HL-2A装置上成像型中性粒子分析器的物理设计和初步实验结果

Physical design and primary experimental results of imaging neutral particle analyzer on HL-2A tokamak

在HL-2A装置上发展了基于硫化锌银闪烁体的成像型中性粒子分析器,对磁约束聚变等离子体中高能量粒子(EP)的分布、能量和螺距角等关键信息,以及EP与磁流体不稳定性之间的相互作用等物理问题进行了研究.在中性束注入路径上逃逸出的具有等离子体中快离子能量和螺距角信息的中性粒子,通过由入射孔和碳微晶体膜片组成的准直系统后转化为离子,在装置边缘磁场中受洛伦兹力偏转而撞击到闪烁体屏上.通过分析发光点的位置和光强度,可以推断出装置中快离子的位置、能量和螺距角等关键信息.在HL-2A装置高能量粒子物理实验中,通过该诊断和理论计算初步证实了长寿模不稳定性是由能量、螺距角和位置分别为E=12.5—32 keV,θ~149.2°(v///v~0.86)和R=170.5—171.5 cm的芯部快离子激发.

The imaging neutral particle analyzer(INPA)based on scintillator(ZnS(Ag))is designed and used on HL-2A tokamak to investigate the distribution of energetic particles(EPs)and even their interactions with magnetohydrodynamic instabilities.The collimation system is composed of a pinhole of 3 mm in diameter and six circular carbon microcrystal diaphragms each with a thickness of 10 nm.The neutral particles escape from six definite positions in the neutral beam injection path and pass through the collimator system at a certain pitch angle,and the neutral particles become fast ions after passing through the carbon microcrystal diaphragm.The fast ions will hit the scintillator after a 180°deflection by the edge magnetic field.The energy,pitch angle and birthplace can be calculated by the position and light intensity of the impact spots.The images of impact spots caused by long-lived mode are recorded by a high-speed camera through the fiber optic bundle.The longlived mode instabilities approve to be excited by the core EPs with energy value in a range of E~12.5-32 keV pitch angle of v///v~0.86and the birthplace in a range of R~170.5-171.5 cm.