Energy Losses in Simulated Relativistic Michigan A6 Magnetron with Shaped Cathode

摘要

Recently there has been much research interest in improving magnetron performance by employing various priming techniques, such as shaped cathodes and nonuniform magnetic fields. These priming techniques have been successfully applied to reduce magnetron noise and improve mode-locking and efficiency. Inserting a shaped cathode into the simulated Michigan magnetron yields a maximum efficiency (the radiofrequency (RF) output power for a cycle divided by the current times voltage input for that cycle) of 33% as opposed to 15% for the standard cathode. This is a very good efficiency figure for a relativistic high-power magnetron, however, conventional magnetrons often achieve efficiencies greater than 85%. The current effort seeks to characterize the various energy losses with the eventual goal of improving efficiency beyond 33%. The authors have found that for an RF cycle, 41% of the input energy is deposited by the electrons into the anode, 3% of the energy is deposited by electrons in the cathode, 23% is deposited by electrons downstream of the cathode, and 33% is emitted as RF. They will show in detail the spatial profile of the energy deposition by the electrons. The hope is that with a detailed understanding of the energy losses, they can invent means of improving the efficiency without making key tradeoffs, such as going to higher magnetic fields, achieving higher peak efficiency at the expense of longer rise times (which would lead to reduced energy efficiency), increasing device size, or reducing maximum power output.