The role of neutral metastable N-2(A) molecules in the breakdown probability and glow discharge in nitrogen

This is the summary of results of four experiments carried out in order to establish the initiators of electric breakdown in gases after long afterglow periods (tau = 20 s), particularly the role of molecules in the N-2(A(3) Sigma(u)(+)) state in nitrogen. By illuminating nitrogen-filled measuring diodes by nitrogen-filled discharge lamps it was uniquely established that (i) a prolongation of the breakdown time delay, (ii) an increase in the breakdown voltage, (iii) a decrease in the stationary glow current and (iv) a shortening of the discharge quenching time occur due to optogalvanic de-population of the mentioned metastable state. Thus molecules and/or atoms in metastable states do considerably influence the breakdown probability as much as they contribute to the maintainance of glow-discharge currents.