A W-band corrugated waveguide for high-efficiency high-gradient wakefield acceleration

Compact RF structures in the sub-terahertz regime are promising for structure wakefield acceleration due to their ability in achieving high gradients in a reduced footprint. We report on the design, fabrication, and testing of a metallic corrugated waveguide operating at 110 GHz, tailored to the 42 MeV electron beam parameters at the Argonne Wakefield Accelerator (AWA). The experiment utilized the emittance exchange (EEX) beamline at AWA for longitudinal bunch shaping in two configurations: (1) a single short drive bunch to study high decelerating gradients, and (2) a two-bunch scheme featuring a triangularly shaped drive bunch followed by a long witness bunch to probe the wakefield and achieve a high transformer ratio. We will present the experimental design and results, which show good agreement with simulation predictions.