托卡马克中宏观束-等离子体扭曲模不稳定性研究

本文主要研究了具有单一高能离子分量的托卡马克等离子体扭曲模宏观不稳定性。它基本上模拟了中性束平行注入经过电离和电荷交换后在本底等离子体中维持一个稳恒等离子体流的物理过程。高能和本底都用无碰撞的Vlasov等离子体,并取了低频、小拉莫尔半径极限。由于主要考虑束-等离子体无耗散宏观不稳定性,故可用能量原理来分析。结果表明,高能离子束对本底等离子体的外部模没有影响,只影响内部扭曲模的增长率和扰动振幅。对适当选择的速度剖面,束能够完全稳定体系n≥2,m=1模,与Dunlap线性理论结果相反而与目前实验观测一致。m/n=1/1内部扭曲模增长率在所取得模型下随注入能量β_b,注入功率P_bw,轴上安全因子q(0)和束速度的径向剖面分布参数S的不同而出现增稳、减稳及完全稳定的行为。适当选择S,在q(0)<0.924时,高能束能够稳定m/n=1/1模。 关键词：

MACROSCOPICAL BEAM-PLASMA KINK INSTABILITY RESEARCH IN TOKAMAK

In this paper, the kink modes of the plasma in a tokamak with parallel NB injection have been studied. The fast ion component of the plasma has been modelled by a mono-energetic ion beam. Negleiting the dissipative process, an energy principle could be derived from the Vlasov equation in low frequency and small Lamar-radius limit. It is found that none of the entemal kink modes (m≥2) are influenced by the ion beam in the thintorus approximation. But the existance of the fast ion component has changed the kink modes (m = l). Obviausly, by proper choice of the velocity profile of ion beam m = l, n=2 modes can be stabilized absolute. The behaviour of the m/n =1/1 kink mode is very complicated. It could be stabilized or destabilized depending on the beam energy β_b, axial safety factor q(0) and radial velocity profile of the beam. A numerical culculation shows that when q(0)<0.924 and the beam velocity profile is properly chosen, the m/n = 1/1 mode can also be totaly stabilized.