Multispacecraft Analysis of a 3He Rich Solar Energetic Particle Event with ACE/SEPICA and SOHO/HSTOF

A T Bogdanov, E Möbius, B Klecker, M Hilchenbach, D Hovestadt, L M Kistler, M A Popecki, E J Lund, D Heirtzler, A B Galvin, P Bochsler, H Grünwaldt, F M Ipavich, F Gliem

Paper presented at AGU Spring Meeting, 26-29 May 1998, Boston, MA, USA

New results are reported on the energy dependence of the 3He/4He ratio during the 1997 September 19-21 impulsive solar energetic particle (SEP) event. The events have been observed simultaneously by two instruments with complementary energy ranges, the Solar Energetic Particle Ionic Charge Analyzer (SEPICA) on ACE and the time-of-flight mass spectrometer HSTOF on SOHO. The two instruments cover the energy range from ~ 0.1 to 3.5 MeV/nuc. We observe a strong increase of the 3He/4He ratio with energy, starting with < 0.1 at the lower end and reaching ~ 1 at the upper end. This is in agreement with previous ISEE observations and extends their energy range to lower values. The new data set is compared with existing theoretical work on selection and acceleration mechanisms in compact flares.

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Last Update: June 8, 1998, Peter Wurz