34.272 GHz Multilayered Dielectric-Loaded Accelerating Structure

A multilayered 34.272 GHz dielectric accelerating structure is described that is based on the Bragg fiber concept. Alternating radial dielectric layers of permittivities 38 and 9.7 create multiple reflections to confine the accelerating fields, thus greatly reducing the power losses from the external metal wall. The structure will operate at TM03 mode instead of the usual TM01. Numerical examples for 2-and 4-layer structures are presented with detailed analysis of TM (acceleration) modes. We found that the power attenuation of a 34.272 GHz dielectric loaded structure can be reduced from ∼ 20 dB/m for a conventional single layer structure to less than 6 dB/m for a 2 or 4 layer structure. We also present a coupler design for the multilayered dielectric-loaded accelerating structure, which has the capability of mode selection and high efficiency RF transmission.