11 T Dipole Experience

M. Karppinen CERN TE-MSCOn 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 o 2 MB => 4 x 5.5 m CM + spares

LS3 : IR-1,5 and Point-3,7o 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 Nb3Sn0.8 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

M. Karppinen CERN TE-MSC

Mechanical Design Concepts

14 February 2014

CERN FNAL

Pole loading design Integrated pole design

Pole wedge

Shim

Fillerwedge

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

M. Karppinen CERN TE-MSC

CERN 11 T Dipole Coil

14 February 2014

Loading plate2 mm 316LN

SLS (Selective Laser Sintering) End Spacerswith “springy legs”

Braided 11-TEX S2-glasson “open-C” Mica sleeve

ODS (Oxide Dispersion Strengthened) Cu-alloy Wedges

Cou

rtesy

of

D. M

itch

ell,

FN

AL

OST RRP-108/127

14.85

Ø0.7

M. Karppinen CERN TE-MSC

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

A.V. Zlobin et al., ASC2012, Sept 2012

Quench history

Ramp rate dependence

M. Karppinen CERN TE-MSC

FNAL 1 m single aperture model #2

RRP-150/169 strand, 25 µm SS core

Improved quench performanceo 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 addressedo Long trainingo Steady state B0 = 10.5..10.7 T

@1.9Ko Origin of conductor degradation

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

MBHSP02 Quench Performance

14 February 2014

Magnet training

Ramp rate dependence

Courtesy of G. Chlachidze, FNAL

M. Karppinen CERN TE-MSC

MBHSM01 Mirror Magnet

14 February 2014

MBHSM01 Quench Training

M. Karppinen CERN TE-MSC14 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 K1.9 K

Courtesy of G. Chlachidze, FNAL

M. Karppinen CERN TE-MSC

Lessons: Coil Parts Nb3Sn Rutherford cable

o Stainless steel core reduces eddy current effectso Limited compaction reduces mechanical stabilityo Winding tooling and process developmento Braiding S2-glass over Mica-sleeve works well

End partso SLS cost effective, flexible, and fast way of producing

fully functional partso 3-5 iterations required to get the shapes right, all

manual modifications shall be minimisedo 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 geometry14 February 2014

M. Karppinen CERN TE-MSC

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

o Modular tooling for easy scale-upo Understand (= measure) coil dimensional changeso Tight manufacturing tolerances require high

precision quality controlo Material selection and heat treatments (reaction

tool) o First design the impregnation tool then reaction

tool Coil inspection:

o E-modulus risky to measureo High modulus (wrt. Nb-Ti) means tight tolerances

and require accurate dimensional control with CMMo Assembly parameter definition based on CMM data

can be tricky..

Lessons: Coil Fabrication

14 February 2014

M. Karppinen CERN TE-MSC

To Develop: Heaters & Splicing

Outer layer heaterso Heaters and V-tap wiring integrated in polymide

sandwich (“trace”) made as PCBo may not be enough to guarantee safe operation

with redundancyo Inner layer “trace” difficult to bond reliably

Inter-layer heaterso Very efficient heat transfer to coilso Reaction resistant glass-Mica-St.St-Mica-glass

sandwicho “Conventional” heaters with I-L splice

Inter-layer splice (within the coil i.e. high field)o Bring inner layer lead radially out and spliceo Nb3Sn bridge (MSUT concept)o HTS bridge

14 February 2014