Orifice probe for plasma diagnostics: III. Experimental considerations

Experimental methods are presented for the detection and elimination of instrumental effects arising from field penetration and space charge for an orifice probe in low-pressure (<2 × 10 −2 Torr) RF discharge plasmas in argon. A channel orifice, compared with a sharp-edged orifice, provides number density values which are too low. The creation of a dual-peak ion distribution by the insertion of a grid into the plasma is illustrated.