racetrack coil technology – g. ambrosio 1 larp doe review – fnal, june. 5-6, 2007 bnl - fnal -...

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”


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


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


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


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.


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


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


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


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.


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


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)


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


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


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


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


Coil Fabrication

Coil Winding:– Winding machine completed.– Coil winding completed.

• Automatic winding and pneumatic pushers operated nicely.

• Coil looks good, electrical checks good.


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


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


Coil & SS Handling• Support Fixture Lifting:

– Fabrication of beams and collars complete.

– Same beams lift react & impreg tooling.


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


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, …)


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


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

racetrack coil technology – g. ambrosio 1 larp doe review – fnal, june. 5-6, 2007 bnl - fnal -...

Documents

larp doe review fnal

plans long racetrack

sq02 strain analysis

mpa rods

strain peak compressive

strain friction

long slide

bnl fnal