One of the ways to realize undulator acceleration is to ensure particles motion in a magnetostatic undulator, where spatial oscillations of particles in the transverse direction are synchronized with temporal oscillations of transverse high-frequency field, which allows its energy transfer to the accelerated particles. The resonators, tcapable to provide a uniform transverse field, are structurally simpler than resonators with a periodically variable longitudinal field, which makes undulator accelerators an attrac…