Spectroscopic Measurements of SiC Ablations in Air Plasma Freejets

Abstract

In order to investigate silicone carbide (SiC) ablations in detail, the test pieces of SiC were ablated using air plasma freejets, and spectroscopic measurements were performed at three points around the ablating SiC. It was found that spectra measured at each point were quite different with each other both in distribution and in intensity. At the point just upstream of the tip of the test piece, the molecular bands of CN, N₂, and the atomic lines of Si were observed, and in the downstream region, that is, in the pale greenish flow region, strong molecular bands of C₂ appeared. It was suggested that the C₂ molecules were generated by recombination reaction of C atoms originated from the ablation of SiC. Experimental spectra of radiation from the heated test piece were fitted with the black body radiation function to estimate its surface temperature. The brightness temperature thus measured was 3,600K and this was considerably higher than the decomposition temperature of SiC.