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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.

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Two carbon targets were irradiated to create plasma plumes to collide at right angle with two UV laser pulses each other at 10 J/cm2/pulse. The collision results in carbon plasma stagnation. Laser scattered imaging indicates that the carbon large molecular formation takes place much later in time after the laser irradiation and stagnation. Compared with the temporal history of electron density (ne), ion density (ni), and plasma self-emission dominated by carbon Swan band, it is estimated that the carbon large molecular formation has been initiated with the ion collision followed by the C2 formation.