Measurement Method of Plasma Current and Density in Atmospheric Pressure Plasma Jet

We present a measurement method of the plasma current and density in an atmospheric-pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying a high RF voltage. The plasma in the form of a bullet is released as a plume or jet into the atmosphere. To study the characteristics of the atmospheric-pressure plasma, the plasma current is measured using a current probe, and the drift velocity of plasma plume is measured using a photodetector. The current of the plasma plume is estimated by subtracting the ground line current from the power line current in the circuit. The density of plasma plume n is estimated from the plasma plume current I and the drift velocity v as I = envS, where S is the cross section of plasma plume. The density of the released plasma into the atmosphere is estimated as similar to 10(18) m(-3) by the method. (C) 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.