The 60 GHz gyrotron development program

A microwave oscillator capsule of producing 200 kW of CW power at 60 GHz with high purity of the output mode is considered in the context of electron cyclotron resonanace heating of plasmas in controlled thermonuclear fusion experiments. Calculations using TAPER were done for mode conversion in an improved 4 inch diameter collector. The only remaining problem with the design is that it is slightly longer than previous CW collectors. Power density measurements were made on extended 2.5 inch diameter collectors using small diameter coils wound directly onto the collector to properly distribute the beam. The results were very encouraging for future CW operation of this design. Output window activity concentrated on improved surface finish, techniques of edge support, and initial design of a sapphire double disc window.