Reactivity in microplasma operating at medium pressure

IR Tunable Diode Laser Absorption Spectroscopy (TDLAS) and UV broad band absorption spectroscopy measurements are used to detect O$_{3}$, NO and NO$_{2}$ produced by a microplasma made of a micro-hollow cathode geometry. The gas flows through the microplasma; an additional plasma plume may be ignited on the microplasma anode region using an auxiliary anode. The microplasma may be operated in continuous or self-pulsing mode [1]. The current density in the microplasma is about 3 orders of magnitude higher than in the plume and may reach 1000 A/cm$^{2 }$ in a self pulsing mode. It is shown that NO and NO$_{2}$ densities scale as a function of the specific energy (J/l). The effect of the plume ignition is to lower the production of these species. Experimental results are compared with an experimental modeling. \newline \newline [1] A. Rousseau and X. Aubert J. Phys.D~: Appl. Phys. \textbf{39} (2006) 1619--1622.