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Superconducting Detector Magnets Evolution and Outlook

Superconducting Detector Magnets Evolution and Outlook. Roger Ruber and Akira Yamamoto Uppsala University and KEK. Scope of this Presentation. Chronological Evolution Identify Major Technology Steps Indirect cooling Conductor and Coil manufacturing Review Specific Issues Stability

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Superconducting Detector Magnets Evolution and Outlook

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  1. Superconducting Detector MagnetsEvolution and Outlook Roger Ruber and Akira Yamamoto Uppsala University and KEK

  2. Scope of this Presentation • Chronological Evolution • Identify Major Technology Steps • Indirect cooling • Conductor and Coil manufacturing • Review Specific Issues • Stability • Materials and strength • Protection • Future Directions INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  3. Technology Drivers • Momentum resolution • depends on sagitta term • Transparency • reduction of material in the magnet structure • use low radiation length materials • Detector configuration • determines magnet configuration • Cost & reliability INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  4. Solenoid Magnet • Resolution • inside solenoid: dp/p ~ {B·R2solenoid}-1 • outside solenoid: dp/p ~ {B·Rsolenoid}-1 • Transparency • wall thickness: t ~ (R/σh) • B2/2µ0 • Field & Symmetry • axial and uniform • but field lines parallel to particlepath at small angles • Installation • self supporting structure • iron yoke to contain stray field (improves bending power at small angles) INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  5. q Toroid Magnet • Resolution • inside toroid: dp/p ~ sinθ {Bφ·Rin·ln(Rin/Rout)}-1 • Field & Symmetry • tangential field (1/r) • field lines perpendicular to particle path • closed field: centred on and circulating around beam (no influence on beam) • Installation • support required to keep self balance • no stray field: no iron yoke required INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  6. 8 degrees η = -ln tan(θ/2) ATLAS Toroids (2007) Largest Field Volume • good resolution at small forward angles • self contained 4 T field, volume 7000m3, no yoke • open structure barrel, cryostats occupy ~2% volume 8 coils barrel toroid 2x 8 coils end cap toroid INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  7. Sag28mm Toroid Assembly with Barrel Calorimeter and Solenoid Solenoid End Cap Toroid INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  8. Indirect Cooling Support Banding Series Cooling Circuit Aluminium Stabilised Conductor Mandrel CELLO (CEA, 1978) First Generation • monolithic NbTi/Cu conductor soldered to aluminium stabilizer • indirect cooling • BR2 ~ 1 Tm2 H. Desportes, Adv.Cryo.Eng. 25 (1980) 175 INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  9. Design Requirements • Mechanical Safetycoil thickness µ RB2/ (E/M) µ RB2 γ/σh (γ=density) • E/M (stored energy/cold mass) to be increasedscaling parameter that indicates peak temperature at homogeneous energy dump (E = 0.5µ0∫B∙dV ; E/M=H= ∫CpdT) • σh (hoop stress) to be decreasedsuperconductor to be stronger • Thermal Safetyuniform energy absorption andlow peak temperature at quench to decrease thermal stress • fast quench propagationhigh RRR in stabilizer, or active/passive propagation techniques • energy extraction by external dump INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  10. Indirect Cooling Circuit Welded to Al5083 Cylinder 20mm CDF (Tsukuba Univ/FNAL, 1984) Second Generation • co-extruded monolithic conductor • aluminium alloy support cylinder, shrink-fit • BR2 ~ 3 Tm2 H. Minemura et al., NIM A238 (1985) 18 • First full scale use of co-extruded conductor • High quality bonding between superconductor and pure aluminium • Mechanical: 30MPa > yield strength pure Al • Electrical: allowed conductor joints formed by welding between aluminium sections Shrink fit of coil into force support cylinder INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  11. TOPAZ, VENUS (KEK, 1984) • direct internal winding, without mandrel • kapton based insulation VENUS: M. Wake et al., IEEE MAG-21 (1985) 494 TOPAZ: A. Yamamoto et al., JAPL 25 (1986) 1440 TOPAZ features:Insulation and bondingby B-stage epoxy on conductor + GFRP-Kapton on support cylinder • VENUS features: • CFRP vacuum vessel • Force support cylinder formed from extrusion sections – welded in situ INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  12. 35mm ALEPH (CEA, 1987) Third Generation • parallel cooling circuits, thermo-siphon cooling • BR2 ~ 10 Tm2 J.M. Baze et al., IEEE MAG 24 (1988) 126. INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  13. CMS (CEA/CERN/INFN, 2006): Fourth Generation • EM Calorimeter inside solenoid → thin wall not a goal! • 4 layers reinforced conductor • hybrid conductor: pure-Al/A6082 • BR2 ~ 40 Tm2 • Conductor • Pure Al + high strength alloy • YS > 250MPa @ 4K • RRR 1400 400 m3 D. Campi et al., IEEE TASC17-2 (2007) 1185 INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  14. 67 < 2/3 < ６７ ４５ ATLAS Central Solenoid (KEK, 2006) • thin solenoid, fully integrated with LAr calorimeter cryostat • high strength pure aluminium stabilizer • Al-strip quench propagator A. Yamamoto at al., NIM A584 (2008) 53 INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  15. Al Al ATLAS-CS Al3Ni 1µm High Strength Conductor Development • 0.1-2% Ni micro-alloying + 15-20% cold-work hardening Al3Ni precipitated contributes as structural component Pure-Al region keeps low resistivity Peak temperature after a full energy dump is less sensitive to RRR for RRR > 100. INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  16. NbTi/Cu SC 3.4mm Al-Ni alloy BESS Polar (KEK, 2005) • thinnest solenoid, no support cylinder! • wall thickness 1gm/cm2 ~ 0.05X0 A. Yamamoto et al., IEEE TASC12-1 (2002) 438 INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  17. BESS Polar: How Thin is Thin? thickness/diameter ~ 0.2% coil thickness/diameter ~ 0.34% INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  18. SiD Conceptual Design: Future ILC/CLIC Detectors all proposals require • large scale field & volume:BR2 > 35 Tm2 • huge energy: 1.5 ~ 2 GJ SiD proposal requires: • 4~6 layer coil • high strength conductor • integrated dipole magnet 4th ILC Proposal: • double solenoid with end disk! R. Smith et al., IEEE TASC 16-2 (2006) 489 INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  19. Future Technologies Strong conductors • for large field and thin-walled magnets Magnet protection • to prevent high peak temperatures during full energy dump good for physics difficult winding processMOI=moment of inertia magnet safety INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  20. H = E/M = ∫ Cp dt 5,10,20 Thermal Expansion 65, 80, 100 80 120 Temperature [K] E/M: A Scaling Factor for Coil Design Stored energy increased ~300x from CELLO to CMS • Large field volume + transparent coils • leads to increased E/M ratio = enthalpy: CMS 12kJ/kg = 85K mean temperature after homogeneous energy dump • Design aim • peak temperature <120K → differential stress < 30MPa INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  21. Status Aluminium Stabilized Conductor INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  22. Future Development of Stabilized Superconductor Combine ATLAS and CMS technology for high strength stabilizer: ATLAS high strength stabilizer Ni-0.5 ~ 1 % CMS hybrid support A6058 → A7020 Yield strength (0.2%) = 400 MPa RRR ~ 400 S. Sgobba et al., IEEE TASC 16-2 (2006) 521 INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  23. Summary and Outlook Indirect cooling + aluminium based conductor step made for CELLO has seen huge developments in all aspects of the technology: • Scale • Field volume ~700x for ATLAS • Stored energy ~ 300x for CMS • Conductors • advances in scale and strength • Coil winding and assembly • technology: materials(impregnation – bonding) • engineering: scale + accuracy Present state of the art can give 5 T.R&D efforts ongoing for Al-stabilized Nb3Sn/Nb3Al cables and solenoid beyond 10 T INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

  24. Acknowledgements Many thanks for contribution of material and advice Elwyn Baynham (RAL) Yasuhiro Makida (KEK) INSTR08: Roger Ruber - Superconducting Detector Magnets, Evolution and Outlook

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