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 ov er a finite-length grating both in the presence and without a backgrou nd plasma is presented. The most attention is paid to the excitation n ear the frequency of the pi-type resonance used in backward wave oscil lators (BWO) and multiwave Cherenkov generators (MWCG). Based on the o btained 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 phen omenon and some other effects observed in BWO earlier is suggested. (C ) 1997 John Wiley & Sons, Inc.