A Method for Determining the Plasma Space Potential by an RF Probe

Abstract

A method for measuring the space potential of a plasma by means of RF characteristics of Langmuir probe is presented. The principle of the method is based upon a behavior of the RF impedence of the plasma-sheath and -probe system. The sensitivity of the method is expected to be very high, since the RF characteristic at the space potential is much remarkable. For example, it was possible to obtain the space potential in order of 2 mV in a mercury diffusion plasma.