Low Frequency Response of Plasma to MHD Perturbations

MHD stability of the plasma depends critically on the frequency and wave length of the perturbation. Future tokamaks are expected to operate in regimes where the external macro-scale perturbations have much lower frequencies than the intrinsic dynamical time scales of the particles [1]. This situation calls for a detailed re-examination of the assumptions on previous models of the response of the plasma to MHD perturbations [2]. The kinetic formulation of MHD response [3] is examined numerically in this work. The energy and momentum flux across the plasma surface is expressed in terms of the MHD perturbations. Implication on the stability and plasma response [4] relevant for the resistive wall mode, with its time scale dramatically reduced by the external resistive wall, is discussed. \newline [1] B. Hu, \textit{et al.,} Phys. Plasmas \textbf{12}, 057301 (2005). \newline [2] A. Bondeson and M.S. Chu, Phys. Plasmas \textbf{3}, 3013 (1996). \newline [3] T.M. Antonsen, Jr. and Y.C. Lee, Phys. Fluids \textbf{25}, 132 (1982). \newline [4] Y.Q. Liu, \textit{et al.,} Phys. Plasmas \textbf{7}, 3681 (2000).