Phase locking of two long-pulse, high-power magnetrons

We have phase locked a pair of long-pulse, high-power, secondary-emission magnetrons to an RF-isolated low-power driver via a waveguide directional coupler. With the 3 dB hybrid coupler, the peak and average power sent back towards the driver were lower than the total power by factors of 20 and 100, respectively. A dual-channel, thyratron-switched line-type modulator was used to power the magnetrons in parallel. In this experiment the total microwave power from the pair of phase-locked high-power magnetrons was limited to 48 MW for 700 ns pulses and 46 MW for 900 ns pulses because one of the high-power magnetrons would only operate at or below half power. Experimental results from this repetitively-pulsed (10 Hz) phase-locked magnetron pair are presented which show excellent phase stability of several degrees both during the pulse and from pulse-to-pulse