Formation of low voltage micro-plasmas in a liquid environment.

Studies on the formation of a microplasma in a 0.9%w/w saline solution are presented. Single voltage pulses of negative polarity and magnitudes of up to 350V are applied to a several electrode setups. Ohmic heating leads to a phase transition of the liquid surrounding electrode to form a reproducible vapour layer. Evolution of this vapour layer as well as subsequent plasma formation within this layer is observed by means of shadowgraphy using a fast ICCD camera. This along with current-voltage waveforms and time dependant emission spatially and temporally measurements are used to explore the subsequent behaviour during and after the discharges. Spectroscopic studies reveal that, as expected, the plasma contains the products associated with the dissociation of the water molecule. 1