Frischholz, H. (CERN, Geneva, Switzerland)

The LEP (Large Electron Positron colliding beam accelerator) Phase I high-power RF system, by which a total of 16 MW is generated at a frequency of 352 MHz, includes 16 1-MW CW klystron/Y-junction circulator assemblies and a WR 2300 waveguide system. Via the latter, the generated RF power is distributed and supplied to the 128 accelerating structures. All klystrons, circulators, and waveguide components have been delivered, accepted by CERN, and installed in the LEP tunnel. A general description of the RF generation and distribution system is given. The performance of the klystrons and circulators as well as results of the first high-power tests in the LEP ring tunnel are presented. In particular, the tendency of the klystrons to produce spurious sidebands at high output power levels is discussed and the means used to cure it to a large extent are described. Furthermore, an explanation is given of how the problem of frequency arcs in the waveguides between klystron and circulator was overcome