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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. ScandaleCERN 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 • 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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
The BNL Fast Cycling Dipole Model Cross section of GSI-001 Prototype Magnet Courtesy A.Ghosh Walter Scandale - 8 November 2004 - HHH2004 workshop
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
Cables for Fast Pulsed Dipoles A.D. Kovalenko, JINR, 2004 Walter Scandale - 8 November 2004 - HHH2004 workshop
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
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
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
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
Possible parameters see H. Schonauer, April ‘03 Walter Scandale - 8 November 2004 - HHH2004 workshop
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
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
Thank-you for your attention Walter Scandale - 8 November 2004 - HHH2004 workshop