Title: SLAG Modulator Operation and Reliability in the SLC Era
Abstract: A discussion of the operation and reliability of the 244 modulators in the SLAC linac with an emphasis on the past three years of operation. The linac modulators were designed and built in the ~O'S, upgraded for the SLAC Linear Collider (SLC) in the mid 80s, and despite their age are still reliable accelerator components. The 60s modulator operated at 65 MW peak and 83 kW average power. The upgrade resulted in 150 MW peak output at an average power of 87 kW, a modest increase since the repetition rate was dropped from 360 to 120 Hz [ 11. In the present accelerator configuration, the Linac operates as a source of electrons and positrons to a single pass collider. The classic collider is a storage ring filled with oppositely charged, counter-rotating particles which are allowed to collide until an accelerator fault occurs and the stored beams are aborted. A reasonable storage ring can store and collide particles for as long as eight hours with a 10 or 20 minute filling time. A single pass collider, on the other hand, can only produce e- and e+ collisions at whatever rate the source operates. To be effective the SLC must operate at 120 Hz with a very high degree of reliability and on a continuous basis. Fortunately, the linac has a modest excess of modulator/klystron systems which allows some measure of redundancy and hence some freedom from the constraint that all 244 modulatorklystrons operate simultaneously. Nonetheless, high importance is placed on modulator MTBF and MTTR or, in the parlance of reliability experts and accelerator physicists, availability. This is especially true of the modulators associated with the fundamental requirements of a collider such as injection, compression and positron production. The past three years of high power operation will provide a reference for modulator design and reliability. The presentation of material related to modulator characteristics, system operation, problem frequency, repair times, adjustment interventions (e.g., thyratron ranging), component lifetimes (e.g., thyratrons), and improvements for present problems is based on detailed analysis of the 1991 SLC run. I. MODULATOWKLYSTRON DEPLOYMENT The linear accelerator presectly uses 244 modulator/klystron stations, but in 1991 only 243 stations were used to power accelerator structures. Table I presents the 1991 station deployment.
Publication Year: 2005
Publication Date: 2005-08-24
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 6
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