An Explanation for the Different Locations of Electron and Ion Acceleration in Solar Flares

Abstract

RHESSI observations of the 2002 July 23 solar flare have shown that hardX-rays and gamma rays are produced in different locations within theflare volume. The gamma-ray emission, which is a diagnostic of ionacceleration, appears to originate in the vicinity of large loops, whilethe hard X-ray emission, a diagnostic of electron acceleration,originates near shorter loops. The tendency for a stochasticacceleration model based on cascading MHD turbulence to favor ionacceleration in larger acceleration regions has been previously noted.Here we evaluate this effect quantitatively and show that such a modelis consistent with the RHESSI observations.