Modeling Plasmas with a Kappa Electron Energy Distribution

Abstract:

Nonthermal kappa electron energy distributions have been observed in the Earth's magnetosphere and the solar wind, and are likely also present in the solar corona and in solar flares. In order to model the spectra of these plasmas, it is necessary to obtain the appropriate collision rate coefficients. We show that this can be done simply by summing appropriately weighted Maxwellian rate coefficients. The resulting data have similar or better accuracies than are obtained with other approaches. Summing Maxwellians has the additional advantages of being easy to implement and extendable to many different collision processes. We apply this technique to modeling the charge state distribution (CSD) of kappa-distribution plasmas. In particular, we examine the influence of electron impact multiple ionization on the equilibrium CSD and calculate the time variation of the CSD during a solar flare.