A: The radiation of electromagnetic surface waves is investigated for a charged particle rotating around a dielectric cylinder immersed into a homogeneous medium. Formulae are provided for the corresponding electric and magnetic fields and for the radiation intensity. It is shown that the surface waves are radiated on the eigenmodes of the cylindrical waveguide.

We investigate the radiation of surface polaritons by a charged particle rotating around a dielectric waveguide. The general case is considered when the waveguide is immersed in a homogeneous medium. For the evaluation of the corresponding electromagnetic fields the electromagnetic Green tensor is used. A formula is derived for the spectral distribution of the radiation intensity for surface-type modes. It is shown that the corresponding waves are radiated on the eigenmodes of the dielectric cylinder. We demonstrate that the number of radiated quanta for surface polaritons of a given harmonic can be essentially larger than that for guiding modes of the cylinder. The geometry under consideration is of interest from the point of view of generation and transmitting of waves in waveguides, a subject which is of considerable practical importance in microwave engineering and optical fiber communications.

We investigate the radiation from a bunch of relativistic electrons moving along the cylindrical waveguide axis, assuming that the waveguide is partially loaded by a medium with periodic dielectric permittivity and magnetic permeability. The spectral distribution of the radiation energy flux through the cross section of the waveguide is studied at large distances from the medium. The analysis is based on the corresponding exact solution of Maxwell equations for the case of a single electron moving along the waveguide axis. The results of numerical calculations are presented in the special case of layered medium consisting of a finite number of dielectric plates separated by vacuum gaps. We show that under certain conditions on the problem parameters the quasi-coherent Cherenkov radiation generated by the electron bunch inside the plates is self-amplified at certain waveguide modes. A visual explanation of this phenomenon is provided that reproduces the main features to rather good accuracy.

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