Investigation of an atmospheric pressure 2D-array of microdischarges in air using cross-correlation spectroscopy

Summary form only given. A two-dimensional array of micro-discharges in air at atmospheric pressure is studied by cross correlation spectroscopy (CCS) [1]. The array consists of two insulated metal meshes and the discharge is generated by AC voltages at 20 kHz. A gas flow is applied through the array. The temporal resolution of CCS in the sub-ns range allowed to investigate the micro-discharges dynamics within a single micro-discharge hole end-on.The spatio-temporal distribution of the light intensities of the spectral bands of molecular nitrogen corresponding to emissions at 337.1 nm (second positive system (SSP)), 391.5 nm (first negative system (FNS)) and 585.4 nm (first positive system), along with an NO (A-X) transition at 272.4 nm have been recorded. Both air flow rate and plasma power have an impact on the discharge dynamics. At low flow rates and moderate power, the emission is concentrated at a specific position within the hole. High flow rates combined with high power makes the discharge appearance more homogeneous. The flow rate has a strong effect on the NO emission. At higher power, two sets of micro-discharges became evident, on both polarities of the applied high voltage. The characteristics of these discharges also differed from each other. The ratio of intensities of the spectral bands of N2 (SPS and FNS) were used to deduce the electric field strength [2]. The spatially and temporally resolved electric fields results suggest high electric field strengths during the discharge initiation in these micro-hollow structures. Additionally, we combined the CCS study with ICCD imaging and emission spectroscopy. The N2(C-B) measured spectrum was fit with simulated data in Specair to determine the gas temperature which varied from room temperature to more than 500 K depending on power and flow rate.