A Slab-symmetric Dielectric-loaded Structure for High-gradient Acceleration at Thz∗

We present a design for a slab-symmetric accelerating structure to be resonantly excited at terahertz frequencies. The device, consisting of a vacuum gap between dielectriclined walls, combines the advantages of a slab geometry (including strong suppression of transverse beam wakefields and low power density) with the existence of a resonant mode having phase synchronism with relativistic electrons. Accelerating fields of hundreds of MeV/m are predicted when the structure is powered by a high-power FIR radiation source in development at UCLA. Simulation of the structure fields is described and compared with theory, and an experimental program is discussed.