Diagnostics of plasma generated by electrical discharge in organic solutions

This work deals with electrical discharge in organic solutions. The theoretical part was focused on plasma discharge in liquids and also plasma diagnostics. In the experimental part the influence of experimental conditions on the ignition of the discharge in alcohols was observed. Especially, the polarity of the applied voltage, concentration and conductivity of the solution was studied. Moreover, the amount of generated hydrogen peroxide in the ethanol solutions as well as the electrolyte solution of two different conductivities was determined. The results compared the current-voltage characteristic curve during the stable discharge and the phases that preceded it. These phases were the creation of bubbles, occasional ignition and stable discharge. From the recorded average values of current and voltage, current-voltage characteristics were constructed. It was found, that the increasing conductivity of the solution leads to an earlier discharge. In case of negative polarity of the voltage input on the main electrode, there was an earlier discharge than in the positive polarity. Voltage value necessary for the discharge ignition was lower by several hundred volts in the negative polarity. For example, for a solution of 95 vol. % ethanol and conductivity of 200 S, the breakdown voltage for a positive polarity was determinated as 1650 V but at negative polarity this voltage was only 1250 V. Moreover the influence of ethanol concentration on the ignition of the discharge was found, but there was no significant effect. Amount of generated hydrogen peroxide grew linearly with time. In the electrolyte solution, hydrogen peroxide was formed significantly more in comparison to the ethanol solution