Charge exchange and ionisation in N$^{7+}$, N$^{6+}$, C$^{6+}$ - H($n=1, 2$) collisions studied systematically by theoretical approaches

TL;DR

This paper systematically calculates charge exchange and ionisation cross sections for N$^{7+}$ and C$^{6+}$ ions colliding with hydrogen using two theoretical methods, aiding plasma diagnostics in fusion research.

Contribution

It provides detailed, state-resolved cross sections for N$^{7+}$ + H and compares similar ions, showing negligible differences, which simplifies modeling impurity ions in fusion plasmas.

Findings

Charge exchange cross sections are accurately calculated for N$^{7+}$ + H.

Deviations between C$^{6+}$ and N$^{6+}$ collisions are negligible.

Results improve plasma diagnostic data analysis.

Abstract

The introduction of gases like nitrogen or neon for cooling the edge region of magnetically confined fusion plasmas has triggered a renewed interest in state selective cross sections necessary for plasma diagnostics by means of charge exchange recombination spectroscopy. To improve the quality of spectroscopic data analysis, charge exchange and ionisation cross sections for N$^{7+}$ + H($n=1,2$) have been calculated using two different theoretical approaches, namely the atomic-orbital close-coupling method and the classical trajectory Monte Carlo method. Total and state resolved charge exchange cross sections are analysed in detail. In the second part, we compare two collision systems involving equally charged ions, C$^{6+}$ and N$^{6+}$ on atomic hydrogen. The analysis of the data lead to the conclusion that deviations between these two impurity ions are practically negligible. This finding is very helpful when calculating cross sections for collision systems with heavier not completely stripped impurity ions.