Alfven wave heating and current drive

Progress in the theory of Alfven wave (AW) heating, current drive, and plasma flow, which may be relevant for improved confinement scenarios in tokamaks, is discussed. The effect of poloidal mode coupling on the power deposition of AW eigenmodes is investigated. Resonant absorption of the coupled side bands causes a broad power deposition close to the plasma boundary which can surpass the power deposition of the main global AW at the plasma center. A small population of impurities, such as carbon, in a hydrogen plasma can strongly modify the dispersion of the global AW, the AW continuum and the wave dissipation profile. The ponderomotive forces produced by rf fields are expressed as a sum of a gradient (radial derivative) part and of a wave momentum transfer force found to be proportional to wave dissipation. Finally, the rf force is balanced by the friction (or neo-classical viscosity) force to calculate relevant current drive and plasma specie flows. Estimates of AW power requirements to drive substantial heating, current, and poloidal flow are made for plasmas in the Tokamak Chauffage Alfven wave experiment in Brazil (TCABR) [L. Ruchko , Nucl. Fusion 30, 503 (1996)]. The first results of Alfven wave heating and current drive experiments with a low level of wave dissipation in the TCABR are discussed. (C) 2001 American Institute of Physics.