Selective mode excitation in a multimode THz slow-wave structure by a relativistic bunch train

A number of methods for producing sub-picosecond beam microbunching have been developed in recent years. A train of these bunches is capable of generating THz radiation via multiple mechanisms like transition, Cherenkov and undulator radiation. We utilize a bunch train with tunable spacing to selectively excite high order TM0n - like modes in a multimode structure. In this paper we present experimental results obtained at the Accelerator Test Facility of Brookhaven National Laboratory.