Development and test of a planar R-band accelerating structure

Planar accelerating structures, so called muffin tins, are of great interest for new accelerating techniques which are operating at high frequencies. At present the upper frequency limit for high power sources is 29.9855 GHz available at CERN. Therefore a new design of a planar traveling wave constant impedance accelerating structure is presented. A fully engineered 37-cell prototype with an operating frequency of 29.9855 GHz, which is designed for the 2 pi /3-mode, was fabricated by CNC milling technology. The design includes a power coupler, a cavity geometry optimized to compensate the effect of transverse forces, vacuum flanges and beam pipe flanges. Shown are the frequency scan of transmission and reflection measurements compared to numerical simulations with GdfidL. Further, a non resonant bead pull measurement was made to determine and verify the fundamental modes of the structure. The cavity is planned to be powered at the CLIC test stand at CERN. (4 refs).