11 T Dipole Experience

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-3,7

o 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


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


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

Cour

tesy

of D

. Mitc

hell,

FNA

L

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

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 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


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 KSSL at 1.9 K

4.5 K 4.5 K1.9 K

Courtesy of G. Chlachidze, FNAL


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


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


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 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

Documents

11 T Dipole Experience