High-Power Rf Distribution Systemfor the 8-Pack Project

Abstract

The 8-Pack Project at SLAC is a prototype rf system whose goal is to demonstrate the high-power X-band technology developed in the NLC/GLC (Next/Global Linear Collider) program. In its first phase, it has reliably produced a 400 ns rf pulse of over 500 MW using a solidstate modulator, four 11.424 GHz klystrons and a dualmoded SLED-II pulse compressor [1]. In Phase 2, the output power of our system has been delivered into the bunker of the NLCTA (Next Linear Collider Test Accelerator) and divided between several accelerator structures for beam acceleration. We describe here the design, cold-test measurements, and processing of this power distribution system. Due to the high power levels and the need for efficiency, overmoded waveguide and components are used. For power transport, the TE 01 mode is used in 7.44 cm and 4.064 cm diameter circular waveguide. Only near the structures is standard WR90 rectangular waveguide employed. Components used to manipulate the rf power include transitional tapers, mode converters, overmoded bends, fractional directional couplers, and hybrids.