INFLUENCE OF DIELECTRIC COATING OF RF-DISCHARGE ELECTRODES ON THE NEAR-ELECTRODE SHEATH PARAMETERS

The dielectric coating of RF-discharge electrodes, which acts as a dis tributed ballast capacitance, stabilizes a subnormal discharge mode wi th a current density lower than that in the normal mode. The enhanced secondary electron emission coefficient of dielectrics (as compared to that of metals) modifies the near-electrode sheath parameters of the RF discharge driven at 1.76 MHz. Such an influence almost vanishes at the normal current density. The enhancement in the coefficient of the secondary electron emission is due to the different mechanisms of disc harge-electron interaction with a dielectric or metal electrode surfac e. This should be taken into account in calculations of the subnormal 1.76 MHz RF-discharge parameters by setting the appropriate boundary c onditions.