Observations of particle acceleration in solar flaresSolar flares provide several examples of nonthermal particle acceleration. The paper reviews the information gained about these processes via X-ray and gamma-ray astronomy, which can presently distinguish among three separate particle-acceleration processes at the sun: an impulsive accelerator of more than 20 keV electrons, a gradual accelerator of more than 20 keV electrons, and a gradual accelerator of more than 10 MeV ions. The acceleration energy efficiency (total particle energy divided by total flare energy) of any of these mechanisms cannot be less than about 0.1%, although the gradual acceleration does not occur in every flare. The observational material suggests that both the impulsive and gradual accelerations take place preferentially in closed magnetic-field structures, but that the electrons decay in these traps before they can escape. The ions escape very efficiently.
Document ID
19800069040
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Hudson, H. S. (California, University La Jolla, Calif., United States)
Date Acquired
August 10, 2013
Publication Date
January 1, 1979
Subject Category
Solar Physics
Meeting Information
Meeting: Particle acceleration mechanisms in astrophysics