Revisiting Power Flow and Pulse Shortening in a Relativistic Magnetron

The behavior of a six-vane relativistic magnetron with a single radial output slot has been studied in detail by 3-D particle in cell simulations. It is found that a delicate power imbalance caused by the pulsed-power generator and magnetron impedance mismatch is responsible for the shortening of the radiated power pulse. Pulse shortening can be avoided completely, and the radiated power can be considerably increased by decreasing the emitted current when it is too large to be sustainable. When the magnetron current is too high, the voltage decreases, which causes the radiated power to drop and shortens the pulse. This relatively simple electrical power balance is the result of intricate dynamics involving the electron flow within the magnetron, out of the interaction cavity through the axial flow and the electromagnetic modes supported by the structure.