Status of superconducting cavity development for ERL main linac

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

Damping higher-order-modes is important for superconducting main accelerators to suppress beam breakup and to increase the beam current. Our strategy for HOM damping is (1) large beam pipe, (2) optimization of cell shapes and (3) eccentric fluted beam pipe. Two single-cell cavities and one 9-cell cavity of niobium were made to check the performance of the new design cavity. The two single-cell cavities showed the good results of vertical test of 2 K. The vertical test of 9-cell cavity will be done soon.