PLASMA SHEATH THICKNESS IN RADIOFREQUENCY DISCHARGES

The radio-frequency glow discharges of several kinds of gases were examined to measure the ion sheath thickness at the cathode electrode. At intermediate gas pressures around 0.05- 0.5 Torr, the sheath thickness d depends on the pressure P in the expression P1/2d=K0 for almost all of the discharges examined. It was also pointed out that the constant K0 value decreased linearly against a mass of the predominant ion in the plasma. The discrepancy between the sheath thickness measured in this work and by theoretical solution was discussed for the argon discharge.