Speaker
Description
The stability of an anisotropic collisionless plasma layer to small disturbances within the framework of magnetohydrodynamics (MHD) is explored. We base our analysis on moment equations derived from the Vlasov kinetic equation, accounting for heat flow along spatially shearing flows. To determine the complex spectral parameter governing the instability growth rate, we solve the boundary value problem using the WKB approximation, assuming a smooth hyperbolic velocity profile. The resulting general integral dispersion equation describes various body and interface instabilities in the presence of heat flow along the magnetic field—a phenomenon well-studied in infinite stationary anisotropic plasma.
Our findings reveal that reducing the layer width significantly enhances the mirror instability while strongly suppressing the oblique fire-hose instability. Specifically, we focus on the aperiodic oblique fire-hose instability within a confined layer and observe that the spatial gradient in flow velocity plays a crucial role. As the layer width narrows and the velocity gradient increases, the body hose modes transform into surface Kelvin-Helmholtz (KH) modes at the discontinuity surface between the two flow regions.
Keywords: Solar wind, anisotropic plasma instability, MHD shearing flows
