The HW resonators in Jülich

Within the design of a new injector for the cooler synchrotron COSY, a linac option based on pulsed superconducting half-wave resonators (HWR) has been investigated. Two prototypes of the HWRs at 160 MHz were built by different manufacturers. We will present measurements for CW as well as pulsed operation to characterize RF performance and mechanical behavior of the two cavities. Whereas the slight differences in fabrication did not affect the electromagnetic results, the mechanical properties (mechanical eigenresonances, Lorentz-force detuning) significantly differed. To operate the cavities, ancillary systems (coupler, tuner, RF control) were designed and tested; the results of those will be summarized.