Absolute and relative density measurements in a N_2/Ar dielectric barrier discharge by diode-laser absorption spectroscopy and resolved plasma emission

摘要

The population density of metastable Ar 4s′[1/2]° in a 70% Ar/30% N_2, short-pulsed ( < 15-ns full width at half maximum) dielectric barrier discharge was determined from the time-resolved diode-laser absorption as a function of pulse repetition rate for a gas pressure of 100 Torr. The relative population density change of N_2~+ B~2∑_u~+ and N_2 C~ 3Π_u was also determined from N_2~+ first negative and N_2 second positive plasma emission for the same pulse repetition rates and pressure. The net power deposited per pulse was obtained from measurements of the voltage and current wave forms. The fractional energy dissipated in metastable Ar production was estimated from the power and absorption number density measurements to be roughly 20% for pulse repetition rates ≤ 10 kHz, decreasing to ～10% at 30 kHz for 3.5-kV applied voltage and 100 Torr.