Modeling of Mode Interaction in Cylindrical and Coaxial High-Power Gyrotrons using MAGY

Summary form only given. High-power, CW, millimeter-wave gyrotrons operate in very high order modes. Therefore in these devices, a huge number of modes are capable of interacting with the driving electron beam. Effects of mode interaction play a vitally important role in gyrotron operation and should be accurately simulated at the design stage \´ ". MAGY is an effective design code, which allows for simulating the interaction between modes with different frequencies and different azimuthal indexes. So far, it was proven that MAGY results accurately predict startup scenarios for MW gyrotrons with cylindrical resonators. Coaxial gyrotrons demonstrate superior selectivity in comparison to cylindrical gyrotrons. However, coaxial gyrotrons contain complex cavities whose mode spectrum is substantially different from the one in cylindrical gyrotrons. Recently, MAGY model has been developed for simulating the mode interaction in coaxial gyrotrons with a corrugated inner conductor. This model allows users to analyze interaction between many modes co-and counter-rotating. Typically, co-rotating modes form one group of modes with a quasi-equidistant spectrum, while the counter-rotating modes form another group. In this report the results of MAGY simulations of mode interaction in 110 GHz and 140 GHz CPI cylindrical gyrotrons and 165 GHz and 170 GHz FZK coaxial gyrotrons3 will be presented and compared with published experimental data.