Self-Fields in a Planar Orotron

The goal of producing terahertz radiation from miniature electron beam devices has refocused interest in orotrons. The efficiency of these devices improves with increasing current density. However, with increasing current density, self-fields become more important. In this paper, the theory of self-fields in a planar orotron is developed. We find that the parameters of the grating, which provides the slow wave fields that interact with the beam, also affect the self-fields, which give rise to the slow space-charge wave. Thus, the optimization of the grating parameters requires consideration of their impact on the dispersive properties of the slow space-charge wave. We present a sample structure design that is appropriate for a planar orotron.