Electronic Resource
Springer
Space science reviews
38 (1984), S. 89-141
ISSN:
1572-9672
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract The formation of the observed solar cosmic ray (SCR) composition remains an open question. It has become particularly acute after the discovery of 3He-rich events. The 3He/4He abundance ratio revealed in such events exceeds substantially (up to four orders of magnitude) that in the solar atmosphere. The data available on the 3He-rich events are discussed and a list of all such events known up to date is presented. Most of the 3He-rich SCR events can be associated with the corresponding optical flares on the Sun, with X-ray and radiobursts. An analysis of the models of 3He enrichement proposed up to now shows that only preferential 3He heating by plasma mechanisms can provide the observed high enrichment levels (3He/4He ≈ 1). A model involving preferential heating of 3He by induced scattering on ions of the ion acoustic waves generated by flare associated electrons in the solar atmosphere is considered in detail. This model can account for the major properties of the 3He-rich flares. Observational implications of the 3He-rich solar flare model are analyzed; the predictions of the theory are compared with the experimental data available, and promising avenues of further relevant experimental and theoretical research are considered. However it is shown that all main conclusions made based on the expressions ((3.2), (3.11), (3.12)) remain the same.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00180337
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