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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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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 2
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 3
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”
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 4
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 5
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 6
Overview of LARP Magnets
SQSM TQS
LR
LQS
HQTQC
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 7
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 8
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 9
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 10
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 11
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)
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 12
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 13
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 14
• 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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 15
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:
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 16
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)
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 17
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 18
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 19
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
ASC 2012 Nb3Sn IR Quadrupoles for HL-LHC – G. Sabbi 20
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: