Modes in lossy dielectric-loaded metal cylindrical waveguide for gyrotron-traveling-wave amplifier applications

Using properly designed lossy dielectric-coated metal cylindrical waveguide as the linear amplification stage of a gyrotron-traveling-wave amplifier has been proved to be an effective method to obtain high stability. However, the lossy property of the dielectric material complicates the understanding of the fast-slow-wave property and mode identification. This paper is devoted to reveal in depth the modes in lossy dielectric-coated metal cylindrical waveguide for gyro-TWT amplifier applications.