Abstract
A model is suggested for the acceleration of ions, based on Petschek's theory of magnetic field annihilation. It is shown that ions can gain high energies in this model, and that energy distributions similar to those observed can be obtained. It is also shown that this model prevents electrons from gaining high energy, consistent with cosmic-ray observations. It is suggested that if this model is correct, we can obtain, from the observed ion energy distribution, a relation between the (average) plasma density and the (average) magnetic field in regions where the ions are accelerated.