N and C-atoms in R (Ar)-N2-CH4 Flowing Afterglows in High Power RF Jet

Radiative species in Ar RF plasma torch with addition of H2, CH4 and CF4 polluting gases have been analysed by emission spectroscopy. An efficient etching by F atoms of reactor quartz tube is detected from Si atom emission when a few 10-3 CF4 was introduced into the Ar plasma.

The Si emission disappeared with H2 introduction into the Ar - CF4 gas mixture which has been correlated with HF formation. From C atom emission, it is deduced that CF4 as CH4 polluting gases are largely dissociated into the Ar plasma torch. The C-atom density was evaluated from the N-atom density measured by NO titration by considering the part of N+N recombination which populated the N2 (B,v’) radiative states. It is found that the RF 64 MHz plasma jet at 3 kW brought N and C -atoms densities in an afterglow at 3 10-2s near the atmospheric gas pressure which are respectively ~1016 cm-3 and 1015 cm-3 are 101 and 102 higher than in 2450 MHz afterglows at about 100 W and 10 Torr.