Front and rear views of an accelerating segment used in the assembly of the Industrial Materials Pulsed Electron Linear Accelerator (IMPELA). Two of the segment faces shown in the first photograph would be brazed together to form an accelerating segment while two of the faces shown in the second photo would form a radiofrequency (rf) coupling cavity. A complete, 10 MeV accelerator consists of 29 accelerating cavities and 28 coupling cavities brazed together to form a ~3.25 m long structure. Each segment is made of oxygen-free, high-conductivity copper, is machined to a very specific shape to a high degree of accuracy and is then fine-tuned to resonate at a frequency of 1.3 GHz. The IMPELA units generated an average electron beam power of 50 kW.
Special cooling is required to maintain the physical dimensions (which determine the operating frequency) of the structure during high power operation and the holes around the circumference formed the cooling channels for the structure. The plumbing lines to the water-cooled structure are seen in the right-hand photograph which shows the prototype accelerator installed in the shielded room in Bldg. 610 at Chalk River.
The segment above was a test unit presented to J. McKeown, who first proposed the IMPELA series, on the occasion of his retirement and was donated to the Society.
