Regime of Traveling Wave Amplification in the Oversized Circuit with Nonuniform Grating

The results of experimental study of the traveling-wave amplification in the oversized circuit with a nonuniform grating, which has increased depth of every third groove, have been presented and discussed. Measured TWT gain versus both frequency and beam voltage is compared with the calculated dispersion. The peculiarities of the interaction of a sheet electron beam with a traveling wave have been discussed for the region of mode coupling. Obtained results show a good agreement with the preliminary 3D PIC simulations.