Effects of energetic-ion-driven MHD instabilities in a reversed magnetic shear plasma on energetic ion transport

与托卡马克装置不同的是，在大螺旋装置(LHD)中产生了中心区域为正、边缘区域为负的反向磁切变(RS)等离子体。在这样的等离子体中，高能离子同时激发了反向磁剪切Alfven本征模(RSAE)和测地线声学模(GAM)。将观测到的RSAE和GAM的特性，这些不稳定性的非线性耦合，以及它们对高能离子和本底等离子体约束的影响，与托卡马克进行了比较。比较研究对于系统、全面地了解这些不稳定性具有重要意义。

A reversed magnetic shear(RS)-plasma where the shear is positive in plasma central region and negative in the edge region, different from the tokamak RS-plasma was produced in the Large Helical Device(LHD). In such plasma, reversed magnetic shear Alfven eigenmode(RSAE) and geodesic acoustic mode(GAM) were concurrently excited by energetic ions. Characteristics of observed RSAE and GAM, nonlinear coupling of these instabilities, and their impacts on confinement of energetic ions and background bulk plasma were compared with those in tokamaks. The comparison study is important for systematic and comprehensive understanding of these instabilities.