Gain/bandwidth predictions for travelling-wave gyrotron

The small signal gain of a travelling-wave gyrotron is computed using a Pierce description of the interaction between a `fast¿ waveguide mode and a relativistic gyrating electron beam. The mathematical model assumes a matched device containing some selective loss so that moding and backward-wave oscillation problems can be neglected. Whereas from a practical standpoint this simplification may appear excessive, the computed results nevertheless help to expose the basic nature of the amplifying process.