Measurement of the induced plasma current in a planar coil, low-frequency, RF induction plasma source

A 32 cm diameter, tow-frequency (0.56 MHz), planar-coil ICP source is described. The RF generator is coupled to the load via a simple series circuit which allows the coil current to be varied in a straightforward manner. The global electrical properties of argon discharges produced with filling pressures lying in the range 0.4 mTorr-8 Torr are determined. Measurements df both the amplitude and phase of the secondary current induced in the plasma are reported. All of these measurements are combined in an application of transformer theory to yield values of the plasma resistance and inductance and the coupling constant between the induction coil and the plasma.