Dispersion relation of kinetic Alfven waves in superthermal plasma

Abstract

Kinetic Alfven wave has been studied in superthermal plasma in both cases (warm and cold electron limit) in plasma sheet boundary layer. The effect of velocity distribution function (VDF) that exhibit a power law dependence on the high- energy tail and known as superthermal or kappa distribution, have been found to provide a better fitting to the VDF measured by several spacecraft in the plasma environment and is the key subject of this paper. Kinetic effects of electrons and ions are included to study kinetic Alfven wave because both are important in the transition region. In this work we introduce a mathematical formalism that provide expressions for dispersion relations for oblique propagating kinetic Alfven waves resulting from a kappa VDF. The effect of kappa index and thermal corrections on the dispersion relations of KAW is discussed. The method may be suitable to deal with the PSBL, where particle acceleration is also important along with wave emissions.