Simulation of TE6,2-to-Gaussian Internal Mode Converter for a 95-GHz Gyrotron

A Denisov-type mode launcher having dimpled-wall tapered waveguide and a helical cut was combined with a set of four synthesized toroidal mirrors to design a converter for TE
_6,2
cavity mode to TEM
_0,0
Gaussian mode for a transverse output millimeter-wave gyrotron. A commercially available simulation tool, namely, Surf3d was used to design this mode converter, in which the variation of inside launcher boundaries couples the TE
_6,2
eigenmode fed to the launcher with its satellite modes, and thus the surface deformations at the radiator transforms TE
_6,2
cavity mode into a TEM
_0,0
Gaussian-like profile at the launcher cut aperture. This RF beam in TEM
_0,0
Gaussian-like profile was fed to a set of four synthesized toroidal mirrors to achieve an energy conservation of 96% and Gaussian fit of 98.9% after phase corrections within 336 mm of envelope length and 75 mm of envelope radius of the mode converter.