Transcript Response to Review Committee P. Wanderer LARP Magnet Systems Leader DOE Annual Review

US LHC Accelerator Research Program
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Response to Review Committee
P. Wanderer
LARP Magnet Systems Leader
DOE Annual Review
July 14, 2009
OUTLINE
• Why 120 mm?
• Are you throwing away the last five years of R&D?
• What are the options for aperture, besides 120 mm?
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MAGNET NAMES, LENGTH,
APERTURE
QUAD LENGTH, APERTURE
QUAD APERTURE (mm)
140
120
HQ
QA
QB
TQ
100
TQ
LQ
LQ
80
HQ
60
QA
QB
40
LR
20
0
LR
0
1
2
3
4
5
6
7
QUAD LENGTH (m)
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120 mm – LOOKING BACK SEVERAL YEARS
• Goal, first stated several years ago (Kerby):
– “explore engineering phase space”
• Avoid “physicists’ sand box” (P5 committee priorities)
• Tooling available for 90 mm, two layer coils  TQ, LQ
• Four layer coils (based on TQ) 
– High gradient
– High aperture (two outer layer coils)  HQ
• Cost effective, schedule effective way of exploring
both high aperture and gradient
– At that time, no LHC input re: aperture, gradient
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120 mm – LOOKING BACK A YEAR
• Magnet Steering Committee discuss/decide: given
CERN’s decision for 120 mm for the Phase I Upgrade,
choice of 120 mm for LARP makes comparison with
NbTi more straightforward (e.g., harmonics – rescaling
with fraction of aperture; Lorentz forces and self
protection)  increases chance of successful
demonstration of technology.
– Discussed at the review last year, just before
CERN’s aperture decision, when we were looking at
apertures in the range 114 mm – 134 mm.
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120 mm – LOOKING AHEAD
• PAC09: Following GianLuca’s “High Field Magnet”
invited talk, Stefan Fartouk asked him “Why not 150
mm?”
– Fartouk (CERN accel phys) closely involved in Phase I
Upgrade, in charge of quad cross section until
recently.
• Eric will check with Frank Zimmerman later this week
on this topic.
• If “CERN” strongly interested in aperture > 120 mm,
exploring apertures larger than 90 mm will aid
informed decision re: Nb3Sn for LHC IR.
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THE LAST 5 YEARS OF DEVELOPMENT  HQ
• Strand: optimization of Jc vs. stability via reaction
schedule  0.8 mm strand for 120 mm quad HQ
• Cable: anneal to reduce residual strain  HQ cable
• Coil cross section/geometric field quality: TQ (1
wedge) not optimal FQ  HQ (2 wedges)
– i.e., better FQ demo with 2 wedges in any coil
• Coil pole pieces:
– bronze  titanium
– no bonding of poles to coil
– no gap, no axial strain after reaction
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THE LAST 5 YEARS OF DEVELOPMENT  HQ
• Tooling: reaction/impregnation fixtures
– Initial TQ: 2-in-1 … coils not symmetric  1-in-1 for
later TQ and, now, HQ
– Reaction fixture stiffened against bowing.
– Impregnation schedule includes “soak” period for
complete impregnation
• Shell support structure evolution
– Alignment
– Axial segmentation (0.85 mm) – from LR
– “Masters” for insertion of bladders and keys
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HQS – Mechanical Shell based Structure
Components
- Aluminum bolted collars => alignment
-remains in compression from assembly to operating
conditions
- Iron pads and yoke
- Iron master key => alignment
- axial rods => axial preload
- 25 mm aluminum shell => azimuthal preload
- Coil and collar in compression
- Cooling area
Assembly
- 60 mm bladders located outside the key span
- 38 MPa pressure (600 + 50 microns clearance for 220 T/m)
570 mm outer diameter
- Collars, pads and key locations optimize to minimize stress
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9
APERTURE OPTIONS
• HQ: should complete construction, test
• QA (i.e., 5-year plan): 90 mm vs. 120 mm
– Cost, schedule  only choices are 90 or 120
• Issues for 90 mm:
– Pro: schedule (? – now lacks field quality, alignment)
• Is a “1m” coil long enough to get FQ resuls?
• Problem: no QA test results until 2013
– Pro: cost (? – cost to rework coil, support structure)
– Con: field quality random errors – smaller at larger
aperture, since they probably come from random
errors in conductor placement
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CONCLUDING THOUGHT
• Homework for Magnet Steering Committee:
– More carefully review choice of 120 mm for 5-year
plan, especially time-to-first results
– Benchmarks for 5-year plan
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