Magnetic Priming at the Cathode of a Relativistic Magnetron.

Experiments have been performed in testing magnetic priming at the cathode of a relativistic magnetron to study the effects on high-power microwave performance. Magnetic priming consists of N/2 azimuthal magnetic perturbations applied to an N-cavity magnetron for rapid generation of the desired number of electron spokes for the π-mode. Magnetic perturbations were imposed by utilizing three high-permeability nickel-iron wires embedded beneath the emission region of the cathode, spaced 1200 apart. Magnetic priming was demonstrated to increase the percentage of π-mode shots by 15% over the baseline case. Mean peak power for π-mode shots was found to be higher in the magnetically primed case by almost a factor of two. Increases in mean microwave pulsewidth were also observed in the magnetically primed case when compared to the unprimed case (66-ns primed versus 50-ns unprimed). Magnetron starting current for the magnetically primed π-mode exhibited a reduction to 69% of the unprimed baseline starting current. [ABSTRACT FROM AUTHOR]