Examining Microwave Afterglows in N\(_2\) Gas Mixtures Using Spectroscopy and LIF: Application to Surface Cleaning

Abstract

Variations of N, H, O and C-atoms density have been determined along the reduced pressure flowing afterglows of microwave Ar-N₂-H₂ discharges that have been experimented with in Plasmas Labs of Nancy, Montreal, Orsay and Toulouse. In the present chapter, previous experiments in N₂-O₂, N₂ - H₂ and N₂ - CH₄ fulfilled by the LSGS(Nancy), Plasmas Lab (Montreal), LPGP (Orsay), Laplace (Toulouse) and SNPE (Bordeaux) are reported. The active species density is obtained by NO titration for N and O-atoms and by line intensity ratios for the H and C-atoms. A small maximum of N-atom density in the range (0.5-3) 10¹⁵cm^-3 was observed when a few H₂ or CH₄ was added to N₂ and the C/N ratio was about 10^-3 in the afterglow of studied microwave setups.

The results obtained by LIF measurements in Orsay and Toulouse Labs are reported for N and H -atoms. By comparing the TALIF and the results of H-atoms density obtained from OES in N₂-1%H₂ afterglows, it has been chosen the appropriate rate coefficient of the N+H+N₂ reaction.

The surface cleaning by N and O-atoms has been experimented.