ZnS(Ag)闪烁体对EAST中快电子响应的模拟分析  

Simulation analysis of fast electron response of ZnS(Ag)scintillator in EAST

作　　者：王克文 黄娟[1] 常加峰 周瑞杰 WANG Kewen;HUANG Juan;CHANG Jiafeng;ZHOU Ruijie(Institute of Plasma Physics,Hefei Institutes of Physics Science,Chinese Academy of Sciences,Hefei 230026,China;University of Science and Technology of China,Hefei 230026,China)

机构地区：[1]中国科学院合肥物质科学研究院等离子体物理研究所,合肥230026 [2]中国科学技术大学,合肥230026

出　　处：《核技术》2024年第5期21-28,共8页Nuclear Techniques

基　　金：国家重点研发(No.2019YFE03020004);国家自然科学基金(No.11975276)资助。

摘　　要：在托卡马克中,快电子一旦脱离托卡马克磁场约束而损失在真空壁或者限制器上,可能会产生大量杂质,影响装置正常运行,甚至会造成装置的损坏。为了研究快电子的损失行为,在先进实验超导托卡马克(Experimental Advanced Superconducting Tokamak,EAST)上,使用基于ZnS(Ag)闪烁体探头的诊断系统对快电子损失进行探测。为了理解其损失特性,使用Geant4模拟程序模拟了不同初始状态的电子与诊断系统闪烁体探头的相互作用,获得了闪烁体发光强度与入射电子初始状态的曲线关系。模拟结果表明:次级电子与初始电子使闪烁体发光的贡献占据不同的主导能量区间;发光强度随入射电子能量增大而先增大后减小,峰值在12 MeV附近,且斜入射时发光光子数大于垂直入射,而闪烁体的厚度对峰值位置无明显影响。加入磁场后,磁场角度、电子俯仰角都会对发光强度有明显影响。这些结果有助于理解EAST实验中闪烁体探头上探测到的快电子损失信号,为进一步研究快电子损失提供基础。[Background]In a tokamak,when fast electrons are deconfined by the tokamak magnetic field constraint and lost to the vacuum wall or limiter,the device may become damaged and the discharge may be affected.[Purpose]This study aims to explore the loss behavior of fast electrons during discharge using a diagnostic system based on a ZnS(Ag)scintillator probe for detecting the loss of fast electrons on the Experimental Advanced Superconducting Tokamak(EAST).[Methods]The Geant4 simulation program was employed to simulate the interaction between electrons in different initial states and the scintillator probe of the diagnostic system.Firstly,the probe model and the filling material model of stainless steel and ZnS(Ag)coating were established in Geant4.Then,the interaction between electron beam and scintillator probe under different incident conditions(incident energy,angle,scintillator thickness,magnetic field size,etc.)were simulated,and the physical processes were recorded.Finally,the recorded data were accessed by MATLAB programming for analysis.[Results]The results show that the contribution of secondary electrons and initial electrons to the luminescence intensity of scintillators occupies different dominant energy ranges.The luminescence intensity first increases and then decreases with the increase of incident electron energy,with a peak value around 12 MeV,and the number of emitted photons at oblique incidence is greater than that at vertical incidence.When the electron energy is lower than 4.3 MeV,secondary particles dominate the scintillation,and when the electron energy is higher than 4.3 MeV,primary particles dominate.The thickness of the scintillator has no significant effect on the peak position.After,the luminous intensity is considerably affected by the magnetic field angle and electron pitch angle after adding a magnetic field.[Conclusions]The results of this study contribute to the understanding of the fast electron loss signal detected by the scintillator probe in the EAST experiments,providing a basis

关 键 词：托卡马克 闪烁体 GEANT4 快电子 

分 类 号：TL631.24[核科学技术—核技术及应用]