Klystron development by TETD

This article describes recent development status of klystrons and input couplers for high-power RF accelerator systems including a 324-MHz and a 972-MHz klystrons for J-PARC, 1.3-GHz vertical and horizontal MBKs for DESY and a 1.3-GHz TTF-type input coupler for EURO-XFEL. Development of a 5-GHz, 500-kW CW klystron for KSTAR and a 170-GHz quasi CW gyrotron for ITER are also presented as an application to fusion experimental devices.