Acceleration Mechanisms, Flares, Magnetic Reconnection And Shock Waves

Abstract

Acceleration in astrophysics usually means converting a significant fraction of the energy of some source into particles whose individual kinetic energy greatly exceeds the average temperature of the medium. There are three general classifications of acceleration processes. The first is hydrodynamic, second coherent electromagnetic, and third stochastic electromagnetic processes. We shall discuss each of these briefly in terms of the spectrum of accelerated particles. This can be related to an efficiency by the relationships N(>E) α E┌ or an energy efficiency N(>E) α EI-г In astrophysics we frequently emphasize Г without realizing the constraints this imposes upon the efficiency of the acceleration mechanism. So often the relatively flat spectra result in efficiency requirements that challenge the ingenuity of those who wish to invent acceleration mechanisms.