Confined flow multiple beam guns for high power RF applications

Summary form only given. Multiple beam (MB) guns are finding increased application in different types of microwave tubes. The advantages of NIB guns in a microwave tube, for example, in a klystron (MBK), is a decrease of beam voltage, reduced power densities, and lower voltage gradients. Another advantage is increased bandwidth. Double convergent MB guns are capable of providing lower cathode loading and higher Rf power at a given frequency. At present all known MBKs use Brillouin type focusing, where the cathode is shielded from the magnetic focusing field. This type focusing is seldom used in single beam, high power klystrons due to inferior beam transmission as compared to the confined flow type focusing. This program is focused on developing confined flow multiple beam guns for RF power levels in excess of 50 MW at X-Band. A number of advanced, computational tools are used to model and refine the electric and magnetic field configural ions and transport electrons through the 3-D structure. A multiple beam gun configuration was achieved that provided confined flow beam transport through a simulated device without beam interception. Efforts are now focused on refining the modeling capability and improving the beam quality. Progress to date will be reported.