Electrical discharges in the vapour phase in liquid-filled capillaries

In this work electrical discharges in the vapour phase in liquid-filled capillaries are investigated. The vapour phase is generated due to Joule heating of the NaCl solution in a narrow dielectric capillary in which plasma is generated. A repetitive bubble formation regime, a chaotic plasma regime and a periodic intense plasma regime are observed with increasing voltage. The plasma is produced in the bubble and the liquid columns on both sides of the bubble serve as electrodes for the discharges. In the emission spectra contributions of OH, H, Na and O are identified. The OH rotational distribution can be characterized by a superposition of two Boltzmann distributions with temperature parameters of 2800 and 8800 K.