Production of nitrogen oxides in a positive column of a glow-type discharge in air flow

This paper deals with the investigations of a low-current glow-type discharge in air flow as applied to the problem of nitrogen oxide production. The electrode configurations correspond to the classical coaxial plasmatron and to the so-called gliding arc. The discharge burns in a regime of constricted positive column with a typical current density from 47 to 120 A/cm2 and with the related electron density from 0.53⋅1014 to 2.3⋅1014 1/cm3. The gas temperature changes from 3000 to 3610 K. The described conditions provide a flow of NO molecules from the plasma column with the energetic cost for production of one molecule of (30–50) eV. Maximum content of NO molecules [NO] = 4 g/m3 (3500 ppm) was obtained. In spite of a rather high gas temperature, the plasma is still nonequilibrium. The high vibrational levels of the nitrogen molecules are populated, and the main channel of the nitric oxide production is associated with the reaction in which the vibrationally excited nitrogen interacts with atomic oxygen.