Discrete Alfvn eigenmodes in steady-state operation scenarios with negative magnetic shear in the international thermonuclear experimental reactor are investigated in this paper. These magnetohydrodynamic eigenmodes are trapped by the α-induced potential wells along the magnetic field line. Here α =-q2Rdβ/dr with q being the safety factor, β the ratio between plasma and magnetic pressures, and R the major radius, and r the minor radius. Due to negligible continuum damping via wave energy tunneling, these Alfvn eigenmodes could be readily destabilized by energetic particles.
当前的磁约束聚变装置常常运行在先进托卡马克区域内,先进托卡马克区域内存在负磁剪切。在JET(Joint European Torus)装置运行的参数域里,存在有约束在引发气球模驱动的势井里的多支离散阿尔芬本征模。类似于正剪切的情况,这些离散阿尔芬本征模只有很小的耗散率。由于耗散率很小,所以很容易被高能量粒子激发成不稳定性模式。在实验上已经观察到了很多阿尔芬频谱,这种离散阿尔芬本征模式是一种去理解这些现象的潜在的物理机制。
