可见光谱分析在HT-7边界再循环研究中的应用

HT-7超导托卡马克致力于准稳态放电及相关物理的研究。目前HT-7成功获得了长脉冲运行达近64 s的高温等离子体。大量实验证明，器壁上气体再循环对托卡马克等离子体的品质十分重要。采用光学多道分析仪(OSMA)系统通过氢氘比的测量来研究边界粒子的再循环。放电过程中，边界再循环对粒子的平衡起主导地位。在放电平稳，密度可控阶段，氘(氢)再循环起主导作用，此时再循环系数R≤1;而放电的后期随着边界温度的升高，辐射总功率的加强，密度进而处于不可控状态，此时R＞1, 杂质再循环也逐渐趋于主导地位，这是引起等离子体破裂的原因之一。利用此方法还可以进一步研究壁条件对边界再循环的影响。

Visible Spectra Analysis on Edge Recycling in HT-7 Tokamak

The main efforts of HT-7 superconducting tokamak were directed to quasi-steady state discharges and their relevant physics. Significant progress in obtaning high-performance discharges under quasi-steady state in HT-7 has been realized. The long pulse discharges have been obtained with a duration up to 63.95 s. The edge recycling was studied by the ratio of H to D through OSMA (Optical Spectroscopy Multichannel Analyzer) system. During the discharge, recycling dominated the particle balance. In the steady state, when the density was controllable, the deuterium(hydrogen) recycling played an important role and the recycling coefficient R < or = 1. During the later time, R >1 and the density was uncontrollable. The main contribution was from the D(H) recycling and impurity from the surfaces of the limiter and the first wall due to the increased surface temperature and radiation power, and these limited the duration of long duration discharges. The influence of wall conditioning on the edge recycling was also studied through the ratio of H to D.