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, Available online , doi: 10.11884/HPLPB202436.240093
Abstract:
To improve the low frequency radiation characteristics of the radiating-wave simulator based on transverse electromagnetic (TEM) horn, a novel movable simulator made up of exponential-type TEM horn, two vertical perfect electric conductor (PEC) plates at its aperture, two sloping PEC plates and parallel resistance is designed firstly. The effect of different exponential tapered rates, the height of the two vertical PEC plates, the width of the source port and the parallel resistance at the end of two sloping PEC plates to the near-field radiation performance of the novel simulator is simulated and optimized by finite-difference time-domain (FDTD) method. The radiation characteristics of the optimized novel simulator and its arrays is also given. The calculation results show that, the full width at half maximum (FWHM) of the electric field at the testing point which is 3 m away from the optimized novel simulator’s aperture center reaches 18.95 ns, and the optimized novel simulator’s sizes is 6 m×6 m×6.24 m while the normal simulator’s sizes must be 9 m×12 m×6.8 m to get the same low-frequency radiation performance as that of the optimized novel simulator. And higher peak-value of the electric field at the testing point of the optimized novel simulator can be got compared with the normal simulator. In addition, the ratio of the delayed oscillation’s amplitude of the electric field in time-domain at the testing point of the optimized novel simulator to its peak-value is significantly reduced compared with that of the previous studies, while the peak-value of the testing point of the optimized novel simulator keeps high. The electric field’s peak value at the center point in the testing plane of the optimized novel simulator’s 2 × 2 array model is the largest, and the effective region meeting the requirement of field 6dB uniformity on the testing plane of 2 × 2 array model has the largest domain; The effective region on the 2 × 2 array model’s testing plane has the largest horizontal range, followed by 2 × 1 array model; The effective regions on the testing planes of 2 × 2 array model and 1×2 array model have the largest vertical range.
To improve the low frequency radiation characteristics of the radiating-wave simulator based on transverse electromagnetic (TEM) horn, a novel movable simulator made up of exponential-type TEM horn, two vertical perfect electric conductor (PEC) plates at its aperture, two sloping PEC plates and parallel resistance is designed firstly. The effect of different exponential tapered rates, the height of the two vertical PEC plates, the width of the source port and the parallel resistance at the end of two sloping PEC plates to the near-field radiation performance of the novel simulator is simulated and optimized by finite-difference time-domain (FDTD) method. The radiation characteristics of the optimized novel simulator and its arrays is also given. The calculation results show that, the full width at half maximum (FWHM) of the electric field at the testing point which is 3 m away from the optimized novel simulator’s aperture center reaches 18.95 ns, and the optimized novel simulator’s sizes is 6 m×6 m×6.24 m while the normal simulator’s sizes must be 9 m×12 m×6.8 m to get the same low-frequency radiation performance as that of the optimized novel simulator. And higher peak-value of the electric field at the testing point of the optimized novel simulator can be got compared with the normal simulator. In addition, the ratio of the delayed oscillation’s amplitude of the electric field in time-domain at the testing point of the optimized novel simulator to its peak-value is significantly reduced compared with that of the previous studies, while the peak-value of the testing point of the optimized novel simulator keeps high. The electric field’s peak value at the center point in the testing plane of the optimized novel simulator’s 2 × 2 array model is the largest, and the effective region meeting the requirement of field 6dB uniformity on the testing plane of 2 × 2 array model has the largest domain; The effective region on the 2 × 2 array model’s testing plane has the largest horizontal range, followed by 2 × 1 array model; The effective regions on the testing planes of 2 × 2 array model and 1×2 array model have the largest vertical range.
, 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.
Scattering correction method of cone-beam X-ray CT based on slanted hole scattering correction plate
, Available online , doi: 10.11884/HPLPB202436.230362
Abstract:
Compared with two-dimensional fan-beam and parallel-beam CT systems, cone-beam X-ray CT has advantages such as fast scanning speed, high X-ray utilization efficiency, consistent axial and horizontal resolution of reconstructed images, and is the focus of current industrial CT technology development. However, the imaging quality is affected by the presence of scattered radiation. In order to reduce the impact of scattered radiation on image quality, this paper proposes a new scatter correction method based on an slanted hole scatter correction plate. The principle and implementation of this method are thoroughly investigated. By acquiring raw scan data and scan data after using the slanted hole scatter correction plate, scatter field data is obtained using interpolation and smoothing techniques. Then, by subtracting the scatter field data from the original data and performing reconstruction, scatter-free CT images can be obtained. Compared with the grating-based scatter correction plate method, the results show that when applied to cone-beam CT scans of turbine blades, the contrast-to-noise ratio of typical regions (cooling channels within the blades and inner walls of the blades) is improved by 14.2% and 56.8% respectively with the slanted hole scatter correction plate method, whereas with the grating-based scatter correction plate method, the same positions only show an improvement of 5.6% and 27.6% respectively. This validates the superiority of the slanted hole scatter correction plate scatter correction method.
Compared with two-dimensional fan-beam and parallel-beam CT systems, cone-beam X-ray CT has advantages such as fast scanning speed, high X-ray utilization efficiency, consistent axial and horizontal resolution of reconstructed images, and is the focus of current industrial CT technology development. However, the imaging quality is affected by the presence of scattered radiation. In order to reduce the impact of scattered radiation on image quality, this paper proposes a new scatter correction method based on an slanted hole scatter correction plate. The principle and implementation of this method are thoroughly investigated. By acquiring raw scan data and scan data after using the slanted hole scatter correction plate, scatter field data is obtained using interpolation and smoothing techniques. Then, by subtracting the scatter field data from the original data and performing reconstruction, scatter-free CT images can be obtained. Compared with the grating-based scatter correction plate method, the results show that when applied to cone-beam CT scans of turbine blades, the contrast-to-noise ratio of typical regions (cooling channels within the blades and inner walls of the blades) is improved by 14.2% and 56.8% respectively with the slanted hole scatter correction plate method, whereas with the grating-based scatter correction plate method, the same positions only show an improvement of 5.6% and 27.6% respectively. This validates the superiority of the slanted hole scatter correction plate scatter correction method.
, Available online , doi: 10.11884/HPLPB202436.230374
Abstract:
LINAC control network is the reference for optical axis transmission. According to the layout of key equipment in LINAC tunnel, the control network is laid out on the ground and wall of the tunnel. Tracker is the main instrument for measuring LINAC control network, and the angle measurement error is a key factor affecting the accuracy of the tracker. Based on the layout of wall and ground network points and the measurement plan, laser tracker’s angles were decomposed horizontal and vertical angles in all measurement states. Then, through the linkage testing of high-precision CMM and laser trackers, all the decomposed angles were calculated, and the calculated values are used to correct the tracker’s measurement angles. Based on the test results, regardless of the measurement state, measured angle of the tracker is larger than the calculated value. The ground network points’ vertical angle deviation and horizontal angle deviation almost equal to the nominal accuracy of the tracker. When the horizontal angle of wall points exceeds 15 degree, deviation increase significantly, and the deviation should be corrected while measuring the wall network points.
LINAC control network is the reference for optical axis transmission. According to the layout of key equipment in LINAC tunnel, the control network is laid out on the ground and wall of the tunnel. Tracker is the main instrument for measuring LINAC control network, and the angle measurement error is a key factor affecting the accuracy of the tracker. Based on the layout of wall and ground network points and the measurement plan, laser tracker’s angles were decomposed horizontal and vertical angles in all measurement states. Then, through the linkage testing of high-precision CMM and laser trackers, all the decomposed angles were calculated, and the calculated values are used to correct the tracker’s measurement angles. Based on the test results, regardless of the measurement state, measured angle of the tracker is larger than the calculated value. The ground network points’ vertical angle deviation and horizontal angle deviation almost equal to the nominal accuracy of the tracker. When the horizontal angle of wall points exceeds 15 degree, deviation increase significantly, and the deviation should be corrected while measuring the wall network points.
, 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/HPLPB202436.230444
Abstract:
During the commissioning of the primary helium circulator of the high-temperature gas-cooled reactor (HTGR), it could not complete the performance test of the full speed range, because the resistance of the primary loop was lower than the design condition. Based on the theoretical characteristics of the primary helium circulator and similar principles, a method for calculating the commission parameters of the primary helium circulator under different resistance conditions is developed. Combined with the monomeric test operating points of the primary helium circulator, accurately calculated the operating point parameters of the cold and hot performance tests of the primary helium circulator, and guided the completion of the full speed and full power performance tests of the primary helium circulator in HTGR. By comparing and analyzing the commission and factory test results of the primary helium circulator, the feasibility of this calculation method is verified, and provide correction factors for the conversion of working conditions between air medium and helium medium. Through comparing and analyzing the commission and operation data of the primary helium circulator, it can be seen that the commission conditions provided in this article have sufficient enveloping ability, which can cover all operating conditions of the primary helium circulator during the operation of HTGR. This proves that the variable resistance condition commission method of the primary helium circulator meets the performance verification requirements of HTGR, and it can be used to guide the primary helium circulator commission of subsequent HTGR.
During the commissioning of the primary helium circulator of the high-temperature gas-cooled reactor (HTGR), it could not complete the performance test of the full speed range, because the resistance of the primary loop was lower than the design condition. Based on the theoretical characteristics of the primary helium circulator and similar principles, a method for calculating the commission parameters of the primary helium circulator under different resistance conditions is developed. Combined with the monomeric test operating points of the primary helium circulator, accurately calculated the operating point parameters of the cold and hot performance tests of the primary helium circulator, and guided the completion of the full speed and full power performance tests of the primary helium circulator in HTGR. By comparing and analyzing the commission and factory test results of the primary helium circulator, the feasibility of this calculation method is verified, and provide correction factors for the conversion of working conditions between air medium and helium medium. Through comparing and analyzing the commission and operation data of the primary helium circulator, it can be seen that the commission conditions provided in this article have sufficient enveloping ability, which can cover all operating conditions of the primary helium circulator during the operation of HTGR. This proves that the variable resistance condition commission method of the primary helium circulator meets the performance verification requirements of HTGR, and it can be used to guide the primary helium circulator commission of subsequent HTGR.
, 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/HPLPB202436.240048
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/HPLPB202436.230436
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/HPLPB202436.240001
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/HPLPB202436.230426
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/HPLPB202436.230430
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.
