| Paper | Title | Page |
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WEPPD014 |
Undulator Radiation inside a Dielectric Waveguide | |
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| We investigate the radiation from a charge moving along a helix around a dielectric cylinder immersed in a homogeneous medium. The radiation intensity for the modes propagating inside the cylinder is evaluated by the work done by the radiation field on the charge and by evaluating the energy flux through the cross-section of the cylinder. We investigate the relative contributions of the bound modes and the modes propagating at large distances from the cylinder to the total radiation intensity. It is shown that the presence of the cylinder can lead to the considerable increase of the radiation intensity. The insertion of a dielectric waveguide provides an additional mechanism for tuning the characteristics of the undulator radiation by choosing the parameters of the waveguide. The radiated energy inside the cylinder is redistributed among the cylinder modes and, as a result, the corresponding spectrum differs significantly from the homogeneous medium or free-space results. This change is of special interest in the low-frequency range where the distribution of the radiation energy among small number of modes leads to the enhancement of the spectral density for the radiation intensity. The radiation emitted on the waveguide modes propagates inside the cylinder and the waveguide serves as a natural collector for the radiation. | ||