DⅢ-D高性能运行参数下的离散阿尔芬本征模

摘要

The physical features of the discrete Alfven eigenmodes are investigated in the DⅢ-D tokamak plasmas for the high performance discharge conditions, including the negative magnetic shear configuration, the high power heating, the co- and counter- neutral beam injection (NBI), the internal transport barrier, the high bootstrap current fraction case, and the VH-mode discharge. These Alfven eigenmodes exist in a wide radial range of the DⅢ-D plasma with a broad frequency spectrum in the advanced operation regime with the negative magnetic shear. The high power heating, the co-NBI, and the internal transport barrier can help form multiple deep potential wells, thus efficiently trapping the Alfven eigenmodes. These Alfven bound states can be found in even more extended radial range with relatively high frequencies for both the high bootstrap fraction discharge and the VH-mode discharge. These discrete Alfven eigenmodes, developed during the DⅢ-D high performancerndischarges with a broad scope of operating parameters, would be the potential instability which can exist widely in the experiments on the large similar tokamaks.%采用本征模式的数值打靶方法研究了离散阿尔芬本征模在DⅢ-D高性能运行条件下的物理特性,包括负磁剪切位形、高性能加热、正反中性束注入、内部输运垒以及高自举电流和甚高约束运行状态对这种阿尔芬模式的影响.在DⅢ-D托卡马克装置负磁剪切位形及先进运行状态实验参数下这些离散阿尔芬本征模存在于宽的径向区域,且具有广泛的本征频谱；高性能加热、同向中性束注入以及内部输运垒的存在有利于产生多个较深的气球模驱动势阱,由之得以很好地形成这种阿尔芬束缚态本征模；在高自举电流和甚高约束运行条件下这些离散阿尔芬本征模束缚态能够在更广的径向区域存在,且可具有较高的本征频率.另外,参照DⅢ-D装置放电实验数据的时间演变情况,这些离散阿尔芬本征模能在很宽的运行参数范围内出现,使之成为该类大型托卡马克实验中可能广泛存在的潜在不稳定性.