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, Available online ,
doi: 10.11884/HPLPB202335.230117
Abstract:
With the increasing demand on higher precision control of beams in modern particle accelerators, higher requirements are raised for the design and survey of engineering control network. In this paper, the layout and survey scheme of the first-level surface control network for the engineering survey of High Energy Photon Source (HEPS) are introduced in detail. The permanent points of the surface control network are arranged in the tunnel of the particle accelerator building, and the vertical view hole is aligned with the instrument plumb on the top surface of the online station hall, and the observation condition of plane mutual view is formed, the transmission and contact of plane coordinates are realized. In the elevation direction, the communication between the leveling station and the elevation coordinates is realized by means of horizontal viewing holes and doors and Windows. Therefore, the three-dimensional view and observation structure is formed, which has a unique place in the construction of synchrotron radiation light source in China, and effectively ensures the accurate control of accelerator orbit.The scheme that the plane control network adopts the GNSS control network and the corner network of the total station respectively is proposed. The elevation control network adopts the scheme of indoor tunnel ground and outdoor ground level survey scheme. Before the installation of the accelerator tunnel equipment, two surface control network surveys were carried out. The data processing was adjusted in plane + elevation mode, and the accuracy of the measurement process is verified by comparing different survey schemes, and the reliability is verified by comparing the measurement results of two control networks. The average point position standard deviation is 2mm, which indicates that the survey results are reliable and meet the requirements of subsequent control network survey and equipment installation collimation.and the stability of the point is improved by optimizing the design of permanent point marker structure.HEPS requires high stability of permanent control points, through optimal design and special construction, the ultra-high fine and stable bedrock spacer pile was successfully built in the narrow tunnel space, forming a stable three-dimensional permanent control point for the storage ring.It provides a benchmark for long-term monitoring of beam orbit stability, and provides a reference for the subsequent construction of synchrotron radiation light source.
With the increasing demand on higher precision control of beams in modern particle accelerators, higher requirements are raised for the design and survey of engineering control network. In this paper, the layout and survey scheme of the first-level surface control network for the engineering survey of High Energy Photon Source (HEPS) are introduced in detail. The permanent points of the surface control network are arranged in the tunnel of the particle accelerator building, and the vertical view hole is aligned with the instrument plumb on the top surface of the online station hall, and the observation condition of plane mutual view is formed, the transmission and contact of plane coordinates are realized. In the elevation direction, the communication between the leveling station and the elevation coordinates is realized by means of horizontal viewing holes and doors and Windows. Therefore, the three-dimensional view and observation structure is formed, which has a unique place in the construction of synchrotron radiation light source in China, and effectively ensures the accurate control of accelerator orbit.The scheme that the plane control network adopts the GNSS control network and the corner network of the total station respectively is proposed. The elevation control network adopts the scheme of indoor tunnel ground and outdoor ground level survey scheme. Before the installation of the accelerator tunnel equipment, two surface control network surveys were carried out. The data processing was adjusted in plane + elevation mode, and the accuracy of the measurement process is verified by comparing different survey schemes, and the reliability is verified by comparing the measurement results of two control networks. The average point position standard deviation is 2mm, which indicates that the survey results are reliable and meet the requirements of subsequent control network survey and equipment installation collimation.and the stability of the point is improved by optimizing the design of permanent point marker structure.HEPS requires high stability of permanent control points, through optimal design and special construction, the ultra-high fine and stable bedrock spacer pile was successfully built in the narrow tunnel space, forming a stable three-dimensional permanent control point for the storage ring.It provides a benchmark for long-term monitoring of beam orbit stability, and provides a reference for the subsequent construction of synchrotron radiation light source.
, Available online ,
doi: 10.11884/HPLPB202335.230154
Abstract:
7075 aluminum alloy is widely used in the field of aerospace materials as a structural component due to its excellent properties. There are various radiation particles in the spacecraft space environment, which will cause different degrees of irradiation damage to spacecraft materials, and threaten their reliability, and even lead to the failure of space missions. The complex space environment threats the reliability of 7075 aluminum alloy, and even leads to the failure of space missions, by selecting different doses of 3 MeV Fe11+ ions to irradiate 7075 aluminum alloy, using XRD, AFM and Nanoindentation to study the microstructure, surface morphology and hardness changes before and after irradiation, it is found that the tapered protrusions caused by cascade collision evolution and surface defect diffusion are found on the surface and the surface roughness of the sample increased first and then decreased with the increase of dose. In addition, the nanoindentation test show that the hardness of the sample increased after irradiation, and with the increase of dose, the hardness gradually became saturated, it could be seen from the analysis that the irradiation hardening of the sample is caused by the irradiation defects impeding the slippage of dislocations.
7075 aluminum alloy is widely used in the field of aerospace materials as a structural component due to its excellent properties. There are various radiation particles in the spacecraft space environment, which will cause different degrees of irradiation damage to spacecraft materials, and threaten their reliability, and even lead to the failure of space missions. The complex space environment threats the reliability of 7075 aluminum alloy, and even leads to the failure of space missions, by selecting different doses of 3 MeV Fe11+ ions to irradiate 7075 aluminum alloy, using XRD, AFM and Nanoindentation to study the microstructure, surface morphology and hardness changes before and after irradiation, it is found that the tapered protrusions caused by cascade collision evolution and surface defect diffusion are found on the surface and the surface roughness of the sample increased first and then decreased with the increase of dose. In addition, the nanoindentation test show that the hardness of the sample increased after irradiation, and with the increase of dose, the hardness gradually became saturated, it could be seen from the analysis that the irradiation hardening of the sample is caused by the irradiation defects impeding the slippage of dislocations.
, Available online ,
doi: 10.11884/HPLPB202335.230149
Abstract:
Based on the correlation between ground neutron detection and the cosmic ray environment, a dataset was constructed using the detection data of GOES series satellites and various neutron detection stations worldwide for the solar activity quiet period. Models for inverting the cosmic ray proton environment from ground neutron detection data were established based on the Extreme Gradient Boost Decision Tree (XGBoost) and artificial neural network. They use genetic algorithm to solve the optimal hyperparameter and train the parameters of each neuron of the neural network to realize the inversion of the cosmic ray proton environment. The MSE of the model training is 0.499, and the average inversion error of the test set is 26.9% respectively. Compared with the radiation environment model commonly used in aerospace, the error is usually within 200%, which is significantly improved. Multiple other machine learning algorithms, including SVR, BP, and LSTM, were compared and the results showed that the model established in this paper has the advantages of short training time, fast computation speed, and low resource consumption.
Based on the correlation between ground neutron detection and the cosmic ray environment, a dataset was constructed using the detection data of GOES series satellites and various neutron detection stations worldwide for the solar activity quiet period. Models for inverting the cosmic ray proton environment from ground neutron detection data were established based on the Extreme Gradient Boost Decision Tree (XGBoost) and artificial neural network. They use genetic algorithm to solve the optimal hyperparameter and train the parameters of each neuron of the neural network to realize the inversion of the cosmic ray proton environment. The MSE of the model training is 0.499, and the average inversion error of the test set is 26.9% respectively. Compared with the radiation environment model commonly used in aerospace, the error is usually within 200%, which is significantly improved. Multiple other machine learning algorithms, including SVR, BP, and LSTM, were compared and the results showed that the model established in this paper has the advantages of short training time, fast computation speed, and low resource consumption.
, Available online ,
doi: 10.11884/HPLPB202335.230211
Abstract:
The ability of electromagnetic emission mainly depends on the pulse power supply system, and the optimization of pulse power supply is one of the key technologies to make further breakthroughs in electromagnetic emission technology. Inductive energy storage type pulse power supply has great advantages in energy density and has far-reaching development potential. The XRAM pulse power supply based on series charging and parallel discharge has the advantages of simple structure and strong expandability. In this paper, the working principle of diode devices in multilevel XRAM power supply topology is analyzed, and a scheme is proposed to simplify the number of diode devices based on function classification.A simulation model is established for a 30-stage XRAM pulse power supply with a railgun load using ICCOS. Each power module consists of five stages, resulting in a total energy storage capacity of 365 kJ for the system, with an emission efficiency of nearly 20%. By comparing the simulation results of model performance indexes before and after simplification, it is proved that the simplified lower arm diode of the first stage is unfavorable to the operation of the multistage power supply. Simplifying the final countercurrent capacitor series diode in the multistage topology, and the antiparallel diode of charging thyristor under the premise of optimizing the countercurrent capacitor parameters, have no obvious effect on the discharge current of the power module.
The ability of electromagnetic emission mainly depends on the pulse power supply system, and the optimization of pulse power supply is one of the key technologies to make further breakthroughs in electromagnetic emission technology. Inductive energy storage type pulse power supply has great advantages in energy density and has far-reaching development potential. The XRAM pulse power supply based on series charging and parallel discharge has the advantages of simple structure and strong expandability. In this paper, the working principle of diode devices in multilevel XRAM power supply topology is analyzed, and a scheme is proposed to simplify the number of diode devices based on function classification.A simulation model is established for a 30-stage XRAM pulse power supply with a railgun load using ICCOS. Each power module consists of five stages, resulting in a total energy storage capacity of 365 kJ for the system, with an emission efficiency of nearly 20%. By comparing the simulation results of model performance indexes before and after simplification, it is proved that the simplified lower arm diode of the first stage is unfavorable to the operation of the multistage power supply. Simplifying the final countercurrent capacitor series diode in the multistage topology, and the antiparallel diode of charging thyristor under the premise of optimizing the countercurrent capacitor parameters, have no obvious effect on the discharge current of the power module.
, Available online ,
doi: 10.11884/HPLPB202335.230171
Abstract:
With the continuous development of aerospace technology, the demand for Hall-electric propulsionpower processing units（PPUs）in spacecraft is constantly increasing, and high-gain, high-power and high-efficiency PPUs have become the mainstream direction of research. The LLC topology enables soft switching over the full load range and therefore offers broad application prospects in PPU anode power supplies. Due to its primary and secondary gain characteristics, the primary LLC brings great challenges to the resonant inductance design of the high gain converter of the anode power supply. In view of the above problems, this paper proposes an improved secondary LLC resonant topology, which retains the soft switching characteristics of the primary LLC resonant circuit while effectively solving the resonant inductor design problem, so that the PPU anode power supply has high gain performance. In this paper, the mathematical model of the secondary LLC topology is first established by using the time domain analysis method, and then the calculation method of the peak gain is given on the basis of the model, and finally the correctness of the built model is verified by a prototype and the validity of the secondary LLC circuit is verified.
With the continuous development of aerospace technology, the demand for Hall-electric propulsionpower processing units（PPUs）in spacecraft is constantly increasing, and high-gain, high-power and high-efficiency PPUs have become the mainstream direction of research. The LLC topology enables soft switching over the full load range and therefore offers broad application prospects in PPU anode power supplies. Due to its primary and secondary gain characteristics, the primary LLC brings great challenges to the resonant inductance design of the high gain converter of the anode power supply. In view of the above problems, this paper proposes an improved secondary LLC resonant topology, which retains the soft switching characteristics of the primary LLC resonant circuit while effectively solving the resonant inductor design problem, so that the PPU anode power supply has high gain performance. In this paper, the mathematical model of the secondary LLC topology is first established by using the time domain analysis method, and then the calculation method of the peak gain is given on the basis of the model, and finally the correctness of the built model is verified by a prototype and the validity of the secondary LLC circuit is verified.
, Available online ,
doi: 10.11884/HPLPB202335.230173
Abstract:
Dielectric barrier discharge (DBD) is widely used in industry, but the efficiency limits its further application. In this paper, a three-electrode structure combining a DBD structure and a needle-plate structure is proposed. A positive polarity pulsed power supply is applied to the DBD electrode and a negative polarity pulsed power supply is applied to the needle plate electrode. The discharge characteristics, phenomena and spectral intensity of the three-electrode DBD under different structures were analyzed. The results show that the three-electrode structure is more beneficial to the generation of DBD discharge channels, and its discharge uniformity and luminous intensity are stronger than that of the two-electrode DBD, especially under the condition of mesh grounded electrode. When the positive polarity voltage of the three-electrode structure was maintained at 11 kV and the negative polarity voltage was -5 kV, the peak discharge current of DBD in the mesh grounded three-electrode reached 1.54 A, while the peak discharge currents of DBD in the solid grounded three-electrode and the traditional two-electrode were 1.14 A and 0.74 A. During the period of the negative polarity pulse maintenance, the needle mesh gap was in the state of breakdown, and the DBD discharges appeared to have a large discharge current. In the three-electrode structure, the three-electrode DBD discharges also become more intense with the increase of the negative polarity voltage applied to the needle plate. According to the discharge spectra of DBD under different structures, spectral intensity of excited particles is the strongest among the three electrodes DBD grounded with wire mesh. This trend is consistent with the discharge current and power of DBD.
Dielectric barrier discharge (DBD) is widely used in industry, but the efficiency limits its further application. In this paper, a three-electrode structure combining a DBD structure and a needle-plate structure is proposed. A positive polarity pulsed power supply is applied to the DBD electrode and a negative polarity pulsed power supply is applied to the needle plate electrode. The discharge characteristics, phenomena and spectral intensity of the three-electrode DBD under different structures were analyzed. The results show that the three-electrode structure is more beneficial to the generation of DBD discharge channels, and its discharge uniformity and luminous intensity are stronger than that of the two-electrode DBD, especially under the condition of mesh grounded electrode. When the positive polarity voltage of the three-electrode structure was maintained at 11 kV and the negative polarity voltage was -5 kV, the peak discharge current of DBD in the mesh grounded three-electrode reached 1.54 A, while the peak discharge currents of DBD in the solid grounded three-electrode and the traditional two-electrode were 1.14 A and 0.74 A. During the period of the negative polarity pulse maintenance, the needle mesh gap was in the state of breakdown, and the DBD discharges appeared to have a large discharge current. In the three-electrode structure, the three-electrode DBD discharges also become more intense with the increase of the negative polarity voltage applied to the needle plate. According to the discharge spectra of DBD under different structures, spectral intensity of excited particles is the strongest among the three electrodes DBD grounded with wire mesh. This trend is consistent with the discharge current and power of DBD.
, Available online ,
doi: 10.11884/HPLPB202335.220311
Abstract:
The cyclotron is designed as the injector of the Heavy Ion Medical Machines (HIMMs) in Wuwei city and Lanzhou city, China. It provides 10 µA carbon ion beams to fulfill the accumulation requirement in the following synchrotron. Four picoammeters acquire the beam current signals gathered by the radial detectors; meanwhile, the beam time structure is measured with Field Programmable Gate Arrays and a real-time operating system. This paper introduces the mechanical design of the radial detectors and further provides the thermal structure analysis result of probe tips with and without water cooling. Moreover, the hardware and software architecture of the control system for this detector is described, including the motion control and data acquisition system, which can implement beam current data and position simultaneous acquisition at more than 10 kS/s. At last, the laboratory test and acceptance scheme of both mechanical and control systems are listed, and the beam current and turn pattern measurement results at HIMMs are presented in this paper.
The cyclotron is designed as the injector of the Heavy Ion Medical Machines (HIMMs) in Wuwei city and Lanzhou city, China. It provides 10 µA carbon ion beams to fulfill the accumulation requirement in the following synchrotron. Four picoammeters acquire the beam current signals gathered by the radial detectors; meanwhile, the beam time structure is measured with Field Programmable Gate Arrays and a real-time operating system. This paper introduces the mechanical design of the radial detectors and further provides the thermal structure analysis result of probe tips with and without water cooling. Moreover, the hardware and software architecture of the control system for this detector is described, including the motion control and data acquisition system, which can implement beam current data and position simultaneous acquisition at more than 10 kS/s. At last, the laboratory test and acceptance scheme of both mechanical and control systems are listed, and the beam current and turn pattern measurement results at HIMMs are presented in this paper.
, Available online ,
doi: 10.11884/HPLPB202335.230123
Abstract:
Based on the theory of multiple avalanche domains, a two-dimensional numerical model for GaAs PCSS with opposed structure is established. The influence of the width of the trigger region on the output characteristics of GaAs PCSS is investigated. Firstly, the switching transient of PCSS is analyzed. The results show that the rapid increase of the carrier concentration and the drastic evolution of the charge domain make PCSS operate in the ultrafast-switching mode. On this basis, this paper studies the influence of the width on the output characteristics of PCSS. The results show that the increase of the width can accelerate the rapid multiplication of carrier concentration and the rapid evolution of avalanche ionization domain, and thus shorten the delay time and switching time of PCSS. Further, the effects of different trigger positions on the delay time and switching time are analyzed. The results show that the delay time under cathode triggering is significantly lower than that under anode triggering, and the switching time is almost unaffected by the trigger position. The above conclusions can provide significant reference for the study on time jitter and synchronization of GaAs PCSS.
Based on the theory of multiple avalanche domains, a two-dimensional numerical model for GaAs PCSS with opposed structure is established. The influence of the width of the trigger region on the output characteristics of GaAs PCSS is investigated. Firstly, the switching transient of PCSS is analyzed. The results show that the rapid increase of the carrier concentration and the drastic evolution of the charge domain make PCSS operate in the ultrafast-switching mode. On this basis, this paper studies the influence of the width on the output characteristics of PCSS. The results show that the increase of the width can accelerate the rapid multiplication of carrier concentration and the rapid evolution of avalanche ionization domain, and thus shorten the delay time and switching time of PCSS. Further, the effects of different trigger positions on the delay time and switching time are analyzed. The results show that the delay time under cathode triggering is significantly lower than that under anode triggering, and the switching time is almost unaffected by the trigger position. The above conclusions can provide significant reference for the study on time jitter and synchronization of GaAs PCSS.
, Available online ,
doi: 10.11884/HPLPB202335.230148
Abstract:
With the rapid advances in pulsed power technology, high-voltage pulse power supply is gradually developing towards modularization and miniaturization while ensuring high-voltage output. All-solid-state Marx generators generate pulses with flexible parameters adjustment and are increasingly used in a wide range of applications. Synchronous isolated driving is the core technology of solid-state Marx generators. In this paper, a compact solid-state Marx generator based on half-bridge structure was proposed. In each stage, a NPN MOSFET as the charging switch and a PNP MOSFET as the discharging switch forms a half-bridge circuit, and both their gates and sources were short circuited so they can be triggered with the same signal. Using many transformers with their primary windings in series, only one half-bridge circuit on the primary side was used to transfer both the driving power and control signals. Then all the charging switches and discharging switches were driven simultaneously, which greatly simplifies the structure and size of solid-state Marx generators and reduced costs. In this way, a 24-stage solid-state Marx generator prototype was built, and high-voltage square pulses of 10 kV, 1 kHz and 5 μs was obtained on a 10 kΩ resistive load. The feasibility of the scheme is verified, and the length, width and height of the main circuit is only 20 cm×13 cm×5.5 cm.
With the rapid advances in pulsed power technology, high-voltage pulse power supply is gradually developing towards modularization and miniaturization while ensuring high-voltage output. All-solid-state Marx generators generate pulses with flexible parameters adjustment and are increasingly used in a wide range of applications. Synchronous isolated driving is the core technology of solid-state Marx generators. In this paper, a compact solid-state Marx generator based on half-bridge structure was proposed. In each stage, a NPN MOSFET as the charging switch and a PNP MOSFET as the discharging switch forms a half-bridge circuit, and both their gates and sources were short circuited so they can be triggered with the same signal. Using many transformers with their primary windings in series, only one half-bridge circuit on the primary side was used to transfer both the driving power and control signals. Then all the charging switches and discharging switches were driven simultaneously, which greatly simplifies the structure and size of solid-state Marx generators and reduced costs. In this way, a 24-stage solid-state Marx generator prototype was built, and high-voltage square pulses of 10 kV, 1 kHz and 5 μs was obtained on a 10 kΩ resistive load. The feasibility of the scheme is verified, and the length, width and height of the main circuit is only 20 cm×13 cm×5.5 cm.
, Available online ,
doi: 10.11884/HPLPB202335.230186
Abstract:
With the development of networks such as mobile communications, IoT, V2X, and IIoT, the electromagnetic environment is becoming increasingly complex, illegal electronic devices are also increasing day by day, and the phenomenon of coupling and intermodulation of various signals is severe, which brings difficulties to the identification of leaked signal types. Propose a leakage signal classification and recognition method based on fused features, comprehensively utilizing high-dimensional feature extraction methods and graphical dimensionality reduction characterization methods, combined with deep learning models such as residual networks and feature fusion analysis methods, which can more comprehensively distinguish multiple types of electromagnetic leakage signals. The feature has high robustness against noise, good interpretability, and can support the intelligent detection engineering application of radiation sources based on electromagnetic signal type recognition.
With the development of networks such as mobile communications, IoT, V2X, and IIoT, the electromagnetic environment is becoming increasingly complex, illegal electronic devices are also increasing day by day, and the phenomenon of coupling and intermodulation of various signals is severe, which brings difficulties to the identification of leaked signal types. Propose a leakage signal classification and recognition method based on fused features, comprehensively utilizing high-dimensional feature extraction methods and graphical dimensionality reduction characterization methods, combined with deep learning models such as residual networks and feature fusion analysis methods, which can more comprehensively distinguish multiple types of electromagnetic leakage signals. The feature has high robustness against noise, good interpretability, and can support the intelligent detection engineering application of radiation sources based on electromagnetic signal type recognition.
, Available online ,
doi: 10.11884/HPLPB202335.230155
Abstract:
The magnetic components in power supplies are naturally sensitive to external magnetic fields, and their operating characteristics directly affect the output characteristics of the power supply. Modeling the background magnetic field is an important prerequisite for the study of the interference of magnetic components in power supplies by strong stray magnetic fields, but few studies have focused on this application scenario, and the commonly used methods for electromagnetic field analysis are difficult to balance accuracy and efficiency. In this paper, we propose a method to analyze the effects of stray magnetic fields based on the equivalent magnetic circuit network method, which discrete the research object into magnetic circuit units, equivalently form a network model, and obtain the field distribution of the model by solving the equations of the equivalent magnetic circuit system. We take a toroidal ferrite core as an example, and use the equivalent circuit network method to calculate the field distribution of the toroidal core under DC excitation and uniform orthogonal magnetic field, and analyze the effect of the background magnetic field on its equivalent inductance. By comparing the results of the equivalent circuit network method with those of the finite element method, the accuracy and efficiency of the proposed analysis method are demonstrated, and it is shown that the method is applicable to the analysis of power supplies disturbed by the background magnetic field.
The magnetic components in power supplies are naturally sensitive to external magnetic fields, and their operating characteristics directly affect the output characteristics of the power supply. Modeling the background magnetic field is an important prerequisite for the study of the interference of magnetic components in power supplies by strong stray magnetic fields, but few studies have focused on this application scenario, and the commonly used methods for electromagnetic field analysis are difficult to balance accuracy and efficiency. In this paper, we propose a method to analyze the effects of stray magnetic fields based on the equivalent magnetic circuit network method, which discrete the research object into magnetic circuit units, equivalently form a network model, and obtain the field distribution of the model by solving the equations of the equivalent magnetic circuit system. We take a toroidal ferrite core as an example, and use the equivalent circuit network method to calculate the field distribution of the toroidal core under DC excitation and uniform orthogonal magnetic field, and analyze the effect of the background magnetic field on its equivalent inductance. By comparing the results of the equivalent circuit network method with those of the finite element method, the accuracy and efficiency of the proposed analysis method are demonstrated, and it is shown that the method is applicable to the analysis of power supplies disturbed by the background magnetic field.
, Available online ,
doi: 10.11884/HPLPB202335.230166
Abstract:
Driven by the unique polarization distribution characteristics, cylindrical vector beams play an important role in optical tweezers, high resolution imaging, remote sensing, plasma focusing, and other related fields. In order to realize all-fiber high-power cylindrical vector beams MOPA laser, a mode conversion fiber device based on integrated metasurface is independently designed, whose feasibility is analyzed and verified in this demonstration. The self-designed integrated metasurface mode conversion fiber device can be act as a radially polarized vector beam seed with an several watts, and the mode purity is more than 95%. In the experiment, a radially polarized vector beam with an output power of 52.2 W was achieved in the case of a single-stage amplifier by decreasing bending loss and controlling the mode. Moreover, the mode field distribution was maintained well during the amplification. In order to further analyze the obtained mode characteristics, a rotatable polarizer method was used to measure the polarization characteristics and polarization purity, and the mode purity was measured by an incoherent mode superposition method. The results show that the polarization purity of the radially polarized vector beam is approximately 95.2% and the mode purity is about 94% with the maximum output power, which verify the feasibility of the all-fiber scheme.
Driven by the unique polarization distribution characteristics, cylindrical vector beams play an important role in optical tweezers, high resolution imaging, remote sensing, plasma focusing, and other related fields. In order to realize all-fiber high-power cylindrical vector beams MOPA laser, a mode conversion fiber device based on integrated metasurface is independently designed, whose feasibility is analyzed and verified in this demonstration. The self-designed integrated metasurface mode conversion fiber device can be act as a radially polarized vector beam seed with an several watts, and the mode purity is more than 95%. In the experiment, a radially polarized vector beam with an output power of 52.2 W was achieved in the case of a single-stage amplifier by decreasing bending loss and controlling the mode. Moreover, the mode field distribution was maintained well during the amplification. In order to further analyze the obtained mode characteristics, a rotatable polarizer method was used to measure the polarization characteristics and polarization purity, and the mode purity was measured by an incoherent mode superposition method. The results show that the polarization purity of the radially polarized vector beam is approximately 95.2% and the mode purity is about 94% with the maximum output power, which verify the feasibility of the all-fiber scheme.
, Available online ,
doi: 10.11884/HPLPB202335.230111
Abstract:
Compared with other vortex beams, the perfect optical vortex beam has a more stable spatial intensity distribution because the beam radius is independent of the topological charge. In this paper, the transmission characteristics of the perfect optical vortex beam in slant atmospheric turbulence are studied by means of multi-phase screens method and Fourier transform method. The influence of atmospheric turbulence on beam quality is analyzed by using beam drift and aperture evaluation scintillation index. Then the beam quality of the perfect vortex optical beam and Gaussian vortex beam under the same transmission conditions is compared. The results show that POV beam has better beam stability than Gaussian vortex beam. When the topological load increases or the zenith Angle decreases, the ability of POV beam to resist atmospheric turbulence increases. The resistance of POV beam to atmospheric turbulence can be improved by increasing the beam radius without changing the topological charge of POV beam.
Compared with other vortex beams, the perfect optical vortex beam has a more stable spatial intensity distribution because the beam radius is independent of the topological charge. In this paper, the transmission characteristics of the perfect optical vortex beam in slant atmospheric turbulence are studied by means of multi-phase screens method and Fourier transform method. The influence of atmospheric turbulence on beam quality is analyzed by using beam drift and aperture evaluation scintillation index. Then the beam quality of the perfect vortex optical beam and Gaussian vortex beam under the same transmission conditions is compared. The results show that POV beam has better beam stability than Gaussian vortex beam. When the topological load increases or the zenith Angle decreases, the ability of POV beam to resist atmospheric turbulence increases. The resistance of POV beam to atmospheric turbulence can be improved by increasing the beam radius without changing the topological charge of POV beam.
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/HPLPB202335.230146
Abstract:
Rayleigh-Taylor instability (RTI) research in inertial confinement fusion (ICF) is based on modulation targets with multiple structures. In this paper, aiming at the present problems existing in the preparation of modulation targets, three typical modulation targets of planar modulation, planar composite modulation and spherical shell modulation are prepared by two-photon 3D printing process. The target material is photosensitive resin (95%: C23H38N2O8, 5%: C4H6O2). The actual structural parameters of the three modulation targets were analyzed using laser confocal microscopy imaging. The measured morphologies and parameters of the three targets show good matching with the designed structures. To further validate the feasibility of using new two-photon 3D printing process for preparing modulation targets, nanosecond laser targeting experiments were conducted on the “Shenguang II” high-power laser experimental facility. The results show that the modulation of the target surface increased with time due to the action of RTI under direct laser driving. The modulation with an initial peak valley value of 4μm formed a high-density jet with a length of up to 100 μm after 2.5 ns of laser driving, which indicates that the preparation of complex modulation targets based on high-precision 3D printing technology is highly feasible for RTI research.
Rayleigh-Taylor instability (RTI) research in inertial confinement fusion (ICF) is based on modulation targets with multiple structures. In this paper, aiming at the present problems existing in the preparation of modulation targets, three typical modulation targets of planar modulation, planar composite modulation and spherical shell modulation are prepared by two-photon 3D printing process. The target material is photosensitive resin (95%: C23H38N2O8, 5%: C4H6O2). The actual structural parameters of the three modulation targets were analyzed using laser confocal microscopy imaging. The measured morphologies and parameters of the three targets show good matching with the designed structures. To further validate the feasibility of using new two-photon 3D printing process for preparing modulation targets, nanosecond laser targeting experiments were conducted on the “Shenguang II” high-power laser experimental facility. The results show that the modulation of the target surface increased with time due to the action of RTI under direct laser driving. The modulation with an initial peak valley value of 4μm formed a high-density jet with a length of up to 100 μm after 2.5 ns of laser driving, which indicates that the preparation of complex modulation targets based on high-precision 3D printing technology is highly feasible for RTI research.
Precise control of high-energy protons transport in space environment by using bayesian optimization
, Available online ,
doi: 10.11884/HPLPB202335.230231
Abstract:
Considering the geomagnetic field, the relativistic effect and bremsstrahlung radiation of high-energy protons, a single particle motion model of proton transport in the space environment is established. Based on this model, the Bayesian optimization method is proposed to realize the precise control of protons transport from the initial position to the target under a given proton energy. The dependence of the proton launch angle on the launch height is obtained, that is, when the coordinate radial angle is 0° and 180°, the value of the coordinate axial angle will not change the optimal emission direction of the particles. The results should provide theoretical references for the long-distance transport of proton beams in the space environment.
Considering the geomagnetic field, the relativistic effect and bremsstrahlung radiation of high-energy protons, a single particle motion model of proton transport in the space environment is established. Based on this model, the Bayesian optimization method is proposed to realize the precise control of protons transport from the initial position to the target under a given proton energy. The dependence of the proton launch angle on the launch height is obtained, that is, when the coordinate radial angle is 0° and 180°, the value of the coordinate axial angle will not change the optimal emission direction of the particles. The results should provide theoretical references for the long-distance transport of proton beams in the space environment.
, Available online ,
doi: 10.11884/HPLPB202335.230216
Abstract:
A broadband dual-band dual circularly polarized millimeter wave single-fed antenna is designed. The antenna operates in n257(26.5−29.5 GHz) and n260(37.0−40.0 GHz) bands simultaneously. Compared with the traditional circularly polarized antenna, irregular patches stacked up and down are used to realize dual-band dual-circular polarization and improve the isolation of signal reception and transmission. By adding a curved parasitic patch, the antenna extends the axial ratio bandwidth. Rectangular gaps in the metal-frame are used to improve the antenna gain and expand the antenna bandwidth. The measurement results show that the relative impedance (<−10 dB) bandwidth at low frequency and high frequency are 20.4% and 17.0% respectively, and the relative axial ratio (<3 dB) bandwidth of dual-band dual-circular polarization are 14.9% and 11.4% respectively. The antenna bandwidth covers n257 and n260 bands, which can be used for communication between 5G mobile devices and LEO satellites.
A broadband dual-band dual circularly polarized millimeter wave single-fed antenna is designed. The antenna operates in n257(26.5−29.5 GHz) and n260(37.0−40.0 GHz) bands simultaneously. Compared with the traditional circularly polarized antenna, irregular patches stacked up and down are used to realize dual-band dual-circular polarization and improve the isolation of signal reception and transmission. By adding a curved parasitic patch, the antenna extends the axial ratio bandwidth. Rectangular gaps in the metal-frame are used to improve the antenna gain and expand the antenna bandwidth. The measurement results show that the relative impedance (<−10 dB) bandwidth at low frequency and high frequency are 20.4% and 17.0% respectively, and the relative axial ratio (<3 dB) bandwidth of dual-band dual-circular polarization are 14.9% and 11.4% respectively. The antenna bandwidth covers n257 and n260 bands, which can be used for communication between 5G mobile devices and LEO satellites.
, Available online ,
doi: 10.11884/HPLPB202335.230224
Abstract:
A dual band dual circularly polarized shared-aperture microstrip antenna is designed and fabricated, which can operate in the dual circular polarization mode in the C/X band, and the aperture utilization rate of the antenna is effectively improved. The parasitic structure and the L-shaped probe are applied to improve the impedance bandwidth. The shared aperture design is realized by placing the X-band antenna in the gap of the C-band antenna. The good cross-polarization ratio is realized by the symmetrical inversed phase feeding technique. The measurement results show that the impedance bandwidth and 3 dB axial ratio bandwidth of C-band are greater than 23% and 17%, respectively. The impedance bandwidth and 3 dB axial ratio bandwidth of X-band are greater than 28% and 18% respectively. The cross-polarization ratio at the test frequency points is greater than 25 dB.
A dual band dual circularly polarized shared-aperture microstrip antenna is designed and fabricated, which can operate in the dual circular polarization mode in the C/X band, and the aperture utilization rate of the antenna is effectively improved. The parasitic structure and the L-shaped probe are applied to improve the impedance bandwidth. The shared aperture design is realized by placing the X-band antenna in the gap of the C-band antenna. The good cross-polarization ratio is realized by the symmetrical inversed phase feeding technique. The measurement results show that the impedance bandwidth and 3 dB axial ratio bandwidth of C-band are greater than 23% and 17%, respectively. The impedance bandwidth and 3 dB axial ratio bandwidth of X-band are greater than 28% and 18% respectively. The cross-polarization ratio at the test frequency points is greater than 25 dB.
, Available online ,
doi: 10.11884/HPLPB202335.230225
Abstract:
The micro-ejection phenomenon and its internal mechanism analysis of metal materials under intense laser shock are the frontier issues in the field of shock compression science and engineering. Related research is of great significance for understanding the dynamic behavior of materials under extreme loading conditions. With the continuous development of laser technology, scientists at home and abroad have carried out numerous micro-ejection diagnostic experiments based on some large laser devices in various countries in recent years, and made a series of significant progress in the properties of ejection, the growth of instability at the metal interface and the mixing mechanism of ejection. By reviewing the research history of ejecta static and dynamic diagnostic experiments, this paper describes the main mechanism of ejection, influencing factors and ejecta interface mixing mechanism in detail, and then it reviews, classifies and summarizes the important applications of micro-ejection experimental diagnostic methods. Finally, according to the current development trend of ejecta diagnostic experiments at home and abroad, the deficiencies in the current ejection experimental research results are summarized, and the future development direction of ejection experimental research is prospected.
The micro-ejection phenomenon and its internal mechanism analysis of metal materials under intense laser shock are the frontier issues in the field of shock compression science and engineering. Related research is of great significance for understanding the dynamic behavior of materials under extreme loading conditions. With the continuous development of laser technology, scientists at home and abroad have carried out numerous micro-ejection diagnostic experiments based on some large laser devices in various countries in recent years, and made a series of significant progress in the properties of ejection, the growth of instability at the metal interface and the mixing mechanism of ejection. By reviewing the research history of ejecta static and dynamic diagnostic experiments, this paper describes the main mechanism of ejection, influencing factors and ejecta interface mixing mechanism in detail, and then it reviews, classifies and summarizes the important applications of micro-ejection experimental diagnostic methods. Finally, according to the current development trend of ejecta diagnostic experiments at home and abroad, the deficiencies in the current ejection experimental research results are summarized, and the future development direction of ejection experimental research is prospected.
, Available online ,
doi: 10.11884/HPLPB202335.230115
Abstract:
The basic working principle of the vacuum channel stress compensation structure is introduced. The adaptive compensation technology and the optical cabin structure deformation suppression technology subjected to the vacuum negative pressure stress, thermal expansion and cold contraction stresses of the laser beam long-distance vacuum transmission channel in large temperature difference environments are investigated. The installation, debugging and evaluation of the vacuum channel stress compensation structure are carried out with the whole optical system, and the optical transmission stability is verified by some experiments with ambient temperature difference. The experimental results show that the problem of adaptive compensation for vacuum negative pressure stress and thermal expansion and cold contraction stress in the ultra-long laser beam vacuum transmission channel under vacuum negative pressure and large temperature difference environments, and the problem of deformation suppression of the optical cabin structure are solved. The automatic balance of vacuum negative pressure stress in the transmission channel is achieved, and the laser beam drift caused by vacuum negative pressure stress is eliminated. The release of thermal expansion and cold contraction stresses in the vacuum negative pressure channel structure under large temperature difference environments is achieved, the actual effect of maintaining stability of the optical path for a long time is achieved.
The basic working principle of the vacuum channel stress compensation structure is introduced. The adaptive compensation technology and the optical cabin structure deformation suppression technology subjected to the vacuum negative pressure stress, thermal expansion and cold contraction stresses of the laser beam long-distance vacuum transmission channel in large temperature difference environments are investigated. The installation, debugging and evaluation of the vacuum channel stress compensation structure are carried out with the whole optical system, and the optical transmission stability is verified by some experiments with ambient temperature difference. The experimental results show that the problem of adaptive compensation for vacuum negative pressure stress and thermal expansion and cold contraction stress in the ultra-long laser beam vacuum transmission channel under vacuum negative pressure and large temperature difference environments, and the problem of deformation suppression of the optical cabin structure are solved. The automatic balance of vacuum negative pressure stress in the transmission channel is achieved, and the laser beam drift caused by vacuum negative pressure stress is eliminated. The release of thermal expansion and cold contraction stresses in the vacuum negative pressure channel structure under large temperature difference environments is achieved, the actual effect of maintaining stability of the optical path for a long time is achieved.
, Available online ,
doi: 10.11884/HPLPB202335.230153
Abstract:
To evaluate the applicability of lithium-titanate oxide (LTO) battery in pulsed high power laser system (PHPLS), this paper summarizes the requirements of the PHPLS for the primary energy storage device based on the discharge capacity and safety application characteristics of the energy storage medium, analyzes the applicability of the common energy storage medium through analogy and theoretical calculation, and verifies the engineering application feasibility of LTO by discharge performance test and safety test. The results show that the LTO has high discharge capacity and high safety, which can meet the application requirements of the PHPLS, and has the conditions for promotion.
To evaluate the applicability of lithium-titanate oxide (LTO) battery in pulsed high power laser system (PHPLS), this paper summarizes the requirements of the PHPLS for the primary energy storage device based on the discharge capacity and safety application characteristics of the energy storage medium, analyzes the applicability of the common energy storage medium through analogy and theoretical calculation, and verifies the engineering application feasibility of LTO by discharge performance test and safety test. The results show that the LTO has high discharge capacity and high safety, which can meet the application requirements of the PHPLS, and has the conditions for promotion.
, Available online ,
doi: 10.11884/HPLPB202335.220410
Abstract:
This paper introduces the basic principle of spatiotemporal mode-locking (STML) and the theoretical model of STML—attractor dissection. It presents the recent research progress about STML fiber laser from two aspects of spatial optical structures and all-fiber structures, including the improvement of laser cavity type, the enhancement of output performance, and the observation of real-time dynamics, etc. The advantage and insufficiency of the current STML laser are analyzed, and the development direction is forecasted: STML laser possesses great potential in generating high-power and ultrashort pulse, but to some extent, the poor quality of output modes hinders its application; improving the beam quality by self-similar evolution, wavefront shaping, etc. will be the direction to develop STML laser in the future.
This paper introduces the basic principle of spatiotemporal mode-locking (STML) and the theoretical model of STML—attractor dissection. It presents the recent research progress about STML fiber laser from two aspects of spatial optical structures and all-fiber structures, including the improvement of laser cavity type, the enhancement of output performance, and the observation of real-time dynamics, etc. The advantage and insufficiency of the current STML laser are analyzed, and the development direction is forecasted: STML laser possesses great potential in generating high-power and ultrashort pulse, but to some extent, the poor quality of output modes hinders its application; improving the beam quality by self-similar evolution, wavefront shaping, etc. will be the direction to develop STML laser in the future.
, Available online ,
doi: 10.11884/HPLPB202335.230192
Abstract:
This paper presents the problem of the parasitic effect of the transistor for the practical design of high power and high-efficiency power amplifiers (PAs). To solve the prottem, we propose a new method: transferring the impedances at the intrinsic plane into those at the package plane with the help of the package model. In this case, the convenience of the design of the output matching network is improved a lot. Moreover, the design methodology of PAs with compact microstrip resonant cell (CMRC) as well as the topology of the transmission-lines (TLs) are also proposed. The CMRC can provide the required open-circuit for the third harmonic. On this basis, the harmonic impedance conditions can be easily realized by the tuning TLs. The insertion loss of the proposed CMRC at the fundamental is low and the physical dimension is relatively small. To verify the feasibility of the proposed circuit, using a 10W GaN HEMT CGH40010F transistor, a switch-mode class E/F PA operating at 2.2 GHz is designed as a prototype. Simulation results show the power-added efficiency of 78.4%, output power of 40.1 dBm, and power gain of 12.1 dB.
This paper presents the problem of the parasitic effect of the transistor for the practical design of high power and high-efficiency power amplifiers (PAs). To solve the prottem, we propose a new method: transferring the impedances at the intrinsic plane into those at the package plane with the help of the package model. In this case, the convenience of the design of the output matching network is improved a lot. Moreover, the design methodology of PAs with compact microstrip resonant cell (CMRC) as well as the topology of the transmission-lines (TLs) are also proposed. The CMRC can provide the required open-circuit for the third harmonic. On this basis, the harmonic impedance conditions can be easily realized by the tuning TLs. The insertion loss of the proposed CMRC at the fundamental is low and the physical dimension is relatively small. To verify the feasibility of the proposed circuit, using a 10W GaN HEMT CGH40010F transistor, a switch-mode class E/F PA operating at 2.2 GHz is designed as a prototype. Simulation results show the power-added efficiency of 78.4%, output power of 40.1 dBm, and power gain of 12.1 dB.
, Available online ,
doi: 10.11884/HPLPB202335.230139
Abstract:
A novel tightly coupled dipole array antenna with high power and broadband is proposed in this paper. On the basis of conventional tightly coupled dipole array antennas, and by adopting an all-metal structure design, an integrated design of antenna matching layer and sealing layer, and a method of adjusting the antenna structure, a high-power and broadband performance of such an array antenna is obtained. The simulation results show that the standing wave ratio of the array antenna is less than 2 at the broadside in the range of 0.8-4.0 GHz. And the power capacity of an element antenna reaches 0.12 MW within the size of 16 mm × 32 mm in the space full of SF6 at one atmospheric pressure. Moreover, the power capacity of the 10×10 array antenna composed of 100 elements can reach 12 MW within the size of 320 mm × 640 mm in the space full of SF6 at one atmospheric pressure. In addition, the array antenna can achieve a wide-angle scan of 45°. The proposed array antenna provides a solution for high-power microwave broadband antennas to achieve a broadband, large-angle scanning, compact, miniaturized, and low-profile performance.
A novel tightly coupled dipole array antenna with high power and broadband is proposed in this paper. On the basis of conventional tightly coupled dipole array antennas, and by adopting an all-metal structure design, an integrated design of antenna matching layer and sealing layer, and a method of adjusting the antenna structure, a high-power and broadband performance of such an array antenna is obtained. The simulation results show that the standing wave ratio of the array antenna is less than 2 at the broadside in the range of 0.8-4.0 GHz. And the power capacity of an element antenna reaches 0.12 MW within the size of 16 mm × 32 mm in the space full of SF6 at one atmospheric pressure. Moreover, the power capacity of the 10×10 array antenna composed of 100 elements can reach 12 MW within the size of 320 mm × 640 mm in the space full of SF6 at one atmospheric pressure. In addition, the array antenna can achieve a wide-angle scan of 45°. The proposed array antenna provides a solution for high-power microwave broadband antennas to achieve a broadband, large-angle scanning, compact, miniaturized, and low-profile performance.
, Available online ,
doi: 10.11884/HPLPB202335.230132
Abstract:
Using dual energy CT method to detect multilayer spherical shell components with great density difference, it is necessary to study the image reconstruction method based on two sets of projection data. The Method of Reconstructed at First and then Fused Based on Images cannot make full use of dual energy X-ray projection information, by which simulation research shows it is difficult to get good reconstructed image. On this basis, the paper focuses on the Method of Fused Based on Projection Data at First and then Reconstructed. Firstly, considering the structure characteristics of the multilayer spherical shell components with great density difference, the X-ray projection sinogram with clear regional distribution can be obtained through a specially designed scanning mode. Then extract effective projection data respectively from the high and low energy X-ray projection sinogram, do the consistency processing, and integrate them to become one sinogram. Finally use the FBP algorithm to complete the image reconstruction process. The concrete realization of the algorithm based on projection data fuse for dual energy CT of multilayer spherical shell is summarized, and computer simulation shows that better reconstructed images can be obtained.
Using dual energy CT method to detect multilayer spherical shell components with great density difference, it is necessary to study the image reconstruction method based on two sets of projection data. The Method of Reconstructed at First and then Fused Based on Images cannot make full use of dual energy X-ray projection information, by which simulation research shows it is difficult to get good reconstructed image. On this basis, the paper focuses on the Method of Fused Based on Projection Data at First and then Reconstructed. Firstly, considering the structure characteristics of the multilayer spherical shell components with great density difference, the X-ray projection sinogram with clear regional distribution can be obtained through a specially designed scanning mode. Then extract effective projection data respectively from the high and low energy X-ray projection sinogram, do the consistency processing, and integrate them to become one sinogram. Finally use the FBP algorithm to complete the image reconstruction process. The concrete realization of the algorithm based on projection data fuse for dual energy CT of multilayer spherical shell is summarized, and computer simulation shows that better reconstructed images can be obtained.
, Available online ,
doi: 10.11884/HPLPB202335.230063
Abstract:
Target detection by lidar is challenging due to the difficulty in obtaining the complex attitude of targets and capturing the real coincidence between target and facula. To address this problem, in this paper, a real-time mapping method of laser beam to complex targets based on GPU programming is proposed. By taking advantages of modern graphics hardware with respect to GPU programming technology and frame buffer object merit, the proposed approach takes each plane light source matrix as the observer, renders the current scene in the light source spatial coordinate system, and records the rendering results into the memory texture. To realize real-time mapping and rendering, the results observed by the light source in the world coordinates are restored and mapped to the model. Based on deep cache principle of Zbuffer and texture mapping principle, the model information (e.g., light source irradiance, vertex position and patch normal on the vertex of each triangular patch) can be correctly obtained with virtue OSG file reading-writing plug-in. Extensive experiments demonstrate the strong universality of the proposed algorithm. It is powerful in reading three-dimensional files of various formats and is suitable for uniform or non-uniform area light sources. It meets the quasi real-time computational requirements of two area light sources with low requirements on system graphics hardware. Various model information could be acquired in quasi real-time, e.g., the components of the illuminated surface piece, the vertices of the illuminated triangular surface, the normal information and the irradiation intensity received by the vertex of the triangular patch. The algorithm is novel in providing reference and basis for laser illumination, recognition and detection.
Target detection by lidar is challenging due to the difficulty in obtaining the complex attitude of targets and capturing the real coincidence between target and facula. To address this problem, in this paper, a real-time mapping method of laser beam to complex targets based on GPU programming is proposed. By taking advantages of modern graphics hardware with respect to GPU programming technology and frame buffer object merit, the proposed approach takes each plane light source matrix as the observer, renders the current scene in the light source spatial coordinate system, and records the rendering results into the memory texture. To realize real-time mapping and rendering, the results observed by the light source in the world coordinates are restored and mapped to the model. Based on deep cache principle of Zbuffer and texture mapping principle, the model information (e.g., light source irradiance, vertex position and patch normal on the vertex of each triangular patch) can be correctly obtained with virtue OSG file reading-writing plug-in. Extensive experiments demonstrate the strong universality of the proposed algorithm. It is powerful in reading three-dimensional files of various formats and is suitable for uniform or non-uniform area light sources. It meets the quasi real-time computational requirements of two area light sources with low requirements on system graphics hardware. Various model information could be acquired in quasi real-time, e.g., the components of the illuminated surface piece, the vertices of the illuminated triangular surface, the normal information and the irradiation intensity received by the vertex of the triangular patch. The algorithm is novel in providing reference and basis for laser illumination, recognition and detection.
, Available online ,
doi: 10.11884/HPLPB202335.230068
Abstract:
There is an increasingly higher requirement on the pulse source of kicker in the injection and extraction system with the development of accelerators. As a special nanosecond switch, Drift Step Recovery Diode (DSRD) has a great application prospect in pulse power technology for its notably short switching-off time and large working current. However, there are some factors such as pre-pulse that make the pulse waveform deviate from the ideal shape. A prototype of pulse generator was designed and tested. It is based on a basic DSRD circuit, at the same time, the Non-Linear Transmission Line (NTL) is used to shape the pulse, compress the edge and reduce the residual voltage. Its circuit experiment shows that the pulse amplitude on resistor load of 50 Ω is about 10 kV, the rise time and fall time are about 2 ns (10%−90%) and the bottom width (3%−3%) is less than 8 ns.
There is an increasingly higher requirement on the pulse source of kicker in the injection and extraction system with the development of accelerators. As a special nanosecond switch, Drift Step Recovery Diode (DSRD) has a great application prospect in pulse power technology for its notably short switching-off time and large working current. However, there are some factors such as pre-pulse that make the pulse waveform deviate from the ideal shape. A prototype of pulse generator was designed and tested. It is based on a basic DSRD circuit, at the same time, the Non-Linear Transmission Line (NTL) is used to shape the pulse, compress the edge and reduce the residual voltage. Its circuit experiment shows that the pulse amplitude on resistor load of 50 Ω is about 10 kV, the rise time and fall time are about 2 ns (10%−90%) and the bottom width (3%−3%) is less than 8 ns.
, Available online ,
doi: 10.11884/HPLPB202335.220356
Abstract:
The control system for the ion source of the JUNA（Jinping Underground laboratory for Nuclear Astro-physics) was designed and implemented. It is built by using a distributed system model. The hardware adopts PLC, serial device server, servo motor, industrial computer, and other components to realize the remote monitoring and controlling of ion source devices. The software integrates all controlled devices by establishing the EPICS IOC run-time databases. The user interface layer is developed by using Control System Studio to achieve transparent access to all controlled devices by operators. The machine protection system is designed based on safety rules to realize protection in the case of abnormal operations. It is used in the first underground ECR ion source in China and is stable and reliable, which fully meets the needs of the JUNA tuning and physical experiments.
The control system for the ion source of the JUNA（Jinping Underground laboratory for Nuclear Astro-physics) was designed and implemented. It is built by using a distributed system model. The hardware adopts PLC, serial device server, servo motor, industrial computer, and other components to realize the remote monitoring and controlling of ion source devices. The software integrates all controlled devices by establishing the EPICS IOC run-time databases. The user interface layer is developed by using Control System Studio to achieve transparent access to all controlled devices by operators. The machine protection system is designed based on safety rules to realize protection in the case of abnormal operations. It is used in the first underground ECR ion source in China and is stable and reliable, which fully meets the needs of the JUNA tuning and physical experiments.
, Available online ,
doi: 10.11884/HPLPB202335.230088
Abstract:
An improved spiral generator is studied to solve the problem that the second peak value of output voltage waveform is larger than the first peak value and the peak current of input switch and its current rise rate are larger when the number of turns of the traditional spiral generator is large. Numerical simulation and experimental verification are carried out, and the simulation results are basically consistent with the experimental results. Through electromagnetic field analysis of the wave transmission process, it is shown that the additional winding of the improved structure will cause extra reflection, which changes the time when the voltage between the layers is superimposed in the same direction, thus reducing the subsequent oscillations of higher peaks. Finally, an improved spiral generator is tested and it can generate a high voltage pulse with the first peak voltage of 51 kV and the leading edge of 50 ns on a high voltage capacitor load of 15 pF. The volume of the whole generator is less than 0.5 L. The improved spiral generator will then be combined with the semiconductor switch to achieve an all-solid-state design of a high-voltage nanosecond pulse trigger generator in the future.
An improved spiral generator is studied to solve the problem that the second peak value of output voltage waveform is larger than the first peak value and the peak current of input switch and its current rise rate are larger when the number of turns of the traditional spiral generator is large. Numerical simulation and experimental verification are carried out, and the simulation results are basically consistent with the experimental results. Through electromagnetic field analysis of the wave transmission process, it is shown that the additional winding of the improved structure will cause extra reflection, which changes the time when the voltage between the layers is superimposed in the same direction, thus reducing the subsequent oscillations of higher peaks. Finally, an improved spiral generator is tested and it can generate a high voltage pulse with the first peak voltage of 51 kV and the leading edge of 50 ns on a high voltage capacitor load of 15 pF. The volume of the whole generator is less than 0.5 L. The improved spiral generator will then be combined with the semiconductor switch to achieve an all-solid-state design of a high-voltage nanosecond pulse trigger generator in the future.
, Available online ,
doi: 10.11884/HPLPB202335.230099
Abstract:
Piezoelectric ceramic is the main actuator of deformable mirror, which is the core device of adaptive optics system. Its performance directly affects the correction ability of deformable mirror and even adaptive optics system. Performance parameters of the tensile/compressible piezoelectric ceramics (5 mm×5 mm×38 mm) with loading voltage of ±350 V were tested, including displacement, hysteresis, capacitance, impedance and coefficient of thermal expansion, etc. The test results show the tensile capacity of three samples was more than 250 N, and 10 million fatigue tests (±150 N@5 Hz sinusoidal load) were carried out on 5# sample. The experimental results show that the displacement and capacitance of the sample reduced than 5%. Through the tensile/pressure and fatigue test, the properties and service life of the piezoelectric ceramic were examined, which provides some supporting data for the development of deformable mirrors.
Piezoelectric ceramic is the main actuator of deformable mirror, which is the core device of adaptive optics system. Its performance directly affects the correction ability of deformable mirror and even adaptive optics system. Performance parameters of the tensile/compressible piezoelectric ceramics (5 mm×5 mm×38 mm) with loading voltage of ±350 V were tested, including displacement, hysteresis, capacitance, impedance and coefficient of thermal expansion, etc. The test results show the tensile capacity of three samples was more than 250 N, and 10 million fatigue tests (±150 N@5 Hz sinusoidal load) were carried out on 5# sample. The experimental results show that the displacement and capacitance of the sample reduced than 5%. Through the tensile/pressure and fatigue test, the properties and service life of the piezoelectric ceramic were examined, which provides some supporting data for the development of deformable mirrors.
Column
- Cover and Contents
- Laser Damage of Optical Elements
- High Power Laser Physics and Technology
- Operation and Maintenance of Large Scale Scientific Facility
- 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
Display Method:
2023, 35: 091001.
doi: 10.11884/HPLPB202335.230007
Abstract:
The key materials near the target chamber suffer from radiation damage in the laser-driven inertial confinement fusion (ICF) facility, which limits the lifetime of materials and stable operation of ICF facility. This review summarizes the progress of research on irradiation effects of three major types of key materials in or nearest to the target chamber: stainless steel, aluminum alloy, and final optics assembly. The ablation and neutron activation of first-wall materials in the target chamber caused by neutron beam, γ-ray, X-ray and other high-energy particles are introduced and the impact of the target chamber environment on the materials and corresponding protective strategy are analyzed in detail. In addition, various radiation damage phenomena and related damage mechanisms of the final optics assembly near the target chamber under 1ω laser, 3ω laser, and the complex high-energy radiation environment are also elaborated. Hopefully, this review can provide a reference for the construction and development of laser-driven ICF in China.
2023, 35: 091002.
doi: 10.11884/HPLPB202335.220405
Abstract:
Based on optical element’s high precision in-situ measurement requirements, this paper carries out the sensitive factor simulation analysis, studies the influence of systematic structural errors and temperature errors on the measurement results, and designs and builds an in-situ measurement device to carry out measurement experiments of system temperature change, system repeatability and system stability. The results show that the simulation detection model can be used for plane/spherical/aspherical/free surface, the influence on the measurement results is mainly reflected in the low frequency error, the high frequency error is relatively small, the maximum PV value of the measurement surface shape error does not exceed 68nm (about λ/10), and the maximum RMS value does not exceed 15 nm (about λ/40).
Based on optical element’s high precision in-situ measurement requirements, this paper carries out the sensitive factor simulation analysis, studies the influence of systematic structural errors and temperature errors on the measurement results, and designs and builds an in-situ measurement device to carry out measurement experiments of system temperature change, system repeatability and system stability. The results show that the simulation detection model can be used for plane/spherical/aspherical/free surface, the influence on the measurement results is mainly reflected in the low frequency error, the high frequency error is relatively small, the maximum PV value of the measurement surface shape error does not exceed 68nm (about λ/10), and the maximum RMS value does not exceed 15 nm (about λ/40).
2023, 35: 091013.
doi: 10.11884/HPLPB202335.230220
Abstract:
At present, the operating temperature range of fiber lasers is generally narrow, and if the operating temperature range of lasers can be extended, they are expected to be applied in more environments and fields. Recently, the all-fiber oscillator scheme pumped by an air-cooled fiber coupled semiconductor laser (LD) at the National University of Defense Technology has achieved a laser output of 1 kW in the ultra-wide temperature range of −50～50 ℃. By optimizing the system design, the output power of the laser with wide temperature operation is expected to be further improved.
2023, 35: 091004.
doi: 10.11884/HPLPB202335.230258
Abstract:
High-power narrow linewidth fiber lasers have played an important role in the fields of coherent synthesis, spectral synthesis, and nonlinear frequency conversion, attracting extensive attention from domestic and foreign researchers. In recent years, the fiber laser technology group (FLTG) of Wuhan National Laboratory for Optoelectronics (WNLO) at Huazhong University of Science and Technology has been conducting excellent research on domestically manufactured high-power narrow-linewidth linearly polarized fiber laser technology. In 2022, the research team achieved a 1.2 kW narrow linewidth linearly polarized fiber laser output based on a forward-pumping structure and a 3.2 kW narrow linewidth linearly polarized fiber laser output based on a counter-pumping structure, respectively, adopting a fiber oscillator laser (FOL) seed and the homemade polarization-maintaining Yb-doped fibers (PMYDF). Recently, the research team achieved a 4.1 kW narrow linewidth linearly polarized fiber laser output by applying the combination of an optimizing doped component PMYDF and an improved FOL seed for suppressing the TMI and stimulated Brillouin scattering (SBS) effects during the power scaling.
2023, 35: 091005.
doi: 10.11884/HPLPB202335.230069
Abstract:
This paper demonstrates that the single crystal optical parametric amplification process (OPA) satisfies spectral parity-time (PT) anti-symmetry under specific boundary conditions, and the PT symmetry threshold point exhibits a gain jump property. For an OPA with phase mismatch, the PT symmetry of the system can be controlled by instantaneous adjustment of the pump intensity. Based on this property, this paper constructs an ultrafast optical switch, which can combine with amplitude modulated pump to directly convert continuous laser into an ultrashort output pulse sequence. On the other hand, the optical switch can be used for further pulse compression and is promising to be used as an ultrashort mid-infrared seed source. The proposed scheme is easy to directly generate ultrashort pulse sequence with repetition rate higher than 10 GHz because the optical resonant cavity is not required.
This paper demonstrates that the single crystal optical parametric amplification process (OPA) satisfies spectral parity-time (PT) anti-symmetry under specific boundary conditions, and the PT symmetry threshold point exhibits a gain jump property. For an OPA with phase mismatch, the PT symmetry of the system can be controlled by instantaneous adjustment of the pump intensity. Based on this property, this paper constructs an ultrafast optical switch, which can combine with amplitude modulated pump to directly convert continuous laser into an ultrashort output pulse sequence. On the other hand, the optical switch can be used for further pulse compression and is promising to be used as an ultrashort mid-infrared seed source. The proposed scheme is easy to directly generate ultrashort pulse sequence with repetition rate higher than 10 GHz because the optical resonant cavity is not required.
2023, 35: 091006.
doi: 10.11884/HPLPB202335.230079
Abstract:
Photo-transmutation is an important path to handle long-lived fission products. In this research work, an optimization scheme of photo-transmutation induced by Laser WakeField Acceleration (LWFA) driven electrons is proposed. Numerical simulations of photo-transmutation of 135Cs by this scheme are performed. Monte Carlo simulations show that with increasing electron energy, transmutation yield gradually saturates. The transmutation efficiency per unit electron energy has a peak near 40 MeV, with half-maximum energy of 20−120 MeV. To enhance electron charge within the half-maximum energy range and optimize transmutation yield, PIC simulation was used to study the transmission process of ultrashort and ultra-intense lasers in gas plasma. The results show that as plasma density decrease, the energy of electrons gradually increase while their charge are gradually reduced. Moreover, circularly polarized lasers exhibit higher electron energy and charge than linearly polarized ones. Through adjusting the plasma density and laser polarization, it is found that there is an optimal value for transmutation yield under the conditions of circular polarization and specific density. The scheme is expected to promote the studies of nuclide transmutation in a tabletop ultra-intense and ultra-short laser device with high repetition rate, as well as the potential applications in medicine and nuclear-waste management.
Photo-transmutation is an important path to handle long-lived fission products. In this research work, an optimization scheme of photo-transmutation induced by Laser WakeField Acceleration (LWFA) driven electrons is proposed. Numerical simulations of photo-transmutation of 135Cs by this scheme are performed. Monte Carlo simulations show that with increasing electron energy, transmutation yield gradually saturates. The transmutation efficiency per unit electron energy has a peak near 40 MeV, with half-maximum energy of 20−120 MeV. To enhance electron charge within the half-maximum energy range and optimize transmutation yield, PIC simulation was used to study the transmission process of ultrashort and ultra-intense lasers in gas plasma. The results show that as plasma density decrease, the energy of electrons gradually increase while their charge are gradually reduced. Moreover, circularly polarized lasers exhibit higher electron energy and charge than linearly polarized ones. Through adjusting the plasma density and laser polarization, it is found that there is an optimal value for transmutation yield under the conditions of circular polarization and specific density. The scheme is expected to promote the studies of nuclide transmutation in a tabletop ultra-intense and ultra-short laser device with high repetition rate, as well as the potential applications in medicine and nuclear-waste management.
2023, 35: 091007.
doi: 10.11884/HPLPB202335.220422
Abstract:
To improve the calibration accuracy of X-ray detectors, this paper presents a method of placing filters in fluorescent X-ray emission channels to improve the purity of X-rays. Monte Carlo simulation model was established to analyze the relationship between the probability of photoelectric effect in K layer and the atomic number, and the curve of fluorescence intensity and purity with filter thickness was obtained. In atmospheric environment, the energy spectrum distribution and photon flux of fluorescent X-ray source were measured by silicon drift semiconductor detector, and the effect of X-ray tube voltage on photon flux and fluorescence purity was analyzed. When the radiator material is copper and the thickness of the filter (nickel) is 0 μm, 10 μm and 30 μm, the purity of fluorescence X-ray measured is 75.61%, 85.38% and 84.25%, and the photon flux is 3425 phs/s, 2023 phs/s and 1192 phs/s, respectively. The influence of filter thickness on the purity and intensity of fluorescent X-ray is confirmed, which provides a direction for solving the problem that it is difficult to calibrate X-ray detectors with high accuracy due to the lack of monochromatism of fluorescent X-ray light source.
To improve the calibration accuracy of X-ray detectors, this paper presents a method of placing filters in fluorescent X-ray emission channels to improve the purity of X-rays. Monte Carlo simulation model was established to analyze the relationship between the probability of photoelectric effect in K layer and the atomic number, and the curve of fluorescence intensity and purity with filter thickness was obtained. In atmospheric environment, the energy spectrum distribution and photon flux of fluorescent X-ray source were measured by silicon drift semiconductor detector, and the effect of X-ray tube voltage on photon flux and fluorescence purity was analyzed. When the radiator material is copper and the thickness of the filter (nickel) is 0 μm, 10 μm and 30 μm, the purity of fluorescence X-ray measured is 75.61%, 85.38% and 84.25%, and the photon flux is 3425 phs/s, 2023 phs/s and 1192 phs/s, respectively. The influence of filter thickness on the purity and intensity of fluorescent X-ray is confirmed, which provides a direction for solving the problem that it is difficult to calibrate X-ray detectors with high accuracy due to the lack of monochromatism of fluorescent X-ray light source.
2023, 35: 091008.
doi: 10.11884/HPLPB202335.230127
Abstract:
Two 808 nm semiconductor lasers were combined by V-shaped spectral beam combining and locked at 795.8 nm and 800.5 nm respectively. The output power and beam quality in the slow axis were improved significantly. The sum frequency of semiconductor lasers was realized based on the laser source. A laser with an output power of 6.5 W and beam quality of M2=2.2×18.5 was obtained by the spectral beam combining. The M2 in slow axis was improved by 30% and the combining efficiency was 83%. The sum frequency laser with 401.0 nm at a power of 18.3 mW was obtained and the efficiency of sum frequency generation was 0.28%.
Two 808 nm semiconductor lasers were combined by V-shaped spectral beam combining and locked at 795.8 nm and 800.5 nm respectively. The output power and beam quality in the slow axis were improved significantly. The sum frequency of semiconductor lasers was realized based on the laser source. A laser with an output power of 6.5 W and beam quality of M2=2.2×18.5 was obtained by the spectral beam combining. The M2 in slow axis was improved by 30% and the combining efficiency was 83%. The sum frequency laser with 401.0 nm at a power of 18.3 mW was obtained and the efficiency of sum frequency generation was 0.28%.
2023, 35: 092001.
doi: 10.11884/HPLPB202335.220363
Abstract:
One of the main problems occur during inertial confinement fusion (ICF) laser facility’s long-term operation is the gain degeneration of the 400 mm aperture slab amplifier,which will affect the output of the facility and the laser beam quality. A study on gain degeneration causing by several factors was carried out and a normalization theory model from all the factors has been built. The test was accomplished on two groups of 400 mm aperture, 4×2 composition multi-segment slab amplifier with each group includes 9 slabs. The gain degenerating rate was about 10.2% after 10 years, 3 000 shots of work which is in accordance with the theoretical predication. A maintance project for the large aperture slab amplifier has been drawn up to keep the gain degeneration less than 1.5% during long-term operation of the ICF facility.
One of the main problems occur during inertial confinement fusion (ICF) laser facility’s long-term operation is the gain degeneration of the 400 mm aperture slab amplifier,which will affect the output of the facility and the laser beam quality. A study on gain degeneration causing by several factors was carried out and a normalization theory model from all the factors has been built. The test was accomplished on two groups of 400 mm aperture, 4×2 composition multi-segment slab amplifier with each group includes 9 slabs. The gain degenerating rate was about 10.2% after 10 years, 3 000 shots of work which is in accordance with the theoretical predication. A maintance project for the large aperture slab amplifier has been drawn up to keep the gain degeneration less than 1.5% during long-term operation of the ICF facility.
2023, 35: 092002.
doi: 10.11884/HPLPB202335.230170
Abstract:
Aiming at the assembly scheduling problem of optical and mechanical modules for large laser devices, a scheduling priority rule acquisition method based on artificial neural networks (ANNs) is proposed. In the offline phase, this method optimizes the scheduling data through genetic algorithms, extracts task comparison trajectories and feature data from the optimization solution, and uses ANNs to learn the task priority comparison model. In the online phase, a closed-loop decision scheduling mode is constructed based on this model to achieve rapid response and accurate decision-making in dynamic uncertain production environments. Data experiments and practical application cases verify the effectiveness of this method. With the increase of the number of optical-mechanical modules, the advantages of ANN scheduling algorithm become more obvious. When the optimization results of ANN scheduling algorithm and GA algorithm are less than 6%, the computational efficiency of the former is more than 400 times that of the latter.
Aiming at the assembly scheduling problem of optical and mechanical modules for large laser devices, a scheduling priority rule acquisition method based on artificial neural networks (ANNs) is proposed. In the offline phase, this method optimizes the scheduling data through genetic algorithms, extracts task comparison trajectories and feature data from the optimization solution, and uses ANNs to learn the task priority comparison model. In the online phase, a closed-loop decision scheduling mode is constructed based on this model to achieve rapid response and accurate decision-making in dynamic uncertain production environments. Data experiments and practical application cases verify the effectiveness of this method. With the increase of the number of optical-mechanical modules, the advantages of ANN scheduling algorithm become more obvious. When the optimization results of ANN scheduling algorithm and GA algorithm are less than 6%, the computational efficiency of the former is more than 400 times that of the latter.
2023, 35: 092003.
doi: 10.11884/HPLPB202335.220406
Abstract:
In the study of indirectly driven laser fusion, the flat response X-ray diode is the main detector for the measurement of X-ray radiation energy flux. To obtain ideal flat response effect, it usually costs a lot of time to optimize the composite filter parameters of the detector. In this paper, the particle swarm optimization algorithm is developed and applied to optimize the parameters of compound filter of flat response X-ray diode. Compared with the previous work, the method developed in this paper can get the optimized parameters of composite filter more quickly and accurately. On this basis, this paper proposes a new filter combination mode, optimizes its flat response characteristics, and obtains a better parameter ratio than the traditional filter combination. The work in this paper provides a more efficient method for searching the parameters of the composite filter of the response X-ray diode
In the study of indirectly driven laser fusion, the flat response X-ray diode is the main detector for the measurement of X-ray radiation energy flux. To obtain ideal flat response effect, it usually costs a lot of time to optimize the composite filter parameters of the detector. In this paper, the particle swarm optimization algorithm is developed and applied to optimize the parameters of compound filter of flat response X-ray diode. Compared with the previous work, the method developed in this paper can get the optimized parameters of composite filter more quickly and accurately. On this basis, this paper proposes a new filter combination mode, optimizes its flat response characteristics, and obtains a better parameter ratio than the traditional filter combination. The work in this paper provides a more efficient method for searching the parameters of the composite filter of the response X-ray diode
2023, 35: 093001.
doi: 10.11884/HPLPB202335.230058
Abstract:
For compact high-power microwave devices operating at low magnetic field, a compact S-band relativistic magnetron operating at low magnetic field was designed and simulated with three-dimensional particle-in-cell codes. This tube radiates TE11 mode in circular waveguide with diffraction output structure. As the cutoff radius of TE11 mode is the smallest in circular waveguide, compared with higher modes, the radius of the output waveguide could be reduced obviously. The output performance as a function of magnetic field, radius of waveguide and angle was studied. Typical simulation results show that microwave power of 567 MW was generated at 2.37 GHz when the voltage and magnetic field were 352 kV and 0.34 T, the power conversion efficiency was 62.5%, and the radius of waveguide was only 77.5 mm.
For compact high-power microwave devices operating at low magnetic field, a compact S-band relativistic magnetron operating at low magnetic field was designed and simulated with three-dimensional particle-in-cell codes. This tube radiates TE11 mode in circular waveguide with diffraction output structure. As the cutoff radius of TE11 mode is the smallest in circular waveguide, compared with higher modes, the radius of the output waveguide could be reduced obviously. The output performance as a function of magnetic field, radius of waveguide and angle was studied. Typical simulation results show that microwave power of 567 MW was generated at 2.37 GHz when the voltage and magnetic field were 352 kV and 0.34 T, the power conversion efficiency was 62.5%, and the radius of waveguide was only 77.5 mm.
2023, 35: 094001.
doi: 10.11884/HPLPB202335.230090
Abstract:
The theory, method, and experimental studies on mode-locked free-electron laser (FEL) have been of great interests in the world. In this paper, we propose a method to generate mode-locked multi-color free-electron laser radiation pulses based on the electron beam phase space beating. Utilizing an electron beam with head-tail energy chirp and the two modulator-chicane setups in the Shanghai Soft X-ray free-electron laser facility (SXFEL), multiple current pulse trains can be formed and mode-locked multi-color free electron laser pulses can be generated. The simulation results indicate that, with the help the 264 nm seed laser, bunching factor at the 18th harmonic of the seed laser can be formed and ultimately mode-locked multi-color FEL radiation pulse with a central wavelength of approximately 14.58 nm can be generated. This study is of great significance for the development of the mode-locked FEL in China and the performance improvement of the SXFEL facility.
The theory, method, and experimental studies on mode-locked free-electron laser (FEL) have been of great interests in the world. In this paper, we propose a method to generate mode-locked multi-color free-electron laser radiation pulses based on the electron beam phase space beating. Utilizing an electron beam with head-tail energy chirp and the two modulator-chicane setups in the Shanghai Soft X-ray free-electron laser facility (SXFEL), multiple current pulse trains can be formed and mode-locked multi-color free electron laser pulses can be generated. The simulation results indicate that, with the help the 264 nm seed laser, bunching factor at the 18th harmonic of the seed laser can be formed and ultimately mode-locked multi-color FEL radiation pulse with a central wavelength of approximately 14.58 nm can be generated. This study is of great significance for the development of the mode-locked FEL in China and the performance improvement of the SXFEL facility.
2023, 35: 094002.
doi: 10.11884/HPLPB202335.230144
Abstract:
To efficiently adjust the output beam energy of the Hefei Light Source II (HLS-II) linac, this study presents a beam energy adjustment scheme. During the debugging stage, the beam bunch state is observed, and the beam energy is measured using an energy spectrum analysis system. In the storage ring injection stage, three Beam Position Monitors (BPMs) are employed for online beam energy measurement. An automatic phase scanning program is utilized to scan the output phase of the klystrons, deriving the energy gain formula for each acceleration section. By quantitatively adjusting the output phase and high voltage of the klystrons, rapid adjustment of the output beam energy of the linac is achieved. The online application results demonstrate that the proposed scheme can swiftly adjust the beam energy, with the adjusted beam exhibiting excellent quality and a transverse energy spread of less than 0.22%. Furthermore, the implementation of this scheme significantly improves the injection rate.
To efficiently adjust the output beam energy of the Hefei Light Source II (HLS-II) linac, this study presents a beam energy adjustment scheme. During the debugging stage, the beam bunch state is observed, and the beam energy is measured using an energy spectrum analysis system. In the storage ring injection stage, three Beam Position Monitors (BPMs) are employed for online beam energy measurement. An automatic phase scanning program is utilized to scan the output phase of the klystrons, deriving the energy gain formula for each acceleration section. By quantitatively adjusting the output phase and high voltage of the klystrons, rapid adjustment of the output beam energy of the linac is achieved. The online application results demonstrate that the proposed scheme can swiftly adjust the beam energy, with the adjusted beam exhibiting excellent quality and a transverse energy spread of less than 0.22%. Furthermore, the implementation of this scheme significantly improves the injection rate.
2023, 35: 095001.
doi: 10.11884/HPLPB202335.230075
Abstract:
To realize the miniaturization and lightweight design of Tesla transformer with high output voltage, the relationship between the surface flashover characteristics of support insulators and the surface electric field in a 0.5 MPa SF6 gas environment is studied. The electric field simulation model of Tesla transformer is established using the finite element method. Combined with experimental research, the surface flashover process of support insulators is analyzed, and the field equivalent experimental methods and conclusions of key insulation components of Tesla transformer are clarified. Based on the above analysis, the structure of support insulators is optimized. After optimization, the maximum electric field along the concave side of the support insulator decreases by about 81.5%, the average value of tangential electric field intensity decreases by about 10.3%, while the average value of normal electric field intensity decreases by about 30%, the distance along the surface increases by 11.8%, and the electric field unevenness coefficient decreases from 5.03 to 1.2. The electric field distribution is significantly improved, and the optimized insulator can withstand 1 MV negative polarity microsecond pulse voltage.
To realize the miniaturization and lightweight design of Tesla transformer with high output voltage, the relationship between the surface flashover characteristics of support insulators and the surface electric field in a 0.5 MPa SF6 gas environment is studied. The electric field simulation model of Tesla transformer is established using the finite element method. Combined with experimental research, the surface flashover process of support insulators is analyzed, and the field equivalent experimental methods and conclusions of key insulation components of Tesla transformer are clarified. Based on the above analysis, the structure of support insulators is optimized. After optimization, the maximum electric field along the concave side of the support insulator decreases by about 81.5%, the average value of tangential electric field intensity decreases by about 10.3%, while the average value of normal electric field intensity decreases by about 30%, the distance along the surface increases by 11.8%, and the electric field unevenness coefficient decreases from 5.03 to 1.2. The electric field distribution is significantly improved, and the optimized insulator can withstand 1 MV negative polarity microsecond pulse voltage.
2023, 35: 095002.
doi: 10.11884/HPLPB202335.230168
Abstract:
Multiple D-dot voltage probes were designed and calibrated to measure the voltage of a 4 MV induction voltage adder. The frequency response test results indicate that the upper limit of the probe frequency is greater than 270 MHz, which meets the frequency response requirements of the voltage signal to be tested. In calibration, due to the different installation positions of the voltage divider and probe, in order to avoid the mismatch of transmission line impedance causing voltage waveform differences in the fast rising voltage signal at different measurement points, a pulse signal with a front edge of about hundreds of nanoseconds is used for calibration. Due to the low-frequency characteristics of the probe meeting both calibration and actual measurement requirements, the accuracy of calibration can be guaranteed. Considering the direct impact of assembly structure and accuracy on the sensitivity of the probe, the output transmission line probe adopts an online calibration method during the step-by-step installation process of the induction cavity. Due to the influence of electrons and other factors on the voltage probe near the diode, waveform distortion occurs, making it difficult to directly measure the load voltage. The results of multiple experiments on a 4 MV device indicate that the difference between the voltage waveform on the output transmission line and its downstream position is consistent with the voltage waveform calculated using the inductance between the two position, indicating that using the measurement results of the upstream voltage probe of the diode to calculate the diode voltage is effective.
Multiple D-dot voltage probes were designed and calibrated to measure the voltage of a 4 MV induction voltage adder. The frequency response test results indicate that the upper limit of the probe frequency is greater than 270 MHz, which meets the frequency response requirements of the voltage signal to be tested. In calibration, due to the different installation positions of the voltage divider and probe, in order to avoid the mismatch of transmission line impedance causing voltage waveform differences in the fast rising voltage signal at different measurement points, a pulse signal with a front edge of about hundreds of nanoseconds is used for calibration. Due to the low-frequency characteristics of the probe meeting both calibration and actual measurement requirements, the accuracy of calibration can be guaranteed. Considering the direct impact of assembly structure and accuracy on the sensitivity of the probe, the output transmission line probe adopts an online calibration method during the step-by-step installation process of the induction cavity. Due to the influence of electrons and other factors on the voltage probe near the diode, waveform distortion occurs, making it difficult to directly measure the load voltage. The results of multiple experiments on a 4 MV device indicate that the difference between the voltage waveform on the output transmission line and its downstream position is consistent with the voltage waveform calculated using the inductance between the two position, indicating that using the measurement results of the upstream voltage probe of the diode to calculate the diode voltage is effective.
2023, 35: 096001.
doi: 10.11884/HPLPB202335.230051
Abstract:
The wire wrap on the surface of the fuel rods of the sodium cooled fast reactor can strengthen the transverse flow of the coolant between the channels, reduce the unevenness of the temperature distribution in the assembly box, and improve the safety of the reactor. Different types of wire-wrap mixing models are used in sub-channel codes to simulate the effect of wire wrap on simulation results in an assembly. To study the influence of different wire-wrap mixing model on the simulation result of flow and heat transfer, based on the Mikityuk convective heat transfer model and the Cheng-Todreas flow pressure drop model, sub-channel analysis method has been established with the forced cross flow model and the wire-wrapped turbulent mixing model respectively. The results are compared with the data of FFM-2A experiment carried out by ORNL and results of other sub-channel codes. It is found that in the case of low flow rate, the two methods’ simulation result fits the flow and heat transfer of the wire-wrapped assembly well. And in the case of high flow rate, the method of the forced cross flow model is consistent with the experimental results, while the method of the wire wrapped turbulent mixing model overestimates the temperature at the outlet of channel center.
The wire wrap on the surface of the fuel rods of the sodium cooled fast reactor can strengthen the transverse flow of the coolant between the channels, reduce the unevenness of the temperature distribution in the assembly box, and improve the safety of the reactor. Different types of wire-wrap mixing models are used in sub-channel codes to simulate the effect of wire wrap on simulation results in an assembly. To study the influence of different wire-wrap mixing model on the simulation result of flow and heat transfer, based on the Mikityuk convective heat transfer model and the Cheng-Todreas flow pressure drop model, sub-channel analysis method has been established with the forced cross flow model and the wire-wrapped turbulent mixing model respectively. The results are compared with the data of FFM-2A experiment carried out by ORNL and results of other sub-channel codes. It is found that in the case of low flow rate, the two methods’ simulation result fits the flow and heat transfer of the wire-wrapped assembly well. And in the case of high flow rate, the method of the forced cross flow model is consistent with the experimental results, while the method of the wire wrapped turbulent mixing model overestimates the temperature at the outlet of channel center.
2023, 35: 096002.
doi: 10.11884/HPLPB202335.220376
Abstract:
This work proposes a two-electron resonance absorption (TERA) model, which explains the reason for laser-induced single event upset (SEU): when the energy of a single photon is not enough to excite the electron-hole pair, there will be de-excitation from a free-electron with higher energy in the conduction band to provide extra energy to excite the electrons in the valence band to the conductive band. This model can explain the physical mechanism of the material’s absorption of photons in the laser-semiconductor material interaction and explain the effect of the ambient temperature and doping concentration of the material on the absorption coefficient through the importance of the concentration of high-energy electrons in the conduction band for TERA. In our simulation, we use laser as the energy source for the thermal spike model, and the spatial-temporal evolution of the electronic temperature in the material during the laser radiation is simulated. Therefore, the change in absorption coefficient can be explained by the TERA. Moreover, according to the Fermi-Dirac distribution, the free charge density is calculated by the electronic temperature of the material. Furthermore, the accumulated free charge induced by laser radiation is given by the integration over the whole volume of the material. Thus, the numerical solution of the charge excitation process is obtained, through which the total amount of excitation charge when the laser induces SEU can be calculated. The simulation results show that the relationship between laser energy and the total excitation charge is nonlinear, i.e., there is a nonlinear correspondence between laser energy and the linear energy transport of particles, which is consistent with the experimental results.
This work proposes a two-electron resonance absorption (TERA) model, which explains the reason for laser-induced single event upset (SEU): when the energy of a single photon is not enough to excite the electron-hole pair, there will be de-excitation from a free-electron with higher energy in the conduction band to provide extra energy to excite the electrons in the valence band to the conductive band. This model can explain the physical mechanism of the material’s absorption of photons in the laser-semiconductor material interaction and explain the effect of the ambient temperature and doping concentration of the material on the absorption coefficient through the importance of the concentration of high-energy electrons in the conduction band for TERA. In our simulation, we use laser as the energy source for the thermal spike model, and the spatial-temporal evolution of the electronic temperature in the material during the laser radiation is simulated. Therefore, the change in absorption coefficient can be explained by the TERA. Moreover, according to the Fermi-Dirac distribution, the free charge density is calculated by the electronic temperature of the material. Furthermore, the accumulated free charge induced by laser radiation is given by the integration over the whole volume of the material. Thus, the numerical solution of the charge excitation process is obtained, through which the total amount of excitation charge when the laser induces SEU can be calculated. The simulation results show that the relationship between laser energy and the total excitation charge is nonlinear, i.e., there is a nonlinear correspondence between laser energy and the linear energy transport of particles, which is consistent with the experimental results.
2023, 35: 099001.
doi: 10.11884/HPLPB202335.230042
Abstract:
A composite device of intelligent multifunctional laser protection goggles and automatic detection and alarm is designed and developed, which is mainly used for protection and early warning of human eye damage caused by laser radiation. The protection spectacles, detection and alarm system and intelligent composite protective technology are studied. The laser protection and detection and alarm performance of the composite device are tested. The signal interconnection and linkage between the protection spectacles and alarm device are used to combine the protection spectacles’ double spectacles and send alarm signals. The results show that when the laser protection alarm compound device detects the laser irriadiation, it can send out various alarm signals and compound protection response in different ways, including flashing lights of different colors, sound and vibration alarms, and drive the two protection spectacles to recombine. It can effectively protect human eyes from laser of specific wavelengths (532 nm, 1 064 nm, 470 nm, 808 nm and 700−2 000 nm) as well as from supercontinuum laser, and realize cluster linkage alarm and protection through wireless signal interconnection. The laser protection spectacles and detection and alarm composite device has the characteristics of intelligent, modular and multifunctional integration, and its performance meets the design requirements
A composite device of intelligent multifunctional laser protection goggles and automatic detection and alarm is designed and developed, which is mainly used for protection and early warning of human eye damage caused by laser radiation. The protection spectacles, detection and alarm system and intelligent composite protective technology are studied. The laser protection and detection and alarm performance of the composite device are tested. The signal interconnection and linkage between the protection spectacles and alarm device are used to combine the protection spectacles’ double spectacles and send alarm signals. The results show that when the laser protection alarm compound device detects the laser irriadiation, it can send out various alarm signals and compound protection response in different ways, including flashing lights of different colors, sound and vibration alarms, and drive the two protection spectacles to recombine. It can effectively protect human eyes from laser of specific wavelengths (532 nm, 1 064 nm, 470 nm, 808 nm and 700−2 000 nm) as well as from supercontinuum laser, and realize cluster linkage alarm and protection through wireless signal interconnection. The laser protection spectacles and detection and alarm composite device has the characteristics of intelligent, modular and multifunctional integration, and its performance meets the design requirements
2023, 35: 099002.
doi: 10.11884/HPLPB202335.230080
Abstract:
Due to the less information of distant target, it is always challenging to accurately track the target in the task of infrared dim small target tracking. To improve the accuracy, based on correlation filtering framework, the side window filtering method which can extract the edge features of small infrared target is introduced, and an algorithm of distant target tracking is proposed. Specifically, the side window filtering method is used to process the searching area of the current target, this method could restrain the negative influence of background edge on dim small target location. Next, the correlation filters tracking model is constructed with temporal and spatial regularities to achieve accurate target tracking. To verify the performance of the proposed algorithm, six groups of real infrared dim small target image sequences were used for experiments, and the algorithm is compared with other typical algorithms such as KCF, SRDCF and STRCF. The experimental results show that the algorithm could effectively solve the problems of fast motion, low resolution and strong light background in infrared dim small target tracking tasks, getting higher accuracy with image sequences and complex background.
Due to the less information of distant target, it is always challenging to accurately track the target in the task of infrared dim small target tracking. To improve the accuracy, based on correlation filtering framework, the side window filtering method which can extract the edge features of small infrared target is introduced, and an algorithm of distant target tracking is proposed. Specifically, the side window filtering method is used to process the searching area of the current target, this method could restrain the negative influence of background edge on dim small target location. Next, the correlation filters tracking model is constructed with temporal and spatial regularities to achieve accurate target tracking. To verify the performance of the proposed algorithm, six groups of real infrared dim small target image sequences were used for experiments, and the algorithm is compared with other typical algorithms such as KCF, SRDCF and STRCF. The experimental results show that the algorithm could effectively solve the problems of fast motion, low resolution and strong light background in infrared dim small target tracking tasks, getting higher accuracy with image sequences and complex background.
2023, 35: 099003.
doi: 10.11884/HPLPB202335.230071
Abstract:
To solve the heat dissipation problem of high heat flux density solid-state laser, a set of micro-compact embedded manifold S-shaped microchannel heat sink was developed using the MEMS technology and the microchannel/heat source co-design method. The heat exchanger uses continuous S-shaped microchannels and the manifold is used to form tiered and segmented flow. Experiment was conducted, using HFE-7100 as the cooling medium. Results show that the heat sink can dissipate 625 W/cm2, with a local maximum temperature of less than 100 ℃ and an average temperature rise of less than 45 ℃. Compared with the traditional manifold rectangular microchannel heat sink, the heat dissipation performance of S-shaped microchannel increased by 12%, but the flow resistance increased by about 56%. Numerical simulation methods were used to evaluate the structural parameters of the S-shaped microchannel heat sink’s heat dissipation ability and flow resistance by changing the amplitude and wavelength of the S shape according to the average temperature of the heating surface, average Nusselt number of the heat transfer surface, pressure drop, and comprehensive performance factor, to find the optimal structure design parameter combination of the S-shaped microchannel. The results show that the comprehensive performance factor of the heat sink has an optimal value under a specific S-shaped configuration, which will be used in subsequent studies.
To solve the heat dissipation problem of high heat flux density solid-state laser, a set of micro-compact embedded manifold S-shaped microchannel heat sink was developed using the MEMS technology and the microchannel/heat source co-design method. The heat exchanger uses continuous S-shaped microchannels and the manifold is used to form tiered and segmented flow. Experiment was conducted, using HFE-7100 as the cooling medium. Results show that the heat sink can dissipate 625 W/cm2, with a local maximum temperature of less than 100 ℃ and an average temperature rise of less than 45 ℃. Compared with the traditional manifold rectangular microchannel heat sink, the heat dissipation performance of S-shaped microchannel increased by 12%, but the flow resistance increased by about 56%. Numerical simulation methods were used to evaluate the structural parameters of the S-shaped microchannel heat sink’s heat dissipation ability and flow resistance by changing the amplitude and wavelength of the S shape according to the average temperature of the heating surface, average Nusselt number of the heat transfer surface, pressure drop, and comprehensive performance factor, to find the optimal structure design parameter combination of the S-shaped microchannel. The results show that the comprehensive performance factor of the heat sink has an optimal value under a specific S-shaped configuration, which will be used in subsequent studies.
2023, 35: 099004.
doi: 10.11884/HPLPB202335.220360
Abstract:
In a complex electromagnetic environment, magnetic field interference is one of the main reasons for the error of fiber optic gyroscopes. To reduce the influence of the magnetic field generated by the heating plate in the body of the fiber optic gyroscope on the accuracy of the gyroscope, a double-layer heating plate structure is designed, and a comparative analysis of the magnetic field at the fiber optic ring position above the single-layer and double-layer heating plates is carried out by using the finite element method, and the influence of the magnetic field on the accuracy of the fiber optic gyroscope is calculated based on the analysis results. The results show that the magnetic field of both heating plates is non-uniform at the location of the fiber optic ring. The magnetic flux density near the fiber optic ring to the heating plate has a ring-like distribution, while the magnetic flux density away from the heating plate has a strong center and weak center distribution. With the increase in the distance between the fiber ring plane and the heating plate, the maximum magnetic flux density of the single-layer heating plate on the fiber ring plane is about 30 to 122 times that of the double-layer heating plate. The magnetic sensitivity phase error of the fiber optic gyroscope varies sinusoidally with the direction of the magnetic field and the angle between the fiber ring. The phase errors of the magnetic field on the lower surface of the fiber ring are 1.299×10−10 rad and 5.572×10−12 rad, respectively. The above results prove that the magnetic field of the double-layer heating plate interferes with the fiber-optic gyroscope much less than that of the single-layer heating plate and that the electromagnetic interference generated by the double-layer heating plate is much smaller, which is more conducive to improving the accuracy of the fiber-optic gyroscope.
In a complex electromagnetic environment, magnetic field interference is one of the main reasons for the error of fiber optic gyroscopes. To reduce the influence of the magnetic field generated by the heating plate in the body of the fiber optic gyroscope on the accuracy of the gyroscope, a double-layer heating plate structure is designed, and a comparative analysis of the magnetic field at the fiber optic ring position above the single-layer and double-layer heating plates is carried out by using the finite element method, and the influence of the magnetic field on the accuracy of the fiber optic gyroscope is calculated based on the analysis results. The results show that the magnetic field of both heating plates is non-uniform at the location of the fiber optic ring. The magnetic flux density near the fiber optic ring to the heating plate has a ring-like distribution, while the magnetic flux density away from the heating plate has a strong center and weak center distribution. With the increase in the distance between the fiber ring plane and the heating plate, the maximum magnetic flux density of the single-layer heating plate on the fiber ring plane is about 30 to 122 times that of the double-layer heating plate. The magnetic sensitivity phase error of the fiber optic gyroscope varies sinusoidally with the direction of the magnetic field and the angle between the fiber ring. The phase errors of the magnetic field on the lower surface of the fiber ring are 1.299×10−10 rad and 5.572×10−12 rad, respectively. The above results prove that the magnetic field of the double-layer heating plate interferes with the fiber-optic gyroscope much less than that of the single-layer heating plate and that the electromagnetic interference generated by the double-layer heating plate is much smaller, which is more conducive to improving the accuracy of the fiber-optic gyroscope.
