To the choice of a HF structure of a superconducting linear accelerator

High-frequency structures, i.e. standing or travelling wave resonators may be used in superconducting accelerators. If those are compared it will be obvious that a travelling wave resonator has some advantages as regards homogeneity of the field and branch resistance. However, a preference should be given to the simpler structure, i.e. a standing wave resonator. The paper deals with the questions of selecting the structure of a test superconducting accelerator and presents compup.ation results with respect to the particle dynamics in a wide range of initial conditions. A number of alternatives have been considered including a structure presented by two resonators which operate at π-mode oscillations. The first three-cell resonator has a phase velocity β equalling 0.7, the second one, β=1. Thus, a conclusion may be drawn that this system ensures a maximum energy increment of the particles being accelerated in a wide range of the accelerating field intensity values