COUPLER DEVELOPMENT AND GAP FIELD ANALYSIS FOR THE 352 MHz SUPERCONDUCTING CH-CAVITY ∗

The cross-bar H-type (CH) cavity is a multi-gap drift tube structure based on the H-210 mode currently under de-velopment at IAP Frankfurt and in collaboration with GSI. Numerical simulations and rf model measurements showed that the CH-type cavity is an excellent candidate to realize s.c. multi-cell structures ranging from the RFQ exit energy up to the injection energy into elliptical multi-cell cavities. A 19-cell, beta=0.1, 352 MHz, bulk niobium prototype cav-ity is under fabrication at the ACCEL-Company, Bergisch-Gladbach. This paper will present detailed MicroWave Studio [1] simulations and rf model measurements for the coupler development of the 352 MHz superconducting CH-cavity. It describes possibilities for coupling into the super-conducting CH-cavity. First results of the measurements of different coupler concepts, e.g. capacitive and induc-tive coupling at different positions of the CH-cavity are re-ported. Additionally the rf quadrupole content in CH-type gaps was investigated quantitatively.