Tunable Multi-Frequency Radiation Source Based on Gyrotron With Pre-Modulated Beam

Abstract

We propose a multi-frequency radiation source based on a gyrotron which is driven by a pre-modulated electron beam. Modulation occurs in an additional cavity powered by an external weak monochromatic signal with a frequency outside the gyrotron locking band. Using parameters of a 170 GHz MW-level gyrotron as an example, we demonstrate in simulations that an external power of only 0.05-0.2% of the power of free-running generation is sufficient to provide beats regimes with controllable 15–25 MHz interval between main practically equal spectral components. The proposed radiation source is suitable for excitation of plasma waves in the ion-cyclotron frequency range. Theoretical considerations are confirmed in proof-of-principle experiments based on a Ka-band relativistic gyroklystron operating in the self-excitation mode and controlled by the input wave.