A hybrid inverted coaxial magnetron to generate gigawatt levels of pulsed microwave power

A new hybrid version of the inverted coaxial magnetron has been designed and built to generate gigawatt peak-power levels at 3.2GHz with a pulse duration of 30 nanoseconds. Preliminary tests have yielded peak powers of 0.5 GW at 3.2 GHz with an efficiency of 20%. Unlike the usual inverted coaxial magnetron, this device includes a tunable stabilizing cavity which surrounds the cylindrical output waveguide. The 54 vanes attached to the outer wall of the stabilizing circuit form the radial cavities of the anode slow-wave structure. Coupling between the slow-wave structure and stabilizing cavity is designed to force II-mode oscillations in the electron interaction space. Such a configuration substantially increases the maximum power flow obtainable in the interaction space and reduces the probability of RF vacuum breakdown. Modal stability during the leading edge transient is enhanced by including a priming network in the surface of the field emission cathode.