1: PAL SNU, 2: Uni Corp.||2009||||ICPM-2||||||1Sung-Young Yoon, 1Seol-Hye Park, 1Seung-Hun Lee, 1Ho-Cheol Kwon, 2Sung-Youn Cho, and 2Bong-Su Kang and 1Gon-Ho Kim||USA||The mechanism of the bubble layer formation and the geometrical effect of bubble layer figure to micro discharge in electrolyte were studied, using millimeter size electrode driven by bipolar power source. The important factor to generate the plasma inside of high conductivity electrolyte is the complete coverage of electrode surface by bubble layer [1]. The pig spine cord and sodium chloride water solution, which of the concentration range is 0.45-2 %, is used for discharge media. The applied power is range of 35-50 W and the operation frequency is 350 kHz. The several parameters such as bubble layer figure at the electrode, emission spectrum from discharge, voltage and current with applied power, sodium and chlorine concentration of treated media are measured using HSC (High Speed Camera), OES (Optical Emission Spectroscopy), high voltage probe, pearson coil, ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy) and IC (Ion Chromatographic), respectively. The ion concentrations, V-I signals, spectrum and image results shows three phenomena. First, both of the sodium and chlorine concentration increase in same rate with applied power and treated time. Second, necessary power to the plasma ignition is decreased with ion concentration. Third, the plasma electron density and energy has inverse relation with the thickness of bubble layer. Those mean the bubble layer is generated by the film boiling from ion current joule heating and high current is profit to the layer formation in same power. And the high power seems to enhance the plasma density and electron energy by high electric field from thin bubble layer. Those results are expected to contribute to the optimization of power source for electrical discharge in electrolytes.
[1] J. Woloszko, K. R. Stalder and I. G. Brown, “Plasma Characteristics of Repetitively-Pulsed Electrical Discharges in Saline Solutions Used for Surgical Procedures”, IEEE Trans. Plasma Sci., vol. 30, no. 3, pp.1376-1383 (2002).