Use of electrode synthesis technique to design MIG-type guns for high power gyrotrons

We report an application of the Harker electodo synthesis technique to the design of a high power MIG-type gun with a laminar flow beam. The beam is represented by the temperature-limited flow equations of Manuilov and Tsimring. This technique enables the design of temperature-limited guns in the moderate to high space-charge regime. We find this regime is wall-suited to the formation of high power, low velocity spread beams. The gun design reported here has been developed for the-NRL 04 GHz Megawatt Gyrotron. The beam power is 4 MW and the estimated axial velocity spread is 6% for V1/V2 = 1.5. Space-charge fields depress the cathode electric field by approximately 45%. This gun demonstrates the feasibility of obtaining multi-anode designs by the synthesis method. The design procedure makes use of an electron beam simulation code such as the Herrmannsfeldt code.