Investigation of discharge characteristics of DBD plasma produced with multi-needle to plate electrodes in water by optical emission spectroscopy

Abstract Atmospheric DBD Ar and air plasmas were directly generated by the multi-needle to plate electrodes configuration in the water and diagnosed by the electrical measurements and the optical emission spectroscopy. The proportion of displacement current in the total current was much small, which indicated that the input power was almost used to produce the Ar and air plasmas. The corresponding effective power was in the range of 27.79 (34.59)-56.58 (79.87) W for Ar (air) discharge. The gas temperature increased from 607 (629) to 703 (758) K and the electron temperature was in the range of 1.36 (1.39)-1.64 (1.87) eV, and the electron density reached to 10 14  cm −3 orders of magnitude for Ar (air) discharge, when peak applied voltage increased from 7 (9) to 10 (12.5) kV.