Variations on the Relativistic Magnetron

Experiments are described on a symmetrically loaded S-band relativistic magnetron incorporating substantial variations from standard devices. Solid cathodes, ridged cathodes, and propagating beams were used to drive the symmetrically loaded six-vane anode to resonance. Results of geometric parameter studies are presented. Peak powers of 1.15 GW per waveguide (6.9-GW total power) were produced at 4.5 GHz. The magnetron cathode was extended to become the cathode of a load diode; diode impedance was varied to explore Bθ effects in the magnetron. Output power declined when axial current exceeded 15 kA because of these effects. A reflex opening switch was used to shorten the electrical pulse and amplify the electrical power in the magnetron, but high axial current limited microwave power to ~0.1 GW per waveguide. A reflex switch followed by an inverse diode was used with the secondary cathode feeding a magnetron. This scheme isolates from the magnetron the detrimental high current in the reflex switch.