Optimal Electron Energies for Driving Chromospheric Evaporation in Solar Flares
Solar flares: recent advances on observations and modelling
Stephen J. Bradshaw
Jeffrey W. Reep (NRL); David Alexander (Rice University)
Rice University
In the standard model of solar flares, energy deposition by a beam of electrons drives strong chromospheric evaporation leading to a significantly denser corona and much brighter emission across the spectrum. Chromospheric evaporation is generally understood in terms of two different regimes: explosive and gentle evaporation. In this work, we examine the importance of electron energy and stopping depths on these two regimes. We find in the case of explosive evaporation that the atmospheric response does not depend strongly on electron energy. In the case of gentle evaporation, lower energy electrons are significantly more efficient at heating the atmosphere and driving up-flows. We find that the threshold between explosive and gentle evaporation is not fixed at a given beam energy flux, but depends strongly on the electron energy, and at low electron energies a much weaker beam flux can drive explosive evaporation. We will also present recent observations that support these findings.


16:30 - 18:00
EX - C33 (150)