Excitation mechanisms and spectral properties of the ion‐cyclotron parallel‐velocity shear driven instability

[1] The electrostatic ion cyclotron parallel-velocity shear driven instability, and its associated oscillatory mode, is investigated analytically. It is shown that three distinct mechanisms are responsible for this instability, specifically, the ion-kinetic, ion-hydrodynamic and electron-kinetic mechanisms. In separate magnitude ranges of the normalized parallel-wavelength component, a different mechanism dominates, with a transition in each overlapping region. The linearized dispersion equation is solved within these ranges where the effects of inverse ion cyclotron damping, ion hydrodynamic, and inverse electron Landau damping alternately dominate, respectively, in the development of ion cyclotron oscillations. A general criterion of instability is determined by expressing the destabilizing effect of the velocity shear in terms of the perpendicular(magnetic field-normal) component of the wave vector.