Spectroscopic studies of a prototype electrically pumped COIL system

This paper discusses methods, using non-intrusive diagnostic techniques, to characterize the detailed dynamics of I* gain and O 2 (a 1 Δ) yield on a laboratory microwave-discharge flow reactor, for conditions relevant to the electrically driven COIL concept. The key diagnostics include tunable diode laser absorption measurements of I* small-signal gain and temperature, high-precision absorption measurements of reactor I 2 concentrations, absolute and relative spectral emission measurements of O 2 (a 1 Δ) and I* concentrations, and air-afterglgow determinations of O concentrations. We have characterized variations in O and O 2 (a) yields with discharge power and oxygen mole fraction. We observe O 2 (a) yields to increase dramatically with decreasing oxygen mole fraction. We have also demonstrated a spectral fitting analysis technique capable of quantifying the presence of vibrationally excited O 2 (a,v). This combined suite of diagnostics offers a comprehensive approach to performance characterization for electrically driven COIL concepts.