Cryomodule tests of the tesla-like superconducting cavities at KEK-STF

Construction of STF (Superconducting RF Test Facility) is being carried out at KEK. The STF-Baseline superconducting cavity system, which includes four TESLA-like 9-cell cavities, input couplers and frequency tuners, has been developed for the future ILC project. A cryomodule including one of four TESLA-like cavities was assembled, and the first cryomodule test, called the STF Phase-0.5, was carried out in November, 2007. The second cryomodule test for four cavities, called the STF Phase-1.0, has been started in July, 2008. One cavity achieved the maximum accelerating gradient (Eacc,max) of 28 MV/m in a specific pulse width of 1.5 msec and a repetition of 5 Hz. Compensation of Lorentz force detuning at 28 MV/m was successfully demonstrated by a piezo tuner and pre-detuning. (author)