Contrasting Behaviours of AC and DC Excited Plasmas in Contact with Liquid

A comparative study of the needle-to-liquid plasma in the continuous mode with DC and AC excitations is detailed in this paper. All plasmas studied here are shown to be glow discharges. This study is based on measurements of several key parameters, including electrical energy, optical emission intensities of active species, rotational and vibrational temperatures, and temperatures of the needle and liquid electrodes. AC plasmas can produce 1.2~5 times higher excited state active species than DC plasmas under the same dissipated power. AC excited liquid plasmas have the highest energy utilization e±ciency among the three systems (AC excited plasmas, DC excited plasmas with water anode and DC excited plasmas with water cathode); most of the energy is used to produce useful species rather than to heat the electrodes and plasmas.