Spectroscopic Investigations of High-Current Hollow-Cathode Discharges in Flowing Nitrogen at Low Pressures

Abstract

The spontaneous emission from hollow‐cathode discharges in flowing nitrogen is investigated spectroscopically. The vibrational energy distributions in the C³Π_u state of N₂ and the B ²Σ_u⁺ state of N₂⁺ are studied as a function of discharge current, magnetic‐field strength, and gas flow. The rotational energy distributions in these electronic states of N₂ have also been determined. The effective rotational and vibrational excitation temperatures are found to be low, T_R≈2000°K and T_V≈10 000°K respectively. The electronic excitation of N⁺, the dominant emitting atomic species, is found to correspond to much higher temperatures, T_exc=35 000°K.