INERTIA AND ION LANDAU DAMPING OF LOW-FREQUENCY MAGNETOHYDRODYNAMIC MODES IN TOKAMAKS

The inertia and Landau damping of low-frequency magnetohydrodynamical modes are investigated using the drift-kinetic energy principle for th e motion along the magnetic field. Toroidal trapping of the ions decre ases the Landau damping and increases the inertia for frequencies belo w (r/R)(1/2)upsilon(thi)/qR. The theory is applied to toroidicity-indu ced Alfven eigenmodes and to resistive wall modes in rotating plasmas. An explanation of the beta-induced Alfven eigenmode is given in terms of the Pfirsch-Schluter-like enhancement of inertia at low frequency. The toroidal inertia enhancement also increases the effects of plasma rotation on resistive wall modes. (C) 1996 American Institute of Phys ics.