Victrex PEEK (polyetheretherketone) has replaced polycarbonate (PC) in a cooling jacket for the aluminum nitride plasma chamber that the Oak Ridge National Laboratory (ORNL) uses for its new accelerator-based Spallation Neutron Source (SNS). The technology creates pulsed neutron beams for scientific research and industrial development. ORNL opted for extruded Victrex-based TecaPEEK from stock-shape supplier Ensinger Inc. over PC on the basis of PEEK's dimensional stability under pressure, low radio frequency (RF) losses, and ability to be precisely machined. That last factor allowed Ensinger to supply a new one-part design solution.
The original PC cooling jacket had a two-part construction and suffered from cracking and poor tolerances. In manufacture, itMachined Victrex PEEK cooling jacketrequired a great deal of machining, which added a tremendous amount of internal stress. Ensinger, in consultation with its distributor AIN Plastics, a division of ThyssenKrupp, offered ORNL a one-part design using Victrex PEEK for the cooling jacket. Daytona Beach, FL based AIN machined the final part, carrying tolerances of ± .001 inch....