ANALYSIS OF ELECTRON-CYCLOTRON CURRENT DRIVE USING NEOCLASSICAL FOKKER-PLANCK CODE WITHOUT BOUNCE-AVERAGE APPROXIMATION

A new three-dimensional relativistic Fokker-Planck code (poloidal angl e and two dimensions in momentum space) has been developed for the ana lysis of electron cyclotron current drive (ECCD) in tokamak plasmas. T his numerical code takes into consideration trapped electron effects w ithout using the bounce-average approximation. Simulations have been c arried out using the code, and the results were compared with those of a bounce-averaged Fokker-Planck code. There are differences in the cu rrent drive efficiencies calculated by the two codes, and this differe nce is shown to be caused by a change in electron velocity parallel to the magnetic field due to the inhomogeneous magnetic field. (C) 1995 American Institute of Physics.