Cheever, D.
(Dan Cheever)

TUPOS57 Optimal RF Systems for Lightly Loaded Superconducting Structures
Townsend Zwart, Dan Cheever, William S Graves, D. Wang, Abbi Zolfaghari (MIT/BLAC, Middleton, Massachusetts)

Recent developments in the field of RF accelerators have created a demand for power amplifiers that can support very high accelerating gradients, 15-25 MV/m, in superconducting structures with extremely low losses. Free electron lasers (FEL’s) with modest beam current, I< 10 uA, or based on energy recovery linacs (ERL’s) may have intrinsic power demands of less than 1 kW/m. We present the design of an amplifier and external tuner system that will efficiently meet this requirement. The RF amplifier, an Inductive Output Tube (IOT), offers high AC/RF efficiency, flexible power output and switching capability without the need for external modulation. The tuner circuit makes use of low loss ferrite phase shifters to create a moderate quality standing wave (Q~100-1000) between the amplifier and the superconducting cavity. An alternative design based on a shorter cavity structure and employing solid state amplifiers is also presented. The expected performance characteristics of both systems are described.