Mirror Force Induced Wave Dispersion in Alfven Waves
Authors: P.A. Damiano and J.R. Johnson
Abstract:
A recent series of studies of the upward current region of global scale Field Line Resonances using
a hybrid MHD-kinetic electron model shows that the parallel current profi le saturates and broadens
perpendicular to the ambient magnetic field and that the extent of this broadening increases with
the electron temperature. Using MHD simulations, with a parallel Ohm's law derived from the
hybrid simulation results at different temperatures, we explore the nature of this broadening and
illustrate that this dispersion is a result of the increased perpendicular Poynting
flux resulting from the increased parallel electric field associated with mirror force effects. The increased perpendicular
Poynting flux facilitates a dispersion of wave energy across magnetic fi eld lines which in-turn allows
for the acceleration of electrons to carry the fi eld aligned current on adjacent fi eld lines. This
dispersion is additionally amplifi ed as a function of time in the simulation as the precipitation of
weakly trapped electrons requires a progressively larger parallel electric fi eld to accelerate more
strongly trapped populations to carry the current.
__________________________________________________
Submitted to: Physical Review Letters (November 2011)
__________________________________________________
Download PPPL-4714 (pdf 544 KB 9 pp)
__________________________________________________