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Superconducting Magnet Division Construction and test results of Construction and test results of kapton kapton insulated 2G HTS insulated 2G HTS cos cos coil coil L. S. Lakshmi , E. Willen

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SLIDE 1

Superconducting Magnet Division

Construction and test results of Construction and test results of kapton kapton insulated 2G HTS insulated 2G HTS cos cosθ θ θ θ θ θ θ θ coil coil

  • L.S. Lakshmi

Slide No. 1

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

  • Brookhaven

Brookhaven National National Laboratory, Upton Laboratory, Upton, New , New York York-11973 11973

  • Particle Beam Lasers Inc., Northridge, California

Particle Beam Lasers Inc., Northridge, California -91324 91324

  • L. S. Lakshmi
  • , E. Willen
  • , R. C. Gupta
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SLIDE 2

Superconducting Magnet Division

  • Technical Objective
  • Conductor details
  • Coil geometry, winding and testing
  • Test results
  • Summary and Future plan

Presentation outline Presentation outline

G HTS conductor

L.S. Lakshmi

Slide No. 2

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

  • Summary and Future plan

This work is part of HTS Dipole STTR with Particle Beam Lasers Inc. (PI: Eric Willen) Grant Award Number: DE-SC0007738

Pole winding using 2G

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SLIDE 3

Superconducting Magnet Division

Technical context Technical context

To demonstrate a high field (>20 T) cosine theta magnet technology for the particle accelerator program The proposed energy and luminosity upgrade of LHC at CERN will require high field dipole and quadrupole magnets

L.S. Lakshmi

Slide No. 3

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Dipole Dipole NbTi NbTi Magnet (BNL) Magnet (BNL)

There is a compelling need to look for a conductor technology beyond the conventional LTS materials. What are the alternate choices? How do we make them “fit for purpose” ?

Quadrupole Quadrupole Nb Nb3Sn Magnet Sn Magnet ( Courtesy: Bill Sampson, BNL) ( Courtesy: Bill Sampson, BNL)

Cosine theta prototype magnets built in BNL using LTS materials

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SLIDE 4

Superconducting Magnet Division

Alternate conductors: HTS Alternate conductors: HTS

Key features of 2G (REBCO ) conductors High current carrying capability at 4 K It decreases slowly with field Robust mechanical properties Endures high mechanical stress (> 700 MPa) and high mechanical strain (>0.5%)

L.S. Lakshmi

Slide No. 4

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Reference: http://fs.magnet.fsu.edu/~lee/plot/plot.htm

Withstands large heat loads Friendly for “react and wind” technology

Note:

  • Anisotropic electrical and mechanical properties
  • Critical bend radius is 6 mm
  • Material cost is significant

complete replacement of conventional LTS might not be a cost-effective solution

  • High field magnets in a hybrid structure (LTS+HTS)

a practically viable new generation magnet technology for the LHC upgrade

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SLIDE 5

Superconducting Magnet Division

Objective Objective

Inner pole Retainer piece for Mid-plane winding Mandrel

Feasibility study

Design and build prototype 2G HTS cos θ

coils and a flat coil for a performance comparison Pole winding (θ= 70⁰ ) and mid-plane winding with complex end-geometry Optimize the winding parameters and

L.S. Lakshmi

Slide No. 5

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Pole winding Mid-plane winding

Optimize the winding parameters and tooling for the complete coil Suitability of Kapton CI wrapping for turn- to-turn insulation and conductor protection- a unique and important design feature of this magnet. Electrical test at 77 K : to understand the conductor / coil performance in the complex end geometry of a cos θ magnet

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SLIDE 6

Superconducting Magnet Division

Conductor details Conductor details

Kapton CI wrapped 2G conductor (supplied by SuperPower Inc.)

Bare conductor specification

Width: 12.14 mm; Thickness: 0.12mm; Total length : 14 m Thickness of HTS layer: 1µm; Hastelloy : 50µm; Cu Stabilizer: 65µm Transport properties at 77 K, self field

L.S. Lakshmi

Slide No. 6

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

The conductor Ic is very uniform along the entire length. Kapton wrapping process did not cause any Ic degradation

After kapton CI wrapping

Spirally wrapped with about 30% overlap between the adjacent Kapton layers Thickness of the kapton CI tape : 25 µm Thickness of the wrapped conductor: 0.177-0.240 mm Transport properties at 77 K, self field Average Ic : 483 A; Minimum Ic : 477 A

Note : Transport current was tested at every 5 m at 77K; Ic is defined under the voltage criterion of 1µV/cm

N= 28

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SLIDE 7

Superconducting Magnet Division

Pole winding: fixtures Pole winding: fixtures

Pole Pole

  • L.S. Lakshmi

Slide No. 7

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Mandrel Mandrel

50 mm 50 mm

Material: aluminium

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SLIDE 8

Superconducting Magnet Division

Pole winding Pole winding

Conductor Conductor off

  • ff-spooling station

spooling station

L.S. Lakshmi

Slide No. 8

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Propeller winding station Propeller winding station

Coil winding tension < 5 Coil winding tension < 5 lb lb

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SLIDE 9

Superconducting Magnet Division

coil coil after the curing process after the curing process

L.S. Lakshmi

Slide No. 9

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Coil after activating the polyimide adhesive at 225 Coil after activating the polyimide adhesive at 225 ⁰ ⁰ ⁰ ⁰ ⁰ ⁰ ⁰ ⁰C C

Coil after uninstalling the inner pole Coil after uninstalling the inner pole

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SLIDE 10

Superconducting Magnet Division

Voltage tap lay Voltage tap lay-out in the coil

  • ut in the coil

Voltage tap lay Voltage tap lay-out in the innermost and outermost coil turns

  • ut in the innermost and outermost coil turns

L.S. Lakshmi

Slide No. 10

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

1 1 2 2

3 4

5 6 7 8 8 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16

Step 1: coil after installing the voltage taps Step 1: coil after installing the voltage taps

  • voltage taps are installed in the smaller straight and critical bend sections
  • f the innermost coil turn
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SLIDE 11

Superconducting Magnet Division

Electrical Test : Preparation Electrical Test : Preparation

Step 2: after reinstalling the winding on the mandrel and the restraining bars Step 2: after reinstalling the winding on the mandrel and the restraining bars

L.S. Lakshmi

Slide No. 11

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Step 3: after Kevlar wrapping Step 3: after Kevlar wrapping

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SLIDE 12

Superconducting Magnet Division

Test results Test results

Y axis represents the end-to end voltage in the coil block (V1-V16)

L.S. Lakshmi

Slide No. 12

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Conductor length :14 m

Dipole coil: I Dipole coil: I-V test at 77 K; self field V test at 77 K; self field

Based on 1µ µ µ µV/cm criterion: Ic= 204 A 0.1µ µ µ µV/cm criterion: Ic= 187.8 A

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SLIDE 13

Superconducting Magnet Division

Field components at 77 K; I = 200A Field components at 77 K; I = 200A

B || || || || - 0.23 T

( max.at the curved sections)

L.S. Lakshmi

Slide No. 13

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Courtesy : Ramesh Gupta

B ⊥ ⊥ ⊥ ⊥ -0.16 T

(max. at the top and bottom coil surface)

B total - 0.23 T

( max. at the curved sections)

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SLIDE 14

Superconducting Magnet Division

Ic Ic (expected) :pole winding (expected) :pole winding

B || || || || - 0.23 T

( maximum at the curved sections) Production wire (M3-909-3)

L.S. Lakshmi

Slide No. 14

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

Ic (average)= 483 A ( bare conductor) Ic (measured) = 204 A (pole winding, 77 K) Ic (calculated) in the coil=217 A (Lift factor* Ic(average)of the bare conductor)

0.448

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SLIDE 15

Superconducting Magnet Division

How do the small coil sections behave? How do the small coil sections behave?

V5 V5 V6 V6 V10 V10 V9 V9

Inner most turn (straight sections) Inner to outer turn and Outer turn

L.S. Lakshmi

Slide No. 15

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

V4 V4 V5 V5 V11 V11

Innermost turn (straight sections) Outer most turn (straight sections)

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SLIDE 16

Superconducting Magnet Division

current distribution in the coil current distribution in the coil

Ic= 204 A; N=27

No local degradation in the complex curved sections of the coil

L.S. Lakshmi

Slide No. 16

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012 V2 V2-V1 V1 V3 V3-V2 V2 V4 V4-V3 V3 V5 V5-V4 V4 V6 V6-V5 V5 V7 V7-V6 V6 V8 V8-V7 V7 V9 V9-V8 V8 V10 V10-V9 V9 V11 V11-V10 V10 V12 V12-V11 V11 V13 V13-V12 V12 V14 V14-V13 V13 V15 V15-V14 V14 V16 V16-V15 V15

27 27 24 24 24 24 25 25 28 28 23 23 24 24 23 23 26 26 24 24 27 27 26 26 27 27 26 26 24 24

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SLIDE 17

Superconducting Magnet Division

Summary and future plans Summary and future plans

  • cos θ magnet using 2G HTS material is practically feasible.
  • Kapton CI insulation provides good mechanical stability.
  • The coil carries significant current 204 A at 77 K, self field condition (as

expected)

  • No significant current drop–out across the complex bend sections.

L.S. Lakshmi

Slide No. 17

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012

  • High N value ( >25) of the coil and the small critical bend sections confirms

that the winding and curing process caused no electrical/ mechanical degradation.

  • Mid-plane winding will be tested at 77 K.
  • Next phase-design, build and test two-layer dipole coil. Measure the field
  • harmonics. Test the coil in a hybrid coil set up in the future.
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SLIDE 18

Superconducting Magnet Division

Acknowledgement Acknowledgement

We acknowledge the contribution of our engineers and the technical staff members.

L.S. Lakshmi

Slide No. 18

LT LTHF HFSW12 SW12

Napa, CA, November 6, 2012