Digital Control System for the Thermionic Cathode in an Electron Gun

Microwave Electron Guns (MEGs) have been designed in which electrons were accelerated within the gun to kinetic energies up to 1,000 KeV. However, this MEG has some inherent limitations. During half of the RF cycle electronsare accelerated back to the cathode and heat it leading to a current increase during the macropulse. This positive feed-back, if not controlled, can destroy the cathode. This paper will discuss a fast digital control system which is capable of regulating the heat source by keeping the cathode's current at a specified value. System simulations of the MEG digital controller show promising results which can improve MEG stability and avoid expensive repairs.