To further research on high-parameter plasma,we plan to develop a two-dimensional hard X-ray(HXR)imaging system at the HL-3 tokamak to measure HXRs with energies ranging from 20 to 300 keV.The application of an array-...To further research on high-parameter plasma,we plan to develop a two-dimensional hard X-ray(HXR)imaging system at the HL-3 tokamak to measure HXRs with energies ranging from 20 to 300 keV.The application of an array-structured detector ensures that this system can measure HXR-radiation spectra from the entire plasma cross section.Therefore,it is suitable for the study of fast-electron physics,such as radio-frequency wave current drives,fast electrons driving instabilities,and plasma disruptions in fusion research.In this study,we develop a simulation for calculating fast-electron bremsstrahlung in the HL-3 tokamak based on the Monte Carlo simulation code Geant4,in which the plasma geometry and forward scattering of fast-electron bremsstrahlung are considered.The preliminary calculation results indicate that the HXR energy deposi-tion on the detector is symmetrically distributed,even though the plasma distribution is asymmetric owing to the toroidal effect.These simulation results are helpful in constructing the relationship between the energy deposition on the detector and parameter distribution on the plasma cross section during HL-3 experiments.This is beneficial for the reconstruction of the fast-electron-distribution function and for optimizing the design of the HXR-imaging system.展开更多
在核工业的一些工作场所中往往同时存在β射线和γ射线,准确测量β粒子和γ粒子能谱对于相关工作人员的辐射防护十分重要。本文利用Geant4模拟了β粒子和γ粒子在叠层闪烁体探测器中的能量沉积,研究了材料和结构对叠层闪烁体探测器甄别...在核工业的一些工作场所中往往同时存在β射线和γ射线,准确测量β粒子和γ粒子能谱对于相关工作人员的辐射防护十分重要。本文利用Geant4模拟了β粒子和γ粒子在叠层闪烁体探测器中的能量沉积,研究了材料和结构对叠层闪烁体探测器甄别性能的影响。模拟结果显示,对于双层结构的闪烁体探测器,第1层和第2层选用不同材料的闪烁体对β粒子的甄别影响不大,主要影响对γ粒子的甄别。γ粒子的误甄别率和识别率分别随第1层和第2层材料原子序数的增加而增加。3层结构闪烁体探测器对于γ粒子的误甄别率明显低于双层结构,并且γ粒子的误甄别率随第1层闪烁体厚度的增加而增加。经过对模拟结果分析,采用0.2 mm BC-444+17.8 mm BC-444+25 mm BaF_(2)的3层闪烁体结构甄别性能较好,对β粒子和γ粒子的平均识别率和误甄别率分别为96.7%、41.1%和<0.001%、0.16%。展开更多
A new scintillating fiber detector inside magnetic shielding tube was designed and assembled for use in the next round of fusion experiments in the experimental advanced superconducting tokamak to provide D–T neutron...A new scintillating fiber detector inside magnetic shielding tube was designed and assembled for use in the next round of fusion experiments in the experimental advanced superconducting tokamak to provide D–T neutron yield with time resolution.In this study,Geant4 simulations were used to obtain the pulse height spectra for ideal signals produced when detecting neutrons and gamma rays of multiple energies.One of the main sources of interference was found to be low-energy neutrons below 10–5 MeV,which can generate numerous secondary particles in the detector components,such as the magnetic shielding tube,leading to high-amplitude output signals.To address this issue,a compact thermal neutron shield containing a 1-mm Cd layer outside the magnetic shielding tube and a 5-mm inner Pb layer was specifically designed.Adverse effects on the measurement of fast neutrons and the shielding effect on gamma rays were considered.This can suppress the height of the signals caused by thermal neutrons to a level below the height corresponding to neutrons above 4 MeV because the yield of the latter is used for detector calibration.In addition,the detector has relatively flat sensitivity curves in the fast neutron region,with the intrinsic detection efficiencies(IDEs)of approximately 40%.For gamma rays with energies that are not too high(<8 MeV),the IDEs of the detector are only approximately 20%,whereas for gamma rays below 1 MeV,the response curve cuts off earlier in the low-energy region,which is beneficial for avoiding counting saturation and signal accumulation.展开更多
基金supported by the National Natural Science Foundation of China(No.12305239)Scientific Research Foundation of Chongqing University of Technology(No.2023ZDZ053)National Key R&D Program of China(No.2019YFE03010001).
文摘To further research on high-parameter plasma,we plan to develop a two-dimensional hard X-ray(HXR)imaging system at the HL-3 tokamak to measure HXRs with energies ranging from 20 to 300 keV.The application of an array-structured detector ensures that this system can measure HXR-radiation spectra from the entire plasma cross section.Therefore,it is suitable for the study of fast-electron physics,such as radio-frequency wave current drives,fast electrons driving instabilities,and plasma disruptions in fusion research.In this study,we develop a simulation for calculating fast-electron bremsstrahlung in the HL-3 tokamak based on the Monte Carlo simulation code Geant4,in which the plasma geometry and forward scattering of fast-electron bremsstrahlung are considered.The preliminary calculation results indicate that the HXR energy deposi-tion on the detector is symmetrically distributed,even though the plasma distribution is asymmetric owing to the toroidal effect.These simulation results are helpful in constructing the relationship between the energy deposition on the detector and parameter distribution on the plasma cross section during HL-3 experiments.This is beneficial for the reconstruction of the fast-electron-distribution function and for optimizing the design of the HXR-imaging system.
文摘在核工业的一些工作场所中往往同时存在β射线和γ射线,准确测量β粒子和γ粒子能谱对于相关工作人员的辐射防护十分重要。本文利用Geant4模拟了β粒子和γ粒子在叠层闪烁体探测器中的能量沉积,研究了材料和结构对叠层闪烁体探测器甄别性能的影响。模拟结果显示,对于双层结构的闪烁体探测器,第1层和第2层选用不同材料的闪烁体对β粒子的甄别影响不大,主要影响对γ粒子的甄别。γ粒子的误甄别率和识别率分别随第1层和第2层材料原子序数的增加而增加。3层结构闪烁体探测器对于γ粒子的误甄别率明显低于双层结构,并且γ粒子的误甄别率随第1层闪烁体厚度的增加而增加。经过对模拟结果分析,采用0.2 mm BC-444+17.8 mm BC-444+25 mm BaF_(2)的3层闪烁体结构甄别性能较好,对β粒子和γ粒子的平均识别率和误甄别率分别为96.7%、41.1%和<0.001%、0.16%。
基金supported by the University Synergy Innovation Program of Anhui Province(No.GXXT-2022-001)the Institute of Energy,Hefei Comprehensive National Science Center(Anhui Energy Laboratory)under Grant No.21KZS205 and 21KZL401the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228).
文摘A new scintillating fiber detector inside magnetic shielding tube was designed and assembled for use in the next round of fusion experiments in the experimental advanced superconducting tokamak to provide D–T neutron yield with time resolution.In this study,Geant4 simulations were used to obtain the pulse height spectra for ideal signals produced when detecting neutrons and gamma rays of multiple energies.One of the main sources of interference was found to be low-energy neutrons below 10–5 MeV,which can generate numerous secondary particles in the detector components,such as the magnetic shielding tube,leading to high-amplitude output signals.To address this issue,a compact thermal neutron shield containing a 1-mm Cd layer outside the magnetic shielding tube and a 5-mm inner Pb layer was specifically designed.Adverse effects on the measurement of fast neutrons and the shielding effect on gamma rays were considered.This can suppress the height of the signals caused by thermal neutrons to a level below the height corresponding to neutrons above 4 MeV because the yield of the latter is used for detector calibration.In addition,the detector has relatively flat sensitivity curves in the fast neutron region,with the intrinsic detection efficiencies(IDEs)of approximately 40%.For gamma rays with energies that are not too high(<8 MeV),the IDEs of the detector are only approximately 20%,whereas for gamma rays below 1 MeV,the response curve cuts off earlier in the low-energy region,which is beneficial for avoiding counting saturation and signal accumulation.
