Simulation of a Magnetron Using Discrete Modulated Current Sources

Magnetrons are microwave oscillators and are extensively used for commercial and military applications requiring power levels from the kilowatt to the megawatt range. It has been proposed that the use of gated field emitters with a faceted cathode in place of the conventional thermionic cathode could be used to control the current injection in a magnetron, both temporally and spatially. In this research, this concept is studied using the 2-D particle trajectory simulation Lorentz2E and the 3-D particle-in-cell (PIC) code VORPAL. The magnetron studied is a ten cavity, rising sun magnetron, which can be modeled easily using a 2-D simulation. The 2-D particle trajectory code is used to model the electron injection from gated field emitters in a slit type structure, which is used to protect the gated field emitters. VORPAL is used to study the magnetron performance for a cylindrical, a five-sided, and a ten-sided cathode. Finally, VORPAL is used to simulate a modulated, addressable, ten-sided cathode. The aspects of magnetron performance for which improvements are desired include mode control, efficiency, start oscillation time, and phase control. The simulation results show that the modulated, addressable cathode reduces startup time from 100 ns to 35 ns, increases the power density, controls the RF phase, and allows active phase control during oscillation