Full-wave simulations of ICRF heating regimes in toroidal plasmas with non-Maxwellian distribution functions

At the power levels required for significant heating and current drivein magnetically-confined toroidal plasma, modification of the particle distributionfunction from a Maxwellian shape is likely [T. H. Stix, Nucl. Fusion, 15 737(1975)], with consequent changes in wave propagation and in the location andamount of absorption. In order to study these effects computationally, both thefinite-Larmor-radius and the high-harmonic fast wave (HHFW), versions of thefull-wave, hot-plasma toroidal simulation code TORIC [M. Brambilla, Plasma Phys.Control. Fusion 41, 1 (1999) and M. Brambilla, Plasma Phys. Control. Fusion44, 2423 (2002)], have been extended to allow the prescription of arbitrary velocitydistributions of the form f(v||, v_perp, psi , theta). For hydrogen (H) minority heating of adeuterium (D) plasma with anisotropic Maxwellian H distributions, the fractionalH absorption varies significantly with changes in parallel temperature but isessentially independent of perpendicular temperature. On the other hand, forHHFW regime with anisotropic Maxwellian fast ion distribution, the fractionalbeam ion absorption varies mainly with changes in the perpendicular temperature.The evaluation of the wave-field and power absorption, through the full wavesolver, with the ion distribution function provided by either aMonte-Carlo particleand Fokker-Planck codes is also examined for Alcator C-Mod and NSTX plasmas.Non-Maxwellian effects generally tends to increase the absorption with respect tothe equivalent Maxwellian distribution.