Electrostatically Focussed TWT for Space Communications

There is a significant and growing NASA requirement for small efficient space communications amplifiers in the range of five- to 50-watts at 20 GHz and above. These powers are too high for solid state technology. Traveling wave tubes, on the other hand, are not very efficient at these low power levels as currently constructed. Also, their price per-watt is high, as is their size and weight per-watt. We propose to close this technology gap with a revolutionary miniature TWT design that can be constructed for under a few hundred dollars and utilizes cathode ray tube design and assembly technology. It will be electrostatically focussed and use a ladder-type slow wave circuit. Feasibility will be tested in PHASE I using sophisticated computer modeling tools for the RF and focusing structures. A prototype beam tester will be constructed to analyze beam-focussing parameters and a slow wave structure will be constructed and cold tested. The objective is to determine if the focusing and RF structures can be combined in one integrated device, and, if so, over what range of frequency, power, bandwidth and beam perveance.CRT fabrication techniques, such as glass-rodded assemblies and all-glass envelope construction will be tested - with a view to mass-producing miniature, low mass TWT's. NASA benefits include more efficient, lower cost satellite communications.