Emissive probe characteristic in an inductive plasma source

Summary form only given. Two new features of a time averaged emissive probe characteristic have been studied in an inductive source. One is the effect of harmonics of the RF fluctuation. Without the higher harmonics, the derivative of the time averaged emissive probe I-V characteristic has two peaks whose separation approximately indicates the peak to peak RF amplitude. When higher harmonics of the RF fluctuations are present, the derivative has more than two peaks. Experimental I-V characteristics involving the first and second harmonics, and the resulting differentiated curve containing three peaks, has been measured in E-mode operation. The other effect is an additional heating of the emissive probe by collected electrons. When the ICP is operated in the H-mode, it can be characterized by a high RF fluctuation and high density mode. Under these circumstances, the time averaged input power to the probe by collected electrons becomes larger than the external heating and induces additional emission current from the probe. This additional emission current appears as a current distortion in the I-V characteristic curve.