11 T Dipole Experience M. Karppinen CERN TE-MSC On behalf of CERN-FNAL project teams The HiLumi LHC Design Study (a sub-system of HL-LHC) is co-funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
11 T Dipole for DS Upgrade Create space for additional collimators by replacing 8.33 T MB with 11 T Nb 3 Sn dipoles compatible with LHC lattice and main systems. MB.B8R/L MB.B11R/L 119 Tm @ 11.85 kA (in series with MB) 11 T Nb 3 Sn LS2 : IR-2 15,66 m (IC to IC plane) o 2 MB => 4 x 5.5 m CM + spares LS3 : IR-1,5 and Point-3,7 0.8 m 5.5 m Nb 3 Sn 5.5 m Nb 3 Sn Collim. o 4 x 4 MB => 32 x 5.5 m CM + spares 180 x 5.5-m-long Nb 3 Sn coils Joint development program between CERN and FNAL underway since Oct-2010. 14 February 2014 M. Karppinen CERN TE-MSC
11 T Dipole Design Features 11.25 T at 11.85 kA with 20% margin at 1.9 K 60 mm bore and straight 5.5-m-long coldmass 6-block coil design, 2 layers, 56 turns (IL 22, OL 34), no internal splice Separate collared coils, 2-in-1 laminated iron yoke with vertical split, welded stainless steel outer shell 14 February 2014 M. Karppinen CERN TE-MSC
11 T Model Dipole Magnetic Parameters � Single-aperture Single-aperture Twin-aperture FNAL CERN Parameter MBHSP01 MBHSP02 60 Aperture (mm) Yoke outer diameter (mm) 400 510 550 Coil length (m) 1.80 0.88 1.8 0.88 - 1.8 - 5.4 Nominal bore field @11.85 kA (T) 10.86 11.07 11.25 11.25 13.6 (1 14.1 (2 13.9 (1 13.9 (1 Short-sample bore field at 1.9 K (T) 0.80 (1 0.78 (2 0.81 (1 0.81 (1 Margin B nom /B max at 1.9 K Stored energy at 11.85 kA (kJ/m) 473 482 484 969 F x per quadrant at 11.85 kA (MN/m) 2.89 3.11 3.16 3.16 F y per quadrant at 11.85 kA (MN/m) -1.57 -1.56 -1.59 -1.59 1) OST� ø 0.7� mm� RRP-108/127� 2) OST� ø 0.7� mm� RRP-150/169� 14 February 2014 M. Karppinen CERN TE-MSC
Mechanical Design Concepts CERN FNAL Coil stress <150 MPa • Loading plate Shim at all times up to 12 T design field Yoke gap closed at RT • and remain closed up to 12 T Filler wedge Pole wedge Pole loading design Integrated pole design 14 February 2014 M. Karppinen CERN TE-MSC
CERN 11 T Dipole Coil Loading plate SLS (Selective Laser 2 mm 316LN Sintering) End Spacers w ith “springy legs” Courtesy of D. Mitchell, FNAL ODS (Oxide Dispersion Strengthened) Cu-alloy Braided 11-TEX S2-glass Wedges on “open - C” Mica sleeve 14.85 Ø0.7 OST RRP-108/127 14 February 2014 M. Karppinen CERN TE-MSC
MBHSP01 Quench Performance A.V. Zlobin et al., ASC2012, Sept 2012 FNAL 2 m single-aperture model #1 RRP-108/127 strand, no core B max =10.4 T at 1.9 K and 50 A/s (78% of SSL) long training irregular ramp rate Quench history dependence Conductor degradation in coil OL mid-plane blocks and leads lead damage during reaction - confirmed by autopsy Ramp rate dependence 14 February 2014 M. Karppinen CERN TE-MSC
MBHSP02 Quench Performance FNAL 1 m single aperture model #2 Courtesy of G. Chlachidze, FNAL RRP-150/169 strand, 25 µm SS core Improved quench performance o B max = 11.7 T – 97.5% of design field B=12 T (78% of SSL at 1.9 K) Field quality meets the present Magnet training requirements Issues to be addressed o Long training o Steady state B 0 = 10.5..10.7 T @1.9K o Origin of conductor degradation in OL mid-plane blocks in coil fabrication or assembly process? Ramp rate dependence 14 February 2014 M. Karppinen CERN TE-MSC
MBHSM01 Mirror Magnet 14 February 2014 M. Karppinen CERN TE-MSC
MBHSM01 Quench Training Highest quench current at 4.5 K: 12.9 kA (92-100) % of SSL at 1.9 K: 14.1 kA (89-97) % of SSL About 4% degradation observed at 4.5 K after the 1.9 K training SSL at 1.9 K SSL at 4.5 K 4.5 K 1.9 K 4.5 K Courtesy of G. Chlachidze, FNAL M. Karppinen CERN TE-MSC 14 February 2014
Lessons: Coil Parts Nb 3 Sn Rutherford cable o Stainless steel core reduces eddy current effects o Limited compaction reduces mechanical stability o Winding tooling and process development o Braiding S2-glass over Mica-sleeve works well End parts o SLS cost effective, flexible, and fast way of producing fully functional parts o 3-5 iterations required to get the shapes right, all manual modifications shall be minimised o Rigid metallic parts need features to make the “legs” flexible (“springy legs”, “ accordeon ”,..) o Dielectric coatings to develop: reactor paint, sputtering, plasma coating, .. o Epoxy-glass saddles (electrical insulation, softer for cable tails/splice, axial loading) ODS wedges to minimise plastic deformation and distortion of the coil geometry 14 February 2014 M. Karppinen CERN TE-MSC
Lessons: Coil Fabrication Min 3 Practice coils: Cu-cable, 2 X Nb3Sn Mirror test to qualify coil technology Tooling design o Modular tooling for easy scale-up o Understand (= measure) coil dimensional changes o Tight manufacturing tolerances require high precision quality control o Material selection and heat treatments (reaction tool) o First design the impregnation tool then reaction tool Coil inspection: o E-modulus risky to measure o High modulus (wrt. Nb-Ti) means tight tolerances and require accurate dimensional control with CMM o Assembly parameter definition based on CMM data can be tricky.. 14 February 2014 M. Karppinen CERN TE-MSC
To Develop: Heaters & Splicing Outer layer heaters o Heaters and V-tap wiring integrated in polymide sandwich (“trace”) made as PCB o may not be enough to guarantee safe operation with redundancy o Inner layer “trace” difficult to bond reliably Inter-layer heaters o Very efficient heat transfer to coils o Reaction resistant glass-Mica-St.St-Mica-glass sandwich o “Conventional” heaters with I -L splice Inter-layer splice (within the coil i.e. high field) o Bring inner layer lead radially out and splice o Nb 3 Sn bridge (MSUT concept) o HTS bridge 14 February 2014 M. Karppinen CERN TE-MSC
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