Diagnostic analyses were performed on a dc arcjet diamond reactor using optical emission spectroscopy. Rotational and vibrational excitation temperatures were determined from C2 and CH emission spectra and observed to differ widely at all locations in the plasma except near the substrate. Temperatures were observed to converge at the substrate, indicating thermal equilibration of the plasma. Rotational excitation temperatures for C2 and vibrational excitation temperatures for CH appear to closely track the plasma gas temperature, while vibrational excitation temperatures for C2 and rotational excitation temperatures for CH are anomalously high. A detailed analysis was conducted to identify the dominant excitation processes responsible for producing emission. Results show that (1) excitation to the excited state for both C2 and CH is most likely due to thermal excitation near the substrate, (2) in the plasma bulk, emission by CH is produced primarily by chemiluminescent reactions while emission by C2 is produced by electron impact excitation, and (3) optical emission spectroscopy may be used as a nonintrusive probe of the plasma gas temperature.
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Research Article| March 01 1995
Plasma diagnostics of a direct‐current arcjet diamond reactor. II. Optical emission spectroscopy
S. W. Reeve;
S. W. Reeve, W. A. Weimer; Plasma diagnostics of a direct‐current arcjet diamond reactor. II. Optical emission spectroscopy. J. Vac. Sci. Technol. A 1 March 1995; 13 (2): 359–367. https://doi.org/10.1116/1.579365
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