Generation of 1 GW of 11.7 GHz Power using a Metamaterial-based Power Extractor for Structure-based Wakefield Acceleration

We present our recent experimental efforts toward producing one gigawatt of power at 11.7 GHz with a metallic metamaterial-based power extractor for use in structure-based wakefield acceleration (SWFA). SWFA is a novel acceleration scheme in which high-charge electron bunches are passed through a power extractor structure to produce a high-intensity wakefield. The resulting wakefield can either be used to accelerate a witness bunch in the same beamline or passed through a waveguide to a secondary acceleration beamline. Our approach uses a specifically-tailored metamaterial for the power extractor structure. The properties of the metamaterial allow us to overcome some of the difficulties encountered by other SWFA techniques. Here, we present the Stage 3 experimental design. The Stages 1 and 2 experiments generated 80 MW and 380 MW RF pulses, respectively, with several-nanosecond duration using the 65 MeV beam at the Argonne Wakefield Accelerator. The Stage 3 design includes significant design improvements, including an all-copper structure, fully-symmetric coupler design, and treatment to reduce breakdown risk. With these improvements, simulations predict over 1.1 GW of output power. The experimental run is scheduled for February 2021.