Accession Number : ADP001435

Title :   Radio and X-Ray Evidence for Electron Acceleration in Solar Flares,

Corporate Author : COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANIZATION EPPING (AUSTRALIA) DIV OF RADIOPHYSICS

Personal Author(s) : Stewart,R. T.

Report Date : 27 DEC 1982

Pagination or Media Count : 16

Abstract : Radio and X-ray observations, as well as gamma-ray and interplanetary electron observations, are briefly reviewed for evidence of electron acceleration during solar flares. The evidence suggests that in some large flares a second stage of particle acceleration takes place where ions and electrons are accelerated to very high energies. This second stage follows no more than several minutes after the first or impulsive stage, which occurs during the initial minute or so of the solar flare. During the impulsive phase electrons are accelerated to energies of approximately approx. 10-100 keV, probably by bulk energization, where stored magnetic energy is converted into thermal energy. Energy-loss arguments favor the electrons having a quasi-thermal (near-Maxwellian) electron velocity distribution. During large flares second-phase electrons are accelerated to much higher energies, approx. 10 MeV, and appear to have a power-law velocity distribution. The second-stage acceleration mechanism may be associated with a coronal shock wave, but so far there is no clear evidence that electrons with energies > or = 100 keV are directly associated with a shock wave. (Author)

Descriptors :   *Solar flares, *Electrons, High acceleration, Electron energy, High energy, Energy conversion, Shock waves, Solar corona, Australia

Distribution Statement : APPROVED FOR PUBLIC RELEASE