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Technological Challenges for the LHC Upgrade W. Scandale CERN Accelerator Technology Department

Technological Challenges for the LHC Upgrade W. Scandale CERN Accelerator Technology Department. Thanks to the valuable contributions of D. Tommasini. CERN-CARE Workshop HHH2004, 8 November 2004. Outlook. Present context A road map for the upgrade of the LHC luminosity

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Technological Challenges for the LHC Upgrade W. Scandale CERN Accelerator Technology Department

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  1. Technological Challenges for the LHC Upgrade W. ScandaleCERN Accelerator Technology Department Thanks to the valuable contributions of D. Tommasini CERN-CARE Workshop HHH2004, 8 November 2004

  2. Outlook • Present context • A road map for the upgrade of the LHC luminosity • Technological challenges • High-field superconducting magnets for the LHC-IR • Medium-field fast-cycling superconducting magnets for the LHC-injector complex • SPL and RCS • Conclusive remarks Walter Scandale - 8 November 2004 - HHH2004 workshop

  3. Present Context • LHC in operation within about 30 months • GSI program based on SIS100 and SIS300 approved • EU-CARE activities settled • HHH-network investigating • Possible scenarios for LHC upgrade • New concepts for Interaction Regions design • Possible use of high-field and for medium-field fast-pulsed magnets • NED-Joint Research Activity (NED-JRA) launching • R&D for high-field Nb3Sn superconducting wire • New concepts for the design of high-field superconducting IR magnets • HIPPI-Joint Research Activity (HIPPI-JRA) launching • R&D for high-intensity pulsed linear accelerators • Optimization of up to 200 MeV Linac • Beam dynamics and RF component design for Linac up to the GeV energy • Potential interest of CEA-Saclay, CERN, GSI and INFN to strengthen the SC magnet R&D program • US-LARP very active on high-field Nb3Sn superconducting quadrupoles (about 2 M$/year from DOE) Walter Scandale - 8 November 2004 - HHH2004 workshop

  4. A Road Map for the LHC Upgrade See LHC Project Report 626 • Baseline hardware: ultimate performance -> Lmax~ 2.3x1034/cm2 s-1 • Ultimate bunch intensity -> Ib = 1.7•1011 protons per bunch • Requires RF batch compression in the PS or Linac4 • Two collision points (instead of four) with f = 315 mrad (instead of 300) • Luminosity increase by reducing b* -> Lmax~ 4.6x1034/cm2 s-1 • IR quadrupole upgrade (higher aperture - higher pole field) -> b*=0.25 m • larger crossing angle -> f = 445 mrad (Crab crossing RF-cavities?) • Beam density increase and LHC turn-around upgrade • RF upgrade for bunch compression in the LHC • Super-PS and super-SPS injecting at 1TeV (first step for future LHC energy upgrade) • Beam energy increase • Higher field dipoles (14 T) and higher gradient quadrupoles (500 T/m) • Mass production of a new superconductor (most likely Nb3Sn) Walter Scandale - 8 November 2004 - HHH2004 workshop

  5. A Time-Window for LHC-IR Upgrade Radiation damage limit ~700 fb-1 • Due to the high radiation doses to which they will be submitted, the life expectancy of LHC IR quadrupole magnets is estimated ~5-7 years • IR-quadrupoles will have to be replaced in 2013-2015,thereby offering an opportunity ofupgrading LHC IR optics to improve luminosity Courtesy of F. Ruggiero and Jim Strait • Mid-2010’s is also the earliest time frame when one can expect to need final-focusing quadrupole magnets for any of the proposed projects of linear colliders.At least one needs very strong wide final triplets Walter Scandale - 8 November 2004 - HHH2004 workshop

  6. IR based on High Fields Magnets with reduced b* New Interaction Regions: beam dynamics versus magnet technology and design See PAC03 pp 42-44 blue DIPOLES red QUADRUPOLES green RF-CAVITIES Walter Scandale - 8 November 2004 - HHH2004 workshop

  7. R&D needed for High Field Magnets • SC Cable • High performance SC cable aiming at a non-Cu JC up to 1500 A/mm2 @15 T at a temperature of 4.2 K or 1.9 K • Insertion and magnet design • Simultaneous optimization of optics and magnet design • 15 T dipoles and 12 T - 100 mm quadrupoles of accelerator type (reasonable quench margin and good field region, easy to build) • Particle loss hardness • Upgrade of the Heat Transfer in SC cables; • Comparative study among 4.2 K and 1.9 K solutions (imposing the constraint of the LHC cryogenic plant) • Upgrade simultaneously radiation hardness (cable insulators and coil design) and local collimator layout Walter Scandale - 8 November 2004 - HHH2004 workshop

  8. SC conductor for High Field Magnets See CARE-HHH-AMT workshop WAMS 22-24 March 2004 Archamps http://amt.web.cern.ch/amt/activities/workshops/WAMS2004/WAMS2004_index.htm • High Temperature Superconductors (HTS)are not yet ready for large-scale applications requiring high current densities under high magnetic fields. It will take at least another decade before they become competitive in terms of performances, yield and cost • The upper critical field of MgB2is too low • Nb3Alexhibits promising properties but there are serious manufacturing issues that have yet to be resolved • At present, the only serious candidate to succeed NbTi, suitable for industrial production, is the intermetallic compoundNb3Sn (world production still rather low: ~15 t/year). R&D on Nb3Sn conductor started in the frame of CARE-NED Walter Scandale - 8 November 2004 - HHH2004 workshop

  9. High Field Magnets: recent results A series of record-breaking dipole magnet models, opening the 10-to-15 T field range (however, not yet of accelerator class) D20 (cosq) 13.5 T at 1.8 K in a 50-mm bore (LBNL, 1997) MSUT (cosq) RD-3 (Racetrack) 11 T on first quench at 4.4 K in a 50-mm-bore (Twente University, 1995) 14.7 T at 4.2 K in a 25-mm gap (LBNL, 2001) Walter Scandale - 8 November 2004 - HHH2004 workshop

  10. The ‘poor man’ way: LHC-IR upgrade with new NbTi quadrupoles -> b*=0.25 m See EPAC 04 pp 608-10 The quadrupole aperture is matched to the real beam size Comparison between NbTi, NbTiTa and Nb3Sn conductors Walter Scandale - 8 November 2004 - HHH2004 workshop

  11. The EU Joint Research Activity CARE-NED • The main objective of the NED JRA is to develop a large-aperture (more than 88 mm), high-field (up to 15 T)dipole magnet model relying on high-performance Nb3Sn conductors (non-Cu JC up to 1500 A/mm2 @15 T and 4.2 K). • Such magnet is aimed at demonstrating the feasibility of the LHC-IR upgrade scenarios based on high field dipole and quadrupole magnets and is meant to complement the US-LARP. • In addition, the NED model could be used to upgrade the CERN superconducting cable test facility (presently limited to 10-10.5 T). • The NED JRA proposal involves 7 collaborators (CEA/Saclay, CERN, INFN-Milan and Genoa, RAL, Twente University and Wroclaw University), plus several industrial sub-contractors. • EU funding limited to 25 % of the original request -> new resources needed soon to complete the program Walter Scandale - 8 November 2004 - HHH2004 workshop

  12. De-scoping CARE-NED • Given the present State of the Art and the magnet requirements foreseen for LHC IR upgrade and for IR’s of future linear colliders, we established the following road-map: • revisit magnetic and mechanical designs to achieve enhanced performances with coils made from brittle conductors, • address coil cooling issue under high beam losses, • keep promoting high-performance Nb3Sn wire development (to ensure the survival of multiple suppliers including in EU), • improve mechanical robustness and assess radiation hardness of Nb3Sn conductor insulation, • put into practice all of the above in magnet models and prototypes. Walter Scandale - 8 November 2004 - HHH2004 workshop

  13. Beam Density Increase The upgrade of the injector chain is needed Poor-man way: RF upgrade for batch compression in the PS • Up to 160 MeV: LINAC 4 • Up to 2.2 GeV: the SPL (or a super-BPS) See CARE-HIPPI Rich-man way: The superconducting way: • Up to 60 GeV a SC super-PS • Up to 1 TeV a super SPS • SC transfer lines to LHC The normal conducting way: • Up to 30 GeV a refurbished PS • Up to 450 GeV a refurbished SPS See CARE-HHH and CARE-NED • A 1 TeV booster ring in the LHC tunnel may also be considered • Easy magnets (super-ferric technology?) • Difficult to cross the experimental area (a bypass needed?) Walter Scandale - 8 November 2004 - HHH2004 workshop

  14. Low Energy Injector Upgrade: LINAC4 & SPL see CERN-AB-2004-21 0.9•1014 particles at 2 Hz for the PS booster 2.3•1014 particles at 50 Hz for the PS Walter Scandale - 8 November 2004 - HHH2004 workshop

  15. Upgrade of the Injector Rings:Booster, PS and SPS • Basic investigations still needed • Main constraints: • Use the existing tunnels • Increase the beam density and the beam intensity possibly by a large factor • Fast repetition rate to speed-up the LHC injection process • Expected challenges • Fast-cycling SC magnets • Powerful RF within a limited space • Cryogenic, vacuum • Ejection optimization, loss control, beam disposal, instrumentation Walter Scandale - 8 November 2004 - HHH2004 workshop

  16. Recent Activity on Fast Cycling Dipoles SIS 200 (abandonned) • 4 T central field, 1 T/sec ramp • Design based on RHIC dipoles • Costeta, Rutherford cable • One phase He cooling BNL model : optimize to higher ramp-rate • Wire twist pitch 4 mm instead of 13 mm • Stabrite coating instead of no coating • Stainless steel core (2x25 microns) • G-11 wedges instead of copper wedges • Thinner yoke laminations (0.5 mm instead of 6.35 mm), 3.5 % silicon, glued with epoxy. Cable inner edge Courtesy A.Ghosh and P.Wanderer Walter Scandale - 8 November 2004 - HHH2004 workshop

  17. The BNL Fast Cycling Dipole Model Cross section of GSI-001 Prototype Magnet Courtesy A.Ghosh Walter Scandale - 8 November 2004 - HHH2004 workshop

  18. The SIS 300 Fast Cycling Dipole Model Coil Courtesy of G.Moritz SIS 300 • 6 T, 1 T/sec ramp, 100 mm bore • Design based on UNK dipoles, bore from 80 mm to 100 mm • 2-layers Cos, Rutherford cable • One phase He cooling Collars Key Iron yoke Shell Challenges : high operational field for 4.2 K, pulsed, high losses Activity on cable development: • Reduction of conductor AC loss adjusting filament hysteresis, strand matrix coupling current, cable crossover resistance Rc, and adjacent resistance Ra. • A 3.5 micrometer filament diameter was chosen because it appears to be the minimum value that can be reached in a standard copper matrix strand without the onset of proximity coupling. • The use of a Cu-0.5% Mn as an interfilamentary matrix material is also under consideration, to reduce both matrix coupling current losses (due to the high resistivity of CuMn ) and hysteresis losses. C-Clamp Staples Walter Scandale - 8 November 2004 - HHH2004 workshop

  19. Cables for Fast Pulsed Dipoles A.D. Kovalenko, JINR, 2004 Walter Scandale - 8 November 2004 - HHH2004 workshop

  20. R&D Still Needed(a non-exhaustive list) Lowering losses in pulsed magnets • Industrialize filament size 3.5 microns or smaller, reduce twist pitch • Electromagnetic design for minimum amount of superconductor • Optimize cable (cable size, keystone angle, number of strands) • Cored cables and strands with resistive coating : • long term behaviour issues • investigate limits of high Ra/Rc keeping acceptable current sharing • Resistive matrix • Alternatives to Rutherford cables, such as Nuclotron and CICC Other issues • Thermal modelling of magnet cross section under helium flow • Characterization of cable insulation schemes (dielectric/mechanical/thermal) • Manufacture of a small scale prototype for thermal model/parameter validation, for cable testing/characterization, and as coil test facility • Manufacture of an optimized prototype to prepare series production • Field quality during the ramp : modellization and experiments • Develop dedicated magnetic measurement systems for fast varying magnetic fields Walter Scandale - 8 November 2004 - HHH2004 workshop

  21. Pulsed Dipoles for PS and SPS? Initial considerations based on known technology Upgraded PS and SPS may require two different types of pulsed magnets • 3T – 2T/s for the PS • 5T – 1.5 T/s for the SPS The quench limit performance ican be achieved with present technology • Modified RHIC dipoles or Nuclotron/CICC cable based dipoles for PS • Modified (lower losses) « SIS 300 » type dipoles for the SPS Walter Scandale - 8 November 2004 - HHH2004 workshop

  22. 5 T 1 s 3 s 3 s 3 s Technological Challenges Losses are a major concern -> Vigorous R&D program needed • Study and evaluate different scenarios of beam losses in PS and SPS • Study and evaluate a maximum allowed cryogenic budget • Optimize the dipoles not only for good quench performance in condition of cable/iron losses, but also for cryogenic budget • A SC dipole for the SPS may produce 70 W/m peak (35 W/m effective 140 kW for the SPS, equivalent to the cryogenic power of the LHC !) • A rather arbitrary ‘guess’ for beam loss is of about 1012px100GeV/10s= 15 kW • By dedicated R&D magnet losses should be lowered to 10 W/m peak (5 W/m effective  20 kW ), comparable to expected beam loss power Tentative SPS cycle Walter Scandale - 8 November 2004 - HHH2004 workshop

  23. What about High Power Beams ? seeH.Schonauer EPAC 2000 pp966-68 • High power beams: what for? • Improve LHC beam (yet to be seen) • High flux of POT for hadron physics • Feed n-factory Main Ring Cycle Walter Scandale - 8 November 2004 - HHH2004 workshop

  24. Possible parameters see H. Schonauer, April ‘03 Walter Scandale - 8 November 2004 - HHH2004 workshop

  25. Technological Challenges in a 30 GeV RCS see H. Schonauer, April ‘03 • Lattice and beam dynamics • High gt needed but difficult to have dispersion-free SS at the same time • Constraint on 1 together with x=0 and large dynamic aperture • Potential coupled bunch instability during the long injection plateau • RF • Large RF voltage needed, but little space for RF-cavity in dispersion-free SS • Injection capture in an accelerating bucket not truly an adiabatic process • Demanding HOM damper • Difficult adiabatic bunch compression at 30 GeV (too low synchrotron fr.) • Capture loss versus injection energy • Vacuum pipe and bean surroundings • Large shielded ceramic chamber • Tight impedance budget: Z/N < 2 ohms critical • Dipoles and power supplies • Large stored energy (some hundreds of kJ per dipole) • Fast power supplies Walter Scandale - 8 November 2004 - HHH2004 workshop

  26. Conclusion • A staged roadmap for the LHC luminosity upgrade needs R&D on: • High-field (up to 15 T) superconducting cables and magnets • Powerful and sophisticated RF devices for beam manipulations • Medium-field fast-pulsed superconducting cables and magnets • Accelerator design and integration to existing constraints • Upgrading LHC complex is a unique opportunity to • Share technological developments with other communities such as: • Fusion (EFDA) • Nuclear physics (GSI) • NMR developers • Boost the CERN accelerator complex for future applications such as: • High intensity hadron and neutrino physics at intermediate energy • Injector developments for neutrino factory • Initial resources for R&D are presently provided by EU and CERN within the frame of CARE, in particular within the HHH-network and in the NED and the HIPPI JRAs (most likely, more support will be needed soon) Walter Scandale - 8 November 2004 - HHH2004 workshop

  27. Thank-you for your attention Walter Scandale - 8 November 2004 - HHH2004 workshop

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