Usage of Displaced Current in Langmuir Probe Measurement

We investigate the possibility of the usage of displaced current in Langmuir probe measurement theoretically and experimentally. The displaced current flows through the self-generated or artificial capacitance of the reference electrode under an alternative sweep voltage. It can increase the total current afforded by the reference electrode, and eliminate the interference deriving from the finite plasma sheath resistance of the reference electrode. The results in both theory and experiment lead to the conclusion that the usage of displaced current is valid and more efficient with a floating probe method. This method is applied in some harsh plasma environments when the grounded chamber wall can easily be contaminated by the dielectric.