Eccentric-fluted beam pipes to damp quadrupole higher-order modes

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

An eccentric-fluted beam pipe is proposed to damp quadrupole modes in a cavity. The eccentric-flutes act as a mode converter from quadrupole to dipole. Optimizing the parameters of the eccentric-fluted beam pipe allows sufficient damping of both degenerate quadrupole modes. The external Q-values of the eccentric-fluted beam pipe measured with a low power model cavity agree well with those calculated with the 3D electromagnetic field simulation code, MAFIA.