A Novel Temperature Measurement Approach for a High Pressure Dielectric Barrier Discharge Using Diode Laser Absorption Spectroscopy

Tunable Diode-Laser Absorption Spectroscopy (TDLAS) technique based upon peak frequency shifts, $\beta $, and collision-broadened full widths at half maximum, w$_{c}$, of argon metastable 1s$_{3}\to $2p$_{2}$ and 1s$_{5}\to $2p$_{7}$ transitions, separated by 22.5 GHz, was used to measure both the gas temperature and the gas density in a short-pulse excited ($\approx $10 ns applied voltage rise time having $\approx $200 ns duration) argon DBD operating between 50-500 Torr, 1-4 kV total applied voltage, and 5 kHz repetition rate. TDLAS technique is well suited for high pressure environments having a small gas temperature rise ($\Delta $T$<$100 K) where the Doppler width component w$_{D }<<$ w$_{c}$. If there is no resonance between the absorber and the perturber and the absorbing transition terminates on a metastable state then, according to Lindholm-Foley theory, $\beta $ and w$_{c}$ scale as nT$^{0.3}$ where n is number density. Using the perfect gas law, the proportionality parameters $\beta _{o}$ (frequency shift/Torr) and $\Gamma _{o}$ (collisional broadening width/Torr) permits self-consistent measurements of both gas temperature and density. Reproducibility and accuracy of the temperature measurements were determined through the simultaneous independent measurements of these four parameters. The effects of applied voltage rise time on the power deposition and also metastable production efficiency will be reported.