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RF for the e- Ring

RF for the e- Ring. From a basic Design to a Conceptual design Some Issues N eeding Study. E. Ciapala CERN. Energy = 70 GeV (50 GeV ). RF and beam parameters – T. Linnecar, 2008 Workshop. Energy loss / turn @ 70 (50) GeV = 707 (184) MeV Beam current Ib = 74 mA

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RF for the e- Ring

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  1. RF for the e- Ring From a basic Design to a Conceptual design Some Issues Needing Study E. Ciapala CERN 2nd Workshop on the LHeC, Divonne, Sept 2009

  2. Energy = 70GeV (50 GeV) RF and beam parameters – T. Linnecar, 2008 Workshop • Energy loss / turn @ 70 (50) GeV= 707 (184) MeV • Beam current Ib= 74 mA • Beam Power Pb= 54 (14) MW • Total RF voltage Vrf= 900 (250) MV • (Overvoltage for QL, + Some Reserve ....) • Frf= 1002 GHz, h = 89100 • Fs = 1406 (1124) Hz, Qs = ~0.125 (0.1) 2nd Workshop on the LHeC, Divonne, Sept 2009

  3. Energy = 70GeV (50 GeV) RF System – Basic Design – T. Linnecar, 2008 Workshop • Assume 500 kW cw coupler - LHC has >350kW kW => feasible • Leads to 100 (28) SC Cavities • Cavity Diameter 50 cm … • Conservative gradient – 6 MV/m => Ltot = 150 (42) m • Few cavities/klystron 1 => 100 (28) with 500 kW Klystrons • 2 => 50 (14) @ 1 MW Klystrons • Klystron Powering : LEP Style PC for 1 cav/klystron (4MW) on surface (?) • Upgrade or doubling for 2 cavs/klystron • HV bunkers, LLRF & Controls – Space needed underground.. 2nd Workshop on the LHeC, Divonne, Sept 2009

  4. Study Topics - 1 Basic Design to a Conceptual Design • Exact RF Voltage Requirements. • Vtotfor Quantum Lifetime > 20hrs (as LEP) • Margin for feedback systems (Need RF Power and Voltage) • Margin for cavity/klystron trips (2 klystron margin ?) • Beam Loading considerations – optimum coupling ? • (LEP < 8mA, cavities matched for 12 mA) • Easy to Estimate … 2nd Workshop on the LHeC, Divonne, Sept 2009

  5. Study Topics - 2 Basic Design to a Conceptual Design • Cavity and Cryomodule • Define a cavity geometry, number of cells • Helium: Is 2K needed, 4.5 K may be adequate at this gradient. • - LHC cw 400MHz sputtered cavities can easily run at 8 MV/m (Pushed to 11MV/m) • - Needs Study & Cost Estimation • Cryomodule – Need schematic design, with dimensions, decide number of cavities per cryomodule. • Overall heat load estimations, static & dynamic. • Cryo System • Total cooling power needed - from above • He supply system - Connection to existing system – new separate system? • Location & footprints of additional cryo plant elements on surface and underground 2nd Workshop on the LHeC, Divonne, Sept 2009

  6. Study Topics - 3 Basic Design to a Conceptual Design • RF Power System • Suitable klystrons, number of klystrons • Power coupler design • Arrangement for feeding multiple (2) cavities/klystron, layout – space requirements • Waveguide components – Circulators, Vector Modulators etc. • Stability studies & LLRF conceptual design – Important in view of high intensity and beam loading. PC Power Converter PC Power Converter PC PC D. Valuch PC D. Valuch One Cavity per Klystron Two Cavities per Klystron 2nd Workshop on the LHeC, Divonne, Sept 2009

  7. Study Topics - 4 Basic Design to a Conceptual Design • Some other Important Issues: • Cavity effects - Ponderomotive effects, Microphonics, He oscillations, • Beam transmitted instabilities • ! LEP Experience - many such problems, even with low current, but 8 cavities per klystron made it difficult…. • HOMs and HOM coupler design. (synchrotron) 2nd Workshop on the LHeC, Divonne, Sept 2009

  8. Conclusions • Many issues needing further study: • RF Parameters, voltage & power requirements - in more detail • Cavity Design • Cryomodule design • Optimum RF Power Scheme and component design • Layout and Integration • Study of cavity effects, beam effects, HOMs • However: • Synergy with other projects & studies • SNS, SPL, XFEL, CLIC drive beam, etc. • LEP Experience… 2nd Workshop on the LHeC, Divonne, Sept 2009

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