Thermal evolution of current sheets and flash phase of solar flares
β Scribed by J. Heyvaerts; E. R. Priest
- Publisher
- Springer
- Year
- 1976
- Tongue
- English
- Weight
- 457 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0038-0938
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β¦ Synopsis
The physical conditions in a stationary flow of the Petchek type, allowing reconnection between flux emerging from below the solar photosphere and a preexisting magnetic field, are discussed. It is shown that, when rising in the solar atmosphere, the reconnection region has at first a rather low temperature as compared with its environment. Above a certain critical height, however, this low temperature thermal equilibrium often ceases to be possible, and the sheet rapidly heats, seeking a new thermal equilibrium. During this dynamical process, current-driven microinstabilities may be triggered in the current sheet, giving rise to an enhanced resistivity. High energy particles might be produced by the induced electric field developed during the rapid readjustment of MHD flows that results from this change in the transport properties of the plasma.
π SIMILAR VOLUMES
The properties and development of a high-temperature current sheet characterized by increasing merging velocity are studied and related to the early phases of solar flares. It is shown that the system can be described by the Petschek-type geometry for a wide range of merging velocities. In the diffu
Cyclotron radiation (its frequency spectrum and polarization) of thermal electrons in a neutral current sheet is considered. It is shown that cyclotron radiation is able to escape only from a thin edge of the sheet where the magnetic field is practically homogeneous. Due to this, the frequency spect
Solar X-ray observations from balloons and from the SMM and HINOTORI spacecraft have revealed evidence for a super-hot thermal component with a temperature of > 3 β’ 107K in many solar flares, in addition to the usual 10-20 β’ 106 K soft X-ray flare plasma. We have systematically studied the decay pha