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 B(theta) 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 about 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.