The Destruction of Nitric Oxide by Nitrogen Atoms from Plasma Jets: Designing for Thermal Stratification

Abstract

Following the previous demonstration (Behbahani et al., 1982) that the efficiency of nitrogen plasmas in reducing NO is largely due to N atoms contained in small pockets of very hot gas, the mechanism by which pressure gradients ‘atomize’ temperature distributions into hot ‘droplets’ is considered. This leads to substituting a vortex for the magnetic rotation of the arc, simplifying the plasma jet and making it thermally more stratified. The success of these measures is judged by optical and ionization probe measurements, as well as by the plasma jet's efficiency in reducing NO injected from a central capillary. The efficiency is highest for maximum nitrogen flow rate and minimum power input, as would be expected from a dispersion of rapidly moving hot pockets encapsulating nitrogen atoms. These conditions are then applied to a simulated exhaust gas stream, leading again to surprisingly high reduction efficiencies.