Theory of gyrotron amplifiers in a disk or a helix loaded waveguide

The gyrotron amplifiers in two slow wave structures, the disk and the helix loaded wveguides, are investigated for wide band applications. For each structure, properties of the vacuum waveguide mode are examined in connection with the gyrotron application, and the gyrotron dispersion relation is obtained. For the disk loaded gyrotron, it is found that the group velocity of the waveguide mode can be easily varied by the disk parameters, and the gain and the bandwidth are at least comparable to those of the ordinary gyrotron. In the helix waveguide configuration, the gyrotron utilizing the helix mode can be very broad in its bandwidth. Moreover, the hybrid mode operation, using the helix mode as a carrier, shows possibility of fast wave wide band amplification by contouring waveguide.