HEAVY-ION ACCELERATION BEYOND 10 MEV PER NUCLEON IN IMPULSIVE SOLAR-FLARES

We present the energy spectra of 0.5-9 MeV nucleon(-1) He-4 and simila r to 0.5-20 MeV nucleon(-1) O, Ne-Si, and Fe observed in impulsive fla res with instrumentation on board the SAMPEX satellite between 1992 Ju ly and 1994 July. With the large collecting power of this instrumentat ion, we routinely find O, Ne-Si, and Fe ions accelerated in impulsive flares up to energies of similar to 16 MeV nucleon(-1) and have observ ed Fe accelerated up to between 20 and 28 MeV nucleon(-1). These are t he highest energies of heavy ions observed in typical impulsive flares to date, and they provide an important constraint on acceleration the ories. The majority of events have spectra that are power laws in ener gy for He-4, O, Ne-Si, and Fe.