Patent ID: 8624496
Filing Date: 2014-01-07
Classification: H01J

Abstract:
1. A magnetron comprising: an anode structure oriented about an axis, the anode structure defining an interior chamber and having a plurality of vanes extending radially into the interior chamber and terminating at a vane tip, with each pair of the plurality of vanes defining a cavity to form a plurality of cavities within the interior chamber and each of the plurality of cavities has a resonant frequency; a cathode aligned substantially along the axis, the plurality of vanes and the cathode configured so as to define a first gap between the vane tips of the plurality of vanes and the cathode, wherein the cathode and anode are configured to create an RF field; a conductive output terminal for receiving an output signal; an output coupler disposed in communication with at least one of the plurality of vanes and in electrical communication with the conductive output terminal; a magnetron magnet configured to create an axially aligned magnetic field within the interior chamber; a plurality of variable-permeability blocks affixed in the anode structure, wherein each of the variable-permeability blocks is magnetic-field-dependent and orthogonally-biased with respect to the RF field, for changing the resonant frequency of each of the plurality of cavities of the anode structure; a plurality of variable-strength, localized-field bias magnets, for changing the permeability of each of the plurality of variable-permeability blocks, magnetically connected to said variable-permeability blocks, each of the plurality of bias magnets having a coil; a feedback control circuit in communication with the conductive output, an RF reference signal source generating an RF reference signal, and to the coils of the plurality of bias magnets; and wherein the feedback control circuit is configured to detect an output signal at the conductive output terminal, to detect the reference signal, to compare the output signal to the reference signal, to calculate desired settings for a bias magnet current to be applied to the coils of the plurality of bias magnets based on the comparison, and to generate and apply the bias magnet current to the coils of the plurality of bias magnets.