High-Energy Particles in Solar Flares

Accelerated particles appear to coexist inseparably with most forms of energy release in solar flares and coronal mass ejections. We identify at least five different populations of high-energy electrons and ions. High-energy particles, accelerated efficiently in the flare in great numbers, transport a large fraction of the flare energy to other sites. This behavior makes them an integral part of the flare process. Much new data has come from two spacecraft launched in 1991: the Compton Gamma­Ray Observatory and Yohkoh. This review concentrates on particles in flares, mainly using X-ray and gamma-ray data rather than measurements of “escaping” particles observed in interplanetary space.