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RSS2025 Vol. 37, No. 1
Recommend Articles
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- Cover and Contents
- High Power Laser Physics and Technology
- Inertial Confinement Fusion Physics and Technology
- High Power Microwave Technology
- Particle Beams and Accelerator Technology
- Pulsed Power Technology
- Nuclear Science and Engineering
- Advanced Interdisciplinary Science
- Special Column of 4th Symposium on Frontier of HPLPB
Display Method:
2025,
37: 1-2.
2025,
37: 011001.
doi: 10.11884/HPLPB202537.240437
Abstract:
Thanks to the advantages of compact, high beam quality and high conversion efficiency, narrow linewidth high pulse energy single mode nanosecond-pulsed fiber amplifier is highly desired in laser detection and industry applications. Recently, an all-fiber amplifier with a home-made Yb-doped tapered fiber produces linearly polarized (12.3 dB PER) 100 ns, 1 mJ pulses with 0.49 nm linewidth, M2=1.49, 100 W of average output power and 10 kW peak power at 1 064 nm. It is believed that the pulse energy, output power and beam quality can be further improved by optimizing the Yb-doped fiber and design of amplifier.
Thanks to the advantages of compact, high beam quality and high conversion efficiency, narrow linewidth high pulse energy single mode nanosecond-pulsed fiber amplifier is highly desired in laser detection and industry applications. Recently, an all-fiber amplifier with a home-made Yb-doped tapered fiber produces linearly polarized (12.3 dB PER) 100 ns, 1 mJ pulses with 0.49 nm linewidth, M2=1.49, 100 W of average output power and 10 kW peak power at 1 064 nm. It is believed that the pulse energy, output power and beam quality can be further improved by optimizing the Yb-doped fiber and design of amplifier.
2025,
37: 011002.
doi: 10.11884/HPLPB202537.240354
Abstract:
To research the recoverey pressure of DF laser, experiments were carried out with different mass flowrate on a test bench. Thermal blockage was discovered when the mass flowrate reached 2.475 g·s−1·cm−2. The simulation model of laser cavity and diffuser was established, and the flow fluid was obtained. The simulation showed that the cavity’s pressure rose up quickly when the mass flowrate was 2.475 g·s−1·cm−2, which is coincident with the experiment. The design was optimized based on the result of the simulation and the corresponding experiment was proceeded. The result shows that the thermal blockage was solved with the optimized laser cavity. The laser’s recovery pressure reached 22 kPa with mass flowrate 2.475 g·s−1·cm−2.
To research the recoverey pressure of DF laser, experiments were carried out with different mass flowrate on a test bench. Thermal blockage was discovered when the mass flowrate reached 2.475 g·s−1·cm−2. The simulation model of laser cavity and diffuser was established, and the flow fluid was obtained. The simulation showed that the cavity’s pressure rose up quickly when the mass flowrate was 2.475 g·s−1·cm−2, which is coincident with the experiment. The design was optimized based on the result of the simulation and the corresponding experiment was proceeded. The result shows that the thermal blockage was solved with the optimized laser cavity. The laser’s recovery pressure reached 22 kPa with mass flowrate 2.475 g·s−1·cm−2.
2025,
37: 011003.
doi: 10.11884/HPLPB202537.240232
Abstract:
Stimulated Raman scattering is an effective non-linear frequency conversion method, and has received much attention. However, Raman lasers also have drawbacks, such as wavelength of Raman lasers could not be tuned continuously, and the coverage of Raman laser wavelength is limited. Therefore, more Raman active media are required to improve the coverage of Raman lasers. In this work,1064 nm laser was used as pump source, and pressurized ethane was used as Raman active medium, and 1550 nm Raman laser was produced. Neither obvious backward Raman laser nor higher orders of Stokes Raman lasers were observed in this experiment. By the optimization of experimental parameters, laser induced breakdown was reduced; the first order Stokes(S1) Raman laser photon conversion efficiency was improved to 20.7%, and the maximum S1 energy was 21.2 mJ. Ethane was found to have significant absorption at wavelength of 1550 nm, this was the major reason for the limited photon conversion efficiency and pulse energy of S1 laser. The absorption coefficient of ethane at 1550 nm was measured to be 5.71\begin{document}$ \times {{10}}^{-{8}} $\end{document} ![]()
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Stimulated Raman scattering is an effective non-linear frequency conversion method, and has received much attention. However, Raman lasers also have drawbacks, such as wavelength of Raman lasers could not be tuned continuously, and the coverage of Raman laser wavelength is limited. Therefore, more Raman active media are required to improve the coverage of Raman lasers. In this work,
2025,
37: 012001.
doi: 10.11884/HPLPB202537.240224
Abstract:
To realize high voltage threshold, high linear slope, simple circuit and easy debugging of ramp signal from the scan control module of streak camera, utilizing the advantages of high voltage generated by switching discharge and good linearity of constant current charging slope, we designed a simple circuit to generate high voltage ramp signal. The circuit can adjust and optimize the slope and linear rate of the linear slope signal by adjusting the resistance. The experimental results show that the linear high voltage ramp signal generated by the circuit can provide a voltage of up to 1 700 V, the nonlinear precision of the ramp is less than 3%, and the scanning time is adjustable from 200 ns to 50 μs. Compared with the traditional high voltage ramp signal circuit, the circuit is simple in structure and convenient to debug, and the ramp time can be adjusted steplessly from nanoseconds to microseconds. This can effectively improve the scanning time accuracy of the fringe camera and effectively reduce problems such as circuit crosstalk.
To realize high voltage threshold, high linear slope, simple circuit and easy debugging of ramp signal from the scan control module of streak camera, utilizing the advantages of high voltage generated by switching discharge and good linearity of constant current charging slope, we designed a simple circuit to generate high voltage ramp signal. The circuit can adjust and optimize the slope and linear rate of the linear slope signal by adjusting the resistance. The experimental results show that the linear high voltage ramp signal generated by the circuit can provide a voltage of up to 1 700 V, the nonlinear precision of the ramp is less than 3%, and the scanning time is adjustable from 200 ns to 50 μs. Compared with the traditional high voltage ramp signal circuit, the circuit is simple in structure and convenient to debug, and the ramp time can be adjusted steplessly from nanoseconds to microseconds. This can effectively improve the scanning time accuracy of the fringe camera and effectively reduce problems such as circuit crosstalk.
2025,
37: 012002.
doi: 10.11884/HPLPB202537.240266
Abstract:
During the operation of vacuum system in high-flux laser device, molecular contamination generated by the pump lubricating oil in the vacuum environment may diffuse and deposit on the surface of optical system components, induce damage under high-flux laser irradiation, and reduce the devices’ load capacity. Research has been conducted on the cleanliness control of vacuum systems, and a series of technical measures have been developed to control the vacuum system cleanliness, including optimizing the vacuum pump group, increasing low-temperature cold trap adsorption, and adding online heating regeneration technology for the cold trap. The experimental research results show that after 120 h of continuous operation, the average surface deposition of non-volatile residues in the vacuum system reaches a clean level of 2.86 × 10−9 g/cm2 after 24 h; The transmittance at 350 nm and the damage density curve below 12.3 J/cm2 flux of the fused quartz optical test piece assessment group and control group are basically consistent, proving the effectiveness of this method.
During the operation of vacuum system in high-flux laser device, molecular contamination generated by the pump lubricating oil in the vacuum environment may diffuse and deposit on the surface of optical system components, induce damage under high-flux laser irradiation, and reduce the devices’ load capacity. Research has been conducted on the cleanliness control of vacuum systems, and a series of technical measures have been developed to control the vacuum system cleanliness, including optimizing the vacuum pump group, increasing low-temperature cold trap adsorption, and adding online heating regeneration technology for the cold trap. The experimental research results show that after 120 h of continuous operation, the average surface deposition of non-volatile residues in the vacuum system reaches a clean level of 2.86 × 10−9 g/cm2 after 24 h; The transmittance at 350 nm and the damage density curve below 12.3 J/cm2 flux of the fused quartz optical test piece assessment group and control group are basically consistent, proving the effectiveness of this method.
2025,
37: 013001.
doi: 10.11884/HPLPB202537.240243
Abstract:
Accurate and fast solution of the electromagnetic characteristics problems is of great significance for the study of dynamic characteristics and reliability design of electromagnetic railguns. Based on the COMSOL moving mesh function, a new form of meshing—slip mesh combined with moving mesh—is proposed. The armature area and the track part where the pivot rail is in contact are meshed in to slip mesh, and the rest of the track part is dynamically meshed. This division method can not only solve the problems of low computational accuracy (coarse mesh) and high computational complexity (fine mesh) of “static mesh”, but also accurately solve the dynamic electromagnetic characteristics problems of transient and fast-moving models. The pulsed excitation current was used to simulate and analyze the established electromagnetic railgun model. The computing time and number of computational units of the three static meshes are compared with the meshing method proposed in this paper. The simulation results of different meshing methods on the armature motion velocity and the current density distribution at the armature center position are compared, and it is proved that the proposed meshing method is effective and efficient.
Accurate and fast solution of the electromagnetic characteristics problems is of great significance for the study of dynamic characteristics and reliability design of electromagnetic railguns. Based on the COMSOL moving mesh function, a new form of meshing—slip mesh combined with moving mesh—is proposed. The armature area and the track part where the pivot rail is in contact are meshed in to slip mesh, and the rest of the track part is dynamically meshed. This division method can not only solve the problems of low computational accuracy (coarse mesh) and high computational complexity (fine mesh) of “static mesh”, but also accurately solve the dynamic electromagnetic characteristics problems of transient and fast-moving models. The pulsed excitation current was used to simulate and analyze the established electromagnetic railgun model. The computing time and number of computational units of the three static meshes are compared with the meshing method proposed in this paper. The simulation results of different meshing methods on the armature motion velocity and the current density distribution at the armature center position are compared, and it is proved that the proposed meshing method is effective and efficient.
2025,
37: 013002.
doi: 10.11884/HPLPB202537.240342
Abstract:
A new method of waveform reconstruction based on neural network is proposed to solve the problem of nano-second pulse distortion, which is caused by the existence of parasitic parameters and insufficient bandwidth in high-speed digital acquisition channels. The local mapping relationship between the distortion waveform acquired by the high-speed digital acquisition system and the reference waveform obtained from the oscilloscope is identified through single neural networks. Then, the global waveform is reconstructed by a series of neural networks. The experimental results show that the proposed method can obviously alleviate the problems such as the edge delay, overshoot of the distortion waveform, thus it can improve the power estimation accuracy by 32.5%, as well as improve the frequency response characteristics of the high-speed digital acquisition system.
A new method of waveform reconstruction based on neural network is proposed to solve the problem of nano-second pulse distortion, which is caused by the existence of parasitic parameters and insufficient bandwidth in high-speed digital acquisition channels. The local mapping relationship between the distortion waveform acquired by the high-speed digital acquisition system and the reference waveform obtained from the oscilloscope is identified through single neural networks. Then, the global waveform is reconstructed by a series of neural networks. The experimental results show that the proposed method can obviously alleviate the problems such as the edge delay, overshoot of the distortion waveform, thus it can improve the power estimation accuracy by 32.5%, as well as improve the frequency response characteristics of the high-speed digital acquisition system.
2025,
37: 013003.
doi: 10.11884/HPLPB202537.240296
Abstract:
Studying the transmission characteristics of high-frequency microwaves in plasma can effectively analyze and assess the information transfer process in microwave communication and radar technology. Numerical simulations were employed to analyze the effects of plasma electron density, thickness, and incident wave frequency on microwave reflection, absorption, and transmission. The results indicate that increased plasma thickness and electron density lead to enhanced absorption and reduced transmission; reflection increases slightly with decreased thickness and increased electron density. High-frequency microwaves are more easily transmitted through plasma, with transmission enhancing as frequency increases. Furthermore, the research shows that electron density not only affects energy transmission but also alters the electromagnetic wave shape, causing its broadening. High-density plasma significantly broadens microwave waveforms both spatially and temporally, with inelastic collisions contributing prominently to this broadening. The patterns of waveform changes can provide theoretical support for the restoration of information carried by radar echoes and microwave communications.
Studying the transmission characteristics of high-frequency microwaves in plasma can effectively analyze and assess the information transfer process in microwave communication and radar technology. Numerical simulations were employed to analyze the effects of plasma electron density, thickness, and incident wave frequency on microwave reflection, absorption, and transmission. The results indicate that increased plasma thickness and electron density lead to enhanced absorption and reduced transmission; reflection increases slightly with decreased thickness and increased electron density. High-frequency microwaves are more easily transmitted through plasma, with transmission enhancing as frequency increases. Furthermore, the research shows that electron density not only affects energy transmission but also alters the electromagnetic wave shape, causing its broadening. High-density plasma significantly broadens microwave waveforms both spatially and temporally, with inelastic collisions contributing prominently to this broadening. The patterns of waveform changes can provide theoretical support for the restoration of information carried by radar echoes and microwave communications.
2025,
37: 013004.
doi: 10.11884/HPLPB202537.240353
Abstract:
The design of permanent magnet packaging for a compact S-band 8-cavity all-cavity axial extraction relativistic magnetron (R8 ACAE-RM) with an output mode of TE11 is preliminarily explored. The inner magnetic block is placed at both ends of the anode block in the anode cylinder, and the outer magnetic block is placed outside the RM, which generates a magnetic field of about 0.34 T and a length of 72 mm on the axial uniform zone in the interaction zone, and the weight of the permanent magnet is only 21 kg. Compared with the traditional external magnet system, this design can reduce the weight of the magnet, the magnetic field strength in the interaction zone is more uniform, and the system structure is more compact, which can meet the lightweight and miniaturization requirements of high-power microwave source systems. The device applies π mode as its operating mode, four 90° sector TE11 modes are extracted through all-cavity axial extraction structure, and a coaxial-plate-inserted mode converter is designed for mode conversion, thus to obtain TE11 mode in circular waveguide. In particle-in-cell (PIC) simulation, the proposed R8 ACAE-RM can generate a microwave power of 1.06 GW with a pure TE11 mode at the frequency of 2.44 GHz under the conditions of a guiding magnetic generated by the inner and outer magnetic blocks, a diode voltage of 320 kV, and power conversion efficiency of 47%.
The design of permanent magnet packaging for a compact S-band 8-cavity all-cavity axial extraction relativistic magnetron (R8 ACAE-RM) with an output mode of TE11 is preliminarily explored. The inner magnetic block is placed at both ends of the anode block in the anode cylinder, and the outer magnetic block is placed outside the RM, which generates a magnetic field of about 0.34 T and a length of 72 mm on the axial uniform zone in the interaction zone, and the weight of the permanent magnet is only 21 kg. Compared with the traditional external magnet system, this design can reduce the weight of the magnet, the magnetic field strength in the interaction zone is more uniform, and the system structure is more compact, which can meet the lightweight and miniaturization requirements of high-power microwave source systems. The device applies π mode as its operating mode, four 90° sector TE11 modes are extracted through all-cavity axial extraction structure, and a coaxial-plate-inserted mode converter is designed for mode conversion, thus to obtain TE11 mode in circular waveguide. In particle-in-cell (PIC) simulation, the proposed R8 ACAE-RM can generate a microwave power of 1.06 GW with a pure TE11 mode at the frequency of 2.44 GHz under the conditions of a guiding magnetic generated by the inner and outer magnetic blocks, a diode voltage of 320 kV, and power conversion efficiency of 47%.
2025,
37: 013005.
doi: 10.11884/HPLPB202537.250006
Abstract:
In complex electromagnetic countermeasure environments, it is necessary to take electromagnetic protection measures for the radio frequency front-end of electronic information equipment to resist strong electromagnetic interference and even damage. In response to the problem that existing protective devices reflect strong interference signals exceeding the threshold during operation, which can easily cause secondary electromagnetic threats, we propose a design for a broadband absorptive electromagnetic pulse protection device. By introducing a microstrip line matching stub in the main protection path, the electromagnetic pulse signal is isolated from the output port and transmitted to the matching load for broadband absorption. Within the frequency range of 0.5 GHz to 1.5 GHz (relative bandwidth > 90%), the device achieves good performance with insertion loss less than 1 dB for low-power signals, electromagnetic pulse signal protection isolation greater than 10 dB, and input port return loss greater than 10 dB.
In complex electromagnetic countermeasure environments, it is necessary to take electromagnetic protection measures for the radio frequency front-end of electronic information equipment to resist strong electromagnetic interference and even damage. In response to the problem that existing protective devices reflect strong interference signals exceeding the threshold during operation, which can easily cause secondary electromagnetic threats, we propose a design for a broadband absorptive electromagnetic pulse protection device. By introducing a microstrip line matching stub in the main protection path, the electromagnetic pulse signal is isolated from the output port and transmitted to the matching load for broadband absorption. Within the frequency range of 0.5 GHz to 1.5 GHz (relative bandwidth > 90%), the device achieves good performance with insertion loss less than 1 dB for low-power signals, electromagnetic pulse signal protection isolation greater than 10 dB, and input port return loss greater than 10 dB.
2025,
37: 014001.
doi: 10.11884/HPLPB202537.240210
Abstract:
To improve the design efficiency and construction quality of accelerator facility, and to solve the problems in the design and construction process of existing accelerator facilities, such as the multidisciplinary data island, the poor real-time interaction of data and the weak consistency of data in each system, and long design cycle and high cost, focusing on the construction requirements of accelerator devices, the collaborative design of α irradiation device for CS30 accelerator based on 3DE platform is proposed. On this basis a relatively complete set of accelerator facility collaborative design processes are sorted out, the multidimensional collaborative design of structure, piping, electrical and civil construction is realized, the whole design process is standardized, the design errors are reduced, the design efficiency and quality are improved, and the design cost is saved. Accordingly, the application of 3DE platform in accelerator facility design is promoted, and the construction time of the accelerator facility is effectively shortened.
To improve the design efficiency and construction quality of accelerator facility, and to solve the problems in the design and construction process of existing accelerator facilities, such as the multidisciplinary data island, the poor real-time interaction of data and the weak consistency of data in each system, and long design cycle and high cost, focusing on the construction requirements of accelerator devices, the collaborative design of α irradiation device for CS30 accelerator based on 3DE platform is proposed. On this basis a relatively complete set of accelerator facility collaborative design processes are sorted out, the multidimensional collaborative design of structure, piping, electrical and civil construction is realized, the whole design process is standardized, the design errors are reduced, the design efficiency and quality are improved, and the design cost is saved. Accordingly, the application of 3DE platform in accelerator facility design is promoted, and the construction time of the accelerator facility is effectively shortened.
2025,
37: 014002.
doi: 10.11884/HPLPB202537.240153
Abstract:
The RF linac dedicated to boron neutron capture therapy (BNCT02) in our institute is mainly composed of an ion source, a low energy beam transport line, a radio frequency quadrupole accelerator and three high energy beam transport lines. To ensure the safe operation of the BNCT02 accelerator, a machine protection system (MPS) was designed based on Yokogawa PLC and Experimental Physics and Industrial Control System (EPICS) software toolkit. The MPS adopts a redundant design, consisting of two completely independent subsystems with consistent main input and output signals. The test results show that the response time of the MPS is less than 1.6 ms, and it has the characteristics of high stability and reliability, which meets the operational requirements of the BNCT02 accelerator.
The RF linac dedicated to boron neutron capture therapy (BNCT02) in our institute is mainly composed of an ion source, a low energy beam transport line, a radio frequency quadrupole accelerator and three high energy beam transport lines. To ensure the safe operation of the BNCT02 accelerator, a machine protection system (MPS) was designed based on Yokogawa PLC and Experimental Physics and Industrial Control System (EPICS) software toolkit. The MPS adopts a redundant design, consisting of two completely independent subsystems with consistent main input and output signals. The test results show that the response time of the MPS is less than 1.6 ms, and it has the characteristics of high stability and reliability, which meets the operational requirements of the BNCT02 accelerator.
2025,
37: 014003.
doi: 10.11884/HPLPB202537.240202
Abstract:
A novel service-based EPICS and new front-end data acquisition method based on a high-availability Kubernetes cluster built on the Proxmox VE platform is proposed in this paper to enhance the performance and stability of the data acquisition system. By deploying EPICS services on the Kubernetes cluster, a new efficient front-end data processing and acquisition method is realized. The data acquisition method utilizes distributed data sharing based on the Channel Access protocol to perform real-time processing and analysis of data. This approach offers advantages such as reducing hardware and maintenance costs, improving portability and flexibility, and enhancing data acquisition and processing efficiency. The practical application and testing have demonstrated that this method has the potential for use in large scientific facilities. In the future, its application value in other fields will be explored.
A novel service-based EPICS and new front-end data acquisition method based on a high-availability Kubernetes cluster built on the Proxmox VE platform is proposed in this paper to enhance the performance and stability of the data acquisition system. By deploying EPICS services on the Kubernetes cluster, a new efficient front-end data processing and acquisition method is realized. The data acquisition method utilizes distributed data sharing based on the Channel Access protocol to perform real-time processing and analysis of data. This approach offers advantages such as reducing hardware and maintenance costs, improving portability and flexibility, and enhancing data acquisition and processing efficiency. The practical application and testing have demonstrated that this method has the potential for use in large scientific facilities. In the future, its application value in other fields will be explored.
2025,
37: 01500.
doi: 10.11884/HPLPB202537.240158
Abstract:
To enhance the shock wave generated by underwater electrical wire explosion(UEWE), wires are connected in parallel to form wire-array, but wire-array’s low resistance results in low deposition power. To solve the problem, by using copper sheets, parallel-series wire-arrays with different resistance and same mass were designed, and it was proposed that resistance matching between wire-array and power source is the ideal discharge mode. By parallel-series wire-array, single wire discharge similarity was verified, and miniaturization verification of large devices with high voltage was achieved. With the help of discharge similarity and parallel-series wire-array, the optimal wire-array design of UEWE was proposed at a given energy and wire mass.
To enhance the shock wave generated by underwater electrical wire explosion(UEWE), wires are connected in parallel to form wire-array, but wire-array’s low resistance results in low deposition power. To solve the problem, by using copper sheets, parallel-series wire-arrays with different resistance and same mass were designed, and it was proposed that resistance matching between wire-array and power source is the ideal discharge mode. By parallel-series wire-array, single wire discharge similarity was verified, and miniaturization verification of large devices with high voltage was achieved. With the help of discharge similarity and parallel-series wire-array, the optimal wire-array design of UEWE was proposed at a given energy and wire mass.
2025,
37: 015002.
doi: 10.11884/HPLPB202537.240367
Abstract:
This paper proposes a layout structure of the pulsed power generator based on the bipolar linear transformer driver, achieving flexible stacking of the bipolar linear transformer driver modules. The conduction time of the metal-oxide-semiconductor field effect transistor is regulated by adjusting the voltage of the driver circuit, enabling precise control over the rise time of the pulsed voltage. An integrated core-copper pillar structure and a reverse overshoot discharge circuit are introduced in the linear transformer driver structure, which optimizes the electromagnetic compatibility and reduces the reverse overshoot at the tail of the pulsed waveform. The developed bipolar linear transformer driver device can stably output ±5 kV pulsed voltage with 1 kHz frequency and 1 μs pulse width. The rise time of the pulsed voltage is continuously adjustable from 30 ns to 100 ns. The irreversible electroporation experiments on cells are carried out using the bipolar linear transformer driver.
This paper proposes a layout structure of the pulsed power generator based on the bipolar linear transformer driver, achieving flexible stacking of the bipolar linear transformer driver modules. The conduction time of the metal-oxide-semiconductor field effect transistor is regulated by adjusting the voltage of the driver circuit, enabling precise control over the rise time of the pulsed voltage. An integrated core-copper pillar structure and a reverse overshoot discharge circuit are introduced in the linear transformer driver structure, which optimizes the electromagnetic compatibility and reduces the reverse overshoot at the tail of the pulsed waveform. The developed bipolar linear transformer driver device can stably output ±5 kV pulsed voltage with 1 kHz frequency and 1 μs pulse width. The rise time of the pulsed voltage is continuously adjustable from 30 ns to 100 ns. The irreversible electroporation experiments on cells are carried out using the bipolar linear transformer driver.
2025,
37: 016001.
doi: 10.11884/HPLPB202537.240211
Abstract:
The Monte Carlo (MC) method is one of the most widely applied methods in the simulation study of radiation damage and radiation shielding. When conducting radiation damage studies on large targets such as airports, railways, and ships, the focus is generally on 3D modeling and radiation calculations of these targets; however, the post-calculation data analysis often relies on manual methods, making this aspect of the research technically challenging and inefficient, thus becoming a bottleneck in related research efforts. In this paper, a visualization post-processing method for MC calculations of target particle irradiation is studied, and a post-processing model based on k-dimensional tree (KDtree) + inverse distance weighting (IDW) and genetic algorithm based backpropagation (GABP) neural network is established to realize the visualization analysis of data combined with the model. Compared with traditional data analysis methods, the method proposed in this paper can greatly reduce the difficulty of researchers’ work, improve the speed of data processing, realize the visual display of radiation effects, and enhance the efficiency of post-processing in radiation effects research.
The Monte Carlo (MC) method is one of the most widely applied methods in the simulation study of radiation damage and radiation shielding. When conducting radiation damage studies on large targets such as airports, railways, and ships, the focus is generally on 3D modeling and radiation calculations of these targets; however, the post-calculation data analysis often relies on manual methods, making this aspect of the research technically challenging and inefficient, thus becoming a bottleneck in related research efforts. In this paper, a visualization post-processing method for MC calculations of target particle irradiation is studied, and a post-processing model based on k-dimensional tree (KDtree) + inverse distance weighting (IDW) and genetic algorithm based backpropagation (GABP) neural network is established to realize the visualization analysis of data combined with the model. Compared with traditional data analysis methods, the method proposed in this paper can greatly reduce the difficulty of researchers’ work, improve the speed of data processing, realize the visual display of radiation effects, and enhance the efficiency of post-processing in radiation effects research.
2025,
37: 016002.
doi: 10.11884/HPLPB202537.240192
Abstract:
To study the characteristics and evolution of the gas-liquid two-phase flow pattern in the rod bundle channel of pressurized water reactor, based on the double-layer wire mesh sensor, the air-water two-phase flow pattern experiment of the 3×3 rod bundle channels was carried out at room temperature and pressure. The flow patterns include bubble flow, cap flow and slug flow. The experimental results show that, the critical bubble diameter range for the reversal of lateral lift direction under normal temperature and pressure is 4 to 5.8 mm. In addition, for bubbly flow, the time-averaged void fraction exhibits a “wall peak” distribution at lower superficial gas velocities and a “central peak” distribution at higher superficial gas velocities. For the cap flow, the cross distribution of cap shaped bubbles within adjacent subchannels triggers large-scale mixing of the liquid phase between adjacent subchannels, and the time-averaged void fraction exhibits a “central peak” distribution. For slug flow, large-sized bubbles develop along the axis and cross subchannel gaps to aggregate into slug shaped bubbles, with a more pronounced distribution of the central peak of void fraction. The experimental data are used to evaluate three drift-flux models. The Bestion’s drift-flux model overestimates the drift velocity, resulting in underestimated void fraction predictions. The Ozaki’s drift-flux model provides more accurate predictions of void fraction than the Xu Han model, with an average relative error of 9.8%.
To study the characteristics and evolution of the gas-liquid two-phase flow pattern in the rod bundle channel of pressurized water reactor, based on the double-layer wire mesh sensor, the air-water two-phase flow pattern experiment of the 3×3 rod bundle channels was carried out at room temperature and pressure. The flow patterns include bubble flow, cap flow and slug flow. The experimental results show that, the critical bubble diameter range for the reversal of lateral lift direction under normal temperature and pressure is 4 to 5.8 mm. In addition, for bubbly flow, the time-averaged void fraction exhibits a “wall peak” distribution at lower superficial gas velocities and a “central peak” distribution at higher superficial gas velocities. For the cap flow, the cross distribution of cap shaped bubbles within adjacent subchannels triggers large-scale mixing of the liquid phase between adjacent subchannels, and the time-averaged void fraction exhibits a “central peak” distribution. For slug flow, large-sized bubbles develop along the axis and cross subchannel gaps to aggregate into slug shaped bubbles, with a more pronounced distribution of the central peak of void fraction. The experimental data are used to evaluate three drift-flux models. The Bestion’s drift-flux model overestimates the drift velocity, resulting in underestimated void fraction predictions. The Ozaki’s drift-flux model provides more accurate predictions of void fraction than the Xu Han model, with an average relative error of 9.8%.
2025,
37: 016003.
doi: 10.11884/HPLPB202537.240265
Abstract:
On the pulsed fusion sources such as laser ICF device, Z pinch facility and dense plasma focus device, the neutron activation method are widely applied, which can measure the neutron flux and diagnose the neutron yield from the source. Based on the inorganic scintillation detector, the 909 keV monoenergetic gammas, which are emitted from decay of the activated yttrium nuclei after the inelastic scattering on neutrons, can be measured, and the flux of the DD fusion neutrons can be diagnosed. In this work, an activation detection system using yttrium is developed, in which the LaBr3:Ce scintillator detector is chosen as the gamma sensitive material. The accumulation process of yttrium activation products under continuous irradiation has been physically analyzed, with respect to their half-life of only 15.663 s. An experimental method of calibrating the incident neutron detection efficiency by accelerator-based DD neutron source is thus established. In the experiments, the gamma detector is served as both neutron flux rate monitor and activation gamma measurements. The variation of radiation activity of the yttrium target with the neutron flux rate are simulated. Therefore, the in-situ calibration of the detection efficiency of this yttrium activation system for incident neutrons is achieved, with an accuracy of about 3.8%.
On the pulsed fusion sources such as laser ICF device, Z pinch facility and dense plasma focus device, the neutron activation method are widely applied, which can measure the neutron flux and diagnose the neutron yield from the source. Based on the inorganic scintillation detector, the 909 keV monoenergetic gammas, which are emitted from decay of the activated yttrium nuclei after the inelastic scattering on neutrons, can be measured, and the flux of the DD fusion neutrons can be diagnosed. In this work, an activation detection system using yttrium is developed, in which the LaBr3:Ce scintillator detector is chosen as the gamma sensitive material. The accumulation process of yttrium activation products under continuous irradiation has been physically analyzed, with respect to their half-life of only 15.663 s. An experimental method of calibrating the incident neutron detection efficiency by accelerator-based DD neutron source is thus established. In the experiments, the gamma detector is served as both neutron flux rate monitor and activation gamma measurements. The variation of radiation activity of the yttrium target with the neutron flux rate are simulated. Therefore, the in-situ calibration of the detection efficiency of this yttrium activation system for incident neutrons is achieved, with an accuracy of about 3.8%.
2025,
37: 019001.
doi: 10.11884/HPLPB202537.240373
Abstract:
Ionic liquid ion sources have the capability of generating diverse heavy molecular ions, and their applications have been investigated in the field of ion thrusters. This study aims to determine the quality parameters of ionic liquid ion beams and establish methods for their control. Firstly, the beam acceleration process in an ionic liquid ion source was simulated using Particle-in-Cell (PIC) simulation methods, and the effects of the beam current, acceleration voltage, and emitter-extraction gap on the beam emittance and Twiss parameters were investigated. The results indicate that the normalized emittance decreases with a reduction in the beam current and emitter-extraction gap, as well as with an increase in the acceleration voltage. The kinetic energy broadens during the acceleration process. The acceleration efficiency is not obviously affected by the beam current or acceleration voltage. However, it increases with the expansion of the emitter-extraction gap. Secondly, the control of a centimeter-scale beam was simulated by utilizing the beam parameters derived from the simulation of the acceleration process. The results demonstrate that the divergence, velocity distribution, and specific impulse can be controlled by a set of three-electrode electrostatic lenses without imposing additional demands on the power source on the ionic liquid electric thruster.
Ionic liquid ion sources have the capability of generating diverse heavy molecular ions, and their applications have been investigated in the field of ion thrusters. This study aims to determine the quality parameters of ionic liquid ion beams and establish methods for their control. Firstly, the beam acceleration process in an ionic liquid ion source was simulated using Particle-in-Cell (PIC) simulation methods, and the effects of the beam current, acceleration voltage, and emitter-extraction gap on the beam emittance and Twiss parameters were investigated. The results indicate that the normalized emittance decreases with a reduction in the beam current and emitter-extraction gap, as well as with an increase in the acceleration voltage. The kinetic energy broadens during the acceleration process. The acceleration efficiency is not obviously affected by the beam current or acceleration voltage. However, it increases with the expansion of the emitter-extraction gap. Secondly, the control of a centimeter-scale beam was simulated by utilizing the beam parameters derived from the simulation of the acceleration process. The results demonstrate that the divergence, velocity distribution, and specific impulse can be controlled by a set of three-electrode electrostatic lenses without imposing additional demands on the power source on the ionic liquid electric thruster.
2025,
37: 011004.
doi: 10.11884/HPLPB202537.240304
Abstract:
Femtosecond laser precision machining technology has three characteristics: extremely short duration time to avoid or alleviate thermal effects, extremely high peak power density suitable for any solid material and extremely small focal spot size to achieve precise removal or modification of micro areas, meeting the safety and precision machining needs of various difficult to machine and special materials involved in precision diagnosis/measurement experiments. The application of high stability and high repetition rate femtosecond lasers fills in the gap of low repetition rate femtosecond lasers that cannot achieve high-speed scanning, providing an important energy source for efficient and precise processing of various precision samples/specimens required for precision diagnosis/measurement experiments. This article takes the precision diagnosis/measurement experiments of various institutes of China Academy of Engineering Physics as the starting point for safe, efficient and precise processing requirements of precision samples/specimens. Taking typical application scenarios such as laser X-ray precision target materials and structures, explosive material microstructures, superhard material composite refractive lens structures, micro probe fiber precision fixed structures, and terahertz filter core structures as examples, it introduces the research progress of high-frequency femtosecond laser precision processing technology in the safe, efficient and precise processing of difficult to-machine materials and special materials.
Femtosecond laser precision machining technology has three characteristics: extremely short duration time to avoid or alleviate thermal effects, extremely high peak power density suitable for any solid material and extremely small focal spot size to achieve precise removal or modification of micro areas, meeting the safety and precision machining needs of various difficult to machine and special materials involved in precision diagnosis/measurement experiments. The application of high stability and high repetition rate femtosecond lasers fills in the gap of low repetition rate femtosecond lasers that cannot achieve high-speed scanning, providing an important energy source for efficient and precise processing of various precision samples/specimens required for precision diagnosis/measurement experiments. This article takes the precision diagnosis/measurement experiments of various institutes of China Academy of Engineering Physics as the starting point for safe, efficient and precise processing requirements of precision samples/specimens. Taking typical application scenarios such as laser X-ray precision target materials and structures, explosive material microstructures, superhard material composite refractive lens structures, micro probe fiber precision fixed structures, and terahertz filter core structures as examples, it introduces the research progress of high-frequency femtosecond laser precision processing technology in the safe, efficient and precise processing of difficult to-machine materials and special materials.
2025,
37: 013006.
doi: 10.11884/HPLPB202537.240159
Abstract:
To solve the problems of low inhibition of parasitic mode and measurement accuracy is susceptible to interference of parasitic modes in traditional high power microwave online measurement devices, a high-power TM01 mode coupling device is studied, which is applied to the Ku-band relativistic backward wave oscillator (RBWO) online measurement system. Due to the RBWO emission’s angular inhomogeneity, asymmetric modes is generated, and the traditional single-arm porous circular waveguide coupler cannot solve the competition problem between the TM01 mode and the asymmetric modes, which generally leads to the detection waveform distortion and coupling degree judgment deviation and seriously affects the accuracy of the online evaluation of the output power of TM01 mode of the RBWO. For this reason, combining the four-arm porous coupling structure with the TM01 mode selection network, a novel online mode-selective coupling device is proposed in this paper. Using the field structure difference of different waveguide modes, the proposed device realizes the differential coupling of TM01 mode and other parasitic modes and solves the problem of inaccurate online test power caused by parasitic mode interference. The simulation results show that the coupling degree of the proposed new coupler to TM01 mode is more than 20 dB higher than that of the other modes, and the on-line test waveform and power measured in the high-power experiment are in good agreement with the radiated field test waveform and power, and the coupling stability is significantly improved.
To solve the problems of low inhibition of parasitic mode and measurement accuracy is susceptible to interference of parasitic modes in traditional high power microwave online measurement devices, a high-power TM01 mode coupling device is studied, which is applied to the Ku-band relativistic backward wave oscillator (RBWO) online measurement system. Due to the RBWO emission’s angular inhomogeneity, asymmetric modes is generated, and the traditional single-arm porous circular waveguide coupler cannot solve the competition problem between the TM01 mode and the asymmetric modes, which generally leads to the detection waveform distortion and coupling degree judgment deviation and seriously affects the accuracy of the online evaluation of the output power of TM01 mode of the RBWO. For this reason, combining the four-arm porous coupling structure with the TM01 mode selection network, a novel online mode-selective coupling device is proposed in this paper. Using the field structure difference of different waveguide modes, the proposed device realizes the differential coupling of TM01 mode and other parasitic modes and solves the problem of inaccurate online test power caused by parasitic mode interference. The simulation results show that the coupling degree of the proposed new coupler to TM01 mode is more than 20 dB higher than that of the other modes, and the on-line test waveform and power measured in the high-power experiment are in good agreement with the radiated field test waveform and power, and the coupling stability is significantly improved.
2025,
37: 014004.
doi: 10.11884/HPLPB202537.240168
Abstract:
The terahertz near-field high-throughput material physical property testing system (NFTHZ) integrates a wavelength-tunable terahertz free electron laser (THz-FEL). The instrument uses a linear accelerator with tunable electron energy of 10-18 MeV as the injector. A pre-bunched electron beam can be formed by adjusting the longitudinal/temporal structure of the driving laser. By matching the relationship between the bunching factor, energy of the electron beam at the undulator entrance and the K value of undulator, a terahertz free electron laser with megawatts peak power and an adjustable center wavelength of 0.5-5.0 THz can be achieved. The microwave system provides high-power microwave electric field, accelerating structure and microwave amplitude and phase control system to accelerate the electron beam to the target energy. This article will introduce the development of the microwave system of the NFTHZ facility and the construction progress of the electron linear accelerator.
The terahertz near-field high-throughput material physical property testing system (NFTHZ) integrates a wavelength-tunable terahertz free electron laser (THz-FEL). The instrument uses a linear accelerator with tunable electron energy of 10-18 MeV as the injector. A pre-bunched electron beam can be formed by adjusting the longitudinal/temporal structure of the driving laser. By matching the relationship between the bunching factor, energy of the electron beam at the undulator entrance and the K value of undulator, a terahertz free electron laser with megawatts peak power and an adjustable center wavelength of 0.5-5.0 THz can be achieved. The microwave system provides high-power microwave electric field, accelerating structure and microwave amplitude and phase control system to accelerate the electron beam to the target energy. This article will introduce the development of the microwave system of the NFTHZ facility and the construction progress of the electron linear accelerator.
2025,
37: 014005.
doi: 10.11884/HPLPB202537.240195
Abstract:
The C-band photocathode electron gun is designed. As one of important equipments for the linear injector of the Southern Advanced Photon Source. This paper discusses its RF and coupler design. The C-band electron gun has a working frequency of 5.712 GHz, a 3.6-cell structure, a π-mode acceleration mode, and it adopts a coaxial coupling method. The CST and Superfish codes are used to optimize the cavity microwave structure, reducing the surface electric field of the cavity to enhance the accelerating field strength and suppressing the multimode transmission. Furthermore, COMSOL Multiphysics is applied to analyze the cavity cooling system, reducing frequency drift caused by the cavity heating. Additionally, a water cooling design for the cavity ensures that the maximum temperature rise of the cavity is less than 20 ℃. Under an input power of 18.15 MW, the acceleration gradient of 180 MV/m on the cathode surface is achieved, the ratio of the acceleration gradient to the cathode surface electric field is approximately 0.93, and the cavity quality factor is greater than10000 . The design of the coupler suppresses the transmission of dipole and quadrupole modes, with the S11 parameter being less than −40 dB.
The C-band photocathode electron gun is designed. As one of important equipments for the linear injector of the Southern Advanced Photon Source. This paper discusses its RF and coupler design. The C-band electron gun has a working frequency of 5.712 GHz, a 3.6-cell structure, a π-mode acceleration mode, and it adopts a coaxial coupling method. The CST and Superfish codes are used to optimize the cavity microwave structure, reducing the surface electric field of the cavity to enhance the accelerating field strength and suppressing the multimode transmission. Furthermore, COMSOL Multiphysics is applied to analyze the cavity cooling system, reducing frequency drift caused by the cavity heating. Additionally, a water cooling design for the cavity ensures that the maximum temperature rise of the cavity is less than 20 ℃. Under an input power of 18.15 MW, the acceleration gradient of 180 MV/m on the cathode surface is achieved, the ratio of the acceleration gradient to the cathode surface electric field is approximately 0.93, and the cavity quality factor is greater than
2025,
37: 014006.
doi: 10.11884/HPLPB202537.240289
Abstract:
Negative hydrogen stripping injection is the only feasible scheme for accumulating beam in high current proton synchrotrons. Currently, the China Spallation Neutron Source (CSNS) employs negative hydrogen stripping injection by using a stripping foil. The intense temperature rising of the foil caused by energy deposition from the negative hydrogen beam passing through the foil is a critical issue which affecting the foil's lifetime and the stable operation of the accelerator. Additionally, the residual high power electron beam generated during the stripping process may have severe consequences, including electron ionization within the foil causing further temperature increase, thermal damage to the vacuum box from electron impacts, e-p instability from electrons captured by the proton beam in the vacuum tube, and significant electron cloud effects from secondary electrons. This paper focuses on two main topics: first, comprehensive simulations of the foil’s temperature rise have been conducted using finite element analysis software, taking into account various parameters, including the average number of particle crossings. Simulation results under various software conditions are compared to obtain the temperature field distribution on the stripping foil and predict surface temperature increases for future higher beam power. Secondly, the electron distribution following the stripping process is analyzed based on theoretical calculations and Geant4 simulations. The 3D computational model is refined by considering the electromagnetic field and beam conditions in the CSNS injection area, and a scheme for capturing stripping electrons is proposed by determining the optimal position for the electron collection device.
Negative hydrogen stripping injection is the only feasible scheme for accumulating beam in high current proton synchrotrons. Currently, the China Spallation Neutron Source (CSNS) employs negative hydrogen stripping injection by using a stripping foil. The intense temperature rising of the foil caused by energy deposition from the negative hydrogen beam passing through the foil is a critical issue which affecting the foil's lifetime and the stable operation of the accelerator. Additionally, the residual high power electron beam generated during the stripping process may have severe consequences, including electron ionization within the foil causing further temperature increase, thermal damage to the vacuum box from electron impacts, e-p instability from electrons captured by the proton beam in the vacuum tube, and significant electron cloud effects from secondary electrons. This paper focuses on two main topics: first, comprehensive simulations of the foil’s temperature rise have been conducted using finite element analysis software, taking into account various parameters, including the average number of particle crossings. Simulation results under various software conditions are compared to obtain the temperature field distribution on the stripping foil and predict surface temperature increases for future higher beam power. Secondly, the electron distribution following the stripping process is analyzed based on theoretical calculations and Geant4 simulations. The 3D computational model is refined by considering the electromagnetic field and beam conditions in the CSNS injection area, and a scheme for capturing stripping electrons is proposed by determining the optimal position for the electron collection device.
