Measurements of Fast Time Evolutions of Plasma Potential Using Emissive Probe

Abstract

We present a new method of measuring the floating potential of an emissive probe when the floating potential is very close to the plasma potential. The probe potential at which the probe current becomes zero in the current-voltage curve of the probe is automatically biased by a new probe circuit connected to a bipolar voltage source. This method enables direct measurement of rapid changes in the floating potential with a time resolution of ≃1 µs, giving a continuous data trace. The method was verified experimentally using a DP machine.