R & D status of C-band accelerator unit for SUPERKEKB

In an extensive luminosity upgrade of the KEK-B factory, considered as a future plan, the injector linac has to increase the positron acceleration energy from 3.5 GeV to 8.0 GeV. In order to double the acceleration field (from 21 to 42 MV/m), a design study of the C-band accelerating unit has been started. This paper reports on the R & D status of the C-band components for a high-power test and for a beam-acceleration test at the KEKB injector linac.