A process chamber 133 is disclosed which provides a 360° circular gas/vacuum distribution over a substrate being processed. The substrate being processed is supported on a heated and optionally cooled pedestal assembly 135. The substrate faces a one-piece gas distribution faceplate 122 being connected to an RF power supply outside the vacuum environment of the processing chamber 133. A pumping channel view port is provided to verify and confirm instrumentation readings concerning the degree of surface deposition on process chamber internal surfaces 265. All process chamber wall surfaces 265 facing the region 141 where plasma will be present during processing (except the gas distribution faceplate) are ceramic 234, 236 and therefore highly resistant to corrosion. The pedestal 136, an un-anodized metal, is also covered with a loosely fitting ceramic surface having alignment features to maintain concentricity between the wafer support surface of the pedestal and the wafer being processed. A valve body 226 is contained within the wall of the processing chamber 133 helping to reduce the surface area available for condensation of volatile process gas constituents which condense or cool in vacuum passage surfaces and can contaminate the process chamber 133 if allowed to migrate back to it through the vacuum piping.