Study of 136/170 GHz Dual-Frequency Operation Based on the KIT 2 MW 170 GHz Coaxial-Cavity Pre-Prototype Gyrotron

Theoretical validation of a dual-frequency operation at 136 GHz and 170 GHz is carried out on the basis of the 2 MW 170 GHz coaxial-cavity pre-prototype gyrotron that has been built at Karlsruhe Institute of Technology (KIT). The key components such as the Magnetron Injection Gun (MIG), the coaxial cavity and the quasi-optical output coupler are investigated for the operation at 136 GHz and 170 GHz. The TE28,15 mode is selected as operating mode at 136 GHz. It is shown that the characteristic parameters fit best to those of the $\mathrm{TE}_{34,19}$ mode at 170 GHz. The coaxial triode MIG (cMIG) is intended for the first experiments. The simulated electron beam parameters of the cMIG are taken into account in the interaction simulations. An output power of 2.42 MW with an interaction efficiency of 41.9 % is achieved at 136 GHz in simulations, while the output power at 170 GHz is above 2 MW. The pre-prototype is currently being prepared for initial experimental verification. Measurement results are expected in mid of 2023 and will be presented.