Expansion Pattern of Helium-enriched Shells asssociated with Solar Flares

Abstract

IT is known that shock waves and post-shock plasmas are sometimes released from solar flares^1,2. Recently, helium-enriched shells have been observed more than ten times in these post-shock plasmas^3,4. These shells seem to have been ejected by solar flares from regions deep in the solar atmosphere^3,4. Since these shells always follow shock waves at the Earth's orbit, the ejection of these shells is probably closely related to the expansion of magnetic bottles over the flare region. Here we shall consider the dependence of the thickness of the helium-enriched shell on the longitudinal position of parent flares, and then the large-scale configuration of the expanding shell in interplanetary space.