Drift instabilities driven by slab ion temperature gradient in suprathermal plasmas

TL;DR

This paper investigates how slab ion temperature gradient-driven drift instabilities behave in suprathermal plasmas with Kappa distributions, revealing the influence of suprathermal ions and electrons on instability characteristics.

Contribution

It provides a kinetic analysis of ITG instabilities in suprathermal plasmas, deriving a dispersion relation and exploring effects of suprathermal particles on instability thresholds.

Findings

Suprathermal ions enhance instability at large wavenumbers.

Suprathermal ions suppress instability at small wavenumbers.

Thermal speed ratio influences suprathermal effects.

Abstract

The drift instabilities driven by the slab ion temperature gradient (ITG) in Kappa-distributed plasmas are investigated by the kinetic method. The linear dispersion relation is given in an integral representation involving only the standard plasma dispersion function. The wave frequency and growth rate are derived without the density inhomogeneity. Numerical solutions of the dispersion equation are conducted to show the different effects of the suprathermal ions and electrons. We find that the suprathermal ions can enhance the instability in large wavenumbers but suppress it in small wavenumbers. Thus, the suprathermalization of ions could be one of the factors leading to a lower limit of wavenumbers for the ITG instabilities. Besides, the numerical calculations also imply that the thermal speed ratio affects the intensities of the suprathermal effects. Finally, in the presence of density inhomogeneity, the ITG instability boundary is numerically analyzed.