Magnetron Injection Gun for High-Power Gyroklystron

A magnetron injection gun (MIG) can generate an annular electron beam with a high transverse-to-axial velocity ratio for gyrotron devices. This article compares the different configurations of the MIGs and their suitable applications were analyzed from the theoretical study. Following that, an MIG for a 48-GHz, 2-MW output power gyroklystron was designed and optimized by parameterizing the MIG's geometry and the magnetic field. By using the standard triode-type configuration, a low alpha spread of 8.9% was achieved. The simulation results showed that the magnetic field profile also plays an important role in the MIG design. The angle of the magnetic field on the emitter surface affects the alpha value and the alpha spread, which was not able to be predicted by the synthesis method. It provides an extra degree of freedom for tuning the MIG's performance in the experiment where the geometry of the gun is fixed.