ICRF加热下EAST快离子损失速度空间分布初步研究

Preliminary study of velocity-space distribution of fast-ion loss under ion cyclotron resonance heating in the EAST

基于闪烁体的快离子损失探针(Fast-Ion Loss Detector,FILD)能够测量损失快离子的速度空间分布,是研究核聚变装置中快离子损失控制机理的关键诊断手段。在东方超环(Experimental Advanced Superconducting Tokamak,EAST)上,通过FILDSIM程序在诊断图像与速度空间分布之间建立桥梁,将诊断探测到的信号转化为速度空间分布,获得了离子回旋共振加热(Ion Cyclotron Resonance Heating,ICRH)条件下的快离子损失速度空间分布,为进一步评估和控制离子回旋共振加热下的快离子损失奠定了基础。另外,通过损失快离子反向追踪,探究了探头本体遮挡对诊断探测范围的影响,为损失诊断系统进一步升级提供了依据。

[Background]Scintillator-based fast-ion loss detector(FILD)can measure the velocity-space distribution of fast-ion loss and are key in studying the control mechanism of fast-ion loss in nuclear fusion devices.[Purpose]This study aims to obtain the velocity-space distribution of fast-ion loss from corresponding FILD data and evaluate the capacity of current FILD probe for the further improvement of diagnostic design.[Methods]The FILDSIM code was employed to establish the linkage between the fast-ion image digitized by FILD and the velocityspace distribution of fast-ion loss.The detection coverage of fast ions on the scintillator was assessed through reverse tracing of the lost fast ions,considering the geometry of the FILD probe as well as the pitch angle and gyroradius of fast ions entering the pinhole of the FILD probe.[Results]The obtained velocity-space distribution of fast-ion loss under ICRH indicates that the energy of lost fast hydrogen minority ions is above 200 keV.Moreover,analysis shows that the geometry of the probe,particularly the shell behind the scintillator,obstructs the diagnostic detection range,creating a null region on the scintillator.[Conclusions]The acquisition of the velocity-space distribution of fast-ion loss lays the foundation for further evaluation and control of fast-ion loss under ion cyclotron resonance heating.In addition,the investigation of the probe detection range provides a basis for upgrading diagnostic systems.