High efficiency relativistic magnetron with diffraction output

Recently at Nagaoka University of Technology (Japan) the energy conversion efficiency for an A6 magnetron with modified diffraction output was demonstrated to increase from 3% to 37% in MAGIC particle-in-cell (PIC) computer simulations. The increased efficiency was attributed to improved matching of the A6 magnetron with the antenna. Optimization of the same magnetron design with application of a transparent cathode allows us to increase the energy conversion efficiency to almost 70% and to provide faster start-of-oscillations with gigawatt level of radiation power for an applied voltage of 400 kV. We have also found that the radiated power increases as the square of the applied voltage.