Effect of the general loss-cone distribution function on kinetic Alfvén waves—a kinetic approach

Abstract

AbstractKinetic Alfvén waves are investigated in the presence of a general loss-cone distribution function including finite electron pressure and ion-gyroradius effects. The dispersion relation and damping/growth rate are evaluated for different electron to ion temperature ratios, Te/Ti, using a kinetic approach. The wave frequency ω and damping/growth rate γL are evaluated for two regimes of propagation, k⊥ρi < 1 and k⊥ρi > 1, where k⊥ is the perpendicular wave number and ρi is the ion-gyroradius. An enhancement of the wave frequency and a reduction in the damping rate are predicted by steep loss-cone distribution indices and Te/Ti. The growth of the wave is also noticed at higher values of the distribution index and lower Te/Ti. Plasma parameters appropriate to the plasma sheet boundary layer (PSBL) are used to discuss the propagation of kinetic Alfvén waves from the PSBL to the auroral ionosphere.