Summary of Magnet Discussions

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Summary of Magnet Discussions
P. Wanderer LARP CM9 October 19, 2007
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• We magnet folk would like to thank our SLAC
  hosts, particularly Tom and Naomi.
• We would also like to thank our colleagues from
  CERN for their comments and (bold) proposal.

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Key questions answers

• Where are we?
• We discussed data from several 1m quad and
  other recent Nb3Sn dipoles
• Where do we want to go?
• 200 T/m, 4 m quad by 12/31/09
• more understanding of materials magnets
• c) Carefully evaluate proposed Phase I goal
• When do we get there?
• a) Three long, strong quads by 12/31/09
• b) Initial evaluation Dec. 1 report/revu June08

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Where are we?

• We can make Nb3Sn magnets that
• reach 90 of conductor limit (4.5K)
• with predictable harmonics
• Examples
• 1 m cos2? models (several)
• 1 m and 2 m cos? mirror dipoles
• Mirror one coil iron in place of 2nd coil
• 4 m racetrack coils
• But we dont understand everything yet

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• Materials the fundamental building blocks of
  our magnets

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RRP Strand Development with OST (Barzi)
Increase Subelement Number
RRP0
54/61 restack Jcmax3000 A/mm2
108/127 restack Jcmax2400 A/mm2
Increase Subelement Spacing
RRP1
60/61 restack with spaced SEs Jcmax?3000 A/mm2
114/127 restack with spaced SEs Jcmax3000 A/mm2
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TQ Data BNL-FNAL-LBNL
1.9 K calc
Ic calc /- 0.1 strain
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Strand Production
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RRP-8648, 0.7 mm RRR 3102.09 K
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• TQ - 1 m quadrupoles quench performance at
  4.5 K, 1.9 K
• TQS shell support
• TQC collar support

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TQS01 (technology quad shell support structure)
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Summary (Caspi)

• 4 TQS tests
• Maximum gradients at 4.4K - 178-222 T/m
• Plateau reached after 4-20 quenches with 80-90
  of short-sample
• Maximum gradients at 1.9-3.2K - 192-225 T/m
• Plateau reached after 20 quenches with 80-84
  of short-sample
• Bronze/Titanium islands under axial
  tension/compression
• TQS01 quenches in inner layer straight section
  (near island gaps)
• TQS02a dominated by outer layer quenches
• At 12 kA layer 2 (outer) field is 1.2 T less than
  layer 1 (inner)

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Summary issues (Caspi)

• Unexpected outer layer quenches and plateau.
• PW discussion ? outer layer quenches very
  likely originate in turn with maximum preload (gt
  150 MPa?)
• A monotonic increase in training current between
  4.4K and 1.9K (no jump)
• No gain in current returning from 1.9K to 4.4K
• Epoxy bubbles at 1.9 K on the inner layer free
  surface
• High MIITS (7) degrade the plateau and impacts
  coil stress
• But heating can improve performance (reduces
  strain ?)

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TQS01 TQS02 Plateau QuenchesLietzke Lizarazo

• Three TQS-magnets performed below short-sample
  projections
• TQS01a (coils 5, 6, 7, 8)
• TQS01b (coils 7, 8, 14, 15)
• TQS02a (coils 20, 21, 22, 23) ? coils into
  TQE02
• Quench onset and propagation examined
• Short-sample error?
• Mechanical motion?
• Flux-jumps?
• Local conductor degradation? PW most likely
  cause but source degradation unknown

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TQE02 (likely to be renamed TQC02)uses coils
from TQS02 (Bossert/Ambrosio)
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• Magnet data ? cable testing as a function of the
  usual variables (temperature, background field)
  strain is important ? discuss collaboration with
  CERN

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• HQ Explore larger aperture, higher gradient

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HQ Magnet (Caspi slide Felice)

• 130 mm bore quadrupole with a gradient of
  200 T/m ( 2 layers).
• Option to inserts TQ coils ( 224 layers) ,90 mm
  bore, Gradient 300 T/m
• Cross-section
• 2 layers
• Clear bore diameter 133.6 mm (use with TQ
  coils)
• Outer coil diameter 198.3 mm
• Strand diameter 0.8-1.0 mm (so far 0.7 mm)
• Cable width 15 mm (28-36 strands) - key-stone
• 1 wedge per layer
• Gradient ( 205 T/m) in 130 mm aperture
• 1 m long Nb3Sn coils
• Azimuthal Stress 150 MPa ? Shell support
  structure specifically designed for HQ (Felice)

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Where do we want to go?

• Long range develop Nb3Sn magnet as candidate
  for Phase II upgrade of LHC IR (2016)
• FY08 Evaluate opportunity to contribute Nb3Sn
  quads to Phase I upgrade (2012) HQ?
• FY09 Demonstrate good quench performance of 4 m
  quads, G gt200 T/m
• As resources permit
• Larger aperture/higher gradient (HQ)
• Improve Nb3Sn strand (60/61?114/127)

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• LQ 4 m, G gt 200 T/m, 90 mm aperture, Nb3Sn
  quadrupoles

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LQ features (Ambrosio)

• Change as few things in TQ (1m) series as
  possible
• Conductor
• Coil
• Major issues due to extra length
• Stored energy/quench protection
• Bow in reacted coil caused by coil (Fermilab 4m
  dipole)
• Major choice
• Support structures shell, collar

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.
LRS01 long racetrack, shell 4m (4.5 K)
I (plateau) 91 Iss
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• LQ with collar support structure

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LQ Status (Nobrega Schmalzle)

• Reaction tooling is being fabricated and is a
  single cavity, laminated fixture that can be used
  for both reaction and epoxy impregnation.

Practice
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Assembly LQ based on TQC (Bossert)
Coil Midplane Gap is equal to coil oversize
plus coil midplane shim determined from FEA and
previous experience with short models.
4. Assembly of coils with mid-plane shims.
5. Collaring in 5-6 passes to achieve target
preload.
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• LQ with shell support structure

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2D magnet design from TQS02 to LQS01 (Ferracin)

• TQS
• Structure designed for a 4-layer coil
• Initial design included ss pads
• Key location determined by bladder width
• LQS
• Stainless steel pads (not brittle at 4.2 K)
• Original TQ magnetic design
• Interference keys moved towards mid-plane
• Optimized coil stress (big benefit)
• 8 bladders (small price)
• 4 auxiliary bladders for yoke pre-assembly
• Aluminum shell from 22 mm to 20 mm thick
• Axial rods closer to coil
• Less deflection of end plate

TQS02
LQS01
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Assembly process

• Separate assembly of 4 shell-yoke sub-assemblies
• Similar to TQS
• Yoke laminations compressed with 1 m long tie
  rods
• Shell pre-tensioned with yoke bladders (0.8 m)
  and gap keys
• Assembly of 4 segments
• Segments connected with pins
• Yoke laminations compressed with 3.3 m long tie
  rods
• Insertion of coil-pad sub-assembly
• Bladders (1.6 m) to align and pre-load

• .

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Alignment features

• Holes for pins shell - yoke
• Slots for keys yoke yoke
• Hollow pins between yoke laminations
• Slots for keys pad - yoke
• Interference keys
• Masters to facilitate alignment during assembly
• Alignment options
• No alignment (TQS case)
• Shell-yoke
• Necessary for assembly
• Yoke-yoke and pad yoke
• To be discussed

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How do we get there?

• Projectize 4 m quad RD (LQ)
• Review RD plan, two candidate support
  structures
• review last week of November
• Prioritize LQ
• Track progress closely
• Learn from 1 m RD (e.g., lots of coils)
• First test 1 year from now
• Continuing resolution is a handicap

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LQ Schedule Budget (Ambrosio)
2008 2009

Plan LQ01 shell LQ02 collar LQ03 TBD
FY08 budget (w/o contingency) 3.1M
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Opportunity/challenge

• Make 4/8/16 Nb3Sn quads for replacement of IR
  quads for Phase I upgrade (2012)
• Quads for Phase I ? new funds (inside/outside
  LARP?)
• LARP, CERN discussions underway
• Evaluate cost, staff, schedule
• June 08 IRUWG report, DOE revue