.
During the integration of High Power Microwave (HPM) systems, the docking condition of the microwave source and the transmission-emission subsystem affects the HPM system performance directly. Poor docking conditions may cause radio frequency breakdown at the connection surface, which will result in the reduction of the entire system’s output power. Therefore, diagnosing the docking state of the system is of great engineering significance. For this reason, a non-contact high-power microwave transmission technology is investigated in this paper, and an injection power measurement method is proposed for a Ku-band GW-level HPM system using a conical horn as the feed source. Based on simulation designs, key subassembly of the technology was developed. In addition, the small signal test and power handling capacity assessment of the subassembly were carried out. The experimental outcomes demonstrated that the reflection coefficient was consistently below −26 dB, the coupling coefficient was (−0.31±0.07) dB within the frequency band of (15±0.15) GHz, and the power handling capacity exceeded 900 MW. The experimental and simulation results show that not only the proposed measurement technology has the characteristics of stable coupling coefficient and low test errors, but also can effectively measure the microwave power injected by HPM source through the feed-horn and diagnose the docking state of the HPM system.
, Available online ,
doi: 10.11884/HPLPB202537.240299
Abstract:
For a facility used multi-group magnetic cores, it's operation stability will be affected by the different working points of multi-group magnetic cores reset in parallel. A direct current reset system of the multi-pulse induction cells is developed instead of the original parallel pulsed reset system of a multi-pulse high power Linear Induction Accelerator (LIA) at burst mode. Resetting multi-group magnetic cores one by one is realized by separate relay switch for every induction cell and constant current sources with periodical output with the direct current reset system, the inconsistency in working points caused by parallel pulsed reset is effectively resolved. During engineering implementation, the system operates with two sets of constant current sources and eight switch control boxes to reset 94 groups of induction cell magnetic cores, significantly reducing system complexity and maintenance costs. Practical validation demonstrates that the improved accelerator exhibits enhanced multi-pulse stability, with beam centroid position jitter reduced from 1.3 mm to less than 1 mm. This paper describes the physics design of the direct current reset unit, and introduces the layout of the whole reset system which include the main units. The improvement effect is also presented in this paper.
For a facility used multi-group magnetic cores, it's operation stability will be affected by the different working points of multi-group magnetic cores reset in parallel. A direct current reset system of the multi-pulse induction cells is developed instead of the original parallel pulsed reset system of a multi-pulse high power Linear Induction Accelerator (LIA) at burst mode. Resetting multi-group magnetic cores one by one is realized by separate relay switch for every induction cell and constant current sources with periodical output with the direct current reset system, the inconsistency in working points caused by parallel pulsed reset is effectively resolved. During engineering implementation, the system operates with two sets of constant current sources and eight switch control boxes to reset 94 groups of induction cell magnetic cores, significantly reducing system complexity and maintenance costs. Practical validation demonstrates that the improved accelerator exhibits enhanced multi-pulse stability, with beam centroid position jitter reduced from 1.3 mm to less than 1 mm. This paper describes the physics design of the direct current reset unit, and introduces the layout of the whole reset system which include the main units. The improvement effect is also presented in this paper.
, Available online ,
doi: 10.11884/HPLPB202537.240346
Abstract:
Aiming at the problems of low extraction accuracy and weak anti-interference ability of line structure light centroids in turbid water bodies, this study proposes an improved internal advancement algorithm, which aims to enhance the accuracy and robustness of the extraction of line structure light centroids in complex environments. Firstly, the median filter is used to preprocess the image to suppress the noise, and combined with the eight-neighborhood method to quickly locate the starting point of the light stripe; subsequently, the grayscale neighborhood attribute method is introduced to dynamically estimate the pixel width of the current line of the line structured light, and based on the range of the maximum interclass variance method is applied to adaptively determine the binarized threshold value, which effectively reduces the background interference; finally, the grayscale gravity method is used to calculate the initial centroid in the constrained range of pixel widths and use this as the basis to advance upward and downward to search for the center point of the line structured light. Comparison tests are conducted in various turbid water environments and different structured light patterns. The results show that compared with the original internal advancement algorithm, the root mean square error of this paper's method is reduced by 13.33%, and the running speed of the algorithm is increased by 69.07% compared with Steger's algorithm, which realizes the balance between accuracy and speed.
Aiming at the problems of low extraction accuracy and weak anti-interference ability of line structure light centroids in turbid water bodies, this study proposes an improved internal advancement algorithm, which aims to enhance the accuracy and robustness of the extraction of line structure light centroids in complex environments. Firstly, the median filter is used to preprocess the image to suppress the noise, and combined with the eight-neighborhood method to quickly locate the starting point of the light stripe; subsequently, the grayscale neighborhood attribute method is introduced to dynamically estimate the pixel width of the current line of the line structured light, and based on the range of the maximum interclass variance method is applied to adaptively determine the binarized threshold value, which effectively reduces the background interference; finally, the grayscale gravity method is used to calculate the initial centroid in the constrained range of pixel widths and use this as the basis to advance upward and downward to search for the center point of the line structured light. Comparison tests are conducted in various turbid water environments and different structured light patterns. The results show that compared with the original internal advancement algorithm, the root mean square error of this paper's method is reduced by 13.33%, and the running speed of the algorithm is increased by 69.07% compared with Steger's algorithm, which realizes the balance between accuracy and speed.
, Available online ,
doi: 10.11884/HPLPB202537.240271
Abstract:
The ionization profile monitor (IPM) can provide critical beam distribution information required for real-time debugging and stable operation of high-current proton accelerators. The IPM system of the China Spallation Neutron Source (CSNS) Linac adopts a compact structural design. It collects data in ion mode and performs one-dimensional transverse beam distribution measurement through an optical imaging system. However, the honeycomb mesh structure at the electrode plate apertures blocks some ions or electrons from entering the microchannel plate, causing imaging shadows and introducing beam distribution distortion. Offline numerical algorithms must be used for correction. In this paper, partial differential equation (PDE) restoration and machine learning algorithms are used to correct the imaging shadows and beam distribution distortion caused by the honeycomb mesh of the IPM in the CSNS linac. The unsupervised machine learning method DIP (Deep Image Prior) was employed, and the corrected beam size deviates from the theoretical expectation by less than 10%, while maintaining a good signal-to-noise ratio.
The ionization profile monitor (IPM) can provide critical beam distribution information required for real-time debugging and stable operation of high-current proton accelerators. The IPM system of the China Spallation Neutron Source (CSNS) Linac adopts a compact structural design. It collects data in ion mode and performs one-dimensional transverse beam distribution measurement through an optical imaging system. However, the honeycomb mesh structure at the electrode plate apertures blocks some ions or electrons from entering the microchannel plate, causing imaging shadows and introducing beam distribution distortion. Offline numerical algorithms must be used for correction. In this paper, partial differential equation (PDE) restoration and machine learning algorithms are used to correct the imaging shadows and beam distribution distortion caused by the honeycomb mesh of the IPM in the CSNS linac. The unsupervised machine learning method DIP (Deep Image Prior) was employed, and the corrected beam size deviates from the theoretical expectation by less than 10%, while maintaining a good signal-to-noise ratio.
, Available online ,
doi: 10.11884/HPLPB202537.240280
Abstract:
To improve the vacuum surface flashover of insulators, in this paper, a kind of composite surface structure consisting of micro grooves and molecule self-assembly membrane was proposed and prepared on the surface of alumina vacuum insulators by laser carving, water cleaning and molecule self-assembly. Meanwhile, insulators with only micro grooves or pure molecule membrane were also prepared. Secondary electron emission yield test shows that both the micro groove construction and molecule self-assembly can decrease the secondary electron emission yield of the alumina insulator. Their combination the composite surface structure can further decrease the secondary electron emission yield. Correspondingly, surface flashover voltage test indicated that surface micro groove construction and molecule self-assembly could both improve the surface flashover voltages and their combination could further improve the flashover voltages. The results demonstrate that molecule membrane and the micro grooves in the composite structure can form dual suppression to the development of the vacuum flashover.
To improve the vacuum surface flashover of insulators, in this paper, a kind of composite surface structure consisting of micro grooves and molecule self-assembly membrane was proposed and prepared on the surface of alumina vacuum insulators by laser carving, water cleaning and molecule self-assembly. Meanwhile, insulators with only micro grooves or pure molecule membrane were also prepared. Secondary electron emission yield test shows that both the micro groove construction and molecule self-assembly can decrease the secondary electron emission yield of the alumina insulator. Their combination the composite surface structure can further decrease the secondary electron emission yield. Correspondingly, surface flashover voltage test indicated that surface micro groove construction and molecule self-assembly could both improve the surface flashover voltages and their combination could further improve the flashover voltages. The results demonstrate that molecule membrane and the micro grooves in the composite structure can form dual suppression to the development of the vacuum flashover.
, Available online ,
doi: 10.11884/HPLPB202537.240349
Abstract:
In order to improve the performance of waveform digital readout systems based on Analog to Digital Converter (ADC) technology, this paper proposes a multi-channel mismatch error estimation calibration method. Used two domestically produced high-speed ADCs to form a Time-interleaved A/D Conversion (TIADC) system, and the estimation of channel mismatch error (Gain, Time-skew and Offset) can be obtained by integrating particle swarm optimization (PSO) algorithm and gradient descent (GD) method. Meanwhile, using filter equations and Kaiser window truncation to obtain compensation calibration filter coefficient values. This compensation method can be directly implemented on the TIADC hardware platform using Field-Programmable Gate Array(FPGA) as the central processing unit. Moreover this algorithm can achieve online reconstruction of sampling system data. The experimental results show that the algorithm can effectively compensate for channel mismatch errors, and using the behavior level simulation of Vivado development software, the spurious free dynamic range (SFDR) is increased from 32.1 dBFS to 53.1 dBFS, Improve the SFDR to 60.8 dBFS during hardware platform testing. Also this signal reconstruction method is easy to implement in hardware systems and is not limited by the number of channels. has high engineering applicability. This method has high engineering applicability and is simple and easy to implement.
In order to improve the performance of waveform digital readout systems based on Analog to Digital Converter (ADC) technology, this paper proposes a multi-channel mismatch error estimation calibration method. Used two domestically produced high-speed ADCs to form a Time-interleaved A/D Conversion (TIADC) system, and the estimation of channel mismatch error (Gain, Time-skew and Offset) can be obtained by integrating particle swarm optimization (PSO) algorithm and gradient descent (GD) method. Meanwhile, using filter equations and Kaiser window truncation to obtain compensation calibration filter coefficient values. This compensation method can be directly implemented on the TIADC hardware platform using Field-Programmable Gate Array(FPGA) as the central processing unit. Moreover this algorithm can achieve online reconstruction of sampling system data. The experimental results show that the algorithm can effectively compensate for channel mismatch errors, and using the behavior level simulation of Vivado development software, the spurious free dynamic range (SFDR) is increased from 32.1 dBFS to 53.1 dBFS, Improve the SFDR to 60.8 dBFS during hardware platform testing. Also this signal reconstruction method is easy to implement in hardware systems and is not limited by the number of channels. has high engineering applicability. This method has high engineering applicability and is simple and easy to implement.
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/HPLPB202537.240411
Abstract:
To address the wideband and beam scanning requirements of high-power microwave (HPM) systems, this paper proposes an X-band varactor-based high-power wideband beam-scanning reflectarray antenna. The antenna employs a linearly polarized horn feed and a sandwich-structured embedded patch element, where the nested dual-resonance structure integrated with varactors simultaneously extends the phase tuning range (360°) and operational bandwidth. By eliminating abrupt structural discontinuities and adopting a sandwich dielectric configuration, the design effectively suppresses triple-junction formation, achieving a power capacity of 5 MW in 0.1 MPa SF6 environment. Varactor capacitance adjustment enables a 12% relative tuning bandwidth within 8.55−9.65 GHz. Simulations of an 11×11 rectangular grid reflectarray demonstrate a maximum gain of 25.12 dBi with 54.39% aperture efficiency for a 242 mm aperture and full-band 0°−20° beam scanning capability. Compared with existing technologies, this design exhibits superior tuning bandwidth (12%) and power capacity (5 MW), providing an effective solution for wideband beam control in HPM systems.
To address the wideband and beam scanning requirements of high-power microwave (HPM) systems, this paper proposes an X-band varactor-based high-power wideband beam-scanning reflectarray antenna. The antenna employs a linearly polarized horn feed and a sandwich-structured embedded patch element, where the nested dual-resonance structure integrated with varactors simultaneously extends the phase tuning range (360°) and operational bandwidth. By eliminating abrupt structural discontinuities and adopting a sandwich dielectric configuration, the design effectively suppresses triple-junction formation, achieving a power capacity of 5 MW in 0.1 MPa SF6 environment. Varactor capacitance adjustment enables a 12% relative tuning bandwidth within 8.55−9.65 GHz. Simulations of an 11×11 rectangular grid reflectarray demonstrate a maximum gain of 25.12 dBi with 54.39% aperture efficiency for a 242 mm aperture and full-band 0°−20° beam scanning capability. Compared with existing technologies, this design exhibits superior tuning bandwidth (12%) and power capacity (5 MW), providing an effective solution for wideband beam control in HPM systems.
, 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.
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
- Research News
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2025, 37: 051001.
doi: 10.11884/HPLPB202537.240370
Abstract:
Compared with single-band object detection technology, multispectral object detection technology greatly improves the accuracy of object detection and the robustness in dealing with complex environments by capturing the reflection or radiation information of objects in multiple spectral bands of different wavelengths. Therefore, it has extensive applications in fields such as remote sensing, agricultural detection, environmental protection, industrial production, and national defense security. However, the field of multispectral object detection still faces severe challenges at present: the lack of diverse high-quality datasets and efficient object detection algorithms seriously restricts further development and application of this technology. In view of this, this paper comprehensively explains the production method of multispectral object detection datasets and the important progress of multispectral object detection algorithms. First, the article systematically analyzes the construction process of multispectral datasets, including data acquisition, preprocessing, and data annotation, aiming to provide technical support for the subsequent construction of high-quality multispectral object detection datasets. Second, this paper comprehensively analyzes the historical context of the development of object detection algorithms. These algorithms cover object detection algorithms based on traditional feature extraction technologies, deep learning methods, and their improved versions. In addition, this paper summarizes the key improvements made by algorithm developers in terms of feature fusion, model architecture, and sub-networks to improve the performance of multispectral object detection based on deep learning-based object detection algorithms. Finally, this paper discusses future development direction of multispectral object detection technology, hoping to indicate potential research hotspots and application fields for researchers, and promote the wider application of multispectral object detection technology in actual scenarios and enhance its social value.
Compared with single-band object detection technology, multispectral object detection technology greatly improves the accuracy of object detection and the robustness in dealing with complex environments by capturing the reflection or radiation information of objects in multiple spectral bands of different wavelengths. Therefore, it has extensive applications in fields such as remote sensing, agricultural detection, environmental protection, industrial production, and national defense security. However, the field of multispectral object detection still faces severe challenges at present: the lack of diverse high-quality datasets and efficient object detection algorithms seriously restricts further development and application of this technology. In view of this, this paper comprehensively explains the production method of multispectral object detection datasets and the important progress of multispectral object detection algorithms. First, the article systematically analyzes the construction process of multispectral datasets, including data acquisition, preprocessing, and data annotation, aiming to provide technical support for the subsequent construction of high-quality multispectral object detection datasets. Second, this paper comprehensively analyzes the historical context of the development of object detection algorithms. These algorithms cover object detection algorithms based on traditional feature extraction technologies, deep learning methods, and their improved versions. In addition, this paper summarizes the key improvements made by algorithm developers in terms of feature fusion, model architecture, and sub-networks to improve the performance of multispectral object detection based on deep learning-based object detection algorithms. Finally, this paper discusses future development direction of multispectral object detection technology, hoping to indicate potential research hotspots and application fields for researchers, and promote the wider application of multispectral object detection technology in actual scenarios and enhance its social value.
2025, 37: 051002.
doi: 10.11884/HPLPB202537.240314
Abstract:
Thermal diffusion coefficient is an important parameter of optical components in high-energy and high-power laser systems, and it is related to the laser damage resistance of components. However, the measurement error of the existing thermal diffusion coefficient measurement methods is large under the condition of multi-dimensional thermal conduction. As thermal diffusion length is the basis of thermal diffusion coefficient measurement, our study used the finite element method to simulate the two-dimensional heat conduction under continuous heating of heat source, and summarized the relationship between thermal diffusion length, thermal diffusion coefficient and heating time. On this basis, it proposed a model and method for measuring two-dimensional thermal diffusion length under continuous heating of heat source. Firstly, finite element analysis was used to establish a model to simulate the relationship between thermal diffusion length and thermal diffusion coefficient in one-dimensional heat conduction, and the two models were compared with numerical analytical expressions. The feasibility of using continuous heat source and thermal diffusion length to solve the thermal diffusion coefficient was verified. The effects of heat loss, sample thickness and heat source loading time on the results were discussed. Finally, the practical measurement scheme and measures to improve the measurement accuracy were put forward. This study provides a way to measure the thermal diffusion length of materials or components conveniently and accurately, and is of great significance for fabrication of high power and high energy laser system components.
Thermal diffusion coefficient is an important parameter of optical components in high-energy and high-power laser systems, and it is related to the laser damage resistance of components. However, the measurement error of the existing thermal diffusion coefficient measurement methods is large under the condition of multi-dimensional thermal conduction. As thermal diffusion length is the basis of thermal diffusion coefficient measurement, our study used the finite element method to simulate the two-dimensional heat conduction under continuous heating of heat source, and summarized the relationship between thermal diffusion length, thermal diffusion coefficient and heating time. On this basis, it proposed a model and method for measuring two-dimensional thermal diffusion length under continuous heating of heat source. Firstly, finite element analysis was used to establish a model to simulate the relationship between thermal diffusion length and thermal diffusion coefficient in one-dimensional heat conduction, and the two models were compared with numerical analytical expressions. The feasibility of using continuous heat source and thermal diffusion length to solve the thermal diffusion coefficient was verified. The effects of heat loss, sample thickness and heat source loading time on the results were discussed. Finally, the practical measurement scheme and measures to improve the measurement accuracy were put forward. This study provides a way to measure the thermal diffusion length of materials or components conveniently and accurately, and is of great significance for fabrication of high power and high energy laser system components.
2025, 37: 051003.
doi: 10.11884/HPLPB202537.240362
Abstract:
The electron irradiation effect of a 4H-SiC npn bipolar transistor UV detector is investigated in this paper. When the phototransistor is biased at 5 V, before irradiation, its dark current is about 58 nA, and its responsivity to 365 nm UV light is about 31A/W. After the device is irradiated by a 10 MeV e-beam, the order of magnitude of the dark current decreases to 10−11 A, and the responsivity decreases to about 1/8 of the original one. After irradiation, the responsivity of the device is significantly affected by the bias voltage: it decreases as the bias voltage decreases, and when the phototransistor is biased at 3 V, the responsivity decreases to 2.25 A/W. E-beam irradiation also affects the switching response of the UV detector, which results in a longer total time of response. In this paper, the circuit model of phototransistor operation is established, and the decrease of light generation current, the decrease of transistor gain and the increase of series resistance caused by electron beam irradiation are the main reasons for the degradation of photodetector’s UV response performance.
The electron irradiation effect of a 4H-SiC npn bipolar transistor UV detector is investigated in this paper. When the phototransistor is biased at 5 V, before irradiation, its dark current is about 58 nA, and its responsivity to 365 nm UV light is about 31A/W. After the device is irradiated by a 10 MeV e-beam, the order of magnitude of the dark current decreases to 10−11 A, and the responsivity decreases to about 1/8 of the original one. After irradiation, the responsivity of the device is significantly affected by the bias voltage: it decreases as the bias voltage decreases, and when the phototransistor is biased at 3 V, the responsivity decreases to 2.25 A/W. E-beam irradiation also affects the switching response of the UV detector, which results in a longer total time of response. In this paper, the circuit model of phototransistor operation is established, and the decrease of light generation current, the decrease of transistor gain and the increase of series resistance caused by electron beam irradiation are the main reasons for the degradation of photodetector’s UV response performance.
2025, 37: 052001.
doi: 10.11884/HPLPB202537.240312
Abstract:
With the increasing demand for diagnostics of high-energy-density (HED) materials, X-ray interferometric imaging technology has gained significant attention and application in this field. This paper primarily reviews the latest domestic and international advancements in X-ray interferometric imaging techniques and systems, focusing on the principles and capabilities of X-ray grating imaging based on Talbot and Talbot-Lau interferometry. Talbot and Talbot-Lau interferometry utilize gratings with periodic structures to perform high-precision measurements of X-ray phase, absorption, and scattering properties, enabling non-destructive inspection and imaging of internal structures of samples. This work summarizes the application of these techniques in diagnostic experiments for HED materials, introduces the Talbot Interferometric Analysis (TIA) code, and demonstrates an initial simulation by integrating the TIA program with the Flash hydrodynamics code. The simulation successfully retrieved three types of information: absorption, phase, and dark-field from the Flash model. Finally, the paper concludes with a summary and outlook on the application of X-ray Talbot-Lau interferometric diagnostic technology in HED plasma experiments.
With the increasing demand for diagnostics of high-energy-density (HED) materials, X-ray interferometric imaging technology has gained significant attention and application in this field. This paper primarily reviews the latest domestic and international advancements in X-ray interferometric imaging techniques and systems, focusing on the principles and capabilities of X-ray grating imaging based on Talbot and Talbot-Lau interferometry. Talbot and Talbot-Lau interferometry utilize gratings with periodic structures to perform high-precision measurements of X-ray phase, absorption, and scattering properties, enabling non-destructive inspection and imaging of internal structures of samples. This work summarizes the application of these techniques in diagnostic experiments for HED materials, introduces the Talbot Interferometric Analysis (TIA) code, and demonstrates an initial simulation by integrating the TIA program with the Flash hydrodynamics code. The simulation successfully retrieved three types of information: absorption, phase, and dark-field from the Flash model. Finally, the paper concludes with a summary and outlook on the application of X-ray Talbot-Lau interferometric diagnostic technology in HED plasma experiments.
2025, 37: 052002.
doi: 10.11884/HPLPB202537.240335
Abstract:
This paper discusses early experiments on indirect laser-driven implosion of double-metal-shell targets conducted with a hundred-kilojoule-class laser facility. The design of the double-metal-shell target is derived from the volume ignition scheme, which decouples the radiation ablation and implosion compression processes, thereby improving the robustness of the implosion. However, due to the high difficulty in manufacturing the double-metal-shell target, the neutron yield in the initial experiments was much lower than expected from simulations. To address this issue, two key improvements are proposed: first, optimizing the joint design of the outer shell to reduce the impact of hydrodynamic instability, thus to improve the collision efficiency of the inner and outer shells and the implosion efficiency of the inner core; second, enhancing the coupling efficiency of the hohlraum-target to improve the effective transfer of laser energy. With these improvements, the compression performance and implosion efficiency of the target were significantly enhanced, resulting in a substantial increase in neutron yield, from\begin{document}$ 5.0\times {10}^{7} $\end{document} ![]()
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This paper discusses early experiments on indirect laser-driven implosion of double-metal-shell targets conducted with a hundred-kilojoule-class laser facility. The design of the double-metal-shell target is derived from the volume ignition scheme, which decouples the radiation ablation and implosion compression processes, thereby improving the robustness of the implosion. However, due to the high difficulty in manufacturing the double-metal-shell target, the neutron yield in the initial experiments was much lower than expected from simulations. To address this issue, two key improvements are proposed: first, optimizing the joint design of the outer shell to reduce the impact of hydrodynamic instability, thus to improve the collision efficiency of the inner and outer shells and the implosion efficiency of the inner core; second, enhancing the coupling efficiency of the hohlraum-target to improve the effective transfer of laser energy. With these improvements, the compression performance and implosion efficiency of the target were significantly enhanced, resulting in a substantial increase in neutron yield, from
2025, 37: 052003.
doi: 10.11884/HPLPB202537.240327
Abstract:
To understand the effect of laser focal spot size on the extreme ultraviolet conversion efficiency and the physical mechanism that produces the effect, we developed a two-dimensional transient expansion model of laser ablation of planar target to produce coronal plasma by means of theoretical analysis. It is found that under condition with light intensity of 7.45×1010 W/cm2, full width at half maxima of 5 ns, wavelength of1064 nm, as the laser focal spot radius increases from 60 μm to 300 μm, the corresponding extreme ultraviolet conversion efficiency increases from 1% to 5.5%, while the corresponding extreme ultraviolet conversion efficiency stays at 5.5% after the focal spot radius is larger than 300 μm. This is due to the fact that the plasma in the coronal region generated by laser ablation of planar targets expands from the initial one-dimensional expansion to the subsequent two-dimensional expansion, which determines the saturation size of the plasma region emitting extreme ultraviolet light and ultimately determines the conversion efficiency of the extreme ultraviolet light. Our theoretical analysis on trend of conversion efficiency with focal spot radius can explain the physical phenomena observed in the laser ablation of a tin target experiment.
To understand the effect of laser focal spot size on the extreme ultraviolet conversion efficiency and the physical mechanism that produces the effect, we developed a two-dimensional transient expansion model of laser ablation of planar target to produce coronal plasma by means of theoretical analysis. It is found that under condition with light intensity of 7.45×1010 W/cm2, full width at half maxima of 5 ns, wavelength of
2025, 37: 053001.
doi: 10.11884/HPLPB202537.240391
Abstract:
In the field of high-power microwave radiation, mode converter and horn antenna are commonly used technologies to achieve rotational axisymmetric mode-directed radiation, but the separate design of mode converter and horn antenna often results in a large axial and aperture size of the antenna. To meet the demand for miniaturization of antennas in actual application scenarios, a stepped double semicircular waveguides radiation antenna with mode control and radiation integration is proposed. The antenna is fed with a circular waveguide TM01 mode and divided into two 180° phase difference semicircular waveguides by a plate. Then, two asymmetric stepped semicircular waveguide radiation elements are connected to achieve microwave radiation. The power divider uses a gradually tapered circular waveguide for matching, and a large inner conductor is used to improve power capacity. The dual semicircular waveguide radiation elements use the mode matching method combined with the Particle Swarm Optimization algorithm for phase adjustment and mode control. By integrating mode control and radiation in a multi-region design, a more uniform co-phase electric field distribution is achieved at the radiation aperture, achieving directed radiation, thereby shortening the antenna length and reducing the aperture size. An antenna model with a center frequency of 2.85 GHz is optimized, with dimensions of 1.18λ×1.18λ×2.42λ. Simulation results show that the return loss of the antenna is greater than 15 dB in the 2.75−2.96 GHz band, the realized gain is greater than 15.5 dBi in the 2.71−3 GHz band, the realized gain at the center frequency is 16.14 dBi and the vacuum power capacity is 906 MW. Compared with the traditional mode converter and horn antenna technology route, the proposed antenna has the characteristics of high power capacity and miniaturization.
In the field of high-power microwave radiation, mode converter and horn antenna are commonly used technologies to achieve rotational axisymmetric mode-directed radiation, but the separate design of mode converter and horn antenna often results in a large axial and aperture size of the antenna. To meet the demand for miniaturization of antennas in actual application scenarios, a stepped double semicircular waveguides radiation antenna with mode control and radiation integration is proposed. The antenna is fed with a circular waveguide TM01 mode and divided into two 180° phase difference semicircular waveguides by a plate. Then, two asymmetric stepped semicircular waveguide radiation elements are connected to achieve microwave radiation. The power divider uses a gradually tapered circular waveguide for matching, and a large inner conductor is used to improve power capacity. The dual semicircular waveguide radiation elements use the mode matching method combined with the Particle Swarm Optimization algorithm for phase adjustment and mode control. By integrating mode control and radiation in a multi-region design, a more uniform co-phase electric field distribution is achieved at the radiation aperture, achieving directed radiation, thereby shortening the antenna length and reducing the aperture size. An antenna model with a center frequency of 2.85 GHz is optimized, with dimensions of 1.18λ×1.18λ×2.42λ. Simulation results show that the return loss of the antenna is greater than 15 dB in the 2.75−2.96 GHz band, the realized gain is greater than 15.5 dBi in the 2.71−3 GHz band, the realized gain at the center frequency is 16.14 dBi and the vacuum power capacity is 906 MW. Compared with the traditional mode converter and horn antenna technology route, the proposed antenna has the characteristics of high power capacity and miniaturization.
2025, 37: 053002.
doi: 10.11884/HPLPB202537.240323
Abstract:
To explore the root cause of the reboot and shutdown phenomenon of electronic equipment in a strong electromagnetic field environment, this study considered a certain type of DC-regulated power supply as a test object and observed the susceptibility phenomena exhibited by the power supply under strong continuous wave electromagnetic radiation. In this experiment, the relative variation in voltage was selected as the effect parameter, and the variation feature of the effect parameter with the interference field strength was described. The irradiation test was carried out in the GTEM cell with an interference signal frequency range of 80–1000 MHz and a maximum field strength of 300 V/m. The test results indicate that the output voltage variation of the test power supply can be divided into two stages. When the interference field strength was low, the variation types of voltage included monotone rise, monotone fall, or first rise and then fall. At this stage, the voltage variation did not exceed 20%, and the load equipment could still operate normally. When the interference field strength was high, the voltage variation showed a sudden change. It could be divided into three types of interference phenomena such as shutting down after stopping interference (80–120 MHz, 320–350 MHz), shutting down when jamming (220–270 MHz, 360–420 MHz), rebooting (570–590 MHz, 700–720 MHz, 860–880 MHz), which posed actual threat to the load electrical equipment. There was no obvious correspondence between the susceptibility phenomena of the two stages.
To explore the root cause of the reboot and shutdown phenomenon of electronic equipment in a strong electromagnetic field environment, this study considered a certain type of DC-regulated power supply as a test object and observed the susceptibility phenomena exhibited by the power supply under strong continuous wave electromagnetic radiation. In this experiment, the relative variation in voltage was selected as the effect parameter, and the variation feature of the effect parameter with the interference field strength was described. The irradiation test was carried out in the GTEM cell with an interference signal frequency range of 80–
2025, 37: 054001.
doi: 10.11884/HPLPB202537.240365
Abstract:
The electron beam test platform, as a pre-research project for Shenzhen Superconducting Soft X-ray Free Electron Laser (S3FEL), will be used to overcome several major key technology challenges in high repetition frequency free electron laser. In this paper, the structural design of the injector dump beam window for the Electron Beam Test Platform of S3FEL is carried out, and a brazing water-cooled copper window is designed based on the electron beam parameters. The thermal structural calculation of the beam window is carried out using finite element analysis method, and the temperature, stress and deformation under different cooling channels and cooling water flow rates are analyzed. Considering the cooling effect, economic efficiency and flow vibration factors, the M-type cooling channel with the flow rate of 1 m/s is finally selected for the beam window. In addition, the vacuum distribution at the beam window is calculated, and all the results meet the design requirements, verifying the rationality of the design and ensuring the stable and reliable operation of the facility.
The electron beam test platform, as a pre-research project for Shenzhen Superconducting Soft X-ray Free Electron Laser (S3FEL), will be used to overcome several major key technology challenges in high repetition frequency free electron laser. In this paper, the structural design of the injector dump beam window for the Electron Beam Test Platform of S3FEL is carried out, and a brazing water-cooled copper window is designed based on the electron beam parameters. The thermal structural calculation of the beam window is carried out using finite element analysis method, and the temperature, stress and deformation under different cooling channels and cooling water flow rates are analyzed. Considering the cooling effect, economic efficiency and flow vibration factors, the M-type cooling channel with the flow rate of 1 m/s is finally selected for the beam window. In addition, the vacuum distribution at the beam window is calculated, and all the results meet the design requirements, verifying the rationality of the design and ensuring the stable and reliable operation of the facility.
2025, 37: 054002.
doi: 10.11884/HPLPB202537.240235
Abstract:
The BCD technology integrates Bipolar, Complementary Metal Oxide Semiconductor (CMOS), and Double Diffused MOSFET (DMOS) within a single chip, widely utilized in electronic components and system production. Gate drivers fabricated by BCD technology can reduce transmission delays, lower power consumption, and enhance drive capabilities. However, the radiation effects in space environments may lead to performance degradation and potentially jeopardize the safety of spacecraft. This paper focuses on gate drivers based on BCD technology, employing an enclosed layout structure for total ionizing dose (TID) radiation hardening. Through TID irradiation tests, the electrical parameter variations between hardened and unhardened devices are compared. Results indicate that TID radiation causes degradation in the output voltage and current characteristics of the device, manifesting as a decrease in switching voltage and an increase in output current, while having a negligible impact on the output resistance. Comparing test outcomes from both types of drivers, it is evident that the ring-gate hardening method effectively mitigates edge leakage induced by TID radiation to a certain extent. Nevertheless, functional failure occurs in the devices at 500 krad(Si).
The BCD technology integrates Bipolar, Complementary Metal Oxide Semiconductor (CMOS), and Double Diffused MOSFET (DMOS) within a single chip, widely utilized in electronic components and system production. Gate drivers fabricated by BCD technology can reduce transmission delays, lower power consumption, and enhance drive capabilities. However, the radiation effects in space environments may lead to performance degradation and potentially jeopardize the safety of spacecraft. This paper focuses on gate drivers based on BCD technology, employing an enclosed layout structure for total ionizing dose (TID) radiation hardening. Through TID irradiation tests, the electrical parameter variations between hardened and unhardened devices are compared. Results indicate that TID radiation causes degradation in the output voltage and current characteristics of the device, manifesting as a decrease in switching voltage and an increase in output current, while having a negligible impact on the output resistance. Comparing test outcomes from both types of drivers, it is evident that the ring-gate hardening method effectively mitigates edge leakage induced by TID radiation to a certain extent. Nevertheless, functional failure occurs in the devices at 500 krad(Si).
2025, 37: 055001.
doi: 10.11884/HPLPB202537.240350
Abstract:
Electric blasting based on electromagnetic energy equipment has great application prospects in foundation pit engineering. This article proposes the synergistic rock breaking technology based on pulse power supply and electric explosion load arrays, which achieves controllable electric blasting of large volume hard rock through the superposition of multiple shock waves. The article analyzes the mechanism of overvoltage in the process of electric explosion and the mechanism of overvoltage conduction in the multi-array collaborative process, and proposes the overvoltage suppression method. It compares the rock breaking effects of single pulse power supply and multi-array and the specific energy consumption of the dual load array is 38% of a single load for rock breaking, which indicates the electric explosion load array can effectively achieve controllable electric blasting of large volume hard rocks.
Electric blasting based on electromagnetic energy equipment has great application prospects in foundation pit engineering. This article proposes the synergistic rock breaking technology based on pulse power supply and electric explosion load arrays, which achieves controllable electric blasting of large volume hard rock through the superposition of multiple shock waves. The article analyzes the mechanism of overvoltage in the process of electric explosion and the mechanism of overvoltage conduction in the multi-array collaborative process, and proposes the overvoltage suppression method. It compares the rock breaking effects of single pulse power supply and multi-array and the specific energy consumption of the dual load array is 38% of a single load for rock breaking, which indicates the electric explosion load array can effectively achieve controllable electric blasting of large volume hard rocks.
2025, 37: 055002.
doi: 10.11884/HPLPB202537.240356
Abstract:
The solid-state high-voltage pulse switch with high index, compact structure and good stability is of great significance to the progress of pulse power technology. This paper proposes a high-voltage nanosecond switching technology route based on Photoconductive Semiconductor Switches (PCSS) and thyristor surge suppressor (TSS) arrays, and a new type of high voltage switching module (PCSS triggering thyristor surge suppressors module, PTTSSM) is developed by using PCSS, which is convenient for realizing the high-voltage isolation, as the triggering unit of TSS arrays. The 20 kV PTTSSM has a peak output current of 23.7 A, a pulse width of 122.1 ns, a rise time and a fall time of 55.9 ns and 128.3 ns, respectively, and a size of 60 mm×60 mm×40 mm. The 100 kV PTTSSM has an adjustable peak output voltage of 60−100 kV, a maximum peak output current of 356 A, a pulse width of 1.308 µs, rise time and fall time of 160.4 ns and 2.454 µs, respectively, and its size is 150 mm×100 mm×50 mm. All of them can work stably for a long time. Pulse power supply based on a new solid-state switching module successfully generates a large number of stable low-temperature plasmas in organic wastewater treatment experiments, verifying the feasibility and effectiveness of the switching module-driven plasma generation.
The solid-state high-voltage pulse switch with high index, compact structure and good stability is of great significance to the progress of pulse power technology. This paper proposes a high-voltage nanosecond switching technology route based on Photoconductive Semiconductor Switches (PCSS) and thyristor surge suppressor (TSS) arrays, and a new type of high voltage switching module (PCSS triggering thyristor surge suppressors module, PTTSSM) is developed by using PCSS, which is convenient for realizing the high-voltage isolation, as the triggering unit of TSS arrays. The 20 kV PTTSSM has a peak output current of 23.7 A, a pulse width of 122.1 ns, a rise time and a fall time of 55.9 ns and 128.3 ns, respectively, and a size of 60 mm×60 mm×40 mm. The 100 kV PTTSSM has an adjustable peak output voltage of 60−100 kV, a maximum peak output current of 356 A, a pulse width of 1.308 µs, rise time and fall time of 160.4 ns and 2.454 µs, respectively, and its size is 150 mm×100 mm×50 mm. All of them can work stably for a long time. Pulse power supply based on a new solid-state switching module successfully generates a large number of stable low-temperature plasmas in organic wastewater treatment experiments, verifying the feasibility and effectiveness of the switching module-driven plasma generation.
2025, 37: 055003.
doi: 10.11884/HPLPB202537.240358
Abstract:
Constructing a photoconductive semiconductor switch (PCSS)-metal coil structure, we discovered a new phenomenon of electromagnetic oscillation in vanadium-compensation semi-insulating (VCSI) PCSS. Here the PCSS responds to laser pulse and high-voltage signal while the metal coil generates an oscillating voltage pulse envelope signal. The generation of this oscillating signal is not related to the input bias voltage of the PCSS, the pulse circuit components, or the electrode structure of the PCSS, rather it is related to the output characteristic of the PCSS. This physical phenomenon can be explained using the current surge model in photoconducting antenna. Preparing ohmic contact electrode on the silicon carbide material forms the PCSS, which generates a large number of photogenerated carriers when ultra-fast laser pulses irradiate the surface of the material and Simultaneously applies a bias voltage signal between the electrode. At this time inside the PCSS the electric field causes the transient current, radiating electromagnetic wave to the metal coil to generate oscillating signal.
2025, 37: 056001.
doi: 10.11884/HPLPB202537.240326
Abstract:
Flash radiography enables the diagnosis of rapid physical processes, yet the instantaneous nature of image acquisition results in a severely limited number of projections. This study investigates uncertainty quantification methods for computed tomography (CT) image reconstruction under the typical scenario of a single projection view. Current approaches for single-view CT uncertainty quantification often adopt oversimplified physical models, assuming linearized optical path equations with Gaussian noise. To address this limitation, we derive a more realistic nonlinear reconstruction framework based on the Lambert-Beer’s law, constructing an exponential attenuation model for transmittance with an integrated Gaussian noise term. This formulation yields a nonlinear posterior probability density function, which is subsequently sampled using the Randomize-Then-Optimize (RTO) algorithm combined with Gibbs sampling. The reconstructed image and its associated uncertainty are obtained through statistical analysis of the sampled data. Numerical simulations validate the proposed method, with comparative results against conventional linearized models demonstrating its superior potential for accurate uncertainty estimation in image reconstruction.
Flash radiography enables the diagnosis of rapid physical processes, yet the instantaneous nature of image acquisition results in a severely limited number of projections. This study investigates uncertainty quantification methods for computed tomography (CT) image reconstruction under the typical scenario of a single projection view. Current approaches for single-view CT uncertainty quantification often adopt oversimplified physical models, assuming linearized optical path equations with Gaussian noise. To address this limitation, we derive a more realistic nonlinear reconstruction framework based on the Lambert-Beer’s law, constructing an exponential attenuation model for transmittance with an integrated Gaussian noise term. This formulation yields a nonlinear posterior probability density function, which is subsequently sampled using the Randomize-Then-Optimize (RTO) algorithm combined with Gibbs sampling. The reconstructed image and its associated uncertainty are obtained through statistical analysis of the sampled data. Numerical simulations validate the proposed method, with comparative results against conventional linearized models demonstrating its superior potential for accurate uncertainty estimation in image reconstruction.
2025, 37: 056002.
doi: 10.11884/HPLPB202537.240241
Abstract:
In this study, double-sided Al film was prepared on the surface of polyethylene terephthalate (PET) by controlling different Al target currents with magnetron sputtering technology. The micro-morphology of the Al film was observed using scanning electron microscope (SEM) and atomic force microscope (AFM). Phase analysis of the Al film was carried out using X-ray diffraction (XRD). The adhesion between the Al film and PET was detected by the cross-cut method. The light-blocking property of the Al film was measured by an ultraviolet-visible spectrophotometer. The transmittance of α and β particles in the Al film was detected using a handheld nuclear radiation detector. The results show that the surface of the Al film is smooth and flat with a metallic luster, and the Al grains are uniform and dense. The Al film has no defects such as pores and cracks. As the Al target current increases, the Al grain size, the thickness of the Al film, and the deposition rate all increase, and the roughness of the Al film first decreases and then increases. The light-blocking property of the Al film first improves and then decreases, and the average transmittance of both α and β particles gradually decreases. When the Al target current is 2.0 A, the roughness of the Al film is the minimum, which is 2.49 nm. The light transmittance is the lowest, around 0.025%. The average transmittance of α and β particles is the highest, being 581.7 CPS and 547.2 CPS respectively.
In this study, double-sided Al film was prepared on the surface of polyethylene terephthalate (PET) by controlling different Al target currents with magnetron sputtering technology. The micro-morphology of the Al film was observed using scanning electron microscope (SEM) and atomic force microscope (AFM). Phase analysis of the Al film was carried out using X-ray diffraction (XRD). The adhesion between the Al film and PET was detected by the cross-cut method. The light-blocking property of the Al film was measured by an ultraviolet-visible spectrophotometer. The transmittance of α and β particles in the Al film was detected using a handheld nuclear radiation detector. The results show that the surface of the Al film is smooth and flat with a metallic luster, and the Al grains are uniform and dense. The Al film has no defects such as pores and cracks. As the Al target current increases, the Al grain size, the thickness of the Al film, and the deposition rate all increase, and the roughness of the Al film first decreases and then increases. The light-blocking property of the Al film first improves and then decreases, and the average transmittance of both α and β particles gradually decreases. When the Al target current is 2.0 A, the roughness of the Al film is the minimum, which is 2.49 nm. The light transmittance is the lowest, around 0.025%. The average transmittance of α and β particles is the highest, being 581.7 CPS and 547.2 CPS respectively.
2025, 37: 059001.
doi: 10.11884/HPLPB202537.240398
Abstract:
Radionuclides have been widely used in the fields of nuclear medicine, nuclear security and non-destructive testing, and their accurate identification is the basis of qualitative detection of radionuclides. In the portable nuclide recognition instrument, the traditional energy spectrum analysis method has the shortcomings of high delay and low recognition rate. This paper proposes a lightweight neural network model for nuclide recognition based on kernel pulse peak sequence and its FPGA hardware acceleration method. A lightweight and efficient neural network model is constructed by introducing depth-separable convolution and reciprocal residual modules, and using global average pooling to replace the traditional fully connected layer. For the network training data set, NaI (Tl) detector model was constructed through Monte Carlo toolkit Geant4 to obtain the analog energy spectrum, and then a simulator generated nuclear pulse signal sequences according to the energy spectrum, and 16 kinds of nuclear pulse signal data were constructed. Finally, the trained model is deployed to PYNQ-Z2 heterogeneous chip through optimization methods such as quantization, fusion and parallel computing to achieve acceleration. Experimental results show that the recognition accuracy of the proposed model can reach 98.3%, which is 13.2% higher than that of the traditional convolutional neural network model, and the number of parameters is only 2 128. After FPGA optimization and acceleration, the single recognition time is 0.273 ms, and the power consumption is 1.94 W.
Radionuclides have been widely used in the fields of nuclear medicine, nuclear security and non-destructive testing, and their accurate identification is the basis of qualitative detection of radionuclides. In the portable nuclide recognition instrument, the traditional energy spectrum analysis method has the shortcomings of high delay and low recognition rate. This paper proposes a lightweight neural network model for nuclide recognition based on kernel pulse peak sequence and its FPGA hardware acceleration method. A lightweight and efficient neural network model is constructed by introducing depth-separable convolution and reciprocal residual modules, and using global average pooling to replace the traditional fully connected layer. For the network training data set, NaI (Tl) detector model was constructed through Monte Carlo toolkit Geant4 to obtain the analog energy spectrum, and then a simulator generated nuclear pulse signal sequences according to the energy spectrum, and 16 kinds of nuclear pulse signal data were constructed. Finally, the trained model is deployed to PYNQ-Z2 heterogeneous chip through optimization methods such as quantization, fusion and parallel computing to achieve acceleration. Experimental results show that the recognition accuracy of the proposed model can reach 98.3%, which is 13.2% higher than that of the traditional convolutional neural network model, and the number of parameters is only 2 128. After FPGA optimization and acceleration, the single recognition time is 0.273 ms, and the power consumption is 1.94 W.
2025, 37: 059002.
doi: 10.11884/HPLPB202537.240351
Abstract:
Adding the vortex factors to the Gaussian, Lorenz, and Voigt airglow (aurora) light spectrum profiles of the for the upper atmospheric wind measurement, the vortex expressions of the three profiles of airglow (aurora) light sources are derived theoretically. The three profiles of airglow (aurora) with vortex light are simulated, and it is found that the extinction of the three profiles of light sources varies with the topological charge number l. The Gaussian vortex light rotates around the axis and the phase changes by 2πl, and the central extinction part and phase increase with the increase of l. The main extinction direction of Lorenz vortex is the transverse axis distribution direction. With the increase of l, the light intensity decreases, and the center extinction is carried out in discontinuous mode, which has a spiral spatial phase structure. Voigt vortex light profile is symmetrical on both the transverse and longitudinal sides, and the top is V-shaped extinction along the -z direction. The expressions are derived between the interference intensity of the three profile of vortex light, optical path difference and topological charge number, and the 3D diagram of the interference fringe of the three profiles of vortex light is simulated, and it is found that the spatial spectral intensity produces different fork structures under different topological charge number: with the change of vortex phase, the original spatial distribution changes, and the whole extends and extrudes from the maximum light intensity to both sides, and the influence of vortex phase extrude and dislocation is greater under fractional topological load. The experimental results show that there are fringes outside the bright ring of the Gaussian vortex light with the same topological charge number l, and the total topological phase will increase 2π and the beam waist radius will increase with each increase of topological charge number l by 1.
Adding the vortex factors to the Gaussian, Lorenz, and Voigt airglow (aurora) light spectrum profiles of the for the upper atmospheric wind measurement, the vortex expressions of the three profiles of airglow (aurora) light sources are derived theoretically. The three profiles of airglow (aurora) with vortex light are simulated, and it is found that the extinction of the three profiles of light sources varies with the topological charge number l. The Gaussian vortex light rotates around the axis and the phase changes by 2πl, and the central extinction part and phase increase with the increase of l. The main extinction direction of Lorenz vortex is the transverse axis distribution direction. With the increase of l, the light intensity decreases, and the center extinction is carried out in discontinuous mode, which has a spiral spatial phase structure. Voigt vortex light profile is symmetrical on both the transverse and longitudinal sides, and the top is V-shaped extinction along the -z direction. The expressions are derived between the interference intensity of the three profile of vortex light, optical path difference and topological charge number, and the 3D diagram of the interference fringe of the three profiles of vortex light is simulated, and it is found that the spatial spectral intensity produces different fork structures under different topological charge number: with the change of vortex phase, the original spatial distribution changes, and the whole extends and extrudes from the maximum light intensity to both sides, and the influence of vortex phase extrude and dislocation is greater under fractional topological load. The experimental results show that there are fringes outside the bright ring of the Gaussian vortex light with the same topological charge number l, and the total topological phase will increase 2π and the beam waist radius will increase with each increase of topological charge number l by 1.
2025, 37: 052004.
doi: 10.11884/HPLPB202537.240269
Abstract:
To study the hydrodynamic instability in laser fusion implosion, X-ray diagnostic technology with large field of view and high resolution is needed. Fresnel zone plate (FZP) is a kind of circular aperiodic grating structure, which can realize high spatial resolution imaging of X-ray. In this paper, the simulation research of high-resolution X-ray diagnosis technology based on diffraction imaging is carried out, showing the application prospects of FZP for hydrodynamic instability research. Based on the diffraction theory, the theoretical model of FZP is established, and the structural parameters of FZP with working energy point of 8.04 keV are designed according to the diagnostic experimental environment. Based on the optical simulation model, the color difference of FZP imaging is simulated, and the relationship between spatial resolution and spectral bandwidth is given. The simulation results show that the bandwidth of light source is less than 0.2 keV, and the resolution of FZP is better than 3 μm. The simulation of grid backlight imaging shows that FZP can achieve good resolution (less than 3 μm) within 0.8 mm field of view.
To study the hydrodynamic instability in laser fusion implosion, X-ray diagnostic technology with large field of view and high resolution is needed. Fresnel zone plate (FZP) is a kind of circular aperiodic grating structure, which can realize high spatial resolution imaging of X-ray. In this paper, the simulation research of high-resolution X-ray diagnosis technology based on diffraction imaging is carried out, showing the application prospects of FZP for hydrodynamic instability research. Based on the diffraction theory, the theoretical model of FZP is established, and the structural parameters of FZP with working energy point of 8.04 keV are designed according to the diagnostic experimental environment. Based on the optical simulation model, the color difference of FZP imaging is simulated, and the relationship between spatial resolution and spectral bandwidth is given. The simulation results show that the bandwidth of light source is less than 0.2 keV, and the resolution of FZP is better than 3 μm. The simulation of grid backlight imaging shows that FZP can achieve good resolution (less than 3 μm) within 0.8 mm field of view.
2025, 37: 054003.
doi: 10.11884/HPLPB202537.240083
Abstract:
Industrial linear accelerators are gradually moving towards high average beam power in small, compact shapes. The beam break-up effect due to the transverse wakefield is the main limitation to its performance improvement. The hybrid dielectric-iris-loaded structure is a new miniaturization accelerating structure with high average beam power. The main problem is difficulty in assembly and tuning. Through the study of dielectric based accelerating structures, a miniaturization accelerator with high average beam power was designed and optimized. During the research process, the influence of dielectric structural parameters on the accelerating structure size, accelerating gradient, and beam power was analyzed. The optimized accelerating structure size was reduced by about one-third compared to conventional iris-loaded accelerating structure. It can achieve the same acceleration gradient. The insertion of a simple dielectric tube into the dielectric structure made assembly and tuning easier. The optimized accelerator operats at S-band with the frequency of2856 MHz and voltage of 2.5 MeV. During the research process, beam dynamics is calculated through numerical calculation methods and PARMELA. Our research provides an important groundwork for further development of irradiation linear accelerators.
Industrial linear accelerators are gradually moving towards high average beam power in small, compact shapes. The beam break-up effect due to the transverse wakefield is the main limitation to its performance improvement. The hybrid dielectric-iris-loaded structure is a new miniaturization accelerating structure with high average beam power. The main problem is difficulty in assembly and tuning. Through the study of dielectric based accelerating structures, a miniaturization accelerator with high average beam power was designed and optimized. During the research process, the influence of dielectric structural parameters on the accelerating structure size, accelerating gradient, and beam power was analyzed. The optimized accelerating structure size was reduced by about one-third compared to conventional iris-loaded accelerating structure. It can achieve the same acceleration gradient. The insertion of a simple dielectric tube into the dielectric structure made assembly and tuning easier. The optimized accelerator operats at S-band with the frequency of
2025, 37: 054004.
doi: 10.11884/HPLPB202537.240179
Abstract:
This study focuses on the critical challenge of the integrated storage ring injection system in a compact X-ray light source. Utilizing the 3D electromagnetic field simulation software CST and the beam dynamics simulation software ELEGANT, we conducted multi-parameter optimization design for the key component of the injection system—the perturbator. The phase space evolution behavior of the electron beam during half-integer resonance injection processes was systematically investigated, leading to optimized structural parameters of injection components. For the compact storage ring, the optimized injection scheme demonstrates that the perturbator achieves optimal performance when positioned within an angular range of 150°–210° relative to the injection point, with the electron beam injection offset by 30 mm from the equilibrium orbit. After the perturbator stops working, the injected electron oscillation amplitude is minimized to 3.4 mm. Furthermore, the feasibility of implementing a multi-turn multi-pass injection scheme in the compact storage ring was analyzed. Numerical results indicate that maximum injection efficiency can be obtained when the kicker operates at a frequency of 3 MHz. These findings provide critical insights for enhancing beam stability and operational efficiency in compact synchrotron radiation facilities.
This study focuses on the critical challenge of the integrated storage ring injection system in a compact X-ray light source. Utilizing the 3D electromagnetic field simulation software CST and the beam dynamics simulation software ELEGANT, we conducted multi-parameter optimization design for the key component of the injection system—the perturbator. The phase space evolution behavior of the electron beam during half-integer resonance injection processes was systematically investigated, leading to optimized structural parameters of injection components. For the compact storage ring, the optimized injection scheme demonstrates that the perturbator achieves optimal performance when positioned within an angular range of 150°–210° relative to the injection point, with the electron beam injection offset by 30 mm from the equilibrium orbit. After the perturbator stops working, the injected electron oscillation amplitude is minimized to 3.4 mm. Furthermore, the feasibility of implementing a multi-turn multi-pass injection scheme in the compact storage ring was analyzed. Numerical results indicate that maximum injection efficiency can be obtained when the kicker operates at a frequency of 3 MHz. These findings provide critical insights for enhancing beam stability and operational efficiency in compact synchrotron radiation facilities.
2025, 37: 059901.
doi: 10.11884/HPLPB202537.250091
Abstract:
2262 1664
We have developed a femtosecond laser plane-by-plane direct writing method based on beam shaping, enabling single-step fabrication of the large-area fiber Bragg grating (FBG) planes. Using this innovative approach, we successfully fabricated high-reflectivity (HR) and low-reflectivity (LR) FBG pairs in 20/400-m double-clad fibers and implemented them in an all-fiber oscillator. Under a pump power of
W, the oscillator achieved near-single-mode laser output of
W with an optical–optical conversion efficiency of 73.47%, a beam quality factor M2 of 1.46, and a 3-dB spectral bandwidth of 3 nm without stimulated Raman scattering peaks. The results indicate that femtosecond laser direct writing technology offers both fabrication flexibility and thermal management advantages for high-power grating fabrication, and establishes a key technological pathway for enhancing the performance of all-fiber laser systems.
