Effects of random geometric perturbations on slow wave devices

Summary form only given. Motivated by the current interest in THz source, where miniature circuits are usually required, we evaluate the effects of geometrical random errors introduced during the manufacturing processes on the circuit characteristics. One such study was given in a previous paper, where a pisection lumped element was used to model a periodic slow wave structure. In this paper, we extend the formulation of D. Dialetis and D. Chernin [IEEE Conference Record (1997)] to other geometries, such as the Smith-Purcell radiator or the traveling wave tube. A continuum model is used. Random perturbations are incorporated in the beam-circuit interaction in such a way that, for the traveling wave tube, the Pierce dispersion relation, together with the launching loss, are recovered for an ideal tube free of manufacturing errors. Our preliminary study shows that the effects on gain and efficiency depend not only on the magnitude of the manufacturing errors, but also on the random samples used to represent the axial distribution of these errors. An analytic theory, together with numerical results, will be presented