Fast wave propagation and minority ion heating current drive in a two-ion species tokamak plasma

Local cavity resonances of fast waves in a two-ion species tokamak plasma and current generation due to the asymmetric cyclotron heating of minority ions by fast waves have been investigated. The experimental results demonstrate the existence of a local cavity resonance for fast waves propagating in a deuterium tokamak plasma with a low concentration (5%) of hydrogen minority ions. The local resonance cavity for the fast waves is formed by the hybrid cutoff layer and the outer wall* Current generation by asymmetric minority heating with no net momentum injection into the plasma is studied numerically by solving the Fokker-Planck equation in which the quasi-linear diffusion term for cyclotron absorption is added to the Coulomb collision terms. The results show that the current drive efficiency is better in a hydrogen-deuterium plasma than in a helium^3-deuterium plasma. The applicability of the minority ion heating current drive scheme in a hydrogen tokamak plasma with unavoidable impurity ions as the minority ions is investigated. The practicality of this current drive process for fusion reactors is also discussed.