Parametric instabilities of the inhomogeneous near SOL tokamak plasma, driven by the coupled effect of the high harmonic fast wave and of the ion and electron temperatures gradients, and anomalous heating of the near SOL ions

Abstract

Electrostatic parametric instabilities in the inhomogeneous near-SOL tokamak plasma, driven by the combined action of a high-harmonic fast wave (HHFW) with a frequency near the 30th ion-cyclotron (IC) harmonic and electron and ion temperature gradients, are investigated numerically. The results indicate the parametric decay of the HHFW into a HHIC (Bernstein) wave and HHIC quasimode. The instability is found to exist within a finite wavelength range of the HHFW. The development of the parametric HHIC quasimode decay instability leads to the onset of parametric turbulence accompanied by anisotropic ion heating, with the ion heating rate across the magnetic field significantly exceeding that along the magnetic field.