Abstract

In past, kinetic Alfven waves are widely investigated regarding the transfer of energy from the magnetosphere to the ionosphere. These waves are supposed to be responsible for the acceleration of auroral electrons to exhibit auroral phenomena. The existence of parallel electric fields is always reported in association with the kinetic Alfven waves. In the present investigation, assuming parallel electric fields developed by different mechanism, the dispersion relation and growth/damping rate of the kinetic Alfven Wave (KAW) in the presence of parallel electric field are evaluated with general loss-cone distribution using the kinetic approach. The wave frequency w and growth/damping rate g_L are obtained for two regimes of propagation k_^r_i <1 and k_^r_i >1, where k_^ is perpendicular wave number andr_i is the ion-gyro radius. The results of the present study show that the frequency w and growth/damping rate of wave depend upon the distribution indices, parallel electric field and k_^r_i. The generation of kinetic Alfven wave by the combined effect of parallel electric field and loss-cone distribution indices (J), at a particular range of k_^r_i is noticed. Thus the propagation of kinetic Alfven wave and loss of the Poynting flux from plasma sheet boundary layer (PSBL) to the ionosphere can be explained more effectively on the basis of present investigation. The results of the present study show that the parallel electric field in the presence of loss-cone distribution index is an important parameter to study KAW in the PSBL. The finding of the present investigation is to report that auroral phenomena are suitably described by kinetic Alfven wave in the presence of parallel electric field and the general loss-cone distribution function.

Key words: Kinetic Alfven wave, Plasma-sheet-boundary-layer, Parallel electric field, Kinetic theory, Loss-cone distribution function.