托卡马克超声分子束注入加料的进展

Progress in supersonic molecular beam injection into Tokamaks

超声分子束注入作为一种新的托卡马克加料方法由作者在1992年首次提出并于当年在中国环流器一号(HL-1)装置演示成功,随后相继应用于中国环流器新一号(HL-1M)和中国科学院超导托卡马克HT-7装置。超声分子束注入等离子体呈现出电子密度峰化和温度中空分布的特征;等离子体流极向旋转速度提高,边缘扰动被抑制,等离子体能量约束得到改善。加料效率较常规脉冲送气提高一倍,而滞留器壁的粒子大为减少。近期开展的高气压氢超分子束注入实验,在束流中发现团簇流,可注入等离子体中心区域。多脉冲分子束注入形成电子密度的阶跃上升,如同冰弹丸注入效果。近年来该项技术已陆续应用于国外大型托卡马克和仿星器,是核聚变装置稳态运行的一种有效的加料方法。

Supersonic molecular beam injection (SMBI), a new fuelling method, was first proposed and demonstrated on the HL-1 tokamak in 1992, and successfully developed and used in HL-1M (modified from HL-1) and HT-7 superconducting tokamak. The characteristics of the beam injection are electron density peaking and hollow profile of electron temperature. The increase of the rotation velocity of poloidal plasma flow results in the edge plasma disturbance eliminating and plasma energy confinement improvement. The fuelling efficiency of SMBI is increased to twice as much as that for gas puffing, whereas the particle retention on the surface is reduced. Recently new results of SMBI experiments were obtained by increasing the gas pressure, and the hydrogen clusters within the beam were found to play an important role in the deeper injection. It was also shown that injected particles could penetrate into the core region of the HL-1M plasma, which results in a stair-shaped electron density increment, just as the behavior of ice pellet injection. These results prove effectiveness of SMBI as a promising fuelling tool for stead-state operation of great-size tokamak or stellarator.