Nonequilibrium properties in the plasma sheet observed on 2017 September 10

Abstract:

We investigate the nonequilibrium properties of both a non-Maxwellian electron distribution and nonequilibrium ionization in the plasma sheet observed on 2017 September 10. We apply a Kappa (κ) electron velocity distribution (non-Maxwellian), which represents supra-thermal populations, to find the temperature and density of the plasma sheet. We also apply a nonequilibrium ionization model, which assumes that the plasma is initially in ionization equilibrium at low temperature and heated rapidly by a shock or magnetic reconnection. We search for the best parameters, i.e. Kappa, temperature, characteristic timescale (density×time) that explain the observations by the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory and the X-ray Telescope and EUV Imaging Spectrometer on board Hinode. The plasma sheet has been widely studied in detail by many researchers with various observations under the assumption of a Maxwellian electron velocity distribution and equilibrium ionization. We discuss the nonequilibrium effects comparing the results with the previous studies assuming equilibrium ionization. We also compare the supra-thermal populations in the low corona with those in the interplanetary coronal mass ejection revealed by in-situ observations.