QUASI-LINEAR THEORY FOR A TOKAMAK PLASMA IN THE PRESENCE OF CYCLOTRON-RESONANCE

Quasilinear diffusion equations for the distribution function of trapped and circulating particles interacting with waves in a tokamak by means of cyclotron resonance are derived. The resulting equations reveal new features of quasilinear diffusion and are of two kinds, one which involves bounce resonances overlapping in velocity space and one with well separated bounce resonaces. These two cases correspond to situations where the phase of the wave-particle interaction between successive resonances can be considered as random or deterministic, respectively. An analysis of the conditions of applicability of the new equations is carried out and previous well known forms of the quasilinear diffusion equations are shown to be recovered in the proper limits.