Non-relativistic free-free emission due to $n-$distribution of electrons - Radiative cooling and thermally averaged and total Gaunt factors

TL;DR

This paper calculates free-free emission spectra and radiative losses for plasmas with n-distributed electrons, extending understanding of non-Maxwellian electron distributions and their impact on plasma cooling.

Contribution

It provides detailed calculations of Gaunt factors and radiative losses for n-distributions, covering a wide range of electron energies and ion species, which was not previously available.

Findings

Gaunt factors decrease with decreasing n, approaching Maxwell-Boltzmann values.

Radiative losses are minimized at n=1, indicating thermal plasma behavior.

Tables of Gaunt factors for various energies and n-values are provided.

Abstract

Tracking the thermal evolution of plasmas, characterized by an n-distribution, using numerical simulations, requires the determination of the emission spectra and of the radiative losses due to free-free emission from the correspond- ing temperature averaged and total Gaunt factors. Detailed calculations of the latter are presented, associated to n-distributed electrons with the parameter n ranging from 1 (corresponding to the Maxwell-Boltzmann distribu- tion) to 100. The temperature averaged and total Gaunt factors, with decreasing n tend to those obtained with the Maxwell-Boltzmann distribution. Radiative losses due to free-free emission in a plasma evolving under collisional ionization equilibrium conditions and composed by H, He, C, N, O, Ne, Mg, Si, S, and Fe ions, are presented. These losses decrease with the decrease in the parameter n reaching a minimum when n = 1, and, thus converging to the losses of a thermal plasma. Tables of the thermal averaged and total Gaunt factors calculated for n distributions and a wide range electron and photon energies are presented.