N2/O2 single streamer discharge studies by OPO based TALIF and LIF diagnostics

A streamer is a form of transient discharge which develops from an electron avalanche in an overvolted gap with high propagation velocity, small streamer channel radius, and high density of free. Laboratory streamers are extremely difficult to observe. By acquiring kinetics series of ICCD images and spectra streamer formation and propagation were captured with a time resolution of 50ps and micrometric spatial resolution. Imaging and emission is a valid means of investigation in this phase. On a longer timescale, the kinetics processes initiated by the streamer discharge are developing. Species produce by streamer impact in N2/O2 mixtures are several. Recently, we investigated the temporal evolution of N2(A) metastable produced by single triggered nitrogen streamer employing nanosecond OPO LIF and emission diagnostics simultaneously and finding evidence that maximum density of N2(A) metastable species occurs in microsecond timescale during the streamer channel decay. Among the produced species atomic oxygen is influencing the kinetics of nonequilibrium discharges. It is a precursor for the ozone formation and formation of NxOy species. The channels for O atom formation are dissociation of oxygen molecule by direct electron impact and by N2(A) metastable. O atom production in nanosecond streamer discharge should be expected so to happen in different time scales. Detection can be accomplished by TALIF. A standard system usually employs narrow line tunable nanosecond dye lasers. Recently TALIF with broadband femtosecond lasers were used to determine space- and time-resolved atomic-oxygen distributions in a nanosecond discharge. We propose an alternative way to detect O atoms through TALIF using nanosecond broadband OPO laser. This is an attractive solution because of the simplicity of the use of commercial OPO lasers. Due to the wide tuning range of OPO associated with non-linear crystals laser setup the detection of N2(A), NO, OH with a single laser optical setup can be accomplished.