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Monte Carlo simulation of neutron sensitivity of microfission chamber in neutron flux measurement

Nuclear Science and Techniques 2022年第6期33卷 128-138页

作者： Ze-Peng Wu Xin-Biao Jiang Wen-Shou Zhang Chun-Lei Su Yong-Gang Zhang-Sun Li-Hong Bao State Key Laboratory of Simulation and Effect for Intense Pulse Radiation Northwest Institute of Nuclear TechnologyXi’an 710024China

Microfission chambers loaded with highly enriched fissile materials are widely used for measuring power in reactors. The neutron sensitivity of the microfission chamber is a key parameter that determines the accuracy of the power measurement. To evaluate the performance of the FC4A microfission chamber, in this work, we introduced an accurate and validated model of the microfission chamber, a performed Monte Carlo simulation of the neutron sensitivity of the microfission chamber with GEANT4 code, and conducted an irradiation experiment on the neutron irradiation effect platform #3 of the Xi’an pulsed Reactor. We compared the simulated sensitivity with the experimental results, which showed that the sensitivity obtained from the simulation was in good agreement with the experimental results. In addition, we studied the impact of the design parameters of the fission chamber on the calculated neutron sensitivity of the microfission chamber.

关键词： Microfission chamber Neutron sensitivity Monte Carlo simulation GEANT4

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A novel method for multichannel discharge image diagnosis in gas switches based on multi-axis tomography techniques

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Plasma Science and Technology 2023年第6期25卷 65-71页

作者：张艳红盛亮李阳张美黑东炜 State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear TechnologyXi'an 710024People's Republic of China

The discharge channel is a crucial diagnostic tool for identifying the properties of gas ***,single-view images cannot easily be used to inherently understand the discharge channel characteristics of trigger electrodes.A reconstruction method of the discharge channel in gas switches is proposed based on a multi-axis tomography technique,which uses very few projections of optical images to reconstruct the location of a multichannel discharge in annular *** this paper,an algorithm named TVM-OSEM(total variation minimization ordered subsets expectation maximization)is proposed,which can effectively remove artifact noise to improve the reconstruction accuracy of discharge *** method is validated against simulations of a radiator with high-density-difference *** calculated discharge channel distribution from one experiment is presented.

关键词： discharge channel TVM-OSEM gas switch location

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A 3D Mach-Zehnder Time-Domain EO Sensor for the EMP Measurement

A 3D Mach-Zehnder Time-Domain EO Sensor for the EMP Measurem...

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2024 Photonics and Electromagnetics Research Symposium, PIERS 2024

作者： Shi, Yuewu Chen, Wei Nie, Xin Wu, Wei Wang, Wei Miao, Jianguo North West Institute of Nuclear Technology National Key Laboratory of Intense Pulse Radiation Environment Simulation and Effect Xi'an710024 China

ISBN: (纸本)9798350375909

A three-dimensional (3D) Mach-Zehnder electro-optical sensor for the measurement of electromagnetic pulse (EMP) is designed and fabricated. The Mach-Zehnder modulation structure based on LiNbO3 is used for the design of 3D sensor. Based on a tapered dipole patch antenna model, the electrode and antenna integrated structure is designed. The characteristic of the antennas are simulated and the structure parameters are determined based on CST. The size of the main structure of the fabricated 3D sensor is less than 10 cm × 6 cm × 6 cm. The test results show that the rise time of the sensor is less than 0.6 ns combined with a 1 GHz photo detector, and the measurement range is ±3 kV/m~ ±100 kV/m. The developed 3D sensor can response well to the nanosecond risetime EMP. © 2024 IEEE.

关键词： Microwave antennas

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3D robust anisotropic diffusion filtering algorithm for sparse view neutron computed tomography 3D image reconstruction

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Nuclear Science and Techniques 2024年第3期35卷 13-29页

作者： Yang Liu Teng-Fei Zhu Zhi Luo Xiao-Ping Ouyang School of Nuclear Science and Engineering North China Electric Power UniversityBeijing 102206China State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an 710024China

The most critical part of a neutron computed tomography(NCT) system is the image processing algorithm,which directly affects the quality and speed of the reconstructed *** types of noise in the system can degrade the quality of the reconstructed ***,to improve the quality of the reconstructed images of NCT systems,efficient image processing algorithms must be *** anisotropic diffusion filtering(ADF) algorithm can not only effectively suppress the noise in the projection data,but also preserve the image edge structure information by reducing the diffusion at the image ***,we propose the application of the ADF algorithm for NCT image *** compare the performance of different algorithms in NCT systems,we reconstructed images using the ordered subset simultaneous algebraic reconstruction technique(OS-SART) algorithm with different regular terms as image processing *** the iterative reconstruction,we selected two image processing algorithms,the Total Variation and split Bregman solved total variation algorithms,for comparison with the performance of the ADF ***,the filtered back-projection algorithm was used for comparison with an iterative *** reconstructing the projection data of the numerical and clock models,we compared and analyzed the effects of each algorithm applied in the NCT *** on the reconstruction results,OS-SART-ADF outperformed the other algorithms in terms of denoising,preserving the edge structure,and suppressing *** example,when the 3D Shepp–Logan was reconstructed at 25 views,the root mean square error of OS-SART-ADF was the smallest among the four iterative algorithms,at only *** universal quality index,mean structural similarity,and correlation coefficient of the reconstructed image were the largest among all algorithms,with values of 0.9877,0.9878,and 0.9887,respectively.

关键词： NCT OS-SART Sparse-view Anisotropic diffusion filtering

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Sparse-view neutron CT 3D image reconstruction algorithm based on split Bregman method

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Nuclear Science and Techniques 2024年第9期35卷 41-55页

作者： Teng-Fei Zhu Yang Liu Zhi Luo Xiao-Ping Ouyang School of Nuclear Science and Engineering North China Electric Power UniversityBeijing 102206China State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an 710024China

As a complement to X-ray computed tomography(CT),neutron tomography has been extensively used in nuclear engineer-ing,materials science,cultural heritage,and industrial *** of the attenuation matrix for neutron tomography with a traditional analytical algorithm requires hundreds of projection views in the range of 0°to 180°and typically takes several hours to *** a low time-resolved resolution degrades the quality of neutron *** the number of projection acquisitions is an important approach to improve the time resolution of images;however,this requires efficient reconstruction ***,sparse-view reconstruction algorithms in neutron tomography need to be *** this study,we investigated the three-dimensional reconstruction algorithm for sparse-view neu-tron CT *** enhance the reconstructed image quality of neutron CT,we propose an algorithm that uses OS-SART to reconstruct images and a split Bregman to solve for the total variation(SBTV).A comparative analysis of the performances of each reconstruction algorithm was performed using simulated and actual experimental *** to the analyzed results,OS-SART-SBTV is superior to the other algorithms in terms of denoising,suppressing artifacts,and preserving detailed structural information of images.

关键词： Neutron CT OS-SART Sparse-view 3D reconstruction Split Bregman Total variation

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effects of Preionization Assembly Structural Parameters on Triggering Performance of Multigap Gas Switch Gaps

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IEEE Transactions on Plasma Science 2025年第4期53卷 729-738页

作者： Wen, Zhenming Wang, Zhiguo Jiang, Xiaofeng Fan, Siyuan Qiu, Aici Xi’an Jiaotong University State Key Laboratory of Electrical Insulation and Power Equipment Xi’an710049 China Northwest Institute of Nuclear Technology State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an710024 China

Developing a gas switch with low jitter is crucial for the linear transformer driver (LTD) bricks and modules to be triggered in the proper sequence. Preionization is an effective approach to enhance the triggering performance of gas switches. This article focuses on a disk-shaped preionization assembly (DPA) and analyzes the impact of variations in the DPA structural parameters (gap spacing d and disk height h) as well as the trigger pulse polarity on the triggering characteristics of multigap gas switch gaps. To, respectively, investigate the influence of preionization on the different types of switch gaps, a two-gap gas switch (TGGS) consisting of one trigger gap and one self-breakdown gap is adopted. The trigger experiments for the separate preionization gap and the TGGS equipped with the DPA are conducted. The experimental results demonstrate that the breakdown delay of the preionization gap with large d exhibits the polarity effect. The polarity effect of the breakdown delay and jitter of the trigger and self-breakdown gaps are opposite. The changes of d and h have reversed influence on the breakdown properties of the two types of switch gaps. Because the self-breakdown gap has greater breakdown delay and jitter than the trigger gap, the overall performance of the TGGS is primarily determined by the former. Employing a DPA with larger h and moderate d and adopting a negative trigger pulse could reduce the trigger delay and jitter of the switch. © 1973-2012 IEEE.

关键词： Structural optimization

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simulation research on electromagnetic pulse coupling surface current measurement 6

Simulation research on electromagnetic pulse coupling surfac...

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6th International Conference on Intelligent Control, Measurement and Signal Processing, ICMSP 2024

作者： Wang, Wenbing Wu, Wei Zhao, Mo Zhou, Yifu State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear Technology Xi'an China

ISBN: (纸本)9798331516550

In order to accurately measure the surface current of the equipment under powerful electromagnetic environment, it is necessary to analyze the theory of surface current density and estimate the measurement method via comprehensive simulation. In this research, firstly, the basic principle of surface current measurement is given, then the field enhancement effect of the detector is analyzed. Based on the electromagnetic simulation software CST, the surface current density distribution of the metal shell is simulated, next, the uniformity of magnetic field on the surface of the shell is provided. Furthermore, it is verified that the existence of surface current detector will lead to field enhancement effect similar to the case of electric field measurement. The variables affecting the enhancement factor is simulated and analyzed in detail. Finally, a conclusion is given. This research can supply technical support for the manufacture and usage of surface current detectors. © 2024 IEEE.

关键词： Magnetic field measurement

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A machine learning approach to TCAD model calibration for MOSFET

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Nuclear Science and Techniques 2023年第12期34卷 133-145页

作者： Bai‑Chuan Wang Chuan‑Xiang Tang Meng‑Tong Qiu Wei Chen Tan Wang Jing‑Yan Xu Li‑Li Ding Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an 710024China

Machine learning-based surrogate models have significant advantages in terms of computing efficiency. In this paper, we present a pilot study on fast calibration using machine learning techniques. Technology computer-aided design(TCAD) is a powerful simulation tool for electronic devices. This simulation tool has been widely used in the research of radiation ***, calibration of TCAD models is time-consuming. In this study, we introduce a fast calibration approach for TCAD model calibration of metal–oxide–semiconductor field-effect transistors(MOSFETs). This approach utilized a machine learning-based surrogate model that was several orders of magnitude faster than the original TCAD simulation. The desired calibration results were obtained within several seconds. In this study, a fundamental model containing 26 parameters is introduced to represent the typical structure of a MOSFET. Classifications were developed to improve the efficiency of the training sample generation. Feature selection techniques were employed to identify important parameters. A surrogate model consisting of a classifier and a regressor was built. A calibration procedure based on the surrogate model was proposed and tested with three calibration goals. Our work demonstrates the feasibility of machine learning-based fast model calibrations for MOSFET. In addition, this study shows that these machine learning techniques learn patterns and correlations from data instead of employing domain expertise. This indicates that machine learning could be an alternative research approach to complement classical physics-based research.

关键词： Machine learning radiation effects Surrogate model TCAD model calibration

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PROGRESS OF LOW-β BPM CALIBRATION BASED ON HELICAL SLOW-WAVE STRUCTURE 13

PROGRESS OF LOW-β BPM CALIBRATION BASED ON HELICAL SLOW-WAV...

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13th International Beam Instrumentation Conference, IBIC 2024

作者： Wang, M.W. Wang, Z.M. Wang, D. Zhuo, X. State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Northwest Institute of Nuclear Technology Xi'an China

ISBN: (纸本)9783954502493

Beam Position Monitors (BPMs) are essential in particle accelerators for the precise measurement of beam trajectories. Considering the inherent inaccuracies in manufacturing and assembly, rigorous offline calibration processes are essential to guarantee the precision of beam position measurements. The predominant calibration technique, specifically the wire test method, is tailored for relativistic beams and is inappropriate for low-β beams. This manuscript introduces an innovative approach employing a helical slow-wave structure to emulate the electromagnetic fields of low-energy beams, thus facilitating the calibration of BPMs for low-β scenarios. Employing a helix-based calibration platform, we conducted the calibration of the nonlinear response of BPMs at the Xi'an Proton Application Facility for a 7 MeV proton beam, with results aligning with the simulation. This advancement expands the precision and range of beam position measurements, substantially enhancing the operation and optimization of particle accelerators. © 2024 International Beam Instrumentation Conference. All Rights Reserved.

关键词： Particle accelerators

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First-order primal-dual algorithm for sparse-view neutron computed tomography-based three-dimensional image reconstruction

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Nuclear Science and Techniques 2023年第8期34卷 35-53页

Neutron computed tomography(NCT)is widely used as a noninvasive measurement technique in nuclear engineering,thermal hydraulics,and cultural *** neutron source intensity of NCT is usually low and the scan time is long,resulting in a projection image containing severe *** reduce the scanning time and increase the image reconstruction quality,an effective reconstruction algorithm must be *** CT image reconstruction,the reconstruction algorithms can be divided into three categories:analytical algorithms,iterative algorithms,and deep *** the analytical algorithm requires complete projection data,it is not suitable for reconstruction in harsh environments,such as strong radia-tion,high temperature,and high *** learning requires large amounts of data and complex models,which cannot be easily deployed,as well as has a high computational complexity and poor ***,this paper proposes the OS-SART-PDTV iterative algorithm,which uses the ordered subset simultaneous algebraic reconstruction technique(OS-SART)algorithm to reconstruct the image and the first-order primal–dual algorithm to solve the total variation(PDTV),for sparse-view NCT three-dimensional *** novel algorithm was compared with other algorithms(FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV)by simulating the experimental data and actual neutron projection *** reconstruction results demonstrate that the proposed algorithm outperforms the FBP,OS-SART-TV,OS-SART-AwTV,and OS-SART-FGPTV algorithms in terms of preserving edge structure,denoising,and suppressing artifacts.

关键词： NCT First-order primal-dual algorithm OS-SART Total variation Sparse-view

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