Development of high-power input couplers for superconducting RF cavity system and the research collaboration

A superconducting radio frequency (SRF) cavity system mainly consists of a niobium cavity, an input coupler, a frequency tuner, higher order mode couplers/dampers, magnetic shields, thermal shields, and so on. A high-power input coupler is one of the most critical components of the SRF cavity system and includes varieties of key technologies in the design, fabrication, RF conditioning and beam operation. Many types of high-power input couplers for a pulsed and a continuous-wave operation have been developed at KEK. These fundamental technologies for input couplers obtained at KEK have been widely applied for other SRF accelerator projects in Japan and Asia region. (author)