Experimental investigation of excitation of argon metastables by an electron swarm in argon nitrogen gas mixtures

Excitation of argon metastable levels (43P2+43P0) in a nonselfsustained discharge in Ar(>=99%)+N2(<=1%) gas mixtures has been investigated by measuring N2 second positive group which is the result of excitation transfer from Ar metastables to N2 molecules. The method is based on the assumption, experimentally verified, that addition of small quantities of N2 do not change markedly the probability of Ar excitation. The obtained excitation coefficients for production of Arsup(m) in the E/N range (20-70)x10-21 Vm2 are (3.5-13)x10-22 m2 with an estimated uncertainty of +-50%. Simultaneously, excitation coefficients for direct excitation of nitrogen C-state by swarm electrons in Ar-N2 mixtures have been obtained. A comparison of nitrogen spectra excited by electrons and by argon metastables showed significant differences in relative population of vibrational and rotational levels of the N2(C3PIsub(u)) state in these two cases. (orig.)