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HIGH LUMINOSITY LHC: MAGNETS

CERN, 18 th November 2011 Hi- L umi meeting. HIGH LUMINOSITY LHC: MAGNETS. E. Todesco CERN, Geneva Switzerland With relevant inputs from colleagues M. Bajko , A. Ballarino , O. Bruning , R. De Maria, F. Cerutti , L. Rossi,

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HIGH LUMINOSITY LHC: MAGNETS

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  1. CERN, 18th November 2011 Hi-Lumi meeting HIGH LUMINOSITY LHC:MAGNETS E. Todesco CERN, Geneva Switzerland With relevant inputs from colleagues M. Bajko, A. Ballarino, O. Bruning, R. De Maria, F. Cerutti, L. Rossi, G. L. Sabbi, T. Nakamoto, P. Wanderer, R. Van Weelderen …

  2. APERTURE • Goal of the HL-LHC: increaseluminosity – twopaths • largerintensitysmallerb* • Size of the beam Q1-Q3 is ~ inverse proportional to b* • Note: we do not needstrongerquadrupoles, but larger! • Todaywe have 70 mm aperture quadrupoles • This limitsb* to about 50 cm • Weaimatreducingb* of a factor 4, weshould double the aperture

  3. APERTURE • Aperture is a painfulparameterfor quadrupoles • Larger aperture f smaller gradients G • The technologylimitsBpeak G f (first orderestimate) • Nb3Sn gives 50% moreBpeak - if worksweshouldtakeit • Larger gradients  longer lengths • Larger aperture and larger gradients  largerstoredenergy • Size of the magnetlimited by the tunnel • Irondoes not manage to keep all the flux, largerfringefields Optimal aperture for the LHC triplet versus time

  4. FROM APERTURE TO PERFORMANCE • Estimating the performance related to an aperture is long … • Green: beamdynamics WP2 • Blue: magnet WP3 • Red: energydeposition WP10 • Yellow: powering WP6 Magnetlength Protection Coil aperture Magnet design: Gradient, Current, Yoke Storedenergy Cooling Lay-out Beam aperture Powering Field quality Heatload, Shielding Correctors Crossing angle Beta* Beamscreen & cold bore

  5. HL-LHC BUILDS UP ON PREVIOUS WORK • Upgrade studies started long time ago ! • First scenario: keep the same length and gradient, change from Nb-Ti to Nb3Sn allowing 90 mm aperture and b* =25 cm [O. Bruning, et al., LHC PR 626 (2002)] • HL-LHC relies on complementary programs • Ex-Phase-I [R. Ostojic, et al., LHC PR 1163 (2008)] • The program aimed at a fast upgrade with available technology (Nb-Ti) • Aperture of 120 mm chosen in 2008, MQXC to be tested in a few months • LARP (since 2000) • Development of Nb3Sn technology by US-DOE • Synergy of three BNL, FNAL, LBL, with massive investments since 2005 • Several 90 mm aperture magnets TQ, a 3.4-m-long LQ, a 120 mm HQ • HFM within EUCARD (ongoing) • Nb3Sn technology, radiation resistance, …

  6. MAGNETS FOR THE INNER TRIPLET • Todaywe have twopieces of hardware at 120 mm • MQXC – 120 mm aperture Nb-Ti quadrupole (CERN, G. Kirby) • Innovativefeatures: permeableinsulation[La China, D. Tommasini, PRSTAB 11 (2008)] • All coilsfabricated (CEA contribution) • Short model beingassembled • Test for spring 2012 • Aim of the design study: • Check if thiscanhold 5×1034 peaklumi • Follow-up the test and analyse data

  7. THE CHALLENGE OF NB3SN • Nb3Sn candouble the field of Nb-Ti (from 8 to ~15 T) • Insulation: Nb3Sn has to becookedat 650 C to besuperconductor • Brittle, degradesat 150 -200 MPa • Length • Large experiencewith 1-m-long modelssince the 90s • Scaling to 3.4 m in progress good resultsfrom LARP [G. Ambrosio et al, MT-22]

  8. MAGNETS FOR THE INNER TRIPLET • Todaywe have twopieces of hardware at 120 mm • HQ – 120 mm aperture Nb3Sn quadrupole (LARP – S. Caspi) • Magnetassembled and testedat 4.2 K a few times • Second set of coilsbeingassembled • To betestedalsoat CERN • Results: • Performance wellabove Nb-Ti but still 10% missing • Field quality shows very positive results • Geometricerrors show similarprecision in the coil position as in Nb-Ti ! Nb-Ti operational

  9. 140 mm LAY-OUTS • Indication frombeamdynamics: • Larger apertures cangivelarger performance • Westartedstudying140 mm aperture cases • For a few monthswe go on with four lay outs • Nb-Ti 120 mm • Nb3Sn 120 mm • Nb-Ti 140 mm[G. Kirby, E. Todesco, Hi-Lumitalk] • Nb3Sn 140 mm [P. Ferracin Hi-Lumi talk] • In summer 2012 wewill have completed a first loop • Evaluation of gain in performance from 120 to 140 mm • Understand if 140 mm is possible • Then, management willdecide • Fromthen on, wewill have a Nb3Sn baseline and a Nb-Ti plan B

  10. SEPARATION DIPOLE D1 • Todayisresistive, 20 m 1.28 T, 60 mm wide • Requirements • Aperture: weneed 10 mm more than quads: 130 or 150 mm • Increase the kick of 50% from 26 T m to 40 T m to make room • Makeitsuperconducting to make room • MBXD/E: Nb-Ti separationdipole (KEK) [Q. Xu, T. Nakamoto talk] • Design choice • Large coilto reduce stress and improve FQ • Issues • New regime of saturation (10-20%, 1-5% previously) • Fringefieldin the tunnel from 1 to 10-100 mT

  11. RECOMBINATION DIPOLE D2 • Todayis 80 mm wide 3 T, Nb-Ti • Requirements • Aperture: weneedsomething more • Increase the kick of 50% from 26 T m to 40 T m to makespace • Nb-Ti recombinationdipole (BNL) [R. Gupta, P. Wanderer talk on 17.11.11] • Design choice • 100 mm probablyupperlimit for apertures • Issues • New regime of saturation (10-20%, 1-5% previously) • Fringefield in the tunnel

  12. Q4, COOLING, PROTECTION • Large aperture Q4 [Cea-Saclay] • Today 70 mm aperture (MQY) • Increase up to 85-90 mm • Tightspaceconstraintsgiven by beamseparation • Coolingis a keyparameter and willbetakenintoaccountfrom the beginning in magnet design [R. Van Weelderen] • Contribution of CEA-Grenoble on the study of Nb3Sn at 4.2 K • Easethe path for heatdepositionfromthe coilto the helium bath • Example of MQXC • Protection [INFN-LASA] • In collaboration with CERN QPS team, LARP team

  13. TASKS OF THE WORKPACKAGE • Task 2. IR quadrupoles in Nb3Sn [G. L. Sabbi , LBNL] • Task 3. Separation and recombinationdipoles[T. Nakamoto KEK , P. Wanderer BNL] • Task 4. Cooling[ R. van Weelderen, CERN] • Task 5. Othertopics[J. M. Rifflet, CEA] • Large aperture Q4 • Nb-Ti option for the inner triplet • Resistivequadrupoles in IR3 and IR7

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