racetrack coil technology – g. ambrosio 1 larp doe review – fnal, june. 5-6, 2007 bnl - fnal -...
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BNL - FNAL - LBNL - SLAC
Racetrack Coil Technology (LR, SQ)
& other Supporting R&D activities Giorgio Ambrosio
LARP DOE Review June 5-6, 2007
Outline:- Small Magnets: status and plans- Long Racetrack: status and plans- Other Supporting R&D activities
Racetrack Coil Technology – G. Ambrosio 2 LARP DOE review – FNAL, June. 5-6, 2007
Small Magnets - Goals
• Provide a means of evaluating conductor and cable under operating conditions similar to the TQ
• Validate numerical models related to magnet performance
• Perform training and quench initiation studies
• Investigate dependence of magnet performance on axial loading
• Technology development:– New coil parts– Different assembly procedures– Strain gauge R&D– Data analysis with different data acquisition systems– Field quality measurements– Coil alignment with shell-type structure– Coil fabrication tolerances
“Small racetracks and small quadrupoles
based on these coils:2-layer, 26 cm long”
Racetrack Coil Technology – G. Ambrosio 3 LARP DOE review – FNAL, June. 5-6, 2007
Small Quadrupoles (SQ)
• Aluminum shell– Thickness: 22 mm– Outer diameter: 500 mm
• Iron yokes• Stainless steel pads• 4 bladders and 8 keys for assembly and
pre-load• Axial support
– 4 aluminum rods• Diameter: 25 mm
– Stainless steel end plate• Thickness: 50 mm
– Pre-load applied with hydraulic cylinder
• Strain gauges on shell and rods
Racetrack Coil Technology – G. Ambrosio 4 LARP DOE review – FNAL, June. 5-6, 2007
SQ02 Loading and Quench History
Study of end pre-stress effect on magnet training and performance
• SQ02– After cool-down
• Shell: 95 MPa• Rods: 125 MPa (270 kN)
• SQ02b– Increase of z rod at 293 K
• Same as TQS01 at 293 K– After cool-down
• Shell: 95 MPa• Rods: 190 MPa (415 kN)
• SQ02c– Removal of axial rods– After cool-down
• Shell: 95 MPa
5.5
6.5
7.5
8.5
9.5
10.5
0 10 20 30 40 50
Training quench number
Que
nch
curr
ent
(kA
)SQ02, first thermal cycle, 4.3 KSQ02, second thermal cycle, 4.3 KSQ02b, 4.5 KSQ02b, 1.8 KSQ02c, 4.5 KSQ02c, 1.8 K
Expected short sample limit at 4.3-4.5 K
Expected short sample limit at 1.8 K
Note: Axial loading applied with minimum shell tension
Effect on training: - very good memory (consistent with other Nb3Sn magnets) a series of ‘virgin magnets’ should be used to study the effect on 1st th. cycle- Effect on quench performance can be “disruptive” if end pre-load/support is not sufficient
Racetrack Coil Technology – G. Ambrosio 5 LARP DOE review – FNAL, June. 5-6, 2007
SQ02 Strain Analysis
• Strain on the pole turn during excitation
• Results on a path moving along the cable– From the end of the straight
section to the tip of the island
• Model assumptions:– Fr coeff. 0.2– Separation allowed
• Peak tensile strain – From 1500 to 4500 strain
• Peak compressive strain – From -500 to -1500 strain
Friction plays an important role (stick-
and-slip), but … be aware of the cliff
Racetrack Coil Technology – G. Ambrosio 6 LARP DOE review – FNAL, June. 5-6, 2007
Short-Term Plans: SQ03
• Fabrication and test of 4 new coils– 108/127 strand
• Possible candidate for future magnets
– Conductor evaluation in operational conditions similar to the TQ/LQ magnets
• Cabling degradation
• Transverse stress degradation
• Short sample current
• Coil fabrication: by September• Test: Oct-Nov.
Racetrack Coil Technology – G. Ambrosio 7 LARP DOE review – FNAL, June. 5-6, 2007
Long-Term Plans
PROPOSALS:
• SRK (FY08): small racetrack to test TQ/LQ keystoned cables
• Rad-Hard insul. R&D (FY09+): test SQ with rad-hard insulation & impregnation materials that can withstand the expected dose at Max luminosity
Racetrack Coil Technology – G. Ambrosio 8 LARP DOE review – FNAL, June. 5-6, 2007
Rad-Hard Insulation R&D
Goal: Develop insulation/impregnation scheme that can withstand the expected dose at Max luminosity
Plan A (present mat.) Plan B (new materials)
FY07 Develop plans, schedule, cost
Select alternative materialFY08
Q1-Q2
Prepare samples and fixtures
FY08
Q3-Q4
Irradiation & tests Irradiation & tests
FY09 Small Quad
Rad-Hard Insulation Workshop
Fermilab, April 20, 2007
Racetrack Coil Technology – G. Ambrosio 9 LARP DOE review – FNAL, June. 5-6, 2007
Long Racetrack - GOALS
1. The main goal is to test long Nb3Sn coils
target is to reproduce performance of short coils magnet performance (training, …) are NOT an issue
2. Coils will be tested in an Al-shell-based supporting structure (preloaded using bladders and keys) in order to verify the use of this concept for long magnets
Coil layout: two flat double-layer racetrack coilsTechnology successfully developed at LBNL and successfully modified at FNAL
From 0.3 m to 3.6m
Performed at BNL
Developed at LBNL
Racetrack Coil Technology – G. Ambrosio 10 LARP DOE review – FNAL, June. 5-6, 2007
SRS01 Description
• Two double layer racetrack coils.• Coil total length 0.254 m; straight section 0.152 m.• Total length with horseshoe fixture 0.3 m.• 21 turns per layer, 42 turns total per coil.• Coil and fixture same as SM coils.• Two coils tested were configured as common coil.• Cable was RRP 54/61, 0.7mm strand OD, Cu/non-Cu ratio 0.89.
Racetrack Coil Technology – G. Ambrosio 11 LARP DOE review – FNAL, June. 5-6, 2007
SRS01 QUENCH HISTORY
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
0 2 4 6 8 10 12 14 16 18 20 22
Quench Number
Qu
en
ch
Cu
rre
nt
(A)
Coil #1 Inside Layer
Coil #2 Inside Layer
Coil #1 Transition
Coil #2 Transition
NO QUENCH
Thermal Cycle
100A/s 4A/s 2A/s20A/s
Iss = 9705A
20A/s 2A/s 1A/s2A/S
Thermal Cycle
SRS01 Test
Ramp rate dependence due to long twist pitch.Performance at 1 A/s
shows successful tech. transfer
Racetrack Coil Technology – G. Ambrosio 12 LARP DOE review – FNAL, June. 5-6, 2007
LR Support Structure
• Aluminum shell– Single piece– Length: 3.6 m
• Iron yokes– 50 mm thick laminations
• Iron pads– Half length (1.8 m)
• Stainless steel skins– Full length (3.6 m)
• Bladders• Keys and shims
– Half length (1.8 m)
Racetrack Coil Technology – G. Ambrosio 13 LARP DOE review – FNAL, June. 5-6, 2007
Assembly: tooling & procedures
• Support structure assembled at LBNL with dummy coils– Tooling and procedures performed very well
• Tested at BNL at 77 K• Dummy coils removed and re-inserted at BNL
Support structure is ready to be used for LRS01
Racetrack Coil Technology – G. Ambrosio 14 LARP DOE review – FNAL, June. 5-6, 2007
Instrumentation for 77 K test
• Instrumentation of shell and dummy coils
– Trace on shell– Strain gauges on dummy coils
• Six stations along z axis• Measurements
– Azimuthal and axial shell strain– Horizontal and axial coil strain
Dummy coilstrain gauge
locations
Racetrack Coil Technology – G. Ambrosio 15 LARP DOE review – FNAL, June. 5-6, 2007
FEM analysis of shell strain
• Aluminum shell in tension after cool-down– Different thermal contraction
of aluminum and iron
– Friction between shell and yoke
• Different strain profiles depending on friction factor
Racetrack Coil Technology – G. Ambrosio 16 LARP DOE review – FNAL, June. 5-6, 2007
77 K test results
• Good agreement between measurement and FEM with 0.2 fr. coeff.• Top-bottom asymmetry will be addressed during LRS01 assembly by
using bladders on both bottom and top locations• Longitudinal variation of azimuthal stress in the shell is within
acceptable range (150-250 MPa)• High longitudinal tension in shell and dummy coils
Shell axial stress (MPa) Shell azimuthal stress (MPa) Dummy coil axial strain
Racetrack Coil Technology – G. Ambrosio 17 LARP DOE review – FNAL, June. 5-6, 2007
Coil Fabrication
Coil Winding:– Winding machine completed.– Coil winding completed.
• Automatic winding and pneumatic pushers operated nicely.
• Coil looks good, electrical checks good.
Racetrack Coil Technology – G. Ambrosio 18 LARP DOE review – FNAL, June. 5-6, 2007
Coil Reaction– Oven fabrication and acceptance tests completed
• temperature uniformity and ramp rate met specs. Achieved +/- 3 deg C at 650 C.– LRS01 coils heat treatment completed
Racetrack Coil Technology – G. Ambrosio 19 LARP DOE review – FNAL, June. 5-6, 2007
Coil Impregnation– Fixture fabrication complete, heaters mounted and wired– Dummy coil sectioned and inspected after impregnation very
good!– Improved bonding between coil and protection heater– LRS01 Coils successfully impregnated
Racetrack Coil Technology – G. Ambrosio 20 LARP DOE review – FNAL, June. 5-6, 2007
Coil & SS Handling• Support Fixture Lifting:
– Fabrication of beams and collars complete.
– Same beams lift react & impreg tooling.
Racetrack Coil Technology – G. Ambrosio 21 LARP DOE review – FNAL, June. 5-6, 2007
Plans
SHORT TERM:• LRS01 assembly and pre-load: June 12
– LBNL and FNAL people are planning to attend it
• LRS01 test start: last week of June
LONG TERM:• Depend on LRS01, TQ02s, LM02 performance
– Have all parts and cable available for a new coil
Racetrack Coil Technology – G. Ambrosio 22 LARP DOE review – FNAL, June. 5-6, 2007
FNAL Long Mirror
• FNAL “Mirror magnet” is a cos-theta dipole where a coil is substituted by iron blocks
• Plan: 2m – 4m mirror magnetsFront view of mirror magnet
The plan is to base the scale-up on a well understood design and fabrication technology
FNAL successfully fabricated several dipoles and mirror magnets
Larger probability of success of the LQ by:Several features complementary to LRs Diversity & Risk mitigation
- conductor, keystoned cable, insulation, coil shape, use of wedges, mechanical structure,
Start as soon as possible development and qualification of tooling and infrastructure for Long Quadrupole at FNAL (New 6-m long oven, …)
Racetrack Coil Technology – G. Ambrosio 23 LARP DOE review – FNAL, June. 5-6, 2007
LM01 Test Results
15000
16000
17000
18000
19000
20000
21000
22000
0 5 10 15 20 25 30
Quench number
Qu
ench
cu
rren
t, A
HFDM03
LM01
• LM01 (2m) reached expected SSL at 4.5K– SSL: ~21 kA with 10%
degradation (PIT conductor)
• Similar training to HFDM03– 1m mirror with PIT conductor
• Some detraining at 1.9K under investigation
• LM02 (4m) test in Sept-Oct 07 Open marks show quenches in the leads
Racetrack Coil Technology – G. Ambrosio 24 LARP DOE review – FNAL, June. 5-6, 2007
Conclusions
• Small Magnets:– Useful tools for studying conductors, materials, fabrication
issues plan to continue
• Scale-up: – To date the scale-up efforts (LR and FNAL LM) are showing
encouraging results; – LRS01 test by end of the month– LM02 test in Sept-Oct
• Long shell: – stress and strain in the long shell and in the dummy coils are in
good agreement with FEM results assuming 0.2 fr.– Longitudinal variation of shell azimuthal stress is within
acceptable range for the LR
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