1. Linac RF Source Recommendations for Items 22,23,24,46,47 Chris Adolphsen

2. 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.

3. Klystrons Thales CPI Toshiba 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).

4. Alternatives to be Considered (Long development time, no funding in 2006) 10 MW Sheet Beam Klystron (SBK) Parameters similar to 10 MW MBK Low Voltage 10 MW MBK Voltage e.g. 65 kV Current 238A More beams Perhaps use a Direct Switch Modulator 5 MW Inductive Output Tube (IOT) Drive Output IOT Klystron SLACCPIKEK

5. 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%

6. 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