A Novel Injection-Locked Amplitude-Modulated Magnetron at 1497 MHz

Thomas Jefferson National Accelerator Facility (JLab) uses low efficiency klystrons in the CEBAF machine. In the older portion they operate at 30% efficiency with a tube mean time between failure (MTBF) of five to six years. A highly efficient source (>55-60%) must provide a high degree of backwards compatibility, both in size and voltage requirements, to replace the klystron presently used at JLab, while providing energy savings. GENERAL STATEMENT OF HOW THIS PROBLEM OR SITUATION IS BEING ADDRESSED. We will develop a highly reliable, highly efficient RF source based upon a novel injection-locked amplitude-modulated (AM) magnetron with a lower total cost of ownership, >80% efficiency, and MTBF of six to seven years. The design of the RF source will be based upon a single injection-locked magnetron system at 8 kW capable of operating up to 13 kW, using the magnetron magnetic field to achieve the AM required for backwards compatibility to compensate for microphonics and beam loads. WHAT WAS DONE IN PHASE I. A novel injection-locked 1497 MHz 8 kW AM magnetron with a trim magnetic coil was designed and its operation numerically simulated during Phase I. The low-level RF system to control the trim field and magnetron anode voltage was designed and modeled for operation at the modulation frequencies of the microphonics. A plan for constructing a prototype magnetron and control system was developed. WHAT IS PLANNED FOR THE PHASE II PROJECT Prototype 1497 magnetrons with a trim magnetic coil will be built. A system to control the magnetron will be built and tested to vary the trim coil current and the anode voltage as required to suppress beam emittance growth due to microphonics and changing beam loads. COMMERCIAL APPLICATIONS AND OTHER BENEFITS The immediate outcome of this project is a high efficiency, low cost replacement for the CEBAF accelerator klystrons at JLab with an energy savings payback time of 5 years. Future applications of the novel injection-locked AM magnetron include, commercial magnetron heating applications for more precise material processing in the chemical industry such as microwave driven particle synthesis. Phased array radar systems will also benefit from the injection locked AM magnetron in ground penetrating radar and microwave power transmission.