A QUASI-LINEAR DESCRIPTION FOR FAST-WAVE MINORITY HEATING PERMITTING OFF-MAGNETIC AXIS HEATING IN A TOKAMAK

By keeping only the essential physical effects the simplest as possible, experimentally relevant quasilinear description of fast-wave minority heating in a tokamak is derived in a tractable form suitable for convenient numerical implementation. The resulting quasilinear operator retains all trapped and passing particle effects and permits the minority heating resonance line to be offset from the magnetic axis. Rather than averaging the infinite, homogeneous quasilinear operator, the derivation is carried out in tokamak geometry to properly treat the merging of distinct rf-particle interaction regions. Merging occurs when the banana tips of trapped particles are in the vicinity of the minority resonance or, for both trapped and passing particles, when the minority resonance is tangent or nearly tangent to a flux surface. A phenomenological model of the influence of collisions on merging is also presented.