New Scheme for Current Drive in a Tokamak Reactor

We have studied the feasibility of an efficient current-drive scheme using radio-frequency (rf) waves on the alpha particles produced in a reactor tokamak. Traveling fast waves, generated as waveguide modes in the plasma, are found to be particularly suitable for implementing such a scheme. The scheme involves using rf power to prohibit the alpha particles from slowing down isotropically and in pushing the alpha particles in a preferential direction and thus form an alpha-particle beam, which, through interaction with electrons, sustains a current. Numerical estimates for the current-drive efficiency were obtained using plasma parameters characteristic of the Argonne National Laboratory design of a reactor tokamak.