Compact Waveguide-type Cavity Input Couplers for Shielding Ceramic Window and Balanced Aperture Fields

For high-power operation of charged particle rf accelerators, the input coupler windows must withstand enormous stresses due to charging induced by the highenergy charged particle beam passing by and high rf power passing through. Since most couplers use a single coupling aperture, harmful asymmetrical rf kick on the beam at the coupler-cavity interface exists. If this problem is solved by dual coupling, the size of the structure becomes a problem. The above problems are considered common to both normal conducting and superconducting rf accelerators. In superconducting structures, since the frequency of operation is usually around 1 GHz, compactness of the coupler is also a great concern for the cryostat design. Two new waveguide coupler designs that may solve the above-mentioned problems are discussed.