Temperature distribution in the zone of graphite destruction by a nitrogen plasma jet

Abstract

Using the automated system of high-speed visualization and spatial-temporal spectral diagnostics, the destructive effect of an atmospheric pressured nitrogen plasma jet with a temperature of 0.7 - 1.0 eV on samples of isotropic and anisotropic graphite was studied. Measurements of the electron, vibrational, and rotational temperatures of the plasma in the zone of destructive interaction were performed, and the pattern of the spatial-temporal distribution of the products of graphite destruction (carbon atoms and cyanogen molecules) was revealed. The efficiency of local spectral analysis of near-surface plasma is shown using a combination of longitudinal and transverse periodic scanning of the emission spectra and recording of instantaneous 2D spectra of the selected spectral region containing the CN and N2+ bands. The spectral estimate of the concentration of the graphite destruction main product (carbon atoms) is in quantitative agreement with the results of measuring the mass loss rate of the sample material, made by two-positioned visualization of its surface. In the zone of realizable heat loads of 0.5-1.5 kW/cm2, heating of the graphite surface to temperatures of 2800 ÷ 3600 K was achieved and the rate of loss of its material was 3-15 mg/cm2s, which is consistent with the literature data.