32 T All-Superconducting Magnet

W. Denis Markiewicz User Committee Meeting National High Magnetic Field Laboratory October 1-3, 2009

Contents

Overview Magnet Parameters Schedule Installation Technology Development

Overview

A proposal was submitted to the Major Research Instrumentation program for a 32 T all-superconducting magnet using YBCO coated conductor inner coils.

The proposal was funded with an effective start date of Oct. 1, 2009, for a duration of three years.

The scope of supply includes the full magnet system: inner and outer magnets, cryostat, power supply, and protection electronics.

The installation of the magnet is presently planned for the milli-Kelvin facility.

32 T Magnet Parameters

Total field 32 T Field inner YBCO coils 17 T Field outer LTS coils Cold inner bore Uniformity

YBCO

15 T 32 mm 5x10 -4

Nb3Sn

1cm DSV Current 186 A

NbTi

Inductance Stored Energy 436 H 7.54 MJ YBCO coil Inner radius (mm) Outer radius (mm) 1 20 42 Coil length (mm) Field increment (T) 144 5.7

Conductor length (km) 0.75

2 47 71 240 5.7

2.4

3 77 101 340 5.6

5.2

32 T Magnet System Components

System component Source YBCO coils YBCO conductor Outer magnet Cryostat Power supply Protection electronics Facility NHMFL industry industry industry industry NHMFL NHMFL Both the YBCO conductor and the outer magnet are major components that will require collaboration with industry to establish the design and specification.

32 T Project Schedule

We are here.

The funded project starts Q4 2009 and is planned for three years.

The program has three phases: (1) development, (2) prototype coils, and (3) detailed design, fabrication and procurement.

Major procurements include the YBCO conductor and the outer magnet.

milli-Kelvin Facility

The low noise of the milli-Kelvin facility will offer best advantage for the inherently quiet 32 T superconducting magnet.

The long term goal is the combine the 32 T magnet with a new dilution refrigerator.

Along with the other superconducting magnets, the milli-Kelvin facility has the infrastructure and staff to support the 32 T magnet within the user facility.

milli-Kelvin Facility

The 10 G and 100 G fringe field lines of the 32 T magnet are shown for potential locations in the milli-Kelvin facility.

Technology Development Topics

Ic(B) critical current versus field Ic( θ) critical current versus field orientation Ic( ε) critical current versus strain σ(ε) stress strain curve Es( ε) secant modulus versus strain Joint Ic( ε) Joint resistance Joint strength Joint bend characteristics Insulation conductor Pancake winding Layer winding Quench protection

YBCO Critical Current Characterization

Ic(B), Ic( θ), Ic(ε)

600 500 400 300 200 100 0 0

Conductor is becoming well characterized.

Sufficient data for 32 T design.

Ic(B perp) Ic( θ)

T = 4K 10 B(T) 20 30 6 5 4 3 2 1 0 0 30 60 90 orientation theta (deg) 120

Ic( ε)

YBCO Mechanical Characterization

σ(ε) stress-strain, Es(ε) secant modulus The conductor is mechanically well characterized for the 32 T design.

YBCO stress strain 1200 1000

Mpa 20 4K Mpa 20 77K

800

Mpa 18 4K

600 400

Mpa 18 77K Mpa 21 4K

200 0 0.0E+00 2.0E-03 4.0E-03 6.0E-03 strain 8.0E-03 1.0E-02

Mpa 21 77K

YBCO secant modulus 250 200 150 100 50 0 0.0E+00 2.0E-03 4.0E-03 6.0E-03 8.0E-03 1.0E-02 1.2E-02 strain

E 20 4K E 20 77K E 18 4K E 18 77K E 21 4K E 21 77K

YBCO Joint Characterization

There are a large number of joints in the 32 T YBCO coils.

Measure joint mechanical strength is high with no shear delamination.

The literature suggests high strain tolerance for soldered joints.

Initial in-house measurements show relatively low values, but have been attributed to unconstrained bending in the tensile test.

Further test method refinement and additional tests are underway.

Conductor Insulation

Insulation processes under examination:

Varnish dip coat

facility in place at NHMFL demonstrated ability to coat with 25 μm build debonding observed at high conductor strain examine thinner builds, multiple pass

Varnish spray coat

equipment being assembled objective: thin uniform coat with edge coverage

Oxide coat: ZnO, Al 2 O 3

Very thin coat potential < 1 μm build Issues: adherence, rate of deposition, cost Working with industrial sources YBCO conductor is not supplied with a thin insulation suitable for high field magnet construction.

YBCO Coil Technology Development

Process: Make a series of model and test coils.

Focus on the detailed, systematic evaluation of components and processes.

Establish a reliable technology prior to fabrication of major prototype coils.

Options: Pancake wound coils.

Positives: ease of winding and reinforcement, short conductor lengths.

Negatives: large number of solder connections and components, vulnerability of external joints.

Layer wound coils.

Positives: unified winding pack, fewer connections Negatives: wide direction bend of conductor, joints within windings.

Through a series of small coils, the technology will be established before fabrication of major prototype coils.

YBCO Test Coils

SuperPower I.

Bmax = 26.8 T ΔB = 7.8 T SuperPower II.

Bmax = 27 T ΔB = 7 T NHMFL I.

Bmax = 33.8 T ΔB = 2.8 T NHMFL II.

Bmax = 20.4 T ΔB = 0.4 T

YBCO Test Coils and 32 T YBCO Coils

SuperPower I.

NHMFL I.

SuperPower II.

NHMFL II.

32 T YBCO Coils

Quench Protection at Low Normal Zone Propagation Velocity

Quench protection will be accomplished with densely distributed heaters.

Heater response time and effective normal volume will be measured in series of layer and pancake wound coils.

Quench protection study determines the required amount of copper in the conductor.

Project Staffing

Scott Bole (design) Andy Gavrilin (analysis) Ke Han (materials) Jan Jaroszynski (conductor) David Larbalestier (co-PI) Jun Lu (materials characterization) Denis Markiewicz (PI) Lee Marks (technician) Patrick Noyes (test) Ken Pickard (technician) Andy Powell (electronics) Bill Sheppard (technician) Kevin Smith (administration) Ulf Trociewitz (magnet design) Youri Viouchkov (design) Huub Weijers (test) Vaughn Williams (machine shop) Aixia Xu (conductor)

The End Thank You