CFETR辉光放电清洗的均匀性研究

Uniformity of Glow Discharge Cleaning for CFETR Vacuum Chamber:A Simulation Study

为研究壁表面离子流分布均匀性,设计高效率中国聚变工程实验堆辉光放电清洗(GDC)装置,采用流体模型对氦气辉光放电清洗进行等效二维模拟。阳极区域存在较强的局部电离,使得靠近阳极的第一壁受到更强烈的离子轰击;增加阳极电流该区域离子流密度显著增加,而放电清洗的均匀性并无提高;适当降低放电气压放电不均匀性得到较大改善;内壁电流密度略大于外壁电流密度,而电极径向位置对内外壁电流密度分布影响甚微。分析了阳极电流与电极数目的合理取值,给出了合适的放电气压范围。

The glow discharge cleaning(GDC) of vacuum chamber,for China Fusion Engineering Testing Reactor(CFETR) project,was mathematically modeled,theoretically analyzed and numerically simulated for design optimization of GDC setup.The influence of the discharge variables,including the He-pressure,current/position of anode and electrode-number,on the uniformity of ion-current density distribution was investigated.The simulated results included: first,an intense ionization occurs in the ionization zone closely above the anode,resulting in strong ion-sputtering of the wall nearby;second,as the single-electrode current increases,the ion-current density in the ionization zone significantly increases,bringing about a non-uniform ion-current density distribution;third,the electrode’s radial position little affects the ion-current density distributions on the inner and outer walls;and finally,a lower pressure significantly reduces the non-uniformity and produces a small ion-current difference between the two walls.