Modeling of plasma effect on the diffraction radiation of relativistic beam moving over a grating of finite extent

The rigorous numerical treatment of the relativistic beam radiation over a finite‐length grating both in the presence and without a background plasma is presented. The most attention is paid to the excitation near the frequency of the π‐type resonance used in backward wave oscillators (BWO) and multiwave Cherenkov generators (MWCG). Based on the obtained results, the simultaneous influence of plasma filling and mode conversion at the grating end on radiation efficiency is discussed. A new, more accurate treatment of the generation frequency‐locking phenomenon and some other effects observed in BWO earlier is suggested. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 50–54, 1997.