asc 2012nb 3 sn ir quadrupoles for hl-lhc – g. sabbi 1 nb 3 sn ir quadrupoles for hl-lhc gianluca...

ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 1

Nb3Sn IR Quadrupoles for HL-LHC

GianLuca Sabbi

for the LARP – HiLumi LHC Collaboration

2012 Applied Superconductivity Conference


M. Anerella, J. Cozzolino, J. Escallier, A.K. Ghosh, J. Muratore, S. Peggs, J. Schmalzle, P. Wanderer

H. Bajas, M. Bajko, L. Bottura, G. DeRijk, O. Dunkel, P. Ferracin, J. Feuvrier, L. Fiscarelli, C. Giloux, J. Perez, L. Rossi, S. Russenschuck, E. Todesco

G. Ambrosio, N. Andreev, E. Barzi, R. Bossert, J. DiMarco, G. Chlachidze, F. Nobrega, I. Novitski, V. Kashikhin, J. Kerby, M. Lamm, P. Limon, D. Orris, E. Prebys, M. Tartaglia, D. Turrioni, G. Velev, M. Whitson, R. Yamada, M. Yu, A. Zlobin

S. Caspi, D.W. Cheng, D.R. Dietderich, H. Felice, A. Godeke, S. Gourlay A.R. Hafalia, R. Hannaford, J.M. Joseph, A.F. Lietzke, J. Lizarazo, M. Marchevsky, G. Sabbi, A. Salehi; T. Salmi, R. Scanlan, X. Wang

Contributions


1. Program motivation and goals2. Overview of LARP magnet R&D3. Main achievements to date4. Outstanding technical issues5. Prototype design and development plans

Presentation Outline

Related presentations at ASC 2012:

•G. Ambrosio et al., “Test results and analysis of Long Nb3Sn Quadrupole Series by LARP”

•H. Bajas et al., “Cold Test Results of the LARP HQ01e Nb3Sn quadrupole magnet at 1.9 K”

•D. Cheng et al., “Evaluation of insulating coatings for wind-and-react coil fabrication”

•G. Chlachidze et al., “Test of optimized LARP Nb3Sn quadrupole coil using magnetic mirror structure”

•A. Ghosh “Perspective on Nb3Sn Conductor for the LHC Upgrade Magnets”

•A. Godeke et al., “Review of Conductor Performance for the LARP High-Gradient Quadrupole Magnets”

•E. Todesco et al., “Design studies of NbTi and Nb3Sn Low-β Quadrupoles for the High Luminosity LHC”

•X. Wang et al., “A system for high-field accelerator magnet field quality measurements”


High Luminosity LHC

Physics goals:

• Improve measurements of new phenomena seen at the LHC• Detect/search low rate phenomena inaccessible at nominal LHC• Increase mass range for discovery

Required accelerator upgrades include new IR magnets:

• Directly increase luminosity through stronger focusing decrease *• Provide design options for overall system optimization/integration collimation, optics, vacuum, cryogenics• Be compatible with high luminosity operation Radiation lifetime, thermal margins

Figure of merit is integrated luminosity, with a target of 3000 fb-1


LARP Magnet Program

Goal: Develop Nb3Sn quadrupoles for the LHC luminosity upgrade

Potential to operate at higher field and larger temperature margin

R&D phases:

• 2005-2010: technology development: conductor, coil, structure • 2007-2012: length scale-up from 1 to 4 meters• 2009-2014: incorporation of accelerator quality features

Program achievements to date:

• TQ models (90 mm aperture, 1 m length) reached 240 T/m gradient• LQ models (90 mm aperture, 4 m length) reached 220 T/m gradient• HQ models (120 mm aperture, 1 m length) reached 184 T/m gradient

Current activities:

• Completion of LQ program to extend TQ results to long models • Optimization of HQ, fabrication of LHQ coils and test in mirror • Design and planning of the MQXF IR Quadrupole development


Overview of LARP Magnets

SQSM TQS

LR

LQS

HQTQC


Sub-scale Quadrupoles (SQ)

• Four “SM” racetrack coils• 130 mm bore, length 30 cm

Achieved 97% of SSL at 4.5K & 1.9K

-Validated conductor for TQ01 models -First shell-based quadrupole structure -Verification/optimization of FEA models-Quench propagation/protection studies

CC


Long Racetracks (LR)

SG1 SG2 SG3 SG4 SG5 SG6

• Scale up of “SM” coil and structure: 30 cm to 4 m• Coil R&D: first successful length scale-up• Structure R&D: friction effects, magnet assembly• Achieved 11.5 T, 96% of short sample limit

S1

S2

S3

S4

LRS01b: segmented shell

LRS01a: single shell

P. Ferracin, J. Muratore et al., IEEE Trans. Appl. Supercond. Vol: 18 (2), 2008, pp. 167-170


Technology Quadrupoles (TQ)

• Double-layer, shell-type coil

• 90 mm aperture, 1 m length

• Two support structures:

- TQS (shell based)- TQC (collar based)

• Target gradient 200 T/m

TQC TQS

• Three coil series using different wire design

MJR 54/61; RRP 54/61; RRP 108/127

• More than 30 coils fabricated

• Distributed coil production line

• 15 magnet tests in different configurations

• Two models assembled and tested at CERN


TQ Highlights

Quench performance

•Maximum gradient 240 T/m•20% above target•No retraining

Stress limits

• TQS03a: 120 MPa at pole, 93% SSL• TQS03b: 160 MPa at pole, 91% SSL• TQS03c: 200 MPa at pole, 88% SSL• Peak stresses are considerably higher• Considerably widens design window

Cycling test

•1000 cycles •No change in mechanical parameters•No change in quench levels


Long Quadrupole (LQ)

S1(2)

D1(1)

S2(4)

S3(2)

S4(2)

D2(4)

D3(1)

• TQ length scale-up from 1 m to 4 m• Three series of coils • All models reached 200 T/m target• Recent results and next steps in:

G. Ambrosio et al.4LA-01 (Thursday AM)


High-Field Quadrupole (HQ)

R&D goals:

• Explore “new territory” in energy and force levels (~3xTQ)• Incorporate field quality and full alignment

Main parameters:

• 120 mm aperture, 15 T peak field at 220 T/m (1.9K)• Coil stresses approaching 200 MPa (if pre-loaded for SSL)

Aluminum collar

Bladder location

Aluminum shellMaster key

Loading keys

Yoke-shell alignment

Pole alignment key

Quench heater

Coil


R&D issues – Strain during Coil Reaction

• Results from first HQ models indicated conductor damage in several coils• Traced to excessive strain during the coil reaction phase:

No/insufficient gaps in pole segments to limit longitudinal strain Design/tooling did not include space for azimuthal cable expansion

G. Chlachidze et al., 4LA-03 (Thursday AM)

• HQ02: restored pole gaps and reduced cable size with smaller strand diameter• First coil successfully tested in mirror structure:

• All process improvements incorporated in HQ03 and the Long HQ Coils

Coil spring-back from tooling

“Inverted”ramp-rate

dependencein HQ01a-c


• Large number of insulation failures in coils, coil to parts and coil to heaters• Catastrophic failure in HQ01b test due to inter-layer short through end shoe

Remediation steps:

• Redesigned end parts to improve fit, eliminate high pressure areas • Application of insulating coatings to coil parts:• Improved winding procedures and QA• Redesigned quench heaters to minimize crossings above metallic parts• Increased insulation between coil layers and between coil and heaters• Enhanced electrical QA during coil and magnet fabrication (impulse testing)

R&D issues – Electrical Integrity

D. Cheng et al., 4MA-08Thursday AM


In previous phases of the program, conductor has been adequate to meet the key R&D goals of the model magnets:

• RRP 54/61 for SQ, LR, and 1st generation TQ/LQ/HQ/HQM models Enabled the 2009 milestone of >200 T/m in TQ and LQ

• RRP 108/127 for TQS03, LQS03, HQ/HQM, and LHQ Very good results in TQS03, but lower performance in HQ/HQM and

LQ Limitations observed in current density, stability (RRR), piece length

•Conductor improvements are required for a successful construction project•Several developments are underway, but time window is limited

Increase and control Jc, RRR, piece length in RRP 108/127 Develop/demonstrate possible alternatives (PIT, higher stack RRP) Scale-up to larger billets for faster production an lower cost

R&D Issues – Conductor and Cable

A. Ghosh, paper 2SLE-06 (this session) A. Godeke et al., 4JA-07 (Thursday AM)

See presentations by:


HQ Highlights – Field Quality

Discussion of magnetic measurement system by X. Wang et al., 4JE-04 (Thursday PM)

• Geometric harmonics show good coil uniformity and structure alignment• Persistent current effects are large but within limits set by design study• Large dynamic effects indicate need to better control inter-strand resistance

Cored cables incorporated in second generation coils

Eddy current harmonics for different ramp rates

1.E-03

1.E-02

1.E-01

1.E+00

1 2 3 4 5 6 7 8 9 10

harm

onics

σ

(uni

ts)

Harmonic order

fit

normal

skew

12 kA, R.ref = 21.55 mm

Block positioning error ~29.6 µm.

Analysis of geometric accuracy from random errors

Rc fit 0.2–3.6 µΩ (LHC target: ~20 µΩ)


HQ Highlights – Quench Performance

Latest results from CERN test of HQ01e at 1.9K: H. Bajas, 4LA-02 (Thursday AM)

• Achieved 184 T/m at 1.9K (85% of SSL) – well above performance target However, high rate of coil failures (excessive strain and insulation weakness) • Flux jump effects appear less severe at 1.9K (5-10 times smaller amplitude)• Quench protection studies: energy extraction delay, then removal of IL

heaters

No quench


IR Quadrupole Design Specification

- An aperture increase to 150 mm is expected to result in best overall performance- Requires another significant step in energy & force levels with respect to 120 mm

HigherField

Larger Aperture(same/lower gradient)

Thicker absorbers

More Operating Margin(at same gradient / aperture)

Longer Lifetime

Lower radiation and heat loads

Better Field Quality

Stronger focusing

Higher Gradient(same/lower aperture)

Shorter magnets

Higher T margin

Better IR layout

Stable operation

Easier cooling

More Design Margin(same gradient / aperture) Lower risk

Faster developmentLess cost & timefor small production

Max. luminosity


Next Phase: IR Quadrupole Prototype

Preliminary layout of HL-LHC final focus using 150 mm bore 140 T/m quadrupoles:

Prototype design status:

•Increased cable size to facilitate coil stress management and quench protection Cable R&D underway targeting 18.5 mm width, 1.50 mm mid-thickness,

0.65 deg. keystone angle (D. Dietderich) Strand diameter from 0.778 mm (HQ) to 0.85 mm to limit aspect ratio

•Electrical integrity: increase of cable insulation thickness from 0.1 to 0.15 mm•Preliminary cross-sections were developed for evaluation

•Latest developments presented in: E. Todesco et al., 4LA-05 (Thursday AM)

6.77 m2 x 3.99 m 6.77 m 2 x 3.99 m

R. De Maria et al,HiLumi meeting, 7/26/12


Summary

• A large knowledge base is available after 7 years of fully integrated effort involving three US Labs and CERN

Steady progress in understanding and addressing R&D issues that were perceived as potential show stoppers: conductor performance, mechanical support, degradation due to stress and cycling, length scale-up, coil/structure alignment, field quality, quench protection

• Remaining challenges include: control of dynamic effects, electrical integrity, process documentation and QA, incorporation of rad-hard epoxies, development and selection of production-class conductors

• Next few years will be critical and much work is still left to doIntegrating LARP effort with CERN, US core programs, EuCARD

• HL-LHC IR Quads are a key step for future high-field applications

Acknowledgement:

asc 2012nb 3 sn ir quadrupoles for hl-lhc – g. sabbi 1 nb 3 sn ir quadrupoles for hl-lhc gianluca...

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