Analysis of an uncompensated Langmuir probe in a radio frequency plasma

The non-linear behaviour of the plasma sheath causes distortion of the time-averaged I(V) characteristic unless radio-frequency (RF) compensation techniques are used. In plasmas with large voltage oscillations, sufficient compensation is very difficult to achieve. A new technique has been developed in which the distortion current, ΔI(V), can be separated from the measured time-averaged characteristic, I-barave(V), using the information contained in the harmonics. This means that undistorted dc characteristics, Idc(V), can be obtained without the need for RF compensation components in the probe circuit.