Phase locking of high power oscillators

Summary Form only given, as follows. Extension of microwave sources to power levels of 1-10 GW is inhibited by limits in the electric field in the resonator, and limits on cavity size (mode competition). Therefore, for very high powers, the use of groups of sources locked together in phase to achieve constructive interference is the likely approach. Recent experiments show phase locking of relativistic magnetrons and high-power vircators in the regime of 1-3 GW. The oscillators are coupled together through short lengths of waveguide of an appropriate length. Locking occurs on the time scale of 10 ns and lasts over the duration of the pulse. Power-density enhancement due to source coherence is directly measured in the radiation field. Experiments are now underway to construct a module of several oscillators to reach power >10 GW and to demonstrate the physics principles necessary to use this module on a larger 100-1000-GW array in the future.<>