Fermi Acceleration in Plasmoids interacting with Fast Shocks of Reconnection via Fractal Reconnection

TL;DR

This paper presents a model of particle acceleration in solar flares involving plasmoid ejections and their interaction with fast shocks, explaining nonthermal emission spectra through a Fermi acceleration mechanism.

Contribution

It introduces a novel coupled model of plasmoid ejections and shock interactions, highlighting the role of fractal plasmoid distributions in particle acceleration.

Findings

Fermi acceleration occurs as plasmoids pass through shocks.

Fractal plasmoid distribution explains power-law spectra.

Acceleration continues until proton Larmor radius is reached.

Abstract

We propose the particle acceleration model coupled with multiple plasmoid ejections in a solar flare. Unsteady reconnection produces plasmoids in a current sheet and ejects them out to the fast shocks, where particles in a plasmoid are reflected upstream the shock front by magnetic mirror effect. As the plasmoid passes through the shock front, the reflection distance becomes shorter and shorter driving Fermi acceleration, until it becomes proton Larmor radius. The fractal distribution of plasmoids may also have a role in naturally explaining the power-law spectrum in nonthermal emissions.