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 were investigated. 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. Results show that the current drive efficiency is better in a hydrogen-deuterium plasma than a He3-deuterium plasma. 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