Status of RF Sources in Super-Conducting RF Test Facility (STF) at KEK

The superconducting RF test facility (STF) at KEK has been operational since 2005, and STF Phase-I, which involves the testing of a cryomodule with four superconducting cavities, was successfully completed at the end of 2008. During the testing in STF Phase-I, the evaluation of the two power distribution systems (PDS), the 3-dB hybrid PDS, and the TESLA-type PDS was conducted. A study in which circulators in the tree-like PDS were eliminated was performed with LLRF digital feedback. In the linear PDS, we inserted a reflector and a phase shifter between the cavity coupler and circulator to change the loaded Q of the cavity. A third RF source with a 10-MW horizontal multibeam klystron (MBK) and a bouncer-type modulator is to be constructed in FY2009. KEK will conduct the S1-global test and the STF-II project in the future; preparations are underway for these tests. This report covers the recent development of the RF source in KEK STF.