The chamber is the plasma chamber or vacuum chamber which holds the process gas in low pressure. The chamber is designed as a pressure reservoir. It is made of a material not susceptible to etching from the process gases used, often stainless steel. Some processes require vacuum chambers made of high-purity silica glass.
As a standard, chambers (recipients) are made of stainless steel
In the Bell Jar research plant, the plasma chamber is a bell made of highly pure silica glass