An Unstable Arch Model of a Solar Flare
Abstract
The theoretical consequences of assuming that a current flows along flaring arches consistent with a twist in the field lines of these arches are examined. It is found that a sequence of magnetohydrodynamic (MHD) and resistive MHD instabilities driven by the assumed current (which is referred to as the toroidal current) can naturally explain most manifestations of a solar flare. The principal flare instability in the proposed model is the resistive kink (or tearing mode in arch geometry) which plays the role of thermalizing some of the field energy in the arch and generating X-configured neutral points needed for particle acceleration. The difference between thermal and nonthermal flares is elucidated and explained, in part, by amplitude-dependent instabilities, generally referred to as overlapping resonances. The criteria for the generation of flare shocks strongly depend on the magnitude and gradient steepness of the toroidal current, which also are found to determine the volume and rate of energy release. The resulting model is in excellent agreement with present observations and has successfully predicted several flare phenomena.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 10, 1976
- Accession Number
- ADA030928
Entities
People
- Daniel S. Spicer
Organizations
- United States Naval Research Laboratory