Support cylinder for the heat treatment chamber

Embodiments of the present disclosure generally relates to supporting cylinder for use in a thermal processing chamber. In one embodiment, the support cylinder, a ring body having an inner and outer peripheral surfaces, wherein the opaque quartz glass material, and comprises a ring body to be coated with an optically transparent layer. Optically transparent layer, opaque quartz has a glass material substantially matches or similar thermal expansion coefficient, whereby thermal expansion mismatch is reduced, which may cause thermal stress under high heat load. In one example, opaque quartz glass material is a synthetic black quartz, optically transparent layer comprises a transparent fused quartz material. .The 2A