HAMILTONIAN ANALYSIS OF FAST-WAVE CURRENT DRIVE IN TOKAMAK PLASMAS

The Hamiltonian formalism is used to address the problem of the direct resonant interaction between the fast magnetosonic wave and the elect rons in a tokamak plasma. The intrinsic stochasticity of the electron trajectories in phase space is first derived. Together with extrinsic decorrelation processes, it assesses the validity of the quasilinear a pproximation for the kinetic studies of fast wave current drive (FWCD) . A full-wave solution of the Maxwell-Vlasov set of equations provides the exact pattern of the wave fields in the tokamak geometry, consist ent with a realistic antenna spectrum. The local quasilinear diffusion tensor is then derived from the wave fields and the driven current de nsity profile, the power deposition profile and the current drive effi ciency are computed, including possible nonlinear effects in the kinet ic equation. Several applications of FWCD on existing and future machi nes are given, and the combination of FWCD with other noninductive cur rent drive methods is investigated. Finally, an analytical expression for the current drive efficiency is derived in the moderate to high si ngle-pass absorption regime.