COMPARATIVE-ANALYSIS OF ELECTRON-BEAM QUALITY ON THE OPERATION OF A FEM WITH AXIAL-GUIDE MAGNETIC-FIELD AND A CARM

A theoretical analysis of influence of electron beam quality on the op eration of a Free-Electron Masers (FEM) with axial guide magnetic fiel d and a Cyclotron Autoresonance Masers (CARM), is presented. For both FEM and CARM transverse velocity component achieved by transversely dr iving a rectilinear electron beam. The quality of electron beam depend s on amplitude of initial random transverse oscillations of the partic les. It is shown, that in a FEM operating in the regime far from cyclo tron resonance (including the reversed-guide-held regime) the spread i n the averaged axial particle velocities is equal to the spread in the initial beam and proportional to the square of the amplitude of paras itic initial oscillations. However, in a CARM this spread is linearly proportional to the initial transverse velocity and, thus, essentially exceeds the spread in the FEM for the same quality of electron beam. As a result, a drop in CARM efficiency with decline of beam quality is much more dramatic than in the FEM. (C) 1998 Elsevier Science B.V. Al l rights reserved.