Power-combining and injection-locking magnetrons for accelerator applications

The authors are investigating a number of approaches to achieve phase locking and power combining without the use of circulators. In the method described, the X-band waveguide 3 dB hybrid coupler provides the avenue for both injection locking and power combining of magnetron pairs. A series of experiments were undertaken where two magnetrons are injection locked and power combined, first operating into a matched load, then into a tunable short, and finally into X-band cavities. It was observed that injection-locked magnetrons can be used to drive a moderate Q cavity at long pulse without a circulator with excellent phase coherency. The cavity transient impedance does not preclude the magnetrons from filling the cavity, at least when the cavity fill time is less than the magnetron phase lock time.<>