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HIGH LUMINOSITY LHC: MAGNETS

HIGH LUMINOSITY LHC: MAGNETS

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HIGH LUMINOSITY LHC: MAGNETS

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  1. HI LUMI and LARP collaboration meeting FNAL, 7th May 2012 HIGH LUMINOSITY LHC:MAGNETS E. Todesco CERN, Geneva Switzerland With contributions from G. Ambrosio, M. Bajko, L. Bottura, H. Felice, P. Fessia, P. Ferracin, L. Fiscarelli, G. Kirby, T. Nakamoto, J. M. Rifflet, L. Rossi, S. Russenschuck, G. L. Sabbi, T. Salmi, M. Segreti, P. Wanderer, R. Van Weelderen, Q. Xu, …

  2. CONTENTS • Inner triplet quadrupoles • Layouts • Where are wetoday? • HQ test [LARP collaboration, S. Caspi and G. Sabbi] • MQXC assembly[CERN, G. Kirby] • The 140 mm option • Somehighlights on the othermagnets • Separationdipole D1 [KEK, Q. Xu, T. Nakamoto, A. Yamamoto] • Two-in-one quadrupole MQZ [CEA, M. Segreti, J. M. Rifflet] • Future steps, decisions and open issues www.cern.ch/hilumi/wp3

  3. THE INNER TRIPLET: First lay-out • Two technologies / two apertures • Guidelines • 20% margin on the loadline (~2 K for Nb-Ti, ~5 K for Nb3Sn) • 1.9 K operationaltemperature • For Nb3Sn 140 mm a first X-section with a 0.8 mm strand, 40 strands • Four gradients: 100 – 118 - 150 - 170 T/m Operational gradients and lengths of the four options [S. Fartoukh, R. De Maria, B. Holzer, P. Ferracin]

  4. THE INNER TRIPLET: APERTURE Aperture of the triplet versus time

  5. THE INNER TRIPLET: A FEW WORDS ABOUT FIELD QUALITY • Critical issues • Thesemagnets are become important at7 TeVafter squeeze • Atinjectionenergythey are in the shadowof the main dipoles • Transfer functionis the most important quantity • Reproducibilityisrequired, within a fraction of unit at 7 TeV • Multipoles are an issues onlyat 7 TeV • Veryrelaxedlimitsat injection  I would not worrytoomuch about magnetization Comparison in strengthbetween main dipoles and IT quadrupoles

  6. CONTENTS • Inner triplet quadrupoles • Layouts • Where are wetoday? • HQ test [LARP collaboration, S. Caspi and G. Sabbi] • MQXC assembly[CERN, G. Kirby] • The 140 mm option • Somehighlights on the othermagnets • Separationdipole D1 [KEK, Q. Xu, T. Nakamoto, A. Yamamoto] • Two-in-one quadrupole MQZ [CEA, M. Segreti, J. M. Rifflet] • Future steps, decisions and open issues www.cern.ch/hilumi/wp3

  7. THE INNER TRIPLET: HQ RESULTS • First results of HQ testedat 1.9 K [talk by H. Bajas]  Operational value (14.6 kA) withone quench  91% of design short samplereachedwithsomegymnastic 90% of short sample Operationalcurrent HQ training at 1.9 K [H. Bajas, M. Bajko, et al.]

  8. THE INNER TRIPLET: HQ RESULTS • First results of HQ testedat 1.9 K [talk by X. Wang]  Spikes in the transferfunctionof ~10 units • Origin not understood, muchlargerat 4.2 K (100 units) • Lowerathigherfieldwhere the magnetbecomescritical for optics –not an issue for operation HQ transferfunctionat 1.9 K [L. Fiscarelli, S. Russenschuck]

  9. THE INNER TRIPLET: HQ RESULTS • First results of HQ testedat 1.9 K [talk by X. Wang] • Significantdecayinduced by ramp rate effects • Exponential in time, time constants around 30 s • Amplitude: 130 unitsat injection, but 10 unitsat 7 TeV • Not nice but not critical for operation (when squeeze starts, decayiswell over) Decay of HQ transferfunctionat injection, 1.9 K Decay amplitude versus currentat 1.9 K

  10. THE INNER TRIPLET: HQ RESULTS • First results of HQ testedat 1.9 K [talk by X. Wang] • Not badgeometricharmonicsat 7 TeVwithin 1.5 units • Except a large a3 (4.6 units) due to the twodifferentconductors • Dcmagnetization of b6 : 20 unitsat injection • It willbebetterwithcoil of 108/127 but looks not critical (simulations ongoing) Geometricharmonicsat 7 TeV b6 versus currentat 1.9 K [L. Fiscarelli, S. Russenschuck]

  11. THE INNER TRIPLET: MQXC • Magnet 0 assembled in January-April [G. Kirby talk] • Nowyoked • Field quality • Good geometricnearlywithintargets • Test at 1.9 K in May-June MQXC fieldqualitymeasuredat room temperature [P. Galbraith, J. Garcia Perez, S. Russenschuck] MQXC yoked [G. Kirby, J. Perez, et al]

  12. CONTENTS • Inner triplet quadrupoles • Layouts • Where are wetoday? • HQ test [LARP collaboration, S. Caspi and G. Sabbi] • MQXC assembly[CERN, G. Kirby] • The 140 mm option • Somehighlights on the othermagnets • Separationdipole D1 [KEK, Q. Xu, T. Nakamoto, A. Yamamoto] • Two-in-one quadrupole MQZ [CEA, M. Segreti, J. M. Rifflet] • Future steps, decisions and open issues www.cern.ch/hilumi/wp3

  13. THE INNER TRIPLET: THE Nb3SN OPTION MQXF • 120 mm does not give the maximum performance • We are making a first iterationon the design of a larger aperture Nb3Sn quadrupole • Aperture, strand and cableoptimization – mostcritical aspects to befixed to start as soon as possible [P. Fessia talk] • Critical aspects: stress, protection • Strategy: MQXF shouldbe a simple scaling of HQ • The magnetshould not be more challenging • 140/150 mm considered • Cablewith 40 strands • To have more coil, less stress • Strand of 0.8 to 0.9 mm

  14. THE INNER TRIPLET: THE Nb3SN OPTION MQXF - MARGIN • To have a more faircomparisonwefix the gradient for each aperture: • 150 T/m with 140 mm • 140 T/m with150 mm • Largerstrandgivesslightlymore margin(up to +3%) • Operationalcurrentsfrom15 to 17.5 kA • Short sampleat 22 kA in some cases canbeannoying (limit of test stations ?)

  15. THE INNER TRIPLET: THE Nb3SN OPTION MQXF - STRESS • Largercable smaller stress (10-15%) • Notwithstandinglarger apertures, one can manage to stay on the samelevel of HQ (alreadyprettyhigh)

  16. THE INNER TRIPLET: THE Nb3SN OPTION MQXF - PROTECTION • One has three phases • Detection time – you take all the Io2 - Open switch, quench heater firing • Delay to quench coil – only resistance is the dump resistor • Coil is quenched • Resistance is dump resistor plus the coil resistance which is increasing with temperature

  17. THE INNER TRIPLET: THE Nb3SN OPTION MQXF - PROTECTION • Present case of HQ (total available 17 MIITS at 300 K) • Example of a typical quench at 1.9 K and 15 kA • 10 ms of detection time plus 2 ms switch opening: 3 MIITS • 10 ms (?) to quench all the coil 1.5 MIITS • 9 MIITS taken by the coil all quenched + dump resistor We are tight ! - and this is not short sample … Going to 140/150 mm we should try to gain ... Fit of quench data at 15.1 kA with simple model, 0.01 s delay to quench all HQ [test data from H. Bajas and M. Bajko]

  18. THE INNER TRIPLET: THE Nb3SN OPTION MQXF - PROTECTION • First case: detection time • MIITS scaleswith square of cable cross-sectional area S2 • Detection time scaleswithS/Io • Quality factor proportional to fraction of MIITS used by detection: Io/S • This todayiseating 20% of the budget in HQ (3 MIITS out of 17) • Largerstrandgivesa bit largermargin(+20%) • Nearly in the shadow, but at least is not worse

  19. THE INNER TRIPLET: THE Nb3SN OPTION MQXF - PROTECTION • Third case: magnettotallyquenched(no dump resistor) • This happensafterfiring of quenchheaters • We assume all magnetresistiveat 1.9 K,  magnetheats  resistanceincreases  decayfaster and faster • Weestimate the MIITS for this case, and compare of the cable MIITS • All cases are rathersimilar(largerstranddoes not change the picture) • The totallyquenchedcoileats 40% of the budget • The onlyway to improvethis aspect is to add more copper

  20. THE INNER TRIPLET: THE Nb3SN OPTION MQXF • Choice of the cable: ~0.85 mm diameterstrand, 40 strands • For the 140 mm • 2% percent more margin on loadline • 20% more margin on detection time • Same stress as HQ • For 150 mm 0.85 or 0.9 mm strandis marginal • 1% percent difference in margin • 20% more margin on detection time • 5 MPaless • Disadvantages of largerstrand • Larger filament • Self fieldinstabilities

  21. THE INNER TRIPLET: THE Nb3SN OPTION MQXF • First planning withsharebetween CERN and LARP [P. Fessia, G. L. Sabbi] • Conceptual design endedwith 2012, • Tooling and structure in 2013, first half 2014 • 12 coilswound in 2014 and first half 2015, • two structures, twomagnets, three test in mid 2015

  22. THE INNER TRIPLET: THE Nb3SN OPTION MQXF - DESIGN • First design of cold mass accounting for cooling and stainlesssteel He vessel[P. Ferracin] HQ cross-section MQXF 140 mm cross-section (samescale)

  23. CONTENTS • Inner triplet quadrupoles • Layouts • Where are wetoday? • HQ test [LARP collaboration, S. Caspi and G. Sabbi] • MQXC assembly[CERN, G. Kirby] • The 140 mm option • Somehighlights on the othermagnets • Separationdipole D1 [KEK, Q. Xu, T. Nakamoto, A. Yamamoto] • Two-in-one quadrupole MQZ [CEA, M. Segreti, J. M. Rifflet] • Future steps, decisions and open issues www.cern.ch/hilumi/wp3

  24. THE SEPARATION DIPOLE • Main guidelines [talk by T. Nakamoto, Q. Xu, A. Yamamoto] • Aperture 10 mm largerthanquadrupole • Nb-Ti conductor • Large aperture  large stress  thick coil to reduce stress • 2 layer 15 mm cable as in the LHC dipoles • Heavy radiation  larger margin  30% on the loadline • Operational field of 6.3 T • 40 Tm needed length of 6-7 m • As in the triplet, fieldquality criticalonlyat 7 TeV • Problem: LHC cable not enough long for 150 mm case D1 150 mm aperture cross-section [Q. Xu, T. Nakamoto, A. Yamamoto]

  25. THE SEPARATION DIPOLE • Fringefield • Fringefieldis large (~0.15 T on th cryostat) – but no specavailable • Methods to compensate • Largerironyoke (cost, doubles the weight) • Thicker cryostat (from 10 to 60 mm) • Correction coils(5-10 turnsneeded) D1 in the cryostat [Q. Xu, T. Nakamoto, A. Yamamoto] Fringefield on the cryostat versus turns of correctingcoil [Q. Xu, T. Nakamoto, A. Yamamoto]

  26. THE MATCHING SECTION QUARUPOLE • Two-in-one quadrupolereplacing Q4 [talk by M. Segreti] • Larger aperture: from 70 mm today to 85-90 mm • Guidelines • Nb-Ti • Strength not critical one can makeit longer (thincoil) • Reduce as much as possible magneticcoupling • Main issue • Magneticfieldqualityb3at 7 TeV • Ironissaturated, aperture are close, cross-talk difficult to avoid A possible Q4 cross-section [M. Segreti, J. M. Rifflet]

  27. STRATEGY AND NEXT DEADLINES • Decidenow the cable for 140/150 mm • Wait for a first estimate of energydeposition (June) to choose aperture • Shielding for the coil, and final performance • Heatloads, energymap for the cooling conditions • Poweringschemeand protection estimates for final layou-outs • Estimate of vacuum conditions • Is it possible to have no beamscreen? • Specs on b6at injection for the triplet comingsoon • Impact on filament size • Providefieldqualityestimatesto WP2 to have a guess of correctors

  28. THE INNER TRIPLET: TENTATIVE SUMMARY OF HQ RESULTS • Performance • The additionalperformance given by 1.9 K isthere(91% reached) • Evenwith54/61conductor ! • But signs of ramp rate effects – heating ? • Magneticmeasurements made at 14 kA, just 4% below nominal • Field quality – magnetis ver close to be OK • Transfer function • Spikes to beunderstood • Large ramp rate effectswithdecay – couldbecured by coredcable - do wenededit ? • Botheffectsnot a showstopperbut shouldbeaddressed • Multipoles: Geometricrather close to target • b6mgnetization of 20 unitsat injection probably not an issue – betterwith 108/127 • Congratulations to the LARP team !

  29. THE INNER TRIPLET: TENTATIVE SUMMARY OF HQ RESULTS • Most emphasis put up to now on • Performance (quench) • Field quality • Very close to targets in both cases • Next challenges • Protection • Cooling • Energydeposition

  30. D1, Q4 and COOOLING - SUMMARY • D1 • Notwithstanding the large aperture, with a lot of coil the stress is as in the LHC dipoles • Length of 6 m, 6 T operationalfield • Fringefieldis an issue • Active correction couldbe an interestingtechnologicaldevelopment • Q4 • Hereweneedverythincoil • Separate as much as possible magnetically the two apertures • Cooling • All steps to betaken to remove the heat in the most effective way • Heatloadsgive a highertemperature on the coil – istemperaturemarginenough ?