Linac RF Source
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Linac RF SourceRecommendations for Items 22,23,24,46,47Chris Adolphsen
Modulators (115 kV, 135 A, 1.5 ms, 5 Hz)Baseline Choice: DESY/FNAL Pulse TransformerPros: Seven units built by industry - no major reliability problems. Choice for the XFEL: DESY continuing to work with industry on improvements. FNAL working on a more cost efficient and compact design.Cons: Susceptible to single-point failures, large oil-filled transformer (in tunnel for single tunnel design), high labor cost to assemble.
Alternate Choice: Marx GeneratorPros: Solid state, 1/n redundant modular design for inherent high availability and reliability. No transformer, air cooled. Highly repetitive IGBT modules, cheap to manufacture: may be up to 50% less expensive.Cons: No working model - first prototype in 2006. Need to develop long-haul 115 kV transmission line if have clustered rf sources.
KlystronsBaseline Choice: 10 MW Multi-Beam Klystrons Only high power, high efficiency tube available (two Thales tubes have achieved full spec after gun fix, only few hundred hours operation at 10 MW).
Alternatives to be Considered(Long development time, no funding in 2006)10 MW Sheet BeamKlystron (SBK)Parameters similar to10 MW MBKLow Voltage10 MW MBKVoltage e.g. 65 kVCurrent 238AMore beams
Perhaps use a Direct Switch Modulator5 MW Inductive Output Tube (IOT)DriveOutputIOTKlystronSLACCPIKEK
RF Components per LinacAverage cryomodule gradient = 31.5 MV/mOverhead for BNS and failed units = 5%Number of cavities (ignoring BC, Undulator) 1.05*(250-5)/(0.0315*1.038) = 7868Number of 8-cavity cryomodules = 984Number of 10 MW rf stations = 328Beam Power / RF Power Capability 245 GeV * 9.5 mA / (328 * 10 MW) = 71%
RF Distribution Math(for 35 MV/m Max Operation)35 MV/m * 9.5 mA * 1.038 m = 345 kW (Cavity Input Power)24 Cavities1/.93 (Distribution Losses)1/.89 (Tuning Overhead)10.0 MW10 MW Klystron