Corona-discharge devices are commonly used in a variety of research and development applications. They are known to produce a considerable amount of electromagnetic radiation, mainly in the uv region of the spectrum. The mechanism involved is presumed to be the ionization and radiative recombination of the gases surrounding the high-voltage terminal of the device. A series of high-resolution emission spectra of corona discharge has been measured in atmospheres of nitrogen, helium, and air. (The nitrogen and helium are Air Products 99.995% purity, total hydrocarbons less than 0.5 ppm.) These data are presented here and are compared with published spectroscopic reference data. All the emission lines reported in the spectroscopic reference literature were detected, as well as other lines, which may conceivably be due to impurities.
F. Grum and L. F. Costa, "Spectral emission of corona discharges," Appl. Opt. 15, 76-79 (1976)