Development of superconducting cavity for ERL main linac

Umemori, Kensei*; Sakai, Hiroshi*; Sakanaka, Shogo*; Sawamura, Masaru; Shinoe, Kenji*; Takahashi, Takeshi*; Furuya, Takaaki*

High current operation of ERL excites higher-modes excited in the cavities, which cause current threshold due to beam instability and heat load into the cryomodules. A new shape for the ERL cavity was designed to solve the problems. Niobium single-cell cavities and a 9-cell cavity were fabricated to check manufacture processes surface treatment processes. The vertical test has been in progress to estimate the cavity performance. Another elements such as an input coupler and a HOM damper are also been developing.