Dissipation Range Dynamics: Kinetic Alfven Waves and the Importance of Electron Beta

Robert J. Leamon, Norman F. Ness, Charles W. Smith and Hung K. Wong

Journal of Geophysical Research, submitted (1998)

Abstract:

In a previous paper we argued that the damping of obliquely propagating Kinetic Alfven waves, chiefly by resonant mechanisms, was a likely explanation for the formation of the dissipation range for interplanetary magnetic field fluctuations. This suggestion was based largely upon observations of the dissipation range at 1 AU as recorded by the Wind spacecraft. We pursue this suggestion here with both a general examination of the damping of obliquely propagating Kinetic Alfven waves and an additional examination of the observations. We explore the damping rates of Kinetic Alfven waves under a wide range of interplanetary conditions using numerical solutions of the linearized Maxwell-Vlasov equations and demonstrate that these waves display the nearly isotropic dissipation properties inferred from the previous paper. Using these solutions, we present a simple model to predict the onset of the dissipation range and compare these predictions to the observations. In the process we demonstrate that electron Landau damping plays a significant role in the damping of IMF fluctuations which leads to significant heating of the thermal electrons.