Effect of poloidal electric field on electron cyclotron current drive in a tokamak geometry

Abstract

Effect of a poloidal electric field on the electron cyclotron current drive is studied in a tokamak geometry. A general discussion of its influence on the electron phase-space dynamics and current drive efficiency is presented. It is shown that the modification to the current drive efficiency increases as the heating location is moved out in the major radius. It is concluded that the modification is only moderate to insignificant (< 10% fur low magnetic field side heating and <3% for high field side heating) for a poloidal electrostatic potential variation of order inverse aspect ratio under an efficient current drive. (C) 2000 American Institute of Physics [S1070-664X(00)00612-1].