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 temperature gradients, and anomalous heating of the near-SOL ions

Electrostatic parametric instabilities in the inhomogeneous near-scrape-off layer (SOL) tokamak plasma, driven by the combined action of a high-harmonic fast wave (HHFW) with a frequency near the 30th ion-cyclotron harmonic and electron and ion temperature gradients, are investigated numerically. The results indicate the parametric decay of the HHFW into a high-harmonic ion-cyclotron (HHIC) (Bernstein) wave and HHIC quasimode. The instability exists only over a finite range of HHFW wavelengths. The development of the parametric HHIC quasimode decay instability in the near-SOL plasma 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.