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, Available online , doi: 10.11884/HPLPB202436.230342
Abstract:
Aiming at the output characteristics of diesel generator set with pulse load, an index is proposed to evaluate the consistency of output voltage (current) waveform to judge the simulation degree of the model. Also, a dynamic limiting method for synchronous generator excitation voltage output based on BP neural network algorithm is proposed, which is applied to the model optimization of diesel generator set. Experimental results show that 18 groups of real-time waveform proximity of waveforms are less than 90% among the 27sets of examples, but the optimized simulation model become better because all the test groups are higher than 90%, indicating that the optimized simulation model is more effective, and can be applied to the further research on diesel generator set with pulse load.
Aiming at the output characteristics of diesel generator set with pulse load, an index is proposed to evaluate the consistency of output voltage (current) waveform to judge the simulation degree of the model. Also, a dynamic limiting method for synchronous generator excitation voltage output based on BP neural network algorithm is proposed, which is applied to the model optimization of diesel generator set. Experimental results show that 18 groups of real-time waveform proximity of waveforms are less than 90% among the 27sets of examples, but the optimized simulation model become better because all the test groups are higher than 90%, indicating that the optimized simulation model is more effective, and can be applied to the further research on diesel generator set with pulse load.
, Available online , doi: 10.11884/HPLPB202436.240048
Abstract:
The far-field wavefront inversion exhibits degeneracy states, leading to the problem of encountering multiple solutions when recovering the wavefront. In comparison to traditional iterative algorithms, the combination of phase modulation and deep learning in the phase inversion method not only significantly reduces computational complexity but also effectively solves multi-solution problems. This method possesses strong real-time capabilities and a simple structure, showcasing its unique advantages. In this paper, different Walsh functions are used to modulate the phase, and a deep learning approach is taken to train a convolutional neural network to obtain the 4th-30th order Zernike coefficients from the modulated single-frame far-field intensity maps so as to recover the original wavefront, which solves the problem of multiple solutions of phase inversion. For the residual wavefront of the turbulent aberration of 3-15 cm atmospheric coherence length, the ratio of its RMS to the RMS of the original wavefront can reach 7.8%. In addition, this paper also deeply investigates the effects of various factors such as Zernike order, random noise, occlusion, and intensity map resolution on the wavefront recovery accuracy. The results show that this deep learning-based phase inversion method exhibits good robustness in complex environments.
The far-field wavefront inversion exhibits degeneracy states, leading to the problem of encountering multiple solutions when recovering the wavefront. In comparison to traditional iterative algorithms, the combination of phase modulation and deep learning in the phase inversion method not only significantly reduces computational complexity but also effectively solves multi-solution problems. This method possesses strong real-time capabilities and a simple structure, showcasing its unique advantages. In this paper, different Walsh functions are used to modulate the phase, and a deep learning approach is taken to train a convolutional neural network to obtain the 4th-30th order Zernike coefficients from the modulated single-frame far-field intensity maps so as to recover the original wavefront, which solves the problem of multiple solutions of phase inversion. For the residual wavefront of the turbulent aberration of 3-15 cm atmospheric coherence length, the ratio of its RMS to the RMS of the original wavefront can reach 7.8%. In addition, this paper also deeply investigates the effects of various factors such as Zernike order, random noise, occlusion, and intensity map resolution on the wavefront recovery accuracy. The results show that this deep learning-based phase inversion method exhibits good robustness in complex environments.
, Available online , doi: 10.11884/HPLPB202436.240019
Abstract:
To compare the effects of different physics lists on the dose of proton boron capture therapy (PBCT) by Monte Carlo simulation Geant4. Geant4 was used to establish PBCT model with different three physics lists (FTFP, QBBC and QGSP). Compared the dose distribution of three physics lists with and without boron using an 80 MeV proton beam, as well as the nuclear reaction product data of a 3 MeV proton beam bombards pure boron. There is no significant difference in the dose distribution of the three physics lists in the water phantom with and without boron, and the consistency of the different physics models PDD’s curves are good. The PBCT nuclear reaction products obtained from FTFP physics list are significantly less than those obtained from QBBC and QGSP physics lists. The yields, mean energies and energy ranges of the alpha particles obtained from the QGSP physics list are more consistent with the actual situation than that of the QBBC physics list. The QGSP physics list in Geant4 is more suitable for MC simulation studies of PBCT, after a comprehensive evaluation of the inelastic scattering models used by the three physics lists and the simulated nuclear reaction data.
To compare the effects of different physics lists on the dose of proton boron capture therapy (PBCT) by Monte Carlo simulation Geant4. Geant4 was used to establish PBCT model with different three physics lists (FTFP, QBBC and QGSP). Compared the dose distribution of three physics lists with and without boron using an 80 MeV proton beam, as well as the nuclear reaction product data of a 3 MeV proton beam bombards pure boron. There is no significant difference in the dose distribution of the three physics lists in the water phantom with and without boron, and the consistency of the different physics models PDD’s curves are good. The PBCT nuclear reaction products obtained from FTFP physics list are significantly less than those obtained from QBBC and QGSP physics lists. The yields, mean energies and energy ranges of the alpha particles obtained from the QGSP physics list are more consistent with the actual situation than that of the QBBC physics list. The QGSP physics list in Geant4 is more suitable for MC simulation studies of PBCT, after a comprehensive evaluation of the inelastic scattering models used by the three physics lists and the simulated nuclear reaction data.
, Available online , doi: 10.11884/HPLPB202436.230442
Abstract:
Impacted by various factors such as geographical position, sun and atmospheric environment, it is impossible to obtain the real images of space targets under various postures and illumination conditions, let alone the interaction between laser, sun and background light. In this paper, a real-time target image generation method under multi-light source irradiation is proposed. This method is based on the modern graphics card programming technique and frame caching object advantages. At the GPU (Graphics Processing Unit) side, shader language is used to efficiently calculate target brightness values and enhance realism under the influence of multi-light source. The open-source 3D graphics engine named OSG (Open Scene Graph) helps support 3D model files of various formats and improve the compatibility with the domestic Kirin operating system as well as common battlefield situation display software. Simulation experiments demonstrate the effectiveness and superiority of the proposed method.
Impacted by various factors such as geographical position, sun and atmospheric environment, it is impossible to obtain the real images of space targets under various postures and illumination conditions, let alone the interaction between laser, sun and background light. In this paper, a real-time target image generation method under multi-light source irradiation is proposed. This method is based on the modern graphics card programming technique and frame caching object advantages. At the GPU (Graphics Processing Unit) side, shader language is used to efficiently calculate target brightness values and enhance realism under the influence of multi-light source. The open-source 3D graphics engine named OSG (Open Scene Graph) helps support 3D model files of various formats and improve the compatibility with the domestic Kirin operating system as well as common battlefield situation display software. Simulation experiments demonstrate the effectiveness and superiority of the proposed method.
, Available online , doi: 10.11884/HPLPB202436.230436
Abstract:
With the development of adaptive optics (AO) technology in laser field, a variety of improvement measures based on software monitoring and hardware protection have been added to the classical AO system to ensure the stable and continuous light output of laser AO system. Facing the reliability challenge brought by the increase of structural complexity, how to build a system failure model to evaluate the reliability of laser AO system has become an important part of the development of laser AO system. In this paper, a dynamic fault tree (DFT) method is proposed to evaluate the reliability of laser AO system, and the dynamic fault tree is established according to the dynamic relationship between the equipment. The bottom event failure rate is estimated by combining the manufacturer information, fatigue life test and historical data. The reliability parameters of DFT are obtained by using binary decision graph and Markov model. Using DFT to analysis the reliable running time of the AO system increasing by the improvement measures, the result shows more than ten times improvement relative to the basic fault tree. During the actual system joint commissioning, no self-induced failure occurred during the expected reliable running time, which is consistent with the DFT estimate. It is proved that the reliability evaluation of laser AO system with improved measures is more accurate by using DFT method.
With the development of adaptive optics (AO) technology in laser field, a variety of improvement measures based on software monitoring and hardware protection have been added to the classical AO system to ensure the stable and continuous light output of laser AO system. Facing the reliability challenge brought by the increase of structural complexity, how to build a system failure model to evaluate the reliability of laser AO system has become an important part of the development of laser AO system. In this paper, a dynamic fault tree (DFT) method is proposed to evaluate the reliability of laser AO system, and the dynamic fault tree is established according to the dynamic relationship between the equipment. The bottom event failure rate is estimated by combining the manufacturer information, fatigue life test and historical data. The reliability parameters of DFT are obtained by using binary decision graph and Markov model. Using DFT to analysis the reliable running time of the AO system increasing by the improvement measures, the result shows more than ten times improvement relative to the basic fault tree. During the actual system joint commissioning, no self-induced failure occurred during the expected reliable running time, which is consistent with the DFT estimate. It is proved that the reliability evaluation of laser AO system with improved measures is more accurate by using DFT method.
, Available online , doi: 10.11884/HPLPB202436.240032
Abstract:
In order to estimate the aircraft pose in complex situation, this paper proposes a new method of aircraft pose estimation based on neural network line extraction. This method uses 3D model to render images, and forms dataset through adding backgrounds. The dataset is enhanced to make the algorithm robust. The line extraction model uses convolutional neural network to extract deep features, and uses heatmap to obtain aircraft feature lines. The target pose is solved by combining the aircraft feature line, the aircraft 3D model and the perspective-n-line method. The accuracy of the line extraction model is 91% in complex background. The accuracy is 84% after adding sorts of noises. The aircraft pose is solved by using EPnL algorithm and nonlinear optimization. The average angle error is about 0.57°, and the average translation error is about 0.47% when the target is in a complex background. After adding sorts of noises to the image, the average angle error is about 2.11°, and the average translation error is about 0.93%. The aircraft pose estimation method proposed in this article can accurately predict the aircraft pose under complex backgrounds and various types of noise, and its application scenarios are more extensive.
In order to estimate the aircraft pose in complex situation, this paper proposes a new method of aircraft pose estimation based on neural network line extraction. This method uses 3D model to render images, and forms dataset through adding backgrounds. The dataset is enhanced to make the algorithm robust. The line extraction model uses convolutional neural network to extract deep features, and uses heatmap to obtain aircraft feature lines. The target pose is solved by combining the aircraft feature line, the aircraft 3D model and the perspective-n-line method. The accuracy of the line extraction model is 91% in complex background. The accuracy is 84% after adding sorts of noises. The aircraft pose is solved by using EPnL algorithm and nonlinear optimization. The average angle error is about 0.57°, and the average translation error is about 0.47% when the target is in a complex background. After adding sorts of noises to the image, the average angle error is about 2.11°, and the average translation error is about 0.93%. The aircraft pose estimation method proposed in this article can accurately predict the aircraft pose under complex backgrounds and various types of noise, and its application scenarios are more extensive.
, Available online , doi: 10.11884/HPLPB202436.230424
Abstract:
The Geant4 program was used to simulate the effect of micropore shape on the performance of CsI:Tl X-ray scintillation screen based on silicon microchannel array. The simulated scintillation screen performance parameters include: scintillation photons, bottom light output, transmission efficiency, percentage of n times total reflection, and Modulation transfer function versus spatial resolution. The shapes of the micropores were set to be square and circular during the simulation process, and the microchannel array period was the same for both hole shapes, which was 10 μm. The simulation results show that the number of scintillation photons in square micropores is better than that in circular micropores, and the number of fluorescent photons is directly proportional to the cross-sectional area of the micropores; Thickness less than 400 μm, the bottom light output of square micropores is better than that of circular micropores,.When the thickness greater than 400 μm, the situation is opposite; The transmission efficiency of circular micropores is better than that of square micropores; When the thickness of 40 and 200 μm ,the spatial resolution of the square micropores scintillation screen is better than that of the circular micropores scintillation screen with the same thickness. A square microporous CsI: Tl scintillation screen sample was prepared, and the relationship between its MTF and spatial resolution was measured. When the MTF was 0.1, the spatial resolution was 22.6 lp/mm.
The Geant4 program was used to simulate the effect of micropore shape on the performance of CsI:Tl X-ray scintillation screen based on silicon microchannel array. The simulated scintillation screen performance parameters include: scintillation photons, bottom light output, transmission efficiency, percentage of n times total reflection, and Modulation transfer function versus spatial resolution. The shapes of the micropores were set to be square and circular during the simulation process, and the microchannel array period was the same for both hole shapes, which was 10 μm. The simulation results show that the number of scintillation photons in square micropores is better than that in circular micropores, and the number of fluorescent photons is directly proportional to the cross-sectional area of the micropores; Thickness less than 400 μm, the bottom light output of square micropores is better than that of circular micropores,.When the thickness greater than 400 μm, the situation is opposite; The transmission efficiency of circular micropores is better than that of square micropores; When the thickness of 40 and 200 μm ,the spatial resolution of the square micropores scintillation screen is better than that of the circular micropores scintillation screen with the same thickness. A square microporous CsI: Tl scintillation screen sample was prepared, and the relationship between its MTF and spatial resolution was measured. When the MTF was 0.1, the spatial resolution was 22.6 lp/mm.
, Available online , doi: 10.11884/HPLPB202436.240076
Abstract:
In the field of computational electromagnetics, the Discontinuous Galerkin Time Domain (DGTD) method typically relies on irregular grid partitioning in model space and high-order polynomial interpolation calculations on elements. When comparing two-dimensional spatial quadrilateral mesh partitioning to triangular mesh partitioning at the same interpolation order, quadrilateral meshing offers fewer degrees of freedom and higher computational efficiency. However, traditional basis function spaces, relying on isoparametric transformations and polynomial tensor product interpolation, only possess low-order completeness on quadrilateral elements. Consequently, their stability and accuracy are significantly influenced by grid distortion. Addressing this challenge, this thesis proposes a high-order B-spline interpolation DGTD method based on irregular quadrilateral meshes for solving Maxwell's equations. The advantage of B-spline interpolation lies in its high-order completeness on irregular elements, effectively eliminating internal degrees of freedom within the elements. Furthermore, the coefficient matrices of the discrete system for Maxwell's equations also possess exact analytical forms.. Utilizing this method to analyze the eigenmodes of cavities and the electromagnetic scattering of wedge structures, the results indicate that increasing the maximum allowable time step by 2.5 times, and reducing the required unknowns by 25% compared to COMSOL software, the proposed algorithm exhibits notable advantages in terms of higher stability and precision.
In the field of computational electromagnetics, the Discontinuous Galerkin Time Domain (DGTD) method typically relies on irregular grid partitioning in model space and high-order polynomial interpolation calculations on elements. When comparing two-dimensional spatial quadrilateral mesh partitioning to triangular mesh partitioning at the same interpolation order, quadrilateral meshing offers fewer degrees of freedom and higher computational efficiency. However, traditional basis function spaces, relying on isoparametric transformations and polynomial tensor product interpolation, only possess low-order completeness on quadrilateral elements. Consequently, their stability and accuracy are significantly influenced by grid distortion. Addressing this challenge, this thesis proposes a high-order B-spline interpolation DGTD method based on irregular quadrilateral meshes for solving Maxwell's equations. The advantage of B-spline interpolation lies in its high-order completeness on irregular elements, effectively eliminating internal degrees of freedom within the elements. Furthermore, the coefficient matrices of the discrete system for Maxwell's equations also possess exact analytical forms.. Utilizing this method to analyze the eigenmodes of cavities and the electromagnetic scattering of wedge structures, the results indicate that increasing the maximum allowable time step by 2.5 times, and reducing the required unknowns by 25% compared to COMSOL software, the proposed algorithm exhibits notable advantages in terms of higher stability and precision.
, Available online , doi: 10.11884/HPLPB202436.230421
Abstract:
Aiming at the application requirements of array antenna with high-power capacity, high efficiency and low profile characteristics, a high-power capacity and high efficiency open waveguide array antenna is proposed and designed. The antenna consists of a compact 16-way waveguide power distribution network, 4×4 rectangular open waveguide unit cells and ceramic sealing radome. By designing the size of the open waveguide and loading E-plane metal bar on the surface of the open waveguide, the electric field distribution on the radiation aperture surface is more uniform, and the radiation gain of the unit cell is improved. The step matching structure is used to realize the size transformation from the output port of the waveguide power distribution network to the interface of the open waveguide unit cell, and the impedance bandwidth of the system is improved. The ceramic radome loaded on the array keeps the interior of the antenna in a vacuum state and improves the power capacity of the antenna. According to the application requirements of X-band high-power array antenna, a 16-element open waveguide array with a center frequency of 9.5 GHz is optimized and designed, the simulation results show that the aperture efficiency is greater than 90% and the reflection coefficient is less than -13.9 dB in the range of 9.25～9.65 GHz. The antenna is processed and tested, the measured antenna reflection curve and radiation pattern at the center frequency are in good agreement with the simulation results, the antenna gain at the center frequency is 21.7 dBi. The overall profile height of the antenna is twice the wavelengths at the central frequency, and the power capacity in vacuum obtained by simulation is 40 MW, which has the characteristics of high power capacity, high efficiency and low profile.
Aiming at the application requirements of array antenna with high-power capacity, high efficiency and low profile characteristics, a high-power capacity and high efficiency open waveguide array antenna is proposed and designed. The antenna consists of a compact 16-way waveguide power distribution network, 4×4 rectangular open waveguide unit cells and ceramic sealing radome. By designing the size of the open waveguide and loading E-plane metal bar on the surface of the open waveguide, the electric field distribution on the radiation aperture surface is more uniform, and the radiation gain of the unit cell is improved. The step matching structure is used to realize the size transformation from the output port of the waveguide power distribution network to the interface of the open waveguide unit cell, and the impedance bandwidth of the system is improved. The ceramic radome loaded on the array keeps the interior of the antenna in a vacuum state and improves the power capacity of the antenna. According to the application requirements of X-band high-power array antenna, a 16-element open waveguide array with a center frequency of 9.5 GHz is optimized and designed, the simulation results show that the aperture efficiency is greater than 90% and the reflection coefficient is less than -13.9 dB in the range of 9.25～9.65 GHz. The antenna is processed and tested, the measured antenna reflection curve and radiation pattern at the center frequency are in good agreement with the simulation results, the antenna gain at the center frequency is 21.7 dBi. The overall profile height of the antenna is twice the wavelengths at the central frequency, and the power capacity in vacuum obtained by simulation is 40 MW, which has the characteristics of high power capacity, high efficiency and low profile.
, Available online , doi: 10.11884/HPLPB202436.230433
Abstract:
The existing heterodyne power combiners are not suitable for applications that the input and output of signal need to be the same direction with limited space. In order to solve the problem, this paper designs a high-power and miniaturized heterodyne power combiner operating at frequencies of 9.3 GHz and 9.7 GHz. Based on the traditional filter-based heterodyne power combiner, the proposed design utilizes a over-mode rectangular waveguide E-plane power combiner. The waveguide filters are parallel and the input ports are also located on the same plane, so that the combiner is suitable for the specific applications. The size of the rectangular waveguide are reduced to suppress higher-order modes. Besides, the distance between mode strips is decreased in integer multiples of half-wavelength of the waveguide to compresses the overall length with high power capacity. The combiner has a length of 9.2 λ a width of 1.5 λ and a height of 2.8 λ, while λ is the wavelength corresponding to the frequency of 9.5 GHz in free space. At 9.3 GHz and 9.7 GHz, the return loss of the combiner is more than 20 dB, its combining efficiency is more than 98% , and the isolation between input ports is more than 20 dB. At microwave pulse breakdown threshold of 80 MV/m, the combiner provides power capacities of 310 MW.
The existing heterodyne power combiners are not suitable for applications that the input and output of signal need to be the same direction with limited space. In order to solve the problem, this paper designs a high-power and miniaturized heterodyne power combiner operating at frequencies of 9.3 GHz and 9.7 GHz. Based on the traditional filter-based heterodyne power combiner, the proposed design utilizes a over-mode rectangular waveguide E-plane power combiner. The waveguide filters are parallel and the input ports are also located on the same plane, so that the combiner is suitable for the specific applications. The size of the rectangular waveguide are reduced to suppress higher-order modes. Besides, the distance between mode strips is decreased in integer multiples of half-wavelength of the waveguide to compresses the overall length with high power capacity. The combiner has a length of 9.2 λ a width of 1.5 λ and a height of 2.8 λ, while λ is the wavelength corresponding to the frequency of 9.5 GHz in free space. At 9.3 GHz and 9.7 GHz, the return loss of the combiner is more than 20 dB, its combining efficiency is more than 98% , and the isolation between input ports is more than 20 dB. At microwave pulse breakdown threshold of 80 MV/m, the combiner provides power capacities of 310 MW.
, Available online , doi: 10.11884/HPLPB202436.230443
Abstract:
An novel ultra-wideband thin frequency selective surface (FSS) absorber loaded with lumped resistors is presented in this article. The proposed absorber consists of a single FSS lossy layer with a single resonance structure, and features thinness, ultra-wide bandwidth and polarization-insensitivity. The absorber is designed with lumped resistors loaded at positions that deviates from the central symmetry axis of the unit cell. It also features the nonuniformly wide metallic strips and the addition of branches with circular tops. All these specific design effectively enhances the bandwidth of the absorber. Both an equivalent circuit model and full wave simulation demonstrate that the proposed absorber achieves over 90% absorption in the frequency range of 6.0-26.77 GHz, with a fractional bandwidth of 126.8%. The thickness of the proposed absorber is 0.086 λL (the wavelength at the lowest frequency), which is only 1.09 times the ultimate thickness based on Rozanov’s theory. A prototype of the proposed absorber is fabricated, good agreements between experimental and simulated results are observed, validating the effectiveness of the design.
An novel ultra-wideband thin frequency selective surface (FSS) absorber loaded with lumped resistors is presented in this article. The proposed absorber consists of a single FSS lossy layer with a single resonance structure, and features thinness, ultra-wide bandwidth and polarization-insensitivity. The absorber is designed with lumped resistors loaded at positions that deviates from the central symmetry axis of the unit cell. It also features the nonuniformly wide metallic strips and the addition of branches with circular tops. All these specific design effectively enhances the bandwidth of the absorber. Both an equivalent circuit model and full wave simulation demonstrate that the proposed absorber achieves over 90% absorption in the frequency range of 6.0-26.77 GHz, with a fractional bandwidth of 126.8%. The thickness of the proposed absorber is 0.086 λL (the wavelength at the lowest frequency), which is only 1.09 times the ultimate thickness based on Rozanov’s theory. A prototype of the proposed absorber is fabricated, good agreements between experimental and simulated results are observed, validating the effectiveness of the design.
, Available online , doi: 10.11884/HPLPB202436.230371
Abstract:
In order to reduce the jitter of the direct current self-breakdown voltage, not affect the self-breakdown voltage as much as possible, an auxiliary discharge electrode structure with an auxiliary discharge needle implanted in the cathode center is designed based on the discharge gap of the annular electrode. The influence of the diameter, length and top chamfer of the auxiliary discharge needle on the field distortion is studied by electric field simulation. The direct current self-breakdown characteristics of the unintroduced auxiliary discharge needle and the introduce auxiliary discharge needle in dry air and SF6 gas are studied by experiments. The results show that the smaller the diameter and the longer the length of the auxiliary discharge needle, the weaker the shielding effect of the electrode ring on the electric field, the stronger the field distortion intensity;the influence of the implatation of auxiliary discharge needle on the direct current self-breakdown of SF6 gas discharge gap is small,and with the increase of the field distortion coefficient, the percentage drop of self-breakdown voltage of dry air at the same air pressure is 2～3 times that of SF6 gas; the auxiliary discharge needle has a beneficial effect on the breakdown stability of dry air and SF6 gas discharge gap under the condition of direct current , the dispersion reduction percentage is about 25% higher than that without auxiliary discharge needle.
In order to reduce the jitter of the direct current self-breakdown voltage, not affect the self-breakdown voltage as much as possible, an auxiliary discharge electrode structure with an auxiliary discharge needle implanted in the cathode center is designed based on the discharge gap of the annular electrode. The influence of the diameter, length and top chamfer of the auxiliary discharge needle on the field distortion is studied by electric field simulation. The direct current self-breakdown characteristics of the unintroduced auxiliary discharge needle and the introduce auxiliary discharge needle in dry air and SF6 gas are studied by experiments. The results show that the smaller the diameter and the longer the length of the auxiliary discharge needle, the weaker the shielding effect of the electrode ring on the electric field, the stronger the field distortion intensity;the influence of the implatation of auxiliary discharge needle on the direct current self-breakdown of SF6 gas discharge gap is small,and with the increase of the field distortion coefficient, the percentage drop of self-breakdown voltage of dry air at the same air pressure is 2～3 times that of SF6 gas; the auxiliary discharge needle has a beneficial effect on the breakdown stability of dry air and SF6 gas discharge gap under the condition of direct current , the dispersion reduction percentage is about 25% higher than that without auxiliary discharge needle.
, Available online , doi: 10.11884/HPLPB202436.240042
Abstract:
High-altitude electromagnetic pulse (HEMP), as a wide-area electromagnetic attack method, can cause severe impacts on the power equipment and even collapse of power infrastructure, posing significant challenges to the electromagnetic safety of novel power systems. This article focused on latest research progress on the power system effects in HEMP late-time environment. Firstly, the mechanism of geomagnetic disturbance generation and the calculation method of induced geomagnetic field are analyzed. The calculation method of geomagnetically induced current (GIC) is provided. Then, the effects and mechanisms of typical primary power equipment, such as power transformers, current transformers, circuit breakers, etc. under extreme GIC conditions are summarized. Next, the extreme GIC injection devices and simulated experiment methods are discussed. And the experimental and simulation results acquired by Defense Threat Reduction Agency (DTRA) and Electric Power Research Institute (EPRI) are also discussed, as well as the power system effects simulation and assessment. Finally, we summarized the main conclusions reached by the present work, and analyzed the future research from the perspective of effects mechanism, primary power equipment characteristics, simulated experimental methods, and system-level effects assessment.
High-altitude electromagnetic pulse (HEMP), as a wide-area electromagnetic attack method, can cause severe impacts on the power equipment and even collapse of power infrastructure, posing significant challenges to the electromagnetic safety of novel power systems. This article focused on latest research progress on the power system effects in HEMP late-time environment. Firstly, the mechanism of geomagnetic disturbance generation and the calculation method of induced geomagnetic field are analyzed. The calculation method of geomagnetically induced current (GIC) is provided. Then, the effects and mechanisms of typical primary power equipment, such as power transformers, current transformers, circuit breakers, etc. under extreme GIC conditions are summarized. Next, the extreme GIC injection devices and simulated experiment methods are discussed. And the experimental and simulation results acquired by Defense Threat Reduction Agency (DTRA) and Electric Power Research Institute (EPRI) are also discussed, as well as the power system effects simulation and assessment. Finally, we summarized the main conclusions reached by the present work, and analyzed the future research from the perspective of effects mechanism, primary power equipment characteristics, simulated experimental methods, and system-level effects assessment.
, Available online , doi: 10.11884/HPLPB202436.240034
Abstract:
Accurate measurement of the intense pulse electron beam is required by upgrade of linear induction accelerator. This is achieved by not only the technology of beam position monitor (BPM) design and assamble, but also the calibration of BPM. This paper describes the research of calibration technology based on the measuring principle of intense pulse electron beam position monitor in linear induction accelerator. Theoretic method is used to calculate calibrated effects in different signal calculation, polynomial fit and calibration. Characteristic plane calibration is provided according to the analytic results. In the system of BPM position calibration,The No.23RRM (resistive ring monitor) of multi-pulse electron linear induction accelarator is calibrated in different calibration and experimental data processed in different method. The experimental results validate the theoretic results. The calibration method of intense pulse electron beam position monitor is decided according to the results of research.
Accurate measurement of the intense pulse electron beam is required by upgrade of linear induction accelerator. This is achieved by not only the technology of beam position monitor (BPM) design and assamble, but also the calibration of BPM. This paper describes the research of calibration technology based on the measuring principle of intense pulse electron beam position monitor in linear induction accelerator. Theoretic method is used to calculate calibrated effects in different signal calculation, polynomial fit and calibration. Characteristic plane calibration is provided according to the analytic results. In the system of BPM position calibration,The No.23RRM (resistive ring monitor) of multi-pulse electron linear induction accelarator is calibrated in different calibration and experimental data processed in different method. The experimental results validate the theoretic results. The calibration method of intense pulse electron beam position monitor is decided according to the results of research.
, Available online , doi: 10.11884/HPLPB202436.230425
Abstract:
The Institute of High Energy Physics of the Chinese Academy of Sciences completed the research and development of the high quality factor 1.3 GHz superconducting cryomodule in June 2023, taking the lead in the world to realize the technical route of the medium temperature baking. Eight 1.3 GHz 9-cell superconducting cavities with the medium temperature baking process are integrated. During the integration test of the cryomodule, the temperature of the high-order mode (HOM) coupler of the superconducting cavity was abnormal, which made the superconducting cavity unable to work stably under high gradient. In this paper, the electromagnetic analysis of the higher-order mode coupler is carried out by the HFSS software and eigenmode Solver in CST software and the thermal analysis of the high-order mode coupler is carried out by theory and Ansys Workbench software. Combining with the high-power experiment of cavity, the reason that caused the abnormal performance of the superconducting cavity was found. Also, the cooling structure of the HOM coupler in the superconducting cavity was further optimized to solve the instability of the superconducting cavity under high gradient in the module.
The Institute of High Energy Physics of the Chinese Academy of Sciences completed the research and development of the high quality factor 1.3 GHz superconducting cryomodule in June 2023, taking the lead in the world to realize the technical route of the medium temperature baking. Eight 1.3 GHz 9-cell superconducting cavities with the medium temperature baking process are integrated. During the integration test of the cryomodule, the temperature of the high-order mode (HOM) coupler of the superconducting cavity was abnormal, which made the superconducting cavity unable to work stably under high gradient. In this paper, the electromagnetic analysis of the higher-order mode coupler is carried out by the HFSS software and eigenmode Solver in CST software and the thermal analysis of the high-order mode coupler is carried out by theory and Ansys Workbench software. Combining with the high-power experiment of cavity, the reason that caused the abnormal performance of the superconducting cavity was found. Also, the cooling structure of the HOM coupler in the superconducting cavity was further optimized to solve the instability of the superconducting cavity under high gradient in the module.
, Available online , doi: 10.11884/HPLPB202436.230413
Abstract:
A fluorescence target historical image data storage system based on MongoDB database was constructed to address the issues of historical image data storage, continuously increasing data generated by the system, and slow historical data retrieval speed of the Heavy Ion Research Facility in Lanzhou (HIRFL) fluorescence target. In order to save, observe and analyze fluorescence target beam images, this article establishes an EPICS based historical data archiving system to obtain PV (Process Variable) data of fluorescence target images. The obtained data is stored using MongoDB database sharding technology, and the image conversion and web page implementation are achieved through the Django framework. Image classification algorithms are applied in the system to improve data read and write speed. This system can stably obtain, store, and observe fluorescence target beam history images on HIRFL, providing convenience for beam analysis and tuning work.
A fluorescence target historical image data storage system based on MongoDB database was constructed to address the issues of historical image data storage, continuously increasing data generated by the system, and slow historical data retrieval speed of the Heavy Ion Research Facility in Lanzhou (HIRFL) fluorescence target. In order to save, observe and analyze fluorescence target beam images, this article establishes an EPICS based historical data archiving system to obtain PV (Process Variable) data of fluorescence target images. The obtained data is stored using MongoDB database sharding technology, and the image conversion and web page implementation are achieved through the Django framework. Image classification algorithms are applied in the system to improve data read and write speed. This system can stably obtain, store, and observe fluorescence target beam history images on HIRFL, providing convenience for beam analysis and tuning work.
, Available online , doi: 10.11884/HPLPB202436.240001
Abstract:
In order to investigate the motion law of the plasma sheath in a dense plasma focus (DPF) device and the influence of related design parameters, this paper uses a self-developed FOI program to conduct two-dimensional magnetohydrodynamic simulation of the plasma sheath motion process and focus formation process in the Mather type discharge chamber structure, and obtains results similar to the visible light experimental images of the Livermore National Laboratory in the United States. At the same time, the influence of different pressure, current, anode radius and cathode-anode gap on the motion law of the plasma sheath is explored. The calculation results show that the plasma sheath will compress the gas radially with a certain degree of curvature, which is one of the reasons for the instability phenomenon; the axial velocity of plasma sheath is inversely proportional to the square root of pressure, and is proportional to the current. The larger the anode size of the device, the smaller the axial velocity of sheath. To increase the current, it is necessary to extend the anode length to match the focusing time with the current peak. The gap between cathode and anode has little effect on the axial motion process of plasma sheath near the anode.
In order to investigate the motion law of the plasma sheath in a dense plasma focus (DPF) device and the influence of related design parameters, this paper uses a self-developed FOI program to conduct two-dimensional magnetohydrodynamic simulation of the plasma sheath motion process and focus formation process in the Mather type discharge chamber structure, and obtains results similar to the visible light experimental images of the Livermore National Laboratory in the United States. At the same time, the influence of different pressure, current, anode radius and cathode-anode gap on the motion law of the plasma sheath is explored. The calculation results show that the plasma sheath will compress the gas radially with a certain degree of curvature, which is one of the reasons for the instability phenomenon; the axial velocity of plasma sheath is inversely proportional to the square root of pressure, and is proportional to the current. The larger the anode size of the device, the smaller the axial velocity of sheath. To increase the current, it is necessary to extend the anode length to match the focusing time with the current peak. The gap between cathode and anode has little effect on the axial motion process of plasma sheath near the anode.
, Available online , doi: 10.11884/HPLPB202436.230354
Abstract:
A compact repetitive pulse power source is developed as an experimental platform for high power relativistic magnetron with low magnetic field. In order to obtain better output pulse waveform with a compact structure, the pulsed power source designed based on PFN-Marx technology has a coaxial structure. A circular pulse forming net (PFN) is carried out with the impedance of 4 Ω, working voltage of 50kV, and electrical length of 53 ns, consisting of 13 ceramic capacitors with the capacitance of 1nF. Two PFN devices in series by a gas switch and an insulation plate form a circular high-voltage pulse generation module. Multiple pulse generation modules are coaxial and stacked in a metal cylinder. Inductive isolation is used between the modules. After all switches are turned on, all modules are discharged in series to generate a fast rising-time high-power square wave pulse. Moreover, repetitive operation is achieved through synchronous control of the trigger switch and charging power supply. In experiments the 22-stage PFN-Marx pulsed power source developed was charges to 51 kV, and a high-voltage square wave pulse of 516 kV was obtained on a load of 84 Ω, with pulse width (FWHM) of 104 ns, flat top of 63 ns and rising-time of 11 ns. This power source can operate stably at a repetition rate of 20 Hz for 15 seconds.
A compact repetitive pulse power source is developed as an experimental platform for high power relativistic magnetron with low magnetic field. In order to obtain better output pulse waveform with a compact structure, the pulsed power source designed based on PFN-Marx technology has a coaxial structure. A circular pulse forming net (PFN) is carried out with the impedance of 4 Ω, working voltage of 50kV, and electrical length of 53 ns, consisting of 13 ceramic capacitors with the capacitance of 1nF. Two PFN devices in series by a gas switch and an insulation plate form a circular high-voltage pulse generation module. Multiple pulse generation modules are coaxial and stacked in a metal cylinder. Inductive isolation is used between the modules. After all switches are turned on, all modules are discharged in series to generate a fast rising-time high-power square wave pulse. Moreover, repetitive operation is achieved through synchronous control of the trigger switch and charging power supply. In experiments the 22-stage PFN-Marx pulsed power source developed was charges to 51 kV, and a high-voltage square wave pulse of 516 kV was obtained on a load of 84 Ω, with pulse width (FWHM) of 104 ns, flat top of 63 ns and rising-time of 11 ns. This power source can operate stably at a repetition rate of 20 Hz for 15 seconds.
, Available online , doi: 10.11884/HPLPB202436.240022
Abstract:
The repetitive narrow pulse signal generator with a sub-nanosecond front, high-voltage amplitude, and approximately Gaussian single-cycle waveform is extensively applied in areas such as ultra-wideband detection and electromagnetic compatibility testing. This paper introduces the design of an all-solid-state repetitive pulse generator utilizing a Marx circuit architecture, which incorporates components like mica capacitors, avalanche transistors, surface-mount technology resistors, and inductors. To meet the signal output specifications, the printed circuit board layout and microstrip lines have been optimized. Through fine-tuning the matching circuit element parameters, the generator successfully delivers a unipolar negative pulse signal with a peak value of approximately 1 kV, a pulse width of around 650 ps, a leading edge of approximately 450 ps, and a trailing edge of about 700 ps across a 50 Ω resistive load. The resulting pulse waveform exhibits similar, smooth, and steep leading and trailing edges, achieving a repetition rate of 10 kHz. Both the peak value and full width at half maximum jitters are maintained at less than 10%.
The repetitive narrow pulse signal generator with a sub-nanosecond front, high-voltage amplitude, and approximately Gaussian single-cycle waveform is extensively applied in areas such as ultra-wideband detection and electromagnetic compatibility testing. This paper introduces the design of an all-solid-state repetitive pulse generator utilizing a Marx circuit architecture, which incorporates components like mica capacitors, avalanche transistors, surface-mount technology resistors, and inductors. To meet the signal output specifications, the printed circuit board layout and microstrip lines have been optimized. Through fine-tuning the matching circuit element parameters, the generator successfully delivers a unipolar negative pulse signal with a peak value of approximately 1 kV, a pulse width of around 650 ps, a leading edge of approximately 450 ps, and a trailing edge of about 700 ps across a 50 Ω resistive load. The resulting pulse waveform exhibits similar, smooth, and steep leading and trailing edges, achieving a repetition rate of 10 kHz. Both the peak value and full width at half maximum jitters are maintained at less than 10%.
, Available online , doi: 10.11884/HPLPB202436.230285
Abstract:
This article investigates the Ricker pulse to address the issue of low radiation efficiency in time-domain antennas. Firstly, it highlights the high center frequency of the Ricker pulse, which is advantageous for improving antenna radiation efficiency. This article then proceeds to explain the power synthesis method for generating Ricker pulses, starting with precise time delay control. It describes the design of a unipolar pulse and the optimization of its falling edge using the sharpening capacitor method. With this unipolar pulse as a foundation, a Ricker pulse is designed, featuring a peak-to-peak value of 5.1 kV, a main peak half-width of 350 ps, and a center frequency of 0.5 GHz. To verify the correctness of the analysis, the article proposes a simple method to calculate the radiation efficiency of all-metal time-domain antennas. Both the designed Ricker pulse and a single-pole pulse with the same pulse width are used to excite the same antenna. The results demonstrate that the amplitude radiation efficiency of the single-pole pulse is only about 60%. In contrast, the Ricker pulse achieves over 80% efficiency. Similarly, the power radiation efficiency of the single-pole pulse is less than 40%, while the Ricker pulse can exceed 60% efficiency. This article derives a theoretical formula for the optimal delay of synthesizing high-order Gaussian pulses and proposes a simplified method for calculating the time-domain radiation efficiency of all-metal antennas. The utilization of Ricker pulses as excitation has proven to be highly effective in enhancing the radiation efficiency of antennas, thereby minimizing the potential damage to transmission systems caused by reflected power. Additionally, this technique holds immense value in antenna miniaturization and exhibits promising applications in time-domain technologies like ground penetrating radar and high-power microwave sources.
This article investigates the Ricker pulse to address the issue of low radiation efficiency in time-domain antennas. Firstly, it highlights the high center frequency of the Ricker pulse, which is advantageous for improving antenna radiation efficiency. This article then proceeds to explain the power synthesis method for generating Ricker pulses, starting with precise time delay control. It describes the design of a unipolar pulse and the optimization of its falling edge using the sharpening capacitor method. With this unipolar pulse as a foundation, a Ricker pulse is designed, featuring a peak-to-peak value of 5.1 kV, a main peak half-width of 350 ps, and a center frequency of 0.5 GHz. To verify the correctness of the analysis, the article proposes a simple method to calculate the radiation efficiency of all-metal time-domain antennas. Both the designed Ricker pulse and a single-pole pulse with the same pulse width are used to excite the same antenna. The results demonstrate that the amplitude radiation efficiency of the single-pole pulse is only about 60%. In contrast, the Ricker pulse achieves over 80% efficiency. Similarly, the power radiation efficiency of the single-pole pulse is less than 40%, while the Ricker pulse can exceed 60% efficiency. This article derives a theoretical formula for the optimal delay of synthesizing high-order Gaussian pulses and proposes a simplified method for calculating the time-domain radiation efficiency of all-metal antennas. The utilization of Ricker pulses as excitation has proven to be highly effective in enhancing the radiation efficiency of antennas, thereby minimizing the potential damage to transmission systems caused by reflected power. Additionally, this technique holds immense value in antenna miniaturization and exhibits promising applications in time-domain technologies like ground penetrating radar and high-power microwave sources.
, Available online , doi: 10.11884/HPLPB202436.230422
Abstract:
To investigate the spatial distribution characteristics of active particles in atmospheric pressure pulse driven plasma jet, a coaxial double ring plasma jet reactor was used. Under external pulsed power excitation, the relative intensity changes of characteristic peaks of each active particle in different ionization regions along the axial space were studied. The results show that active particle characteristic peaks such as NO, OH, N2, N2+, He, can be detected at all measurement points of the pulse excited plasma jet, with the emission spectral bands and characteristic peaks corresponding to OH, N2, N2+ particles being more significant; In the upstream ionization section between the high-voltage electrode and the grounding electrode, the relative intensities of characteristic peaks of active particles NO, OH and N2 are higher near the high-voltage electrode and grounding electrode, while lower in the middle of the upstream ionization section. The relative intensities of characteristic peaks of different levels of He and N2+ gradually decrease along the airflow direction; In the midstream ionization section from the grounding electrode to the reactor nozzle, the axial distribution of relative intensities of active particles NO, OH and characteristic peaks of different energy levels N2, N2+ and He shows a gradually decreasing trend with the direction of the airflow; In the downstream ionization section from the reactor nozzle to the end of the plasma jet, the axial distribution of the relative intensity of the characteristic peaks of active particles OH and NO gradually weakens with the direction of gas flow. The relative intensity of the characteristic peaks of different energy levels N2, N2+ and He shows a pattern of first increasing and then decreasing, providing strong support for the in-depth study of the energy transfer process and reaction mechanism of pulse driven plasma jet.
To investigate the spatial distribution characteristics of active particles in atmospheric pressure pulse driven plasma jet, a coaxial double ring plasma jet reactor was used. Under external pulsed power excitation, the relative intensity changes of characteristic peaks of each active particle in different ionization regions along the axial space were studied. The results show that active particle characteristic peaks such as NO, OH, N2, N2+, He, can be detected at all measurement points of the pulse excited plasma jet, with the emission spectral bands and characteristic peaks corresponding to OH, N2, N2+ particles being more significant; In the upstream ionization section between the high-voltage electrode and the grounding electrode, the relative intensities of characteristic peaks of active particles NO, OH and N2 are higher near the high-voltage electrode and grounding electrode, while lower in the middle of the upstream ionization section. The relative intensities of characteristic peaks of different levels of He and N2+ gradually decrease along the airflow direction; In the midstream ionization section from the grounding electrode to the reactor nozzle, the axial distribution of relative intensities of active particles NO, OH and characteristic peaks of different energy levels N2, N2+ and He shows a gradually decreasing trend with the direction of the airflow; In the downstream ionization section from the reactor nozzle to the end of the plasma jet, the axial distribution of the relative intensity of the characteristic peaks of active particles OH and NO gradually weakens with the direction of gas flow. The relative intensity of the characteristic peaks of different energy levels N2, N2+ and He shows a pattern of first increasing and then decreasing, providing strong support for the in-depth study of the energy transfer process and reaction mechanism of pulse driven plasma jet.
, Available online , doi: 10.11884/HPLPB202436.230341
Abstract:
An off-line calibration platform is designed based on the requirement of off-line calibration of induction cavity azimuthal transmission line current probe.The analog device is a flat-plate transmission line structure, which has lower distortion than on-line calibration.The source of cross-platform calibration error is analyzed, and the measures to reduce the error are put forward.The analysis shows that the installation eccentricity and probe longitudinal installation depth are the biggest sources of cross-platform calibration error, which need to be paid attention to in engineering design. An off-line calibration platform is established and the error analysis is carried out. The result of 3.3% cross-platform calibration error is obtained.
An off-line calibration platform is designed based on the requirement of off-line calibration of induction cavity azimuthal transmission line current probe.The analog device is a flat-plate transmission line structure, which has lower distortion than on-line calibration.The source of cross-platform calibration error is analyzed, and the measures to reduce the error are put forward.The analysis shows that the installation eccentricity and probe longitudinal installation depth are the biggest sources of cross-platform calibration error, which need to be paid attention to in engineering design. An off-line calibration platform is established and the error analysis is carried out. The result of 3.3% cross-platform calibration error is obtained.
, Available online , doi: 10.11884/HPLPB202436.240031
Abstract:
The adder topology solid state modulator is a device that uses insulated gate bipolar transistors (IGBTs) to discharge the stored energy of capacitors to generate high voltage pulses. Compared with pulse forming network (PFN) type modulator, it has lots of advantages such as modularity, good stability, and long lifespan. However, the normal operation of IGBT requires the use of gate drive circuit to amplify the control signal, and the performance of the drive circuit directly affects the switching characteristics of the IGBT, ultimately affecting the quality of pulse voltage. Especially the turn-on jitter index of the drive circuit, which is one of the key factors affecting the pulse voltage repetition precision. Based on the operating characteristics of IGBT in the adder topology solid state modulator, the drive circuit was studied with the goal of improving pulse voltage repetition precision. The impact of turn-on jitter on voltage repetition precision was analyzed, the design principle was introduced, the drive circuit board was developed, and its working performance was experimentally tested using a discharge module. The test results indicate that the turn-on jitter of the drive circuit is 300 ps, which is three times better than commercial driving circuits. At the charging voltage of 1 kV, the discharge module discharges on a 0.5 Ω load, forming a pulse voltage with the rise time of 500 ns and the peak-to-peak value of turn-on jitter below 5 ns. When the desaturation fault occurs, the drive circuit can turn off the IGBT within 4 µs. This drive circuit meets the working requirements of high pulse repetition precision solid state modulators.
The adder topology solid state modulator is a device that uses insulated gate bipolar transistors (IGBTs) to discharge the stored energy of capacitors to generate high voltage pulses. Compared with pulse forming network (PFN) type modulator, it has lots of advantages such as modularity, good stability, and long lifespan. However, the normal operation of IGBT requires the use of gate drive circuit to amplify the control signal, and the performance of the drive circuit directly affects the switching characteristics of the IGBT, ultimately affecting the quality of pulse voltage. Especially the turn-on jitter index of the drive circuit, which is one of the key factors affecting the pulse voltage repetition precision. Based on the operating characteristics of IGBT in the adder topology solid state modulator, the drive circuit was studied with the goal of improving pulse voltage repetition precision. The impact of turn-on jitter on voltage repetition precision was analyzed, the design principle was introduced, the drive circuit board was developed, and its working performance was experimentally tested using a discharge module. The test results indicate that the turn-on jitter of the drive circuit is 300 ps, which is three times better than commercial driving circuits. At the charging voltage of 1 kV, the discharge module discharges on a 0.5 Ω load, forming a pulse voltage with the rise time of 500 ns and the peak-to-peak value of turn-on jitter below 5 ns. When the desaturation fault occurs, the drive circuit can turn off the IGBT within 4 µs. This drive circuit meets the working requirements of high pulse repetition precision solid state modulators.
, Available online , doi: 10.11884/HPLPB202436.230306
Abstract:
With the increasing and extensive applications of high-voltage nanosecond solid-state pulse generators in various fields such as biology, industry, and environment, the pulse waveform, voltage amplitude, pulse duration, and pulse repetition frequency have become essential controllable variables for specific pulse power applications. To further reduce the size and cost of the pulsed power supply, a high-voltage nanosecond pulse modulator with high repetition frequency is proposed with positive Marx circuit, drivers with multiple pulse transformers as the core, and ns rising time. This driver enables the design of a high-voltage nanosecond pulse modulator with ns-level rise time and high repetition frequency. The proposed driver features a compact structure and eliminates the need for multiple isolated power supplies for driving. It allows the gate voltage of two MOSFETs to rise and fall rapidly and synchronously at a high repetition frequency, enabling the generation of gate voltage with controllable amplitude within one hundred nanoseconds. In the case, not only is the maximum pulse width not limited by the magnetic core saturation, but also the negative bias voltage makes switch can be reliably turned off, improving the reliability of the circuit. In addition, the influence of different turns and magnetic core materials on the driving waveform is studied. A 14-stage pulse modulator prototype is developed. Test results show that the output voltage and pulse width of the modulator based on the drivers are continuously adjustable, with the ability to change the pulse profile. The maximum output voltage reaches 5.5 kV with 100 ns to 50 ms width, minimum rise time of approximately 18 ns, and a continuous repetition frequency of 100 kHz.
With the increasing and extensive applications of high-voltage nanosecond solid-state pulse generators in various fields such as biology, industry, and environment, the pulse waveform, voltage amplitude, pulse duration, and pulse repetition frequency have become essential controllable variables for specific pulse power applications. To further reduce the size and cost of the pulsed power supply, a high-voltage nanosecond pulse modulator with high repetition frequency is proposed with positive Marx circuit, drivers with multiple pulse transformers as the core, and ns rising time. This driver enables the design of a high-voltage nanosecond pulse modulator with ns-level rise time and high repetition frequency. The proposed driver features a compact structure and eliminates the need for multiple isolated power supplies for driving. It allows the gate voltage of two MOSFETs to rise and fall rapidly and synchronously at a high repetition frequency, enabling the generation of gate voltage with controllable amplitude within one hundred nanoseconds. In the case, not only is the maximum pulse width not limited by the magnetic core saturation, but also the negative bias voltage makes switch can be reliably turned off, improving the reliability of the circuit. In addition, the influence of different turns and magnetic core materials on the driving waveform is studied. A 14-stage pulse modulator prototype is developed. Test results show that the output voltage and pulse width of the modulator based on the drivers are continuously adjustable, with the ability to change the pulse profile. The maximum output voltage reaches 5.5 kV with 100 ns to 50 ms width, minimum rise time of approximately 18 ns, and a continuous repetition frequency of 100 kHz.
, Available online , doi: 10.11884/HPLPB202436.230426
Abstract:
Large-scale coherent beam combining is one of the effective techniques to break through the limit of a single laser, and obtain extreme characteristics laser such as ultra-high peak/average power, ultra-high pulse energy, ultra-high spatial/spectral brightness, and the key to large-scale coherent beam combining is active phase control. Active phase control technology can control the phase of each beam actively, compensate for coherence degradation and efficiency reduction caused by phase noise, and realize high-quality combined laser. Since the proposal of coherent beam combining technology, researchers have developed a variety of active phase control methods for phase correction, among which active phase control methods suitable for large-scale coherent laser beam combining have developed rapidly. In this paper, active phase control methods for large-scale coherent laser beam combining are systematically reviewed, and the principles, characteristics, application scenarios and expansibilities of different methods are analyzed. The latest progress and landmark achievements of coherent beam combining achieved by various active phase control methods are introduced, and the breakthrough result of 6 μs closed-loop locking time for 19-channel coherent beam combining has been reported for the first time. the future development trend of large-scale active phase control methods is predicted.
Large-scale coherent beam combining is one of the effective techniques to break through the limit of a single laser, and obtain extreme characteristics laser such as ultra-high peak/average power, ultra-high pulse energy, ultra-high spatial/spectral brightness, and the key to large-scale coherent beam combining is active phase control. Active phase control technology can control the phase of each beam actively, compensate for coherence degradation and efficiency reduction caused by phase noise, and realize high-quality combined laser. Since the proposal of coherent beam combining technology, researchers have developed a variety of active phase control methods for phase correction, among which active phase control methods suitable for large-scale coherent laser beam combining have developed rapidly. In this paper, active phase control methods for large-scale coherent laser beam combining are systematically reviewed, and the principles, characteristics, application scenarios and expansibilities of different methods are analyzed. The latest progress and landmark achievements of coherent beam combining achieved by various active phase control methods are introduced, and the breakthrough result of 6 μs closed-loop locking time for 19-channel coherent beam combining has been reported for the first time. the future development trend of large-scale active phase control methods is predicted.
, Available online , doi: 10.11884/HPLPB202436.240010
Abstract:
The preparation of Tb3Al5O12 (TAG) phosphors was achieved through the sol-gel method. Thermal analysis data confirm that an increase in the H3BO3 molar ratio correlates with a reduction in the transition temperature of the final phase. Concurrently, scanning electron microscopy revealed that an elevated H3BO3 molar ratio results in larger phosphor particle sizes. Under the excitation wavelength of 275 nm, the emission spectrum manifests multiple peaks within the 480-650 nm range, originating from the 5d→4f transitions of Tb3+ ions. Subsequently, the phosphor@SiO2 aerogel composite luminescent material was successfully synthesized through a combination of physical doping and a supercritical drying process. This composite luminescent material exhibited a substantial increase in the internal quantum yield, reaching 63.64% compared to the standalone phosphor. Excited by a 355 nm laser source, the phosphor@SiO2 aerogel composite luminescent material demonstrated the capability for wire-free, long-distance luminescence with commendable uniformity. These findings demonstrate the potential application prospects of the phosphor@SiO2 aerogel composite luminescent material in the domain of laser emergency lighting.
The preparation of Tb3Al5O12 (TAG) phosphors was achieved through the sol-gel method. Thermal analysis data confirm that an increase in the H3BO3 molar ratio correlates with a reduction in the transition temperature of the final phase. Concurrently, scanning electron microscopy revealed that an elevated H3BO3 molar ratio results in larger phosphor particle sizes. Under the excitation wavelength of 275 nm, the emission spectrum manifests multiple peaks within the 480-650 nm range, originating from the 5d→4f transitions of Tb3+ ions. Subsequently, the phosphor@SiO2 aerogel composite luminescent material was successfully synthesized through a combination of physical doping and a supercritical drying process. This composite luminescent material exhibited a substantial increase in the internal quantum yield, reaching 63.64% compared to the standalone phosphor. Excited by a 355 nm laser source, the phosphor@SiO2 aerogel composite luminescent material demonstrated the capability for wire-free, long-distance luminescence with commendable uniformity. These findings demonstrate the potential application prospects of the phosphor@SiO2 aerogel composite luminescent material in the domain of laser emergency lighting.
, Available online , doi: 10.11884/HPLPB202436.230430
Abstract:
The combination of deep learning technology and adaptive optics technology is expected to effectively improve the wavefront correction effect and better cope with more complex environmental conditions. The research progress of applying deep learning in the direction of wavefront reconstruction and wavefront prediction is detailed, including the specific research methods and corresponding neural network structure design adopted by the researchers in these two research directions, and the performance of these neural networks in different practical application scenarios is analyzed, and the differences between the different neural network structures are compared and discussed, and the specific impacts of the structural differences are explored. The differences between the different neural network structures are compared and discussed, and the specific impacts brought by the structural differences are explored. Finally, the existing methods of deep learning in these two directions are summarized, and the future development trend of the deep integration of deep learning and adaptive optics technology is also prospected.
The combination of deep learning technology and adaptive optics technology is expected to effectively improve the wavefront correction effect and better cope with more complex environmental conditions. The research progress of applying deep learning in the direction of wavefront reconstruction and wavefront prediction is detailed, including the specific research methods and corresponding neural network structure design adopted by the researchers in these two research directions, and the performance of these neural networks in different practical application scenarios is analyzed, and the differences between the different neural network structures are compared and discussed, and the specific impacts of the structural differences are explored. The differences between the different neural network structures are compared and discussed, and the specific impacts brought by the structural differences are explored. Finally, the existing methods of deep learning in these two directions are summarized, and the future development trend of the deep integration of deep learning and adaptive optics technology is also prospected.
, Available online , doi: 10.11884/HPLPB202436.230408
Abstract:
As the first stage of severe accidents in sodium cooled fast reactors, accurate prediction of the occurrence time and location of coolant boiling is of great significance for the safety assessment of Sodium Cooled Fast Reactors (SFR). Based on a two fluid six equation model, conservation equations are constructed for the gas-liquid two-phase flow of sodium. The evaporation-condensation model is used to characterize the interphase mass exchange, and explicit and implicit methods are used to calculate evaporation-condensation model. Constitutive relationships such as Sobolev resistance model, two phase flow heat transfer model, and phase momentum exchange are considered. A porous medium analysis approach which is suitable for simulating SFR coolant boiling was developed, and comparative verification was conducted using KNS-37 L22 loss of flow experiment data. L29 flow data is used to verify the applicability of the model. The results indicate that the established sodium boiling porous medium analysis approach can effectively simulate the boiling phenomenon. It predicts that the boiling time will be around 6.3 seconds, which is 0.2 seconds different from the experiment. The overall trend of temperature and flow rate changes are in good agreement with experimental data.
As the first stage of severe accidents in sodium cooled fast reactors, accurate prediction of the occurrence time and location of coolant boiling is of great significance for the safety assessment of Sodium Cooled Fast Reactors (SFR). Based on a two fluid six equation model, conservation equations are constructed for the gas-liquid two-phase flow of sodium. The evaporation-condensation model is used to characterize the interphase mass exchange, and explicit and implicit methods are used to calculate evaporation-condensation model. Constitutive relationships such as Sobolev resistance model, two phase flow heat transfer model, and phase momentum exchange are considered. A porous medium analysis approach which is suitable for simulating SFR coolant boiling was developed, and comparative verification was conducted using KNS-37 L22 loss of flow experiment data. L29 flow data is used to verify the applicability of the model. The results indicate that the established sodium boiling porous medium analysis approach can effectively simulate the boiling phenomenon. It predicts that the boiling time will be around 6.3 seconds, which is 0.2 seconds different from the experiment. The overall trend of temperature and flow rate changes are in good agreement with experimental data.
, Available online , doi: 10.11884/HPLPB202436.230357
Abstract:
Lead cooled fast reactor has obvious advantages in fuel proliferation and nuclear waste treatment. For the Europe Lead-cooled System(ELSY), based on the “two-step method”, Monte Carlo software is used to generate few group component parameters, and after section correction, it is passed to the determining theory program MORPHY for core calculation. The effects of section modification and angle development order on the calculation accuracy were analyzed, and the effective multiplication factor, normalized flux level and control rod value of the ELSY core were quantified and compared. For different examples, transport correction and neutron multiplication effect correction were adopted, and the core calculation was developed with S4 order. The maximum deviation of effective multiplication factor was 38×10−5, the calculation deviation of control rod value was within 45×10−5, the maximum absolute deviation of normalized neutron flux density was 9.73%, and the average absolute deviation was less than 2%. The feasibility of MORPHY program in the physical analysis of lead-cooled fast reactor is preliminarily verified, which is of reference significance for the subsequent development and use of the program.
Lead cooled fast reactor has obvious advantages in fuel proliferation and nuclear waste treatment. For the Europe Lead-cooled System(ELSY), based on the “two-step method”, Monte Carlo software is used to generate few group component parameters, and after section correction, it is passed to the determining theory program MORPHY for core calculation. The effects of section modification and angle development order on the calculation accuracy were analyzed, and the effective multiplication factor, normalized flux level and control rod value of the ELSY core were quantified and compared. For different examples, transport correction and neutron multiplication effect correction were adopted, and the core calculation was developed with S4 order. The maximum deviation of effective multiplication factor was 38×10−5, the calculation deviation of control rod value was within 45×10−5, the maximum absolute deviation of normalized neutron flux density was 9.73%, and the average absolute deviation was less than 2%. The feasibility of MORPHY program in the physical analysis of lead-cooled fast reactor is preliminarily verified, which is of reference significance for the subsequent development and use of the program.
