Tolerance Investigation on a Helically Corrugated Interaction Circuit of a 265 GHz Gyro-TWA

Gyro-traveling-wave amplifiers (TWAs) with a helically corrugated interaction region (HCIR) are used for broadband, high-power amplification of microwave signals. In this publication, an HCIR for 265 GHz (G-band) and the influence of manufacturing tolerances on the HCIR performance are presented. This is done by using three different approaches. First, the influence of uniform deviations along the HCIR on the wave dispersion is considered. Second, particle in cell simulations for uniform deviations are conducted. Third, the influence of nonuniform randomly distributed manufacturing tolerances is investigated. It is found that uniform deviations along the HCIR strongly degrade gain and bandwidth, which results in small acceptable tolerances for these deviations. However, these constitute systematic errors, which can be compensated by adjusting the manufacturing process. In contrast, nonuniform deviations along the HCIR with Gaussian random distribution, e.g., caused by vibrations during manufacturing, do not exhibit the same characteristics. These are investigated by PIC simulation of HCIRs with random deviations along their outer wall. Their effect on gain and bandwidth has been shown to be smaller compared to uniform deviations, which allows for increased tolerances for nonuniform deviations.