Kinetic study of transverse electron-scale interface instability in relativistic shear flows

Abstract

Interfacial magnetic field structures induced by transverse electron-scale shear instability (mushroom instability) are found to be strongly associated with electron and ion dynamics, which in turn will influence the development of the instability itself. We find that high-frequency electron oscillations are excited normal to the shear interface. Also, on a larger time scale, the bulk of the ions are gradually separated under the influence of local magnetic fields, eventually reaching an equilibrium related to the initial shear conditions. We present a theoretical model of this behavior. Such separation on the scale of the electron skin depth will prevent different ions from mixing and will thereafter restrain the growth of higher-order instabilities. We also analyze the role of electron thermal motion in the generation of the magnetic field, and we find an increase in the instability growth rate with increasing plasma temperature. These results have potential for providing a more realistic description of relativistic plasma flows.