Paper presented at AGU Fall Meeting, 8-12 December 1997, San Fransico, CA, USA
The time-of-flight mass spectrometers CELIAS/STOF and CELIAS/HSTOF on board of the SOHO satellite has the capability of detecting energetic ions between 35 and 600 keV/q (or up to 0.6 MeV/nuc in HSTOF) and determines the mass, energy and charge (charge upper limit in HSTOF) of each particle. We shall report on the flux ratio of energetic He+ and He2+ derived from the data collected in the 2 years since launch and discuss the implications of these observations on the existing models of particle acceleration in corotating interaction regions (CIRs), i.e. the seed particle population for the acceleration process of corotating particle events.