Theoretical Study on the Possibility for Stepwise Tuning of the Frequency of the KIT 2 MW 170/204 GHz Coaxial-Cavity Gyrotron

A first theoretical study on the possibility for stepwise frequency tuning of a dual-frequency 170/204 GHz TE_34,19/TE_40,23-mode coaxial-cavity gyortron pre-prototype, under development at KIT, has been done. A bandwidth of ± 10 GHz around both center frequencies has been considered as tuning range. For each of the two bands, in total 11 modes have been selected to cover the entire frequency range. The theoretical study has shown that just changing the azimuthal index of the operating mode to obtain an appropriate mode series for frequency step-tunability is insufficient because the insert loading constraint is not fulfilled. A new mode series has been found, where the insert loading constraint is obeyed.