Advances in numerical simulations of ion cyclotron heating of non-Maxwellian plasmas

Coupling the full-wave solver TORIC (Brambilla 1999 Plasma Phys. Control. Fusion41 1) and the bounce-averaged quasilinear Fokker–Planck solver SSFPQL (Brambilla 1994 Nucl. Fusion34 1121) allows one to determine the suprathermal ion populations produced by ion cyclotron heating of tokamak plasmas, while taking into account their effects on wave propagation and absorption. By using new numerical methods for the evaluation of the coefficients of the wave equations in non-Maxwellian plasmas and the transmission of data between TORIC and SSFPQL, the interface between the two codes has been made very efficient and accurate. As an example, we have re-analysed a minority heating scenario in the ASDEX Upgrade tokamak. The results illustrate the differences between the quasilinear evolution of fundamental and first harmonic ion cyclotron heating due to the fact that the latter is a finite Larmor radius effect. They also suggest that the main missing element for fully satisfactory self-consistent simulations of ion cyclotron experiments in toroidal devices is the absence of a detailed model for the losses of suprathermal ions due, for example, to interactions with low-frequency turbulence or magnetohydrodynamic instabilities.