The current-drive effect of a laser beat-wave has been investigated with a focus on the seed current near the magnetic axis of the bootstrap-driven tokamk plasma. It is noted that the most important merit of the method is its profile control capabilit...
The current-drive effect of a laser beat-wave has been investigated with a focus on the seed current near the magnetic axis of the bootstrap-driven tokamk plasma. It is noted that the most important merit of the method is its profile control capability. A fluid and a kinetic model have been developed for describing the plasma dynamics during a single pulse of the laser beat-wave. Numerical solutions to the averaging the behavior of the electron distribution function show the existence of an optimum phase velocity of the beat wave for current drive efficiency at a given laser intensity.
Moreover, the efficiency is found to increase monotonically with the laser intensity, suggesting that a high-intensity short-pulsed operation is preferred. The upper limit for the laser intensity is given by the instability threshold of stimulated Raman backscattering. The optimal current-drive efficiency of the scheme is found to be quite comparable to those for obtained by a continuous of current drive.