Analysis of a gyro-TWT in a cylindrical waveguide with a dielectric lining on its wall

Abstract

The cold as well as hot dispersion relation for a gyro-TWT employing a cylindrical waveguide loaded with a dielectric lining on its wall was obtained. An improved approach was given where the effect of dielectric loading was incorporated in the deduction of the hot dispersion relation rather than in an earlier approximate approach where the effect had been considered only in the deduction of the cold dispersion relation. The hot dispersion relation was used to obtain Pierce-type gain expression. The dielectric lining with optimally chosen permittivity and thickness values provided an improvement with respect to the gain as well as bandwidth of the device as compared to a dielectric-free, unloaded device. The gain-frequency responses predicted by the approximate and improved approaches differed more as the permittivity and the thickness of the dielectric lining increased, though the other relevant device parameters like the optimum beam position for maximum gain did not appreciably differ. © 2002 Taylor & Francis Group, LLC.