A model for calculation of magnetron performance

A simplified model of the space charge in a magnetron is proposed, and the performance of the magnetron is calculated; the method differs from that of Welch in the space charge density assigned to the "spokes," and from that of Hull in using energy conservation instead of the principle of induction to identify the operating point. The method is tested by applying it to four known magnetrons, covering a wide range of frequencies, operating voltages and power levels. In all four cases the method predicts the output power correctly within ± 0.5 dB, and the voltage within ± 2 percent, at the nominal operating current and field. It also predicts the frequency pushing, and provides information on the relative phase of the spokes, and other parameters. The spoke phase is found to be always within the range -20° to -60°.