Linac RF SourceRecommendations for Items 22,23,24,46,47

Chris Adolphsen

Modulators (115 kV, 135 A, 1.5 ms, 5 Hz)

• Baseline Choice: DESY/FNAL Pulse Transformer– Pro’s: 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.

– Con’s: Susceptible to single-point failures, large oil-filled transformer (in tunnel for single tunnel design), high labor cost to assemble.

• Alternate Choice: Marx Generator– Pro’s: 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.

– Con’s: No working model - first prototype in 2006. Need to develop long-haul 115 kV transmission line if have clustered rf sources.

Klystrons

Thales CPIToshiba

Baseline 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 to

10 MW MBK

Low Voltage10 MW MBK

Voltage e.g. 65 kVCurrent 238AMore beams

Perhaps use a Direct Switch Modulator

5 MW Inductive Output Tube (IOT)

Drive

Out

put

IOT

Klystron

SLAC CPI KEK

RF Components per Linac

• Average cryomodule gradient = 31.5 MV/m

• Overhead for BNS and failed units = 5%

• Number of cavities (ignoring BC, Undulator)═ 1.05*(250-5)/(0.0315*1.038) = 7868

• Number of 8-cavity cryomodules = 984

• Number of 10 MW rf stations = 328

• Beam 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 Cavities× 1/.93 (Distribution Losses)× 1/.89 (Tuning Overhead)═ 10.0 MW

10 MW Klystron