Influence of a power input coupler and a higher order mode coupler on the dynamics of accelerated particles

The transverse momentum introduced by a power input coupler and a higher order mode coupler is estimated, and the influence of the transverse momentum on the parameters of the accelerated beam is demonstrated with the injector of an energy recovery linac and a superconducting five-cell accelerating structure. Symmetric and asymmetric designs based on coaxial and rectangular waveguides are considered.