Superconducting R&D – Now Strand and Cable R&D

FERMILAB

Magnet Systems Department – Now SC Materials Department (TD)

HTS Insert Coil Test in External Solenoid Field

Emanuela Barzi

All Experimenters’ Meeting, July 11, 20111

Motivation of R&D

High Temperature Superconductors (HTS) are of interest for Muon Collider and/or Neutrino Factory accelerator magnets

The muons initially occupy a large 6D phase space, which must be cooled by a factor O(106). In the muon ionization cooling channel designs, the muons are confined within a lattice of high-field solenoids. The square-root of the final transverse emittance that is achievable is inversely proportional to the solenoid field at the end of the channel. The achievable luminosity in the collider is therefore proportional to this solenoid field, up to fields of about 50 T, beyond which the beam-beam tune shift is expected to limit the luminosity. 2

0 3 6 9 12 15 18 21 24 27 300

200

400

600

800

1000

1200

1400

1600

YBCO (Bparallel)

YBCO (Bperp)

Nb3Sn

NbTi

Applied Field, T

JE (

4.2

K),

A/m

m2

“Study of HTS Wires at High Magnetic Fields” , D. Turrioni, E. Barzi, M. J. Lamm, R. Yamada, A. V. Zlobin, A. Kikuchi . IEEE Trans. On Appl. Superconductivity 19, No 3, Part 3, 3057-3060 (2009).

Why HTS?

“Angular Measurements of HTS Critical Current for High Field Solenoids”, D. Turrioni et al.. Advances in Cryogenic Engineering, V. 54, AIP, V. 986, pp. 451-458 (2008).

1. Magnet design studies - Since 2007, A. Zlobin, V. V. Kashikhin, E. Barzi, E. Terzini“Study of High Field Superconducting Solenoids for Muon Beam Cooling”, V. V. Kashikhin et al.. IEEE Trans. Appl. Sup., V. 18, No. 2, p. 928 (2008).“Towards 50T Solenoids”, E. Barzi - https://indico.fnal.gov/conferenceDisplay.py?confId=3148.Analytical Study of Stress State in HTS Solenoids – Stress distribution in a solenoid was studied for various constraint configurations, max. stresses were produced as a function of coil self-field, and results compared with Finite Element Models. E Terzini, E. Barzi, FERMILAB-TM-2448-TD.

2. HTS Conductor R&D – Ongoing since 2005, E. Barzi, L. Del Frate, V. Lombardo, D. TurrioniConductor characterization – Studies of Je as a function of B, T, angle, and bending, longitudinal and transverse strains.BSCCO-2212 cable development.YBCO Roebel cable.

3. Insert Coil Development – Since 2008, E. Barzi, G. Norcia, A. Bartalesi, A. Cattabiani, G. Gallo, V. Lombardo

Winding methods and tooling, impregnation techniques, splicing procedures, R&D on thermally conductive insulation.Development of modular test setup.Magnetic models for insert and background field were developed to calculate short sample limits of insert coils.Co-wound and impregnated YBCO coil were represented by meso-mechanic models. A. Bartalesi, FERMILAB-MASTERS-2009-04.

4. Insert Coil Test – Since 2009, D. Turrioni, P. Vicini, V. LombardoDevelopment of instrumentation, DAQ, quench protection and detection systems for insert coil tests. Test pancake assemblies in 14 T/77 mm bore existing magnet and provide feedback to coil technology development.

HTS Work Directions

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Conductor SuperPower SCS4050-i

Ic (A) Average @77K,0T 113 A

Ic (A) Minimum @77K,0T 107 A

Ic Standard Deviation 2.7%

Turn to Turn Insulation Spiral Wrapped Kapton

Coil Geometry Double Pancake – no inner splice

Coil ID 19 mm

Coil OD 62 mm

Conductor Thickness 0.1 mm

Conductor + Insulation Thickness

0.2 mm

Packing Factor 50%

Turns per Single Coil 108

Conductor length per Coil 13.9 m

Overall Conductor Length 27.8 m

Coil Resistance @ 300K 2.87 Ohm

Coil Inductance @1kHz 1.5 mH

Double-Pancake Units

Modular Insert Test Setup

14 T solenoid with

77 mm bore

Modular Insert Test Facility

6

Coil1

Coil2

Coil3

Coil4

Modular Test Facility for HTS Insert Coils”, V. Lombardo, A. Bartalesi, E. Barzi, M. Lamm, D. Turrioni and A.V. Zlobin”. IEEE Trans. Appl. Sup., V. 20, No. 3, p. 587 (2010).

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Result - 21.2 T with 14 T Bkg. Field

YBCO Insert Coil

External Magnet

Max Current Reached 335 A

SSL 92%

Peak Field on Conductor

21.5 T

Peak Axial Field 21.2 T

What Next?

This insert coil produced 7.5 T in a 14 T background field (about 9 T at self-field).

This is an intermediate result with respect to our final goal. To develop a technology for 35 T+ solenoid, we need to double (~15 T) the field of the HTS insert in a background field of ~ 20 T provided by Nb3Sn/ NbTi hybrid coils.