Electrostatic instabilities in current-carrying magnetoplasmas with equilibrium density and ion velocity gradients

Detailed studies of electrostatic wave instabilities in a current-carrying magnetoplasma with equilibrium density and ion velocity gradients are presented. For this purpose, a general dispersion relation is derived by using a non-Boltzmann electron response as well as an ion density perturbation, which includes the ion-neutral drag. Our dispersion relation contains previously known results as limiting cases, but it also includes some additional instabilities associated with the electron-wave resonant interaction. The present results can help to understand the origin of the nonthermal electrostatic waves in laboratory and space plasmas where there are free energy sources due to ion velocity gradients and streaming particle motions.