N and C-atoms in R (Ar)-N\(_2\)-CH\(_4\) Flowing Afterglows at High Pressure

Abstract

The plasma and afterglows of N₂ and Ar-N₂ HF discharges are presently studied to precise the N-atom production in afterglow conditions at high gas pressure (up to the atmospheric gas pressure). The production of N-atom density has been analyzed in Ar-N₂ high-pressure flowing afterglows after HF plasmas at a frequency from 13.6 Mhz to 2450 MHz. The plasma length increased when the HF frequency decreased from 2450 to 13.6 MHz and by lowering x in the Ar-xN₂ gas mixture.

It was found that the N+N recombination on the N₂(B,v’) states was reduced by 2.5 for v’=11, by 10 for v’=8 and by 30 for v’=0 by going from pure N₂ to Ar-2%N₂.

The production of N and C-atoms in a double Ar-N₂ and Ar-CH₄ HF flowing afterglows was in the ranges of 10¹⁵cm^-3 and 10¹²cm^-3, respectively. In Ar-N₂-xCH₄ with x=10^-3 – 10^-2 there was a drop of N and C-atoms at x=10^-2 which should result in N+CH₃ reactions. The CH₃ density was about 4 10¹¹ cm^-3 in an Ar-17%N₂-1%CH₄ gas mixture at 14 Torr.