Magnetron structure design using 2- and 3-D EM codes

Abstract

Summary form only given, as follows. Magnetrons, with efficiencies greater than 70% when operated at low voltages, are of great interest to the high power microwave (HPM) community. However, when operated at higher voltages (>100 kV), relativistic magnetrons suffer from short output RF pulses, as well as large decreases in efficiencies (typically less than 30%). Recent 3-D computer simulations have addressed the issue of efficiency limitations. Short rf pulses could be caused by the large electric fields that exist in the vane structures. Using a large slot to vane ratio may lead to the reduction of the electric field stresses, however doing so leads to severe mode competition. The Air Force Research Lab has laid out a method using 2- and 3-D electromagnetic codes to investigate different magnetron structures, which may lend themselves to 'large' mode separation between the Pi-mode and its nearest adjacent modes, while minimizing the electric field stress.