The influence of $(n-n')$-mixing processes in $He^{*}(n) + He(1s^2)$ collisions on $He^{*}(n)$ atoms' populations in weakly ionized helium plasmas

TL;DR

This paper presents semi-classical calculations of $(n-n')$-mixing rate coefficients for helium Rydberg atoms colliding with ground state helium, showing these processes significantly affect atom populations in weakly ionized helium plasmas.

Contribution

It introduces a numerical simulation method for calculating $(n-n')$-mixing rates, highlighting their importance in plasma modeling.

Findings

$(n-n')$-mixing processes significantly influence Rydberg atom populations.

Calculated rate coefficients vary with quantum numbers and temperature.

These processes must be included in plasma models for accuracy.

Abstract

The results of semi-classical calculations of rate coefficients of $(n-n')$-mixing processes due to collisions of Rydberg atoms $He^{*}(n)$ with $He(1s^2)$ atoms are presented. It is assumed that these processes are caused by the resonant energy exchange within the electron component of $He^{*}(n)+He$ collision system. The method is realized through the numerical simulation of the $(n-n')$-mixing processes, and is applied for calculations of the corresponding rate coefficients. The calculations are performed for the principal quantum numbers $n,\mbox{} n'$ in ranges $4 \le n < n' \le 10$, and the atom and electron temperatures, $T_a, T_e$, in domains $5000K \le T_{a} \le T_{e} \le 20000K$. It is shown that the $(n-n')$-mixing processes can significantly influence the populations of Rydberg atoms in non-equilibrium weakly ionized helium plasmas with ionization degree $\sim 10^{-4}$. Therefore, these processes have to be included in the appropriate models of such plasmas.