Phase locking of relativistic magnetrons has been achieved at power levels of ~3 GW at 2.8 GHz, exceeding previous phase-locking power levels by 3 orders of magnitude. Two relativistic magnetrons interact directly through a short waveguide of length l~~nX/2 to allow locking. Power-density enhancement due to source coherence is directly measured in the radiation field. Phase locking occurs in ~5 ns and is reproducible. Extension to 10-100 GW appears feasible with arrays of oscillators.

We have proposed and demonstrated successfully a new approach for generating high-yield K-shell radiation with large-diameter gas-puff Z pinches. The novel load design consists of an outer region plasma that carries the current and couples energy from the driver, an inner region plasma that stabilizes the implosion, and a high-density center jet plasma that radiates. It increased the Ar K-shell yield at 3.46 MA in 200 ns implosions from 12 cm initial diameter by a factor of 2, to 21 kJ, matching the yields obtained earlier on the same accelerator with 100 ns implosions. A new "pusher-stabilizer-radiator" physical model is advanced to explain this result.

A new method is demonstrated for extracting radiation from a virtual cathode oscillator in transverse electric (TE) waveguide modes. The dominant radiation mechanism occurs in the region of the virtual cathode, and is not due to reflexing of electrons. Microwave radiation occurs simultaneously or just after beam pinching in the diode. Electrostatic signals show simultaneous occurrence of the virtual cathode and microwave radiation. At the same time, the electron population divides into a beam population and a reflexing electron population. Inhibition of pinching by an axial guide field suppresses microwave radiation.

Axially resolved z-pinch density, electron temperature, and K-shell emitting mass estimates from charge-coupled device based diagnostics Rev.

Phase locking is considered both for a case in which an oscillator is driven by an external signal without feedback, and for a case in which two coupled oscillators drive each other. A comprehensive sustained oscillator model is used for the driven microwave cavity. The new locking conditions for two coupled oscillators show that phase locking can occur only when the connector contributes the zero or π phase delay. Temporal behavior is solved numerically. Calculations with large priming power agree with the experiments on a high-power magnetron driven vircator in which there is no feedback to the magnetron. The mutual drive calculations also agree with the experiments on high-power coupled magnetrons.