A RELATIVISTIC THEORY OF ELECTRON CYCLOTRON CURRENT DRIVE EFFICIENCY

A fully relativistic theory of electron cyclotron current drive (ECCD) efficiency based on Green's-function techniques is considered. Numerical calculations of the current drive efficiency in a uniform magnetic field are performed. The numerical results with parameter regimes relevant to ITER operations are compared with those of two simplified models in which the electron-electron Coulomb collision operator is respectively approximated by its high-velocity limit and a semi-relativistic form. Our results indicate that the semi-relativistic approximation of the collision operator should be appropriate for modeling the ECCD efficiency under ITER conditions.