ACCELERATION AND ENRICHMENT OF 3He IN IMPULSIVE SOLAR FLARES BY ELECTRON FIREHOSE WAVES

A new mechanism for acceleration and enrichment of He during impulsive solar flares is presented. Low-frequency electromagnetic plasma waves excited by the Electron Firehose Instability (EFI) can account for the acceleration of ions up to 1 MeV amu−1 energies as a single stage process. The EFI arises as a direct consequence of the free energy stored in a temperature anisotropy (T e ‖ > T e ⊥) of the bulk energized electron population during the acceleration process. In contrast to other mechanisms which require special plasma properties, the EFI is an intrinsic feature of the acceleration process of the bulk electrons. Being present as a side effect in the flaring plasma, these waves can account for the This is an unedited preprint of an article accepted for publication in Astrophysical Journal. The final published article may differ from this preprint. Copyright 2002 by The American Astronomical Society. Please cite as 'ApJ preprint doi:10.1086/344593'.