Mode purification in a relativistic magnetron with diffraction output

Summary form only given. Previous MAGIC particle-in-cell simulations performed at the University of New Mexico illustrated a mechanism by which a Gaussian TE₁₁ microwave radiation pattern could be generated by a compact relativistic A6 magnetron with diffraction output (axial extraction) [1]. It employed an upstream strap that locked in the π-mode, something new to relativistic magnetrons [2], and a mode converter affixed to the downstream end of the anode block that acted to disrupt the desired π-mode. During portions of the TE₁₁ RF cycle in which the electric field was low, such as when the polarity reversed, it was found that the polarization underwent rotation. Several changes are introduced in simulations to correct this problem at the expense of power and efficiency. These simulation results will be presented.