Design and testing of a 7.8 GHz power extractor using a cylindrical dielectric-loaded waveguide

Dielectric-loaded power extraction is a method for the generation of high-power radio frequency (rf) waves under development for future particle accelerators. In this method, a high-charge electron beam drives a wakefield in a dielectric-loaded waveguide (the decelerator) and an rf output coupler extracts the rf power into an external waveguide. We report on the experimental demonstration of a 7.8 GHz dielectric-loaded power extractor at the Argonne Wakefield Accelerator facility. We have generated more than 30 MW of rf power with a pulse length of approximately 1.7 ns by passing a single 66 nC electron bunch through the power extractor. We have also used a train of 4 electron bunches to show a clear signature of field superposition. Test results are in good agreement with predictions.