Alpha particle heating in hot diamagnetic cavities

Abstract

Observational data from ISEE 1 are analyzed and a one-dimensional electromagnetic hybrid computer simulation is conducted for the heating of solar wind alpha particles in hot diamagnetic cavities (HDCs). In the simulation, which envisions alpha heating by ion-ion instabilities, low beam densities excite the proton/proton right-hand resonant instability that then pitch-angle scatters the beam without significantly heating the alphas. At greater beam densities, the proton/proton nonresonant instability undergoes saturation through a trapping of all three ion components. These results support the Thomsen et al. (1988) hypothesis that the nonresonant instability is the primary source of ion heating in hot diamagnetic cavities.