Diagnostic of Rf plasma by using langmuir probe and its numerical processing

Langmuir probe is an important diagnostic tool for measuring plasma paramet ers. A tuned single probe has been used to diagnostic the electron energy d istribution function in Ar radio frequency (13.56MHz) glow plasma. The seco nd derivative of probe I-V characteristic was obtained after using numerica l filter procedure to eliminate the statistical noise in measured I-V chara cteristic. A differential circuit has been designed and applied to measure the second derivative of I-V characteristic on line under the same discharg e conditions. The results of the two methods are in agreement with each oth er.