Suppression of Mode Competition in High-efficiency Phase-locking between High-power Magnetrons

Phase-locked magnetrons based on mutual coupling provides an effective scheme to generate higher power microwave associated with power combination. However, the introduction of the mutual-coupled structure between magnetrons brings more parasitic modes in the phase-locked magnetrons, which increases the possibility of mode competition. It is consequently essential to suppress the mode competition to achieve the stable operation of the high-efficiency phase-locked mode, which is characterized by making the output waves of the magnetrons have same phase. In this paper, we propose a scheme of matching the coupling fields to the operating π modes of the magnetrons to suppress the mode competition. Utilizing the 3D electromagnetic simulation software CST, we constructed a mutual coupling phase-locking model for the magnetron. Through the eigenmode solver, the phase locking characteristics are analyzed. By adjusting the frequency separation between the operating mode and the competition modes, high-efficiency phase-locking is achieved. To validate the effectiveness of efficient phase-locking, particle-in-cell (pic) simulation of phase-locking performance of two coupled, MW-level, S-band magnetrons was carried out. The simulation results demonstrate the frequencies of two magnetrons have been locked to the same frequency of 2.535 GHz. The phase difference between the output signals is zero, and the output power of each magnetron reaches 2.4 MW, which is almost same as that of a single magnetron with free running. The phase-locking efficiency reaches 99%. The proposed scheme can be efficiently used in suppressing the mode competition in a large-scale of array based on more magnetrons.