Optimizing coupling in biperiodic accelerating structures

We have studied the electrodynamic and focusing dependence on the coupling slot and coupling cell parameters for circular and rectangular accelerating structures. We find that: (i) for circular structures the coupling slot induced asymmetric electromagnetic fields of the coupling cell have twice the influence on the transverse beam dynamics than those of accelerating cells; (ii) the neighboring cell coupling slot location can influence the beam dynamics from minimally to usefully; and (iii) by increasing the coupling slot area while optimizing its geometry and decreasing the coupling cell area covered by surface currents, the coupling can be increased ~15% with little decrease in shunt impedance