Analytical formulas for the resonant frequency changes due to opening apertures on cavity walls

By introducing couplings between cavities and between cavity-waveguide, one can get different types of RF components such as linear accelerator structures, rf guns and klystrons etc. Based on the perturbation method, the resonant frequency changes due to apertures on a cavity wall have been investigated, and analytical formulas have been derived and compared with numerical and experimental results. The dispersion relation of a periodic disk-loaded slow wave structure, which relates the group velocity explicitly to the shapes and sizes of coupling apertures, is established and verified. These explicitly expressed analytical dispersion relations established in the paper will not only serve as useful tools in the design of forward (electrically coupled) and backward wave (magnetically coupled) linear accelerators, but also show a clear picture of relevant physical processes. (author) 13 refs., 14 figs., 1 tab