11 T Dipole Experience M. Karppinen CERN TE-MSC On behalf of - - PowerPoint PPT Presentation

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 Nb3Sn

11 T Dipole for DS Upgrade

 Create space for additional collimators by replacing 8.33 T MB with 11 T Nb3Sn dipoles compatible with LHC lattice and main systems.  119 Tm @ 11.85 kA (in series with MB)  LS2 : IR-2

• 2 MB => 4 x 5.5 m CM + spares

 LS3 : IR-1,5 and Point-3,7

• 4 x 4 MB => 32 x 5.5 m CM + spares

 180 x 5.5-m-long Nb3Sn coils

• M. Karppinen CERN TE-MSC

 Joint development program between CERN and FNAL underway since Oct-2010.

MB.B8R/L MB.B11R/L

5.5 m Nb3Sn 5.5 m Nb3Sn

0.8 m Collim.

15,66 m (IC to IC plane)

14 February 2014

11 T Dipole Design Features

14 February 2014

• M. Karppinen CERN TE-MSC

 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

11 T Model Dipole Magnetic Parameters

14 February 2014

• M. Karppinen CERN TE-MSC
• Parameter

Single-aperture FNAL Single-aperture CERN Twin-aperture

MBHSP01 MBHSP02

Aperture (mm) 60 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 Short-sample bore field at 1.9 K (T) 13.6 (1 14.1(2 13.9(1 13.9(1 Margin Bnom/Bmax at 1.9 K 0.80(1 0.78(2 0.81(1 0.81(1 Stored energy at 11.85 kA (kJ/m) 473 482 484 969 Fx per quadrant at 11.85 kA (MN/m) 2.89 3.11 3.16 3.16 Fy per quadrant at 11.85 kA (MN/m)

• 1.57
• 1.56
• 1.59
• 1.59

1) OST ø0.7 mm RRP-108/127 2) OST ø0.7 mm RRP-150/169

Mechanical Design Concepts

14 February 2014

• M. Karppinen CERN TE-MSC

CERN

FNAL

Pole loading design Integrated pole design

Pole wedge Shim Filler wedge Loading plate

• Coil stress <150 MPa

at all times up to 12 T design field

• Yoke gap closed at RT

and remain closed up to 12 T

CERN 11 T Dipole Coil

14 February 2014

• M. Karppinen CERN TE-MSC

Loading plate 2 mm 316LN SLS (Selective Laser Sintering) End Spacers with “springy legs” Braided 11-TEX S2-glass

• n “open-C” Mica sleeve

ODS (Oxide Dispersion Strengthened) Cu-alloy Wedges

Courtesy of D. Mitchell, FNAL

OST RRP-108/127

14.85 Ø0.7

 FNAL 2 m single-aperture model #1  RRP-108/127 strand, no core  Bmax=10.4 T at 1.9 K and 50 A/s (78% of SSL)  long training  irregular ramp rate dependence  Conductor degradation in coil OL mid-plane blocks and leads  lead damage during reaction - confirmed by autopsy

MBHSP01 Quench Performance

14 February 2014

• M. Karppinen CERN TE-MSC

A.V. Zlobin et al., ASC2012, Sept 2012 Quench history Ramp rate dependence

 FNAL 1 m single aperture model #2  RRP-150/169 strand, 25 µm SS core  Improved quench performance

• Bmax= 11.7 T – 97.5% of design field

B=12 T (78% of SSL at 1.9 K)

 Field quality meets the present requirements  Issues to be addressed

• Long training
• Steady state B0 = 10.5..10.7 T @1.9K
• Origin of conductor degradation in

OL mid-plane blocks in coil fabrication or assembly process?

MBHSP02 Quench Performance

14 February 2014

• M. Karppinen CERN TE-MSC

Magnet training Ramp rate dependence

Courtesy of G. Chlachidze, FNAL

MBHSM01 Mirror Magnet

• M. Karppinen CERN TE-MSC

14 February 2014

MBHSM01 Quench Training

• M. Karppinen CERN TE-MSC

14 February 2014

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 4.5 K SSL at 1.9 K 4.5 K 4.5 K 1.9 K

Courtesy of G. Chlachidze, FNAL

Lessons: Coil Parts

 Nb3Sn Rutherford cable

• Stainless steel core reduces eddy current effects
• Limited compaction reduces mechanical stability
• Winding tooling and process development
• Braiding S2-glass over Mica-sleeve works well

 End parts

• SLS cost effective, flexible, and fast way of producing

fully functional parts

• 3-5 iterations required to get the shapes right, all

manual modifications shall be minimised

• Rigid metallic parts need features to make the “legs”

flexible (“springy legs”, “accordeon”,..)

• Dielectric coatings to develop: reactor paint,

sputtering, plasma coating, ..

• Epoxy-glass saddles (electrical insulation, softer for

cable tails/splice, axial loading)  ODS wedges to minimise plastic deformation and distortion of the coil geometry

• M. Karppinen CERN TE-MSC

14 February 2014

 Min 3 Practice coils: Cu-cable, 2 X Nb3Sn  Mirror test to qualify coil technology  Tooling design

• Modular tooling for easy scale-up
• Understand (= measure) coil dimensional changes
• Tight manufacturing tolerances require high precision

quality control

• Material selection and heat treatments (reaction tool)
• First design the impregnation tool then reaction tool

 Coil inspection:

• E-modulus risky to measure
• High modulus (wrt. Nb-Ti) means tight tolerances and

require accurate dimensional control with CMM

• Assembly parameter definition based on CMM data can

be tricky..

Lessons: Coil Fabrication

• M. Karppinen CERN TE-MSC

14 February 2014

To Develop: Heaters & Splicing

 Outer layer heaters

• Heaters and V-tap wiring integrated in polymide

sandwich (“trace”) made as PCB

• may not be enough to guarantee safe operation

with redundancy

• Inner layer “trace” difficult to bond reliably

 Inter-layer heaters

• Very efficient heat transfer to coils
• Reaction resistant glass-Mica-St.St-Mica-glass

sandwich

• “Conventional” heaters with I-L splice

 Inter-layer splice (within the coil i.e. high field)

• Bring inner layer lead radially out and splice
• Nb3Sn bridge (MSUT concept)
• HTS bridge
• M. Karppinen CERN TE-MSC

14 February 2014