Magnet Systems Overview

LARP CM17, 11/16/2011 Magnet Systems Overview – G. Sabbi 1

Magnet Systems Overview

GianLuca Sabbi

LARP Collaboration Meeting 17

November 16, 2011

BNL - FNAL - LBNL - SLAC


LARP Magnet R&D Program

Goal: Develop Nb3Sn quadrupoles for the LHC luminosity upgrade

Potential to operate at higher field and/or larger temperature margin

R&D phases:

• 2004-2009: technology development using the SQ and TQ models• 2006-2012: length scale-up to 4 meters using the LR and LQ models• 2008-2014: incorporation of accelerator quality features in HQ/LHQ

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 170 T/m gradient

Current activities:

• Completion of LQ program: assembly and test of LQS03 • Optimization of HQ models: accelerator quality, process control• Engineering design and tooling/parts procurement for LHQ


Program Organization

WBS Description CoordinatorBNL FNAL LBNL

2.1 Design Studies Sabbi2.1.5.1 Hi-Lumi DS Wanderer Ambrosio Sabbi

2.2 Model Quadrupoles Sabbi2.2.2.2 Coil fabrication and instrumentation traces Schmalzle Bossert Hafalia2.2.2.5 Mechanical structure and assembly Anerella Bossert Felice2.2.2.6 Quench protection and test Chlachidze Martchevskii

2.3 Long Quadrupoles Ambrosio2.3.4 LQ

2.3.4.1 Coil & Collar Fab. (FNAL) Nobrega2.3.4.2 Coil Fab. (BNL) Schmalzle2.3.4.3 Shell fab. Felice2.3.4.4 Instruments & Quench Prot. Martchevskii2.3.4.5 Test Prep & Tests Chlachidze2.3.5 LHQ

2.3.5.2 Coil fabrication and instrumentation traces Schmalzle Bossert2.3.5.4 Mechanical structure and assembly Felice

2.4 Materials Ghosh2.4.1.1 Conductor qualification Ghosh Godeke2.4.1.2 Cable design and fabrication Dietderich2.4.1.3 Conductor procurement Ghosh Yamada Dietderich

Task Leader


Program Components

Long QuadrupoleLQS3.7 m long90 mm bore

Long High-Field Quadrupole (LHQ)120 mm bore – Length TBD (3.5-4.5m)

Long QuadrupoleLQS3.7 m long90 mm bore

Long High-Field Quadrupole (LHQ)120 mm bore – Length TBD (3.5-4.5m)

SM

TQS

HQ

LR

LQS

LHQ

• Racetrack coils, shell based structure• Technology R&D in simple geometry• Length scale up from 0.3 m to 4 m

• Cos2 coils with 90 mm aperture • Incorporation of more complex layout• Length scale up from 1 m to 4 m

• Cos2 coils with 120 mm aperture• Explore force/stress/energy limits• Address accelerator quality requirements

Reported by G. Chlachidze in PM session


High-Field Quadrupole (HQ) Design

• 120 mm aperture, coil peak field of 15.1 T at 219 T/m (1.9K SSL)• 190 MPa coil stress at SSL (150 MPa if preloaded for 180 T/m) • Stress minimization is primary goal at all design steps (from x-section) • Coil and yoke designed for small geometric and saturation harmonics• Full alignment during coil fabrication, magnet assembly and powering

Aluminum collar

Bladder location

Aluminum shellMaster key

Loading keys

Yoke-shell alignment

Pole alignment key

Quench heater

Coil


Contributions to the HQ Development

• Cable design and fabrication LBNL• Magnetic design & analysis FNAL, LBNL• Mechanical design & analysis LBNL• Coil parts design and procurement FNAL• Instrumentation & quench protection LBNL• Winding and curing tooling design LBNL, FNAL• Reaction and potting tooling design BNL• Coil winding and curing LBNL, (CERN)• Coil reaction and potting BNL, LBNL, (CERN)• Coil handling and shipping tooling BNL• Structures (quadrupole & mirror) LBNL, FNAL, BNL• Assembly (quadrupole & mirror) LBNL, FNAL, (BNL, CERN)• Magnet test LBNL, FNAL, (CERN)• Accelerator Integration BNL, LBNL, FNAL, (CERN)


HQ Timeline, Issues and Progress

2008 July Selection of 120 mm quadrupole aperture for Phase 1Nov. HQ design completed (cable, coil/tooling, structure)

2009 June Started winding of first coil

2010 May HQ01a test: reached 155 T/m @4.5K (~80%)June HQ01b test: coil damage due to inter-layer short Oct. HQ01c test: insulation OK, limited to 135 T/m by one coil Nov. Discovered broken strands in coil #10 after reactionDec. Started design iteration and fabrication of special coils

2011 Apr. HQ01d test: reached 170 T/m (86%) by coil selection/QAMay HQM01: promising results with lower compaction in coil 12June New cable and coil design approved for lower compaction July HQ01e test: confirms HQ01d, magnetic measurementsSept. HQM02 test: best result to date with coil 13 (one less turn)Oct. Completed first coil with new cable design


HQ01a-e Quench Training

NbTi operating target (120 T/m)


HQ Performance Issues

Time (s)

Extr

actio

n Vo

ltage

(V)

Mechanical issues:

•Ramp rate dependence of first three models is indicative of conductor damage

Electrical issues:

•Large number of insulation failures in coils, in particular inter-layer and coil to parts

HQ01b extraction voltageHQ01a-d Ramp Rate dependence


Coil Analysis Findings

Both mechanical and electrical issues were traced to excessive compaction during the coil reaction phase:

• HQ design assumed less space for inter-turn insulation than TQ/LQ Reaction cavity limits radial & azimuthal expansion

• No/insufficient gaps were included between pole parts to limit longitudinal strain

A detailed analysis will be presented by Helene Felice in the magnet parallel session

Coil spring back in tooling (Over) size measurements of completed coil


Individual Coil Tests in Mirror Structure

Mirror structure allows to test single coils:

Efficient way to study design variations Special coils bring special challenges

Two special coil were fabricated and tested: •#12-HQM01: larger cavity and cored cable•#13-HQM02: standard cavity, one less turn Iron Yoke

Iron Mirror Block

Stainless Skin

G-10 and Kaptonmidplane shims

Horizontal “side shims” are placed here

Side “ear”

• Coil 12 showed some performance limitations, probably related to splice fabrication oversight

• Coil 13: best performing HQ coil to date, at 4.5K and 1.9K, using RRP54/61

• Details will be presented by Rodger Bossert and Guram Chlachidze in PM session

Ramp rate dependence


Design Revisions and Next Steps

Presentations by Dan Dietderich, Helene Felice, Marta Bajko in PM session

Based on the analysis and tests results, the following changes were applied:

•A new cable design was developed using smaller strand diameter (from 0.800 mm to 0.778 mm, to decrease compaction without changes in parts and tooling •Longitudinal gaps were progressively increased and 4mm/m was selected•Some end part modifications to increase insulation layers, avoid sharp points•Increased inter-layer insulation layer thickness to 0.5 mm

Next steps:

•Test of coil 14 (first coil of the new design) in the mirror structure (Dec-Jan)•HQ01e test at CERN: evaluate 1.9K performance and perform independent magnetic measurements (Jan-Feb)•Test of coil 15 (new design and cored cable) in HQ or HQM (Mar-Apr)•A new effort is being organized to understand persisting electrical weaknesses (shorts in coil 14) and apply findings/corrections to both HQ and LHQ


Integration of HQ and LHQ Programs

HQ/LHQ schedule integration was a key discussion topic at the last DOE review

Practice coils

Spare coil test

LHQ01 coils

LQS03 test

HQ coil w new cable tested w mirror

HQ02 w new cable

LHQ

HQ

Will be presented in detail by Giorgio Ambrosio during the magnet parallel session


Accelerator Quality in LARP Models

Design Features LR SQ TQS/LQS TQC HQLHQ

(Goals)

Geometric field quality √ √

Structure alignment √ √ √ √ √

Coil alignment √ √ √

Saturation effects √ √ √

Persistent/eddy currents √

End optimization √ √ √

Cooling channels √ √

Helium containment √ √

Radiation hardness √


Accelerator Quality Requirements

Detailed specifications will be developed by the HL-LHC design study

Preliminary guidance was formulated by CERN in four areas:

Ramp rate: no quench at -150 A/s, starting from 80% of SSL

• Requires control of eddy current losses, particularly in cables

Transfer function: < 1 unit reproducibility in the operating range < 10 units spread for I< Imax/2 & <5 units for I>Imax/2

• Requires control of magnetization and eddy current effects

Persistent currents: injection |b6|<10 units, spread < 10 units

• Requires control of conductor magnetization

Magnetic center: stable during ramp-up within ± 0.04 mm

• Requires control of magnetization and eddy current effects


Current Accelerator Quality Developments

• Structure optimization for alignment, uniform pre-load, minimal training• Field quality measurements and new design features to meet requirements• Structure development oriented toward magnet production and installation • Quench protection, rad-hard epoxy and cooling system studies

PM session: Conductor and cable presentations by Arup Ghosh and Dan Dietderich Production structure and rad-hard epoxy discussion by Peter Wanderer


HQ Structure and Assembly Optimization

• HQ explores stress limits and test results confirm pre-load window is very narrow

• HQ01e: asymmetric loading for better stress uniformity

• Could also be used to optimize geometric field quality


HQ01d-e Magnetic Measurements

• Geometric harmonics are small, indicating good uniformity and alignment• Large persistent current effects indicate need for smaller filament conductors• Large dynamic effects indicate need to better control inter-strand resistance

Geometric and persistent current harmonics Eddy current harmonics for different ramp rates

Detailed presentation by Xiaorong Wang in the magnet parallel session


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

• 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 optimized TQ, LQ, HQ/HQM, and LHQ• Smaller filament size, but needs further development

Accelerator requirements will be a priority in the next phase:

• HQ02: evaluate cored cables for control of dynamic effects• HQM: evaluate coils made with larger RRP stacks and PIT

For construction project, key production issues need to be addressed:

• Improve piece length (cable UL > 1km) and control of Jc, RRR

• Production volume: ~15 tons in a 3-4 year period

LARP Conductor Experience and Needs


Development of smaller filament wires

Work is currently underway to develop wires with smaller Deff

• RRP 169 and 217 stacks under development at OST • PIT (192 tubes) under development by Bruker-AES • Both routes can in principle deliver < 40 m at 0.8 mm

LARP plans – conductor procurement:

• About 20 kg. of RRP 217 wire are currently available• Additional RRP 217 wire is expected from CDP contracts• PIT wire is expected from an exchange with CERN

LARP plans – conductor evaluation:

• Fabricate and characterize HQ cables starting this year• If promising results are obtained, fabricate and test HQ coils


Conductor Jc and RRR vs. TimeE-2004 type high Jc RRP

Sampling of billets produced 2002-2007

no

n-C

u J

c (4

.2 K

), A

/mm

2

0

500

1000

1500

2000

2500

3000

3500

12 T Jc 15 T Jc

12 T

15 T

< Jc >= 2960

< Jc >= 1550

Sampling of billets produced 2002-2007

RR

R

10

100

Residual Resistivity Ratio

Jc (

12T

, 4.2

K)

RRP 54/61: 2002-2007 RRP 108/127: 2008-2011

Both Jc and RRR for 108/127 are significantly lower than for 54/61, and no improvements are

observed for increased production quantity


Conductor Piece Length

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

1 2 3 4 5

Pie

ce L

en

gth

, m

Piece #

10425

10428

10429

10433

12008

12878

12879

13091

• Cable UL for full scale magnets of 120 mm aperture will be ~1 km (considerably higher if aperture is increased to 150 mm)

• Cabling losses are large when strand piece length is comparable to cable UL• After optimization, RRP 54/61 achieved 1-2 pieces per billet (5-10 km

range)• RRP 108/127 is still delivered in relatively short pieces, with min spec 550

m Sample piece lengths for RRP 108/127 billets procured by LARP

Billet #


R&D and Construction Planning

• A CERN-US working group was established in August 2010: Following a request from last DOE review of LARP (7/2010) Composition: 3 US (BNL, FNAL, LBNL) and 2 CERN members

• Goals:

Discuss requirements and development plans for Nb3Sn

Present recommendations to LARP, DOE, CERN management

• Main topics covered: Magnet tests and success criteria for technology demonstration Contributions from US and CERN in the next R&D phase Infrastructure requirements for prototyping and production Baseline and backup options for final design and production

• Findings presented at the 2011 CERN-US meeting and DOE review


CERN and EU Participation

Several key contributions by CERN were discussed as part of this plan:

R&D and design phase:

• HL-LHC Design Study: o Finalize basic requirements (esp. aperture)o Radiation and heat transfer studies

• Conductor and materials development (with EU programs)• Participation in HQ model testing, assembly and fabrication

(preparation for prototyping and production)

Infrastructure and prototyping phase:

• Procure 10 m coil infrastructure at CERN • Full length prototype will be built at CERN by a combined US-

CERN team with target completion by the end of 2015

Production and installation phase:

• CERN to participate in production & lead integration/installation


ID Task Name

1 R&D & Design (US+CERN)2 LQS01/2 tests (RRP 54/61)3 LQS03 tests (RRP 108/127)4 HQ/HQM tests5 LHQ design and fabrication6 LHQ tests7 IR Quad Aperture selection8 IR Quad short model9 HL-LHC Design Study10 IR specification finalized11 IR Construction Project (US+CERN)12 Prototype infrastructure & tooling13 Construction project start14 IR Quad Prototype 15 Production infrastructure & tooling16 Coil and structure fabrication17 Magnet assembly18 Cryostat assembly & test19 String Tests20 Installation

10/1

1/1

2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022

R&D and Construction Schedule

• Target date for installation of new IR Quadrupoles in LHC is 2021• Target date for technology decision (Nb3Sn vs. NbTi) is 2014

As of June 2011(DOE review)


Summary

• Fundamental aspects of Nb3Sn technology have been demonstrated

• R&D effort is now focusing on increased reliability, accelerator integration and production requirements

• Systematic testing of LARP Nb3Sn models and CERN NbTi models will provide a direct comparison for the 2014 technology selection

• Next few years will be critical and much work is still left to do

- Integrate R&D efforts with EuCARD, KEK, US core programs

- Need close participation and direct contributions by CERN

Acknowledgement

Documents

Magnet Systems Overview