Modelling nonperturbative frequency sweeping of MHD modes in magnetic confinement fusion plasmas

Frequency sweeping of magnetohydrodynamic modes for which the sweeping rate is approximately constant have been observed at the Mega-Amp Spherical Tokamak in the presence of heating by energetic particles. A fully nonlinear self-consistent numerical implementation of the Berk-Breizman augmentation of the Vlasov-Maxwell system is applied in the nonperturbative regime; frequency sweeping events phenomenologically comparable to experiment are observed. Experimental observations and simulation results are presented; the existence of a congruence between them is discussed.