A magnetron injection gun with inverted geometry for an 80 MW gyroklystron

A 500 kV, 500 A magnetron injection gun (MIG) is being developed for the University of Maryland Ku-band, coaxial gyroklystron. The gun will have three electrodes, with the cathode at a larger diameter than the intermediate electrode, thus being an inverted form of the normal geometry. This allows the gyroklystron´s inner conductor to be supported through the electron gun, eliminating the need for the beam-intercepting supports and facilitating cooling. It also allows for adjustment of the coax position external to the vacuum. Details of the design, including modeling of the beam trajectories, are discussed.