Influence of the Probe Electrode on Probe Measurements for Atmospheric Pressure Microwave Plasma Torch

In this study, in order to clarify the influence of a probe electrode during probe measurements of an atmospheric pressure microwave plasma, simultaneous observations of probe current and the change of plasma shape using a high-speed camera have been done. Fast and random repetitions of attachment and detachment of the plasma torch to the probe electrode have been observed. It is found that the response time is related to ion sound speed. Different behaviors of the plasma torch for a floating metal electrode or an insulator have been observed. Probe current-voltage characteristics show asymmetric double probe shape (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)