Frequency-Tunable Second Harmonic Gyrotron With Selective Cavity: Design and Simulations

We show numerically that the gyrotron cavity with specially designed rectangular grooves provides a selective gyrotron excitation at the second cyclotron harmonic and allows frequency tuning. Simulations predict that the output power higher than 10 W can be obtained in the 0.3% band near the frequency of 400 GHz for a 15-kV, 0.5-A electron beam. Results obtained by analytical model calculations and particle-in-cell (PIC)-code are in good agreement.