Solar flare mechanism based on magnetic arcade reconnection and island merging
- Princeton Plasma Physics Laboratory
The authors propose a model describing physical processes of solar flares based on resistive reconnection of magnetic field subject to continuous increase of magnetic shear in the arcade. The individual flaring process consists of magnetic reconnection of arcade field lines, generation of magnetic islands in the magnetic arcade, and coalescence of magnetic islands. When a magnetic arcade is sheared (either by foot point motion or by flux emergence), a current sheet is formed and magnetic reconnection can take place to form a magnetic island. A continuing increase of magnetic shear can trigger a new reconnection process and create a new island in the under lying arcade below the magnetic island. The new born island rises faster than the preceding island and merges with it to form one island. Before completing the island merging process, the new born island exhibits two phases of rising motion: a first phase with a slower rising speed and a second phase with a faster rising speed. The flare plasma heating occurs mainly due to magnetic reconnection in the current sheet under the new born island. The new born island represents the X-ray plasma ejecta which shows two phases of rising motion observed by Yohkoh [Ohyama and Shibata (1997)]. The first phase with slower new born island rising speed corresponds to the early phase of reconnection of line-tied field in the underlying current sheet and is considered as the preflare phase. In the second phase, the island coalescence takes place, and the underlying current sheet is elongated so that the line-tied arcade field reconnection rate is enhanced. This phase is interpreted as the impulsive phase or the flash phase of flares. The obtained reconnection electric field is large enough to accelerate electrons to an energy level higher than 10 keV, which is necessary for observed hard X-ray emissions. After merging of the islands is completed, magnetic reconnection continues in the current sheet under the integrated island for a longer period, which is considered as the main phase of flares. The sequence of all these processes is repeated with some time interval while a shear-increasing motion continues. The authors propose that these repetitive flaring processes constitute a set of homologous flares.
- Research Organization:
- Princeton Plasma Physics Laboratory, Princeton, NJ (US)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 756593
- Report Number(s):
- PPPL-3450
- Country of Publication:
- United States
- Language:
- English
Similar Records
A model solar flares and their homologous behavior
Computer modeling of fast collisionless reconnection
Flux Rope Acceleration and Enhanced Magnetic Reconnection Rate
Technical Report
·
Wed Jan 26 23:00:00 EST 2000
·
OSTI ID:750430
Computer modeling of fast collisionless reconnection
Conference
·
Sat Dec 31 23:00:00 EST 1983
·
OSTI ID:5267914
Flux Rope Acceleration and Enhanced Magnetic Reconnection Rate
Technical Report
·
Mon Mar 24 23:00:00 EST 2003
·
OSTI ID:813604