New Results From High-power Oscillator-amplifiers

Results from experiments involving a tandem, X-band BWO-TWT are presented. In this system, a single annular relativistic electron beam is used to drive both slow wave structures in the TM
₀₁
mode. The structures are coupled by a tube of variable length which is designed to cut off the resulting electromagnetic waves. Consequently the beam, modulated by the BWO, is used to drive the TWT. By operating the BWO at low power, pulse shortening effects are avoided, thus allowing for high TWT power outputs with long pulsewidths. The frequency is tunable by varying the beam gamma. The design of two larger, higher power X-band systems operating in the TM
₀₂
mode will also be discussed. The first is a tandem system similar to our present TM
₀₁
experiment, but having a larger 3-inch diameter electron beam. The second is coaxial, with the BWO inside the TWT, each structure having independently controlled electron beams. Some advantages of this arrangement will also he discussed. Structures for conversion of the generated TM waves to TE-modes will be discussed.