Title: Wake fields in a rectangular dielectric-lined accelerating structure with transversal isotropic loading,
Abstract: Dielectric lined waveguides are under extensive study as accelerating
structures that can be excited by electron beams. Rectangular dielectric
structures are used both in proof of principle experiments for new accelerating
schemes and for studying the electronic properties of the structure loading
material. Analysis of Cherenkov radiation generated by high current
relativistic electron bunch passing through a rectangular waveguide with
transversal isotropic dielectric loading has been carried out. Some of the
materials used for the waveguide loading of accelerating structures (sapphire,
ceramic films) possess significant anisotropic properties. In turn, it can
influence excitation parameters of the wakefields generated by an electron
beam. General solutions for the fields generated by a relativistic electron
beam propagating in a rectangular dielectric waveguide have been derived using
the orthogonal eigenmode decomposition method for the transverse operators of
the Helmholtz equation. The analytical expression for the combined Cherenkov
and Coulomb fields in terms of a superposition of LSM and LSE-modes of
rectangular waveguide with transversal isotropic dielectric loading has been
obtained. Numerical modelling of the longitudinal and transverse (deflecting)
wakefields has been carried out as well. It is shown that the dielectric
anisotropy causes frequency shift in comparison to the dielectric-lined
waveguide with the isotropic dielectric loading.