Betatron acceleration in a large solar hard X-ray burst.
Abstract
The problem of diagnosing flare particle acceleration mechanisms from hard X-ray bursts is discussed, and it is argued that the electron trap model of bursts is more amenable to observational investigation at present than models of thick-target type. It is then shown that data for the large X-ray burst of 1972 August 4 are consistent with the source electrons being trapped in a very large vibrating coronal magnetic bottle. Furthermore, the observations show that the burst time profile is not dominated by collisional losses. It is proposed instead that the entire profile is essentially determined by betatron action of the varying trap field on the electrons. This betatron model is then analyzed in detail and shown to predict very well the observed correlation of electron flux and spectral index in this event when it is supposed that the electrons are initially produced by runaway in a direct electric field. Comparison of the model with observations permits inference of the approximate form of magnetic field evolution in the trap. Finally the physics behind this field evolution is briefly considered. Subject headings: flares, solar - X-rays, solar
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1975
- DOI:
- 10.1086/153845
- Bibcode:
- 1975ApJ...200..734B
- Keywords:
-
- Betatrons;
- Electron Energy;
- Particle Acceleration;
- Solar X-Rays;
- Trapped Particles;
- Astronomical Models;
- Data Reduction;
- Electron Density Profiles;
- Electron Flux Density;
- Magnetic Field Configurations;
- Particle Collisions;
- Solar Flares;
- Target Thickness;
- Time Dependence;
- X Ray Sources;
- X Ray Spectra;
- Solar Physics