Kinetic excitation of the shear modified ion-acoustic instability in non-thermal ionospheric plasma: an exact numerical investigation

Abstract The Poisson–Vlasov formalism, pertaining to the well-known kinetic description model of plasmas, is employed to investigate the shear-modified ion-acoustic instability in nonthermal, anisotropic, Cairns-distributed ionospheric magnetoplasma characterized by parallel flow shear. The kinetic dielectric response function of the shear-modified ion-acoustic instability is calculated. The real (oscillatory) frequency and growth rate (imaginary frequency) of the plasma mode under consideration are explored through an exact numerical solution of the kinetic dispersion relation. In particular, the role of parallel flow shear in the excitation of the instability associated with the ion-acoustic mode is thoroughly examined. It is observed that the instability growth rate is significantly influenced by variations in the magnitudes of the relevant dimensionless parameters, including velocity shear S i , nonthermality parameter α , ion temperature anisotropy ratio σ i , and ion-to-electron temperature ratio Λ i , e . The present investigation is relevant for understanding plasma dynamics in space environments comprising nonthermal particle populations, e.g., the upper ionosphere.