Proposal for the production of high frequency guided radiation by relativistic electron beams

This article reports on the possibility of producing short wavelength radiation by a relativistic electron beam interacting with a transverse, spatially periodic magnetic field. Special emphasis is given to the effect of the finite size of the waveguide on the electromagnetic wave. This effect limits strongly the frequency which can be produced with low energy (less than 1 MeV) electron accelerators. A method is proposed to overcome partially this limitation: coupling of an undulating electron beam to the evanescent part of a wave propagating in a dielectric-loaded waveguide allows higher frequency of the produced wave, or reduction of the energy required for the electron beam.