Measurements at TRIUMF on a 80 MHz cavity model for the CERN PS upgrade for LHC

The RF system of the CERN PS is being upgraded to bunch a beam that can be captured by the SPS 200 MHz RF system for injection into LHC. Two identical 80 MHz cavities are part of this PS upgrade program. At CERN, the cavity has been designed using SUPERFISH and MAFIA concerning its shape, tuning devices and amplifier coupling loop. TRIUMF has built a simplified full-scale, copper-lined, wooden model, designed such that the field patterns of the fundamental accelerating mode and the longitudinal modes agree closely to CERN cavity ones. The aim of constructing the wooden model was primarily to check the design of the capacitive tuners, the power coupling loop and the HOM dampers for the longitudinal modes up to 1 GHz. The results of the measurements were used to define the parameters of the tuners and a reliable model to describe the interaction of the coupling loop with the fundamental mode of the final CERN cavity. Four quarter-wave antennae are adequate to damp the first fifteen longitudinal modes. In order not to decrease the shunt impedance of the fundamental mode by more than 5%, three-element filters have been used with the antenna which damps the longitudinal mode at 256 MHz, 336 MHz and 912 MHz