PPPL-4995

On The Toroidal Plasma Rotation Induced By Lower Hybrid Waves

Authors: Xiaoyin Guan, Hong Qin, Jian Liu and Nathaniel J. Fisch

Abstract: A theoretical model is developed to explain the plasma rotations induced by lower hybrid waves in Alcator C-Mod. In this model, torodial rotations are driven by the Lorentz force on the bulk- electron flow across flux surfaces, which is a response of the plasma to the resonant-electron across flux surfaces induced by the lower hybrid waves. The flow across flux surfaces of the resonant electrons and the bulk electrons are coupled through the radial electric fi eld initiated by the resonant electrons, and the friction between ions and electrons transfers the toroidal momentum to ions from electrons. An improved quasilinear theory with gyrophase dependent distribution function is developed to calculate the perpendicular resonant-electron flow. Toroidal rotations are determined using a set of fluid equations for bulk electrons and ions, which are solved numerically by a nite- di erence method. Numerical results agree well with the experimental observations in terms of flow profi le and amplitude. The model explains the strong correlation between torodial flow and internal inductance observed experimentally, and predicts both counter-current and co-current flows, depending on the perpendicular wave vectors of the lower hybrid waves.
__________________________________________________

Submitted to: Physics of Plasmas (October 2013)

__________________________________________________

Download PPPL-4995 (pdf 275 KB 22 pp)
__________________________________________________