Electrical Behavior of Long Linac Tanks and a New Tank-Coupling Scheme

The electrical behavior of long linac tanks can be represented by the behavior of a finite chain of coupled harmonic oscillators.1 A theory is given of chains of oscillators of two kinds, which is appropriate for semi-resonant or resonant coupling structures.2 The perturbation theory given previously is extended to predict the effects of errors in the coupling cells and in the main cells.2 Some advantages of π/2 mode operation of the double chain are discussed. A new accelerating scheme is presented in which the coupling structures are resonant and the tanks are resonantly coupled. The theory, numerical calculations, and measurements on laboratory models3 all indicate that tolerances on power amplifier voltage and phase can be relaxed by as much as a factor of five.