Magnet Systems

1
Magnet Systems

• Jim Kerby
• 20 Apr 2007
• With thanks to my colleagues

2
Current Program

• Current focus Demonstrate by the end of 2009
  that Nb3Sn magnets are a viable choice for an LHC
  IR upgrade
• Known major issues
• Nb3Sn technology Peak field on coil Length
  Consistency
• Three pronged approach
• Predictable and reproducible performance
• TQ models (1m, 90mm bore, Gnom gt 200 T/m, Bcoil gt
  12T)
• Long magnet fabrication
• LQ models (4m, 90mm bore, Gnom gt 200 T/m, Bcoil gt
  12T)
• Predictable and reproducible performance
• HQ models (1m, 90mm bore, Gnom 250 T/m, Bcoil
  gt 15T)
• But several new initiatives are under
  discussionslim Q0 options, for instancewe can
  not be completely locked in the box, and must be
  willing to contribute in the best way possible
  for LHC

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Quadrupole Designs for the LHC IR
From ASC06 HQ Paper
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TQC and TQS Design Concepts
Yoke
Pad
Key
Shell
Axial rod
Filler
TQC
TQS

• Aluminum shell over iron yoke
• Assembly with bladders and keys
• Aluminum rods for axial pre-load

• Stainless steel collars and skin
• Control spacers to limit pre-load
• End support plates, no pre-load

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TQC01 and TQS01 Quench Training

• TQC01 limited to 70 of short sample at 4.5K,
  but achieves 85 at 1.9K
• TQS01 start training at 80 of 4.5 K short
  sample, limited to 87 in one coil
• Maximum quench gradient was close to 200 T/m in
  TQC01 and TQS01

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TQS01b TQS01c Test Results

• TQS01b starts training at 75 of 4.5 K short
  sample, plateau at 82 (1 coil)
• TQS01c Trained at and 4.5K and 1.9K, 80
  plateau is conductor-limited

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Field quality analysis First TQ models show that
the random coil block displacements are mostly
within 50 microns which is factor of three
larger than in production MQXB at the same
fraction of coil aperture. This is an
encouraging result given the differences between
NbTi and Nb3Sn technologies and the fact that
MQXB field quality was polished on many preceding
short models.The measurements reveal opposite
ramp-rate dependences in TQC01 and TQS01 transfer
functions that may be related to different
interstrand contact resistances.
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TQ Next Steps

• Starting from TQ02, we are switching to RRP
  strand
• Higher current density, possibly different
  stress stability characteristics

• Coils use new Ti pole pieces to confirm adequacy
• Assembly to be completed by the end of April
• Test in May at FNAL (4.5K 1.9K)
• Discussion cause of the 80-87 plateau
  planned corrections
• Same coil design as TQC01 (bronze pole with
  stress relief cut)
• Significantly higher collaring pre-load
  (addressing TQC01 problem)
• Two coils possibly damaged during collaring
  (shim displacement)
• Discussion revise plan, minimize impact on
  schedule milestones
• Converged on coil design (Ti poles and no
  stress-relief cut)
• Need to start parts procurement coil winding
  (after TQ02 spares)
• Discussion can we converge on a single
  structure for TQ03?

TQS02 TQC02 TQ03
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LQ Status Plans

• LQ Design Study is proceeding
• Finalized coil envelope and design (TQ)
  structure decision in June 2007 (?)
• Feb 07 Workshop focused on integration with
  other program components
• TQ, LR, other supporting RD and materials
  (conductor)
• LQ Task FY07 plan design procure coil parts
  tooling start practice coils
• Winding/curing tooling design approved by
  internal review on April 9
• End parts will be same as TQ
• Next steps
• Release drawings for winding curing tooling
• Confirm use of Ti pole pieces, determine length
• Discuss reaction and impregnation tooling and
  procedures
• Further clarify how/when feedback from rest of
  program will be integrated
• Further clarify participation of LBNL and BNL

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LQ Design study G. Ambrosio
Technological Quadrupoles
Long Quad. Design Study
Long Racetrack
Long mirror
Long Quadrupole
Practice coils
Goal 4m long, G ? 200 T/m, F 90 mm
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Long Racetrack

• Support structure assembled at LBNL with dummy
  coils
• Tested at BNL at 77 K
• ? Ready to be used for LR01

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LR coils LR01

• LRSC01
• Coil impregnation completed 4/ 16/ 07
• Prep for assembly - underway
• LRSC02
• Coil reaction heat cycle completed 4/ 19/ 07
• Coil prep for impregnation through end of April
• Coil impregnation early/ mid May
• Prep for assembly mid May
• 1st LONG RACETRACK
• Coil assembly mid/ late May
• Hang, wire, cool down end of May
• Cold test start early June

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LQ Mech Design Development
With collars
With Al shell
Analysis of TQC with Ti coils OK!
Hybrid concepts SS shell bladders
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LQ Next Steps

• Conductor
• TQ02 series results ? choice for LQ01 54/61 or
  60/61
• Coil Fabrication Technology
• TQ02 series results ? Pole material (Ti or
  Bronze)
• Mechanical Design
• Complete design of LQ with Al shell
• Analysis of TQC01b, TQ02s and TQ03s
• Generate mechanical design selection criteria
• Quench Protection
• Design QP heaters for LQ, upgrade VMTF QP system

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HQ Status Plans

• HQ Design Study goals, magnetic, mechanical,
  quench analysis reported at ASC
• Main focus is on fundamental technology issues
  HQ is not a prototype
• 4-layer coil w/TQ cable width option of
  standalone test of outer double-layer
• We need a technology HQ as part of the
  achieving the FY09 goal
• HQ can be designed to facilitate the transition
  towards a prototype
• Significant progress on mechanical design
  analysis in recent months
• FY07 HQ task plan is to get started on tooling
  design requires radial envelope
• Recently, more emphasis on standalone outer
  double-layer test (130 mm aperture)
• Responding to CM7 comments, considered increasing
  cable width in outer layers
• No significant advantage in terms of stress
• Quench protection issues not analyzed yet high
  priority
• Strand diameter TBD based on materials feedback
• We have confirmed the choice of a 10 mm cable
  comments?

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• FY07 progress
• Magnetic optimization of coil cross-section and
  ends
• Mechanical design concepts with coil alignment
• Detailed magnetic/mechanical analysis
  comparisons

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Summary of mechanical analysis
Model1 coili polei glued 20 MPa tension
between pole and coil
HQ1 HQ2 HQ3 HQ1out HQ3out HQ3out
Gradient SS (T/m) 312 319 308 185 205 205
Iss (A) 10600 12450 11010 13500 17030 17030
Peak field ss (T) 15.74 16.03 15.49 14.54 15.37 15.37

Gradient comparison (T/m) 300 300 300 185 185 205
Peak field (T) 15.06 14.99 15.04 14.37 13.9 15.37
Fx (MN/m) 3.76 3.38 4.04 2.73 3.19 3.9
Fy (MN/m) -4.93 -4.62 -4.95 -3.48 -4.18 -5.14

sq at 4.2 K in high field (MPa) -165 -152 -136 -149 -153 -179
sq after excitation (MPa) -196 -177 -185 -194 -181 -219
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Nb3Sn Strand Specification Rev-D7/26/06
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RRP-54/61 Production 490 kg
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RRP Strand for LARP

• For FY08 LARP could use strands with the
  127-stack design
• High Jc design has been achieved
• Stability improves with decreasing sub-element
  diameter
• Smaller low field magnetization
• Option to increase strand diameter ? wider cable

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Small Magnet RD

• SQ03
• Fabrication and test of 4 new coils
• 108/127 strand
• Possible candidate for LQ02
• Conductor evaluation in operational conditions
  similar to the TQ/LQ magnets
• Cabling degradation
• Transverse stress degradation
• Short sample current
• Possibly use to address bubbles
• Seen in TQs after 1.9K test

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Radiation study N. Mokhov

• Based on detailed MARS15 modeling and thorough
  analyses of coil apertures, distances to IP,
  low-Z spacers, stainless steel and high-Z liners,
  magnet splitting, and a set of TAS/TAN-type
  absorbers through final focus region, it is shown
  that dipole-first, and shell-type block-type
  quad layouts are feasible for the LHC luminosity
  upgrade up to 1035 cm-2 s-1.
• Work has started on design of radiation damage
  tests of materials for the superconducting
  magnets for the luminosity of 1035.
• Q3-Q4 FY07 plans further studies of block-type
  coil option address a kW-scale heat loads in the
  triplet (possibly) perform calculations on a
  slim dipole design Rad-Dam beam tests in an
  emulated LHC-like environment.
• We have everything to respond to all energy
  deposition Olivers requests, but need someone!

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Rad-Hard Insulation RD

• Goal Develop insulation/impregnation scheme that
  can withstand the expected dose at Max luminosity

Plan A Plan B
FY07 Develop plans, schedule, cost Select alternative material
FY08 Q1-Q2 Prepare samples and fixtures Select alternative material
FY08 Q3-Q4 Irradiation tests Irradiation tests
FY09 SQ and/or TQ
Rad-Hard Insulation Workshop Fermilab, April 20,
2007 (130 600 pm)
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Improved insulation for Nb3Sncables in
superconducting magnets

• The result robust insulation fabric with half
  the conventional thickness
• The silane sizing is stable through Nb3Sn heat
  treatment.
• The tight weave (80 ct) is strong and flexible,
  no broken yarns, no Cu show through
• Conformation with cable is excellent, promotes
  easy coil winding.
• Silane survives heat treat, provides enhanced
  bonding with epoxy in final coil.
• New insulation has 20 higher shear strength!
• Good electrical properties
• We could coordinate materials and braiding
  process to make this new direct-braid insulation
  available to be applied to cable for LARP
  magnets.
• ? Question are you (we) interested?

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• D2 challenges
• D2 apertures have the same polarity and negative
  coupling so most of the magnetic flux returns
  through the iron that needs to be relatively
  thick.
• In spite of high current density, the quench
  field is 10T and the operating field may
  probably be 9T instead of 14.1T quoted in the
  PAC03 paper. It extends magnet length from 10.0m
  to 15.7m.
• The next optimization steps will attempt to
  reduce the yoke OR, while keeping the field
  quality at a reasonable level.

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New initiatives P. Wanderer

• LHC/LARP can benefit from BNL experience in
  developing
• Slim magnets
• direct wind CAD/CAM staff machine produced
  NbTi magnets for
• HERA IR upgrade (multielement)
• BEPC IR upgrade (multielement)
• ILC IR RD (now underway)
• Can we use this technology with Nb3Sn?
• Magnetized TAS
• Discussions with R. Gupta ? High Temperature
  Superconductor for quad coil in TAS
• Basis successful design, construction, operation
  of HTS superferric quadrupole for RIA RD
• Fast-cycling superconducting magnets for PS2 and
  SPS upgrade
• BNL modified RHIC dipole for GSI and fabricated
  and tested short model
• Infrastructure for fast cycling magnet testing is
  available

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Closeout

• New initiatives and participationwelcome!
• Magnet tests exploring the phase spaceas
  upgrades become more real, we will be able to
  suggest real phase space to operate in.
• Proposal for new strand made.options for larger
  diameter as required
• Continued RD and studies on materials and
  cooling to make a real upgrade of LHC
• Thanks to all collaborators on an active and open
  meeting!