AN INTEGRATED DESIGN FOR A BETA=0.175 SPOKE RESONATOR AND ASSOCIATED POWER COUPLER

Low-beta RF spoke resonators have recently been proposed for several proton linear accelerator projects. Unlike established low-beta structures such as quarterwave and split ring resonators, the mechanically more stable spoke resonators and other similar half-wave resonators have never been developed beyond proof of principle. Within the framework of the Department of Energy's Advanced Accelerator Applications Initiative (AAA) (1) spoke resonators have been proposed for the energy range between an RFQ (6.7 MeV) and β=0.48 elliptical cavities (109 MeV). To advance the understanding of spoke resonators for this application, an integrated mechanical and RF design for a β=0.175 spoke resonator with attached power coupler has been completed. The integration of the cavity and coupler was necessary due to the direct coupling of the RF power into the cavity body. In this paper the RF properties of the cavity and the power coupler are presented. Also the coupler influence on the cavity parameters and the coupling characteristics will be given.