" Kinetic Simulations of Multi-scale Electron Acceleration by Alfven Waves ", Peter Damiano, Staff Research Physicist, Princeton Plasma Physics Laboratory.
ABSTRACT: Alfven waves couple the magnetosphere and ionosphere over a range of scales from global scale Field Line Resonances to dispersive scale waves that are thought to power the broadband aurora. In this presentation, we summarize results of 2D simulations of both Field Line Resonances and dispersive scale Alfven waves in a dipolar magnetic field topology using a hybrid gyrofluid-kinetic electron model. This model is an extension of the self-consistent hybrid MHD-kinetic electron model (Damiano et al., 2007) that has been generalized to include ion gyroradius effects based on the kinetic-fluid model of Cheng and Johnson (1999). For global scale waves, it is found that mirror force effects self-consistently result in parallel potential drops sufficient to accelerate a mono-energetic electron beam to keV energies and the wave energy dissipated in this acceleration can damp the wave in a few Alfven cycles. The perpendicular Poynting flux associated with the parallel electric field also disperses wave energy perpendicular to the magnetic field leading to a broadening of the upward parallel current region as electrons are accelerated along adjacent field lines. We also present recent results of the propagation of localized kinetic Alfven wave pulses from a magnetotail source region to the ionosphere for a realistic electron to ion temperature ratio and discuss how the inclusion of ion gyroradius radius effects impact the propagation characteristics of the wave and the accelerated electron distribution function.
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