Unified Theory for Solar Energetic Particles: Basic Composition, ³He-Rich Events, and Prompt Ion Acceleration

Abstract

A theoretical model for solar energetic particles is presented, which consistently describes the basic composition pattern of heavy ions, ³He-enrichments, and rapid ion acceleration to relativistic energies. On the basis of the theory of particle acceleration by nonlinear magnetosonic waves, which can explain the prompt ion acceleration, we obtain the fraction of high-energy ions as a function of the ion mass. Then, noting that random fluctuation velocities of heavy ions due to magnetohydrodynamic turbulence can easily exceed their thermal speeds, we show that the relative abundances of ions accelerated by magnetosonic waves in magnetohydrodynamic turbulence become similar to those of the background plasma. The theory is further applied to the acceleration of ³He particles in the presence of turbulent waves with frequencies near the ³He cyclotron frequency, and it is found that huge enrichments of ³He particles are possible.