Design of a prototype Multi-Frequency Recirculating Planar Magnetron

The Multi-Frequency Recirculating Planar Magnetron (MFRPM) is a type of Recirculating Planar Magnetron^1,2 (RPM) designed for tunable or simultaneous oscillation at more than one primary frequency. Like the RPM, the MFRPM is a crossed-field, high power microwave source that integrates the same advantages over traditional cylindrical cavity magnetrons as UM´s original RPM, such as a large cathode surface area for supplying higher electron current, with the added benefit of producing multiple frequencies using a single HPM device. Previous experimental research3 involved demonstration of the L-band RPM-12A, the first RPM prototype. The RPM-12A was specifically designed for use on the Michigan Electron Long Beam Accelerator with a ceramic insulator (MELBA-C), which drives the RPM by applying a -300kV, 0.3-1.0 μs pulse to the cathode. Design of a dual L/S-band MFRPM prototype is intended to demonstrate simultaneous operation at two different frequencies by modifying the RPM-12A to include a set of linear resonant cavities designed to operate at the second harmonic (2-GHz) relative to the other set of resonant cavities (1-GHz). This design is also intended for use on MELBA-C and, as a proof-of-concept, will not have an optimized RF extraction system; efficient RF extraction is also being explored at UM4. Operating behavior is characterized through particle-in-cell simulations using MAGIC for comparison against experimental results.