Is heating of ions by Alfvén waves via nonresonant interactions applicable in the Earth’s magnetosphere?

Abstract

Heating of ions in Earth’s magnetosphere by enhanced Alfv$\acute{e}$n waves below resonance frequency (nonresonant heating) has been presented in many studies, among these is the study of Wang et al. (2006) in which they stated that in any region in space with low beta plasma, this heating process, i.e. nonresonant ion heating is applicable and effective. In this paper we stress on the inapplicability of this type of heating in the Earth’s magnetosphere. We present; (1) a data set that provides a strong proof that the theory presented by Wang et al. (2006) is not applicable in this region of space (i.e. Earth’s magnetosphere), (2) in addition, we plot altitude profiles for parallel, perpendicular, and total temperatures for hydrogen ions in cusp and central polar cap regions by evaluating observed magnetic activity and Alfv$\acute{e}$n waves into Wang et al. (2006) theory, we find the changes in the altitude behavior in ion temperature profiles are very small, (3) also, we compare between Monte Carlo simulations results of ion temperatures obtained by using Barghouthi model (this model includes the effects of gravity, polarization electric field, divergence geomagnetic field, centrifugal acceleration, resonant ion heating, and with and without nonresonant ion heating effect) in cusp and central polar cap regions with appropriate boundary conditions (Barghouthi et al., 2008), both simulation results of ion temperatures are almost the same. Therefore, we report on the nonresonant ion heating process in central polar cap and cusp regions is not significant.