Abstract
The optical and electrical characteristics of atmospheric pressure He plasma are investigated. The optical emission at the plasma-solution interface confirms the existence of active radicals such as (OH)-O-center dot, O-center dot and H-center dot. The dissipated power was estimated with Lissajous figure. The plasma plume length reaches a maximum length at flow rate of 7.5 L/min, which is accompanied by a peak value of dissipated power and currents. The T-rot and T-vib decrease as He flow rate increases at a fixed discharge voltage. The degradation efficiency and decolorization of MB solution were found to be strongly dependent on the He flow rate.