Higher order mode RE power extraction from polarized cavities with a single output coupler

An important step in simplifying superconducting accelerator structures is to reduce the number and complexity of the couplers. The use of azimuthal shaping to polarize the higher-order transverse modes in superconducting cavities has previously been proposed to couple both polarizations through a single output. Two questions remained: would such structures multipactor? and would both polarizations be adequately damped by a single coupler? To answer these questions, single-cell and multicell polarized S-band structures have been designed, constructed, and tested. Cold tests have shown that single-cell and three-cell structures do not multipactor. The highest surface field level achieved was 31 Mv/m, limited by field emission as with nonpolarized cavities