Observation of Increased Number of Frequency Steps in Multi-Frequency Oscillations with a Two-Cavity Gyrotron

A two-cavity configuration was introduced in order to increase the number of operating frequencies and to decrease their frequency intervals in a multi-frequency gyrotron. Each cavity has a series of oscillation modes, which can be chosen with the cyclotron frequencies of injected electron beams. The experimental observations have shown that the different oscillation modes for each cavity can be selectively excited according to the changes in the magnetic field strength in the cavity. The frequency step tuning with fundamental harmonic oscillations in a frequency range from 180 to 220-GHz has been demonstrated. The obtained results suggest a further multiple-frequency operation is possible with multiply connected cavities.