Analyses of molecular and neutral atomic emission spectra from an electrothermal launcher plasma

Analyses of neutral atomic copper line and C₂ Swan Band (d³Π-a³Π) emission in the 420 to 570 nm spectral region from the experimental electrothermal launcher device “SIRENS” have been performed to determine edge and core plasma densities and temperatures. Time-averaged core arc temperatures of 10,000 to 22,000 °K and arc densities of 7×10²³ to 2×10²⁴ m^-3 have been deduced by measurements along the axis of the device using the relative intensities and the Stark broadening of the copper lines. The observed C₂ band spectra were compared with synthetic spectra calculated using a molecular spectra-radiative transport code. At a discharge energy of 1.56 kJ, for 90° aspect, the C₂ temperature was determined to be about 3500 °K, with a column density of 2×10 ²¹ m^-2. On-axis spectra, at a discharge energy of 1.07 kJ, were found to correspond to a C₂ temperature of about 7500 °K and a column density of 7×10²⁰ m^-2. Because of the lower temperatures, it is believed that the C₂ emission comes from the plasma edge