A simplified procedure to capture N(4S) kinetics during the transients of a strongly emissive pulsed ECR plasma using TALIF

TL;DR

This paper introduces a simplified TALIF-based method for measuring N(4S) density in strongly emissive plasmas, reducing uncertainty and enabling transient analysis, revealing unexpected early-stage density increases during plasma transitions.

Contribution

A new simplified TALIF procedure using absorption peaks for N(4S) density measurement in strongly emissive plasmas, validated and applied to transient plasma analysis.

Findings

Detected unexpected N(4S) density increase at early transition stage.

Validated method reduces experimental uncertainty in emissive plasmas.

Attribution of density enhancement to surface deexcitation processes.

Abstract

A simplified and straightforward methodology that may be used to measure N(4 S) density by TALIF technique in strongly emissive plasmas is presented. The method makes use of the absorption peak intensities instead of the fully integrated absorption line intensity. The use of this method, along with a physics-based fitting/filtering procedure enables strongly reducing the experimental uncertainty and performing measurement even in strongly emitting discharges. After validation, the method was employed to investigate the transients of a strongly emissive pulsed microwave discharge. We especially showed the existence of unexpected increase of N(4 S) density at the early stage of the transition from high-to lowpower phase. The use of a self-consistent quasi-homogenous plasma model taking into account a detailed state-to-state kinetics, enables to attribute this enhancement to surface deexcitation of N(2 D) and N(2 P).