Heating and chemical reactivity of a low frequency, DBD plasma jet in liquid water

Summary form only given. A coaxial, gas fed dielectric barrier discharge was used to produce a plasma jet in liquid water. It was found that a significant fraction of the discharge power was deposited into the water as heat. Actual deposited power was determined via the Manley method. The water heating rates showed a weak dependence on frequency. The plasma discharge, which consisted of streamers inside the source, appeared as a directed plasma jet inside the liquid water, suggesting significant excitation of the gas entering the water. Emission spectra of the air jet revealed nitrogen, hydrogen and oxygen emission lines in deionized water. Methylene blue (MB) was used a chemical reactivity indicator. It was found that the water discharge could significantly reduce the concentration of MB in the water as verified using a spectrophotometer. A comparison of plasma treated MB solution and those treated with simple boiling suggests that MB destruction is a plasma induced-effect, not a thermal one.