Implementing zero-banana-width quasilinear operator for fast ICRF simulations

Numerical simulations of plasma heating with waves in the ion cyclotron range of frequencies (ICRF) require to iteratively couple a solver for wave propagation in plasmas with a solver of the quasilinear kinetic equation. Among the codes developed for this purpose, the TORIC-SSFPQL package is characterized by its high execution speed. The kinetic code SSFPQL, however, was based on a somewhat simplified physical model, in which some important effects of the toroidal geometry were omitted. We have recently improved this model by taking into account in the zero–banana–width limit the influence of toroidal trapping on the ICRF quasilinear operator. To make the extended model compatible with the representation of the ion distribution functions as a truncated series of Legendre polynomials in the velocity pitchangle adopted in SSFPQL, a special approach based on the multiprecision arithmetic had to be developed. We describe these new developments, and present first results obtained with the improved model.