On neutral sheets in the solar wind
β Scribed by G. W. Pneuman
- Publisher
- Springer
- Year
- 1972
- Tongue
- English
- Weight
- 707 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0038-0938
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β¦ Synopsis
The structure and dynamics of neutral sheets in the solar wind is examined. The internal magnetic topology of the sheet is argued to be that of thin magnetic tongues greatly distended outward by the expansion inside the sheet. Due to finite conductivity effects, outward flow takes place across field lines but is retarded relative to the ambient solar wind by the reverse J β’ B force. The sheet thickness as well as the internal transverse magnetic field are found to be proportional to the electrical conductivity to the inverse one third power. Estimating a conductivity appropriate for a current carried largely by the ions perpendicular to the magnetic field, we find sheet dimensions of the order of 500kin representative for the inner solar corona. For a radial field of strength 89 at 2R| the transverse field there is about 2 x 10-aG and decreases outward rapidly.
The energy release in the form of Joulean dissipation inside the sheet is estimated. It is concluded that ohmic heating in current sheets is not a significant source of energy for the overall solar wind expansion, mainly because these structures occupy only a small percentage of the total coronal volume. However, the local energy, release through this mechanism is found to be large -in fact, over 7 times that expected to be supplied by thermal conduction. Therefore, ohmic heating is probably a dominant energy source for the dynamical conditions within the sheet itself.
π SIMILAR VOLUMES
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