Superconducting accelerator development at STF for ILC

The superconducting RF test facility (STF) in KEK is the facility for developing technologies of the International Linear Collider (ILC) main linacs. The STF accelerator is a test linear accelerator using superconducting cavities (SC cavities) and cryomodules of ILC technologies. The injector of the STF accelerator consists of the L-band photocathode RF-gun (normal-conducting cavity), two superconducting 9-cell cavities for pre-acceleration of electron beam. The 12m-cryomodule (8 SC cavities and 1 SC quadrupole magnet with beam position monitor (BPM)) and 6m-cryomodule (4 SC cavities) are followed after the injector. They will be powered by 10 MW multi-beam klystron and the distribution wave-guide system, and the accelerator field and phase are controlled precisely by the fast digital feedback at low-power level. For monitoring SC cavity alignment change during cool-down, the wire position monitors (WPM) are used inside of the cryomodules. Recent developments of the STF accelerator such as cryomodules, high power components, low-level controls, SC quadrupole magnet, BPM and WPM are discussed and summarized in this paper. (author)