One-part design for new cooling jacket of a plasma chamber made from PEEK

When ORNL sought to improve the cooling jacket for the aluminium nitride plasma chamber that produces ions for the SNS, it chose Ensinger Inc. extruded Tecapeek made with Victrex PEEK polymer in place of polycarbonate because of the material's dimensional stability under pressure, low radio frequency (RF) losses, and its ability to be precisely machined resulting in a new one-part design solution.
The plasma chamber containing the RF-driven multicusp ion source measures about 76 mm in diameter and 178 mm in length.

The ions produced are formed into a pulsed beam and accelerated to very high temperatures. The plasma puts a nominal 3 kW heat load on the plasma chamber which must be cooled. The function of the cooling jacket is to cool the plasma chamber by channelling water around it. The original cooling jacket was a two-part design made with a polycarbonate material. It failed however, because of cracking and poor tolerances. Furthermore, the high amount of machining that went into creating the two parts added internal stress.

Ensinger, in consultation with their distributor AIN Plastics, a division of ThyssenKrupp, offered ORNL a one-part design solution using Victrex PEEK polymer. With the help of the machining capabilities of the processor American Industrial Plastics (AIP) of Daytona Beach, FL, USA, the cooling jacket was created in a one-part design with tolerances of +/- 0.025 mm.