A Hybrid Kinetic Model of Asymmetric Thin Current Sheets With Sheared Flows: Application to the Solar wind and Corona

We discuss a model of equilibrium current sheets in a collisionless plasma incorporating ion flows that are asymmetric and sheared across the current sheet. The ions are treated as particles, and the electron contribution is included as a massless fluid. The resulting current sheet is a Vlasov equilibrium and satisfies Ampere's law. The current sheet thickness is shown to be of the order of the ion Larmor radius. It is found that the structure of the current sheet depends on the distribution function of the ions entering the current sheet. A characteristic feature of this class of equilibria is that the pressure is anisotropic and nondiagonal. The asymmetric sheared ion momentum flows as well as the off-diagonal pressure tensor elements play an essential role in the force balance. The model is applied to current sheets co-moving with the solar wind is directly compared with high-resolution WIND MFI magnetic field and WIND 3DP particle data. The agreement is good. In addition, we scale the results to conditions corresponding to the solar corona.

Work supported by ONR.