Development of 20 kW input power coupler for 1.3 GH ERL main linac; High power test of the renewed ceramic window

Shinoe, Kenji*; Sakai, Hiroshi*; Umemori, Kensei*; Sawamura, Masaru; Nakamura, Norio*; Furuya, Takaaki*

We started to develop an input power coupler for a 1.3 GHz ERL superconducting cavity for main linac. We fabricated power coupler components such as ceramic windows and bellows and carried out the high-power test of the components by using a CW 30 kW IOT power source. During this test, the ceramic window was broken by the sudden heat load. We found that this heat load occurred by the unexpected dipole mode. We renewed the ceramic window and successfully carried out the high power test up to CW 27 kW input power.