Particle Acceleration in Solar Flares and Enrichment of 3He and Heavy Ions

TL;DR

This paper explores how turbulence-driven stochastic acceleration in solar flares explains high-energy particles, including the enrichment of 3He and heavy ions, aligning well with observational data.

Contribution

It demonstrates that turbulent plasma waves are the most plausible mechanism for particle acceleration in solar flares, explaining observed spectral features and ion enrichment.

Findings

Stochastic acceleration by turbulence explains high-energy electron and ion production.

The model accounts for the observed 3He enrichment in solar energetic particles.

It predicts increasing heavy ion enhancements with ion mass or charge ratio.

Abstract

We discuss possible mechanisms of acceleration of particles in solar flares and show that turbulence plays an important role in all the mechanism. It is also argued that stochastic particle acceleration by turbulent plasma waves is the most likely mechanism for production of the high energy electrons and ions responsible for observed radiative signatures of solar flares and for solar energetic particle or SEPs, and that the predictions of this model agrees well with many past and recent high spectral and temporal observations of solar flares. It is shown that, in addition, the model explains many features of SEPs that accompany flares. In particular we show that it can successfully explain the observed extreme enhancement, relative to photospheric values, of $^3$He ions and the relative spectra of $^3$He and $^4$He. It has also the potential of explaining the relative abundances of most ions including the increasing enhancements of heavy ions with ion mass or mass-to-charge ratio.