High field magnet R&D status, goals and directions Bruce Strauss August 26, 2013 Fermilab Batavia, Illinois 1

It really started in 1961 Phys Rev Letters 6, 89 (1961), submitted January 9, published February 1, 1961!

Woodstock  1968 Brookhaven Summer Study – 46 th Anniversary this year 3

Direction… “Buy it by the ton.” Paul Reardon, Fermilab

Tevatron Dipole 5 B operating = 4.33 T

LHC Conductor Statistics metric tons of Cu/NbTi composite, Containing about 400 tons of Nb-Ti ingots. Yield: About 7,000 km of large cable, or 300,000 km of SC wire of mm strands. (9 x Ampere-Meters)

History Summary  The vision of 10 T magnets in Chicago in 1913, 2 years after discovery –Bad places in the wire were NOT the cause of Onnes’ wire leaving the superconducting state –Glimpses of the emergence of negative surface energy superconductivity (Shubnikov 1936, Landau 1940s, Abrikosov 1957)  Experimental validation by Kunzler et al. in 1961 made – finally – superconductivity technological from a bulk materials standpoint.  Stability models had by 1968 established the engineering fundamentals for the design of conductors.  The Tevatron development established cryogenics, mechanical engineering and strain management in dipole and quadrupole magnets. The Tevatron changed the SCALE of superconductivity.  Tevatron (FNAL) is finished in 1983 followed by HERA, SSC, RHIC & LHC.  MRI begins about

ITER Conductor Statistics 8 TF CoilsNb 3 Sn826 Tons CS CoilsNb 3 Sn739 Tons PF CoilsNbTi1225 Tons

9 In 1997 when I started at the Department of Energy there were two dipole magnets reported in the literature that had exceeded 11 Tesla, constructed with Nb 3 Sn, and had real bore tubes…

MSUT Magnet 10 “At the very first high-field ramp the current was ramped with 2 A/s to the first quench at a current of 18.7 kA, corresponding to a record central dipole field of T.” A. den Ouden et. al., “Application of Nb 3 Sn Superconductors in High-Field Accelerator Magnets,” IEEE Transactions on Applied Superconductivity, V7, No. 2, June 1977

D20 magnet at LBNL 11

Events and Change—1997 to Construction of the LHC at CERN MSUT at Twente and D20 at LBNL US leaves ITER. At DOE HEP we wondered what to about the three magnet groups at national labs. Sutter gets $500,000/year from John O’Fallon for industrial development of Nb 3 Sn. Conductor Development Group is formed. HEP Nb 3 Sn magnet development resumes with surplus ITER strand. Sutter remarks…

A Convert… 13 “…20 tesla or bust!” Dave Sutter, DOE

Taking Stock 14 As a result of the DOE programs in AARD, GARD, CDP and LARP: J c of Nb 3 Sn doubles D eff minimized RRR optimized Scaling ITER Asymptotic improvements presently A series of dipole and quadrupole magnets have been constructed. Peak field appears to have hit an asymptote.

At 53, LTS’s have reached maturity Data by courtesy of J. Parrell (OST) US-CDP ITER wires HL-LHC wires splendor

The Business of Science ® © Oxford Instruments 2014 “Industrialization” = bridging the gap Product optimization Customer acceptance Manufacturing scale up Process optimization The Innovation Cycle

The Business of Science ® © Oxford Instruments 2014 Nb 3 Sn development for HEP: 10+ years of steady improvement US HEP GOALACHIEVED J c (12T)>3000A/mm Piece length: full billet, no breaks 2007 D s <40 microns with high RRR 2013 Increasing stack count, smaller D s → Materials development is a long term exercise. Sustained customer support (in this case the US DOE) has been key to enabling advances in the field Progress continues

LBNL holds Nb 3 Sn dipole magnet records in 3 configurations … but are hitting a wall at ~14T with a realistic bore ➯ Need a new paradigm D20 RD HD Record dipole fields>~14T in each configuration Incorporating bore reduces peak field attained Detailed investigation suggests limitation is mechanical: Stresses approach 200MPa (Nb 3 Sn limit) Shear stresses / interface stress issues Field performance is correlated with Conductor performance Courtesy of Soren Prestemon (LBL)

J e Sensitive to Operating Temperature Engineering Critical Current Density (A/mm²) Applied Magnetic Field (T) 3.3 K 3.6 K 3.9 K 4.2 K 4.5 K 4.8 K 5.1 K 4.2 K RRP ® data scaled using Nb 3 Sn Scaling Spreadsheet - Matthijs Mentink, Diego Arbelaez, Arno Godeke [LBNL] Available from ot/plot.htm ot/plot.htm Nb 3 Sn (RRP®): Non-Cu J c Internal Sn OI-ST RRP® 1.3 mm, Parrell, J.A.; Youzhu Zhang; Field, M.B.; Cisek, P.; Seung Hong;, "High field Nb 3 Sn conductor development at Oxford Superconducting Technology," Applied Superconductivity, IEEE Transactions on, vol.13, no.2, pp , June doi: /TASC and Nb 3 Sn Conductor Development for Fusion and Particle Accelerator Applications J. A. Parrell, M. B. Field, Y. Zhang, and S. Hong, AIP Conf. Proc. 711, 369 (2004), DOI: /

1986, the 75 th Anniversary…Change!  POSSIBLE HIGH-TC SUPERCONDUCTIVITY IN THE BA-LA- CU-O SYSTEM BEDNORZ JG, MULLER KA Z FUR PHYSIK B-CONDENSED MATTER 64, , Times Cited: 7,656 POSSIBLE HIGH-TC SUPERCONDUCTIVITY IN THE BA-LA- CU-O SYSTEM7,656 Superconductivity induced by doping carriers into an insulating anti- ferromagnetic state Non-Fermi liquid behavior, but strong correlations that still prevent any generally accepted model for superconductivity in the cuprates 21

HTS MAGNETS ARE...

Magnet R&D Issues 23 Conductor Magnet Field Engineering Electrical Insulation Mechanical Engineering Safety and Protection Cryogenics

Magnet R&D Issues 24 Conductor Magnet Field Engineering Electrical Insulation Mechanical Engineering Safety and Protection Cryogenics

HTS Conductors… The highest H irr /H c2, J c (H,T) and J E (H,T), T c Fabricability into wires with flexible architectures Low cost/performance ratio Small environmental footprint High strength Ability to wind as is Long lengths High Current Cables Low ramping losses and magnet protection What do we have now…….? 19 What do magnet builders want?

Preferred conductor features: Multifilament Round or lightly aspected shape with no J c anisotropy Capability to wind in unreacted form while conductor fragility is minimized Nb47Ti (OST)Internal Sn Nb 3 Sn (OST) Bi-2212 (OST) Bi-2223 (AMSC) MgB 2 (Hypertech) YBCO coated conductors next……………

Ni-W alloy (50-75  m) Y 2 O 3 (~75 nm) YSZ (~75 nm) CeO 2 (~75 nm) Ag (<1  m) Copper Stabilizer  m Metallurgical Texture introduced here (RABiTS) Pilot production of m lengths. Now approaching 1km Textured Ni-W alloy (50-75  m) Y 2 O 3 (~75 nm) YSZ (~75 nm) CeO 2 (~75 nm) YBCO (1-5  m) Ag (<1  m) cm 1 cm – 100 m Copper Stabilizer  m The RABiTS CC The IBAD approach – ion-beam-assisted deposition of the textured template 50  m substrate ~ 80nm alumina ~ 10nm IBAD MgO ~ 30nm LMO ~ 30nm Homo-epi MgO ~ 7nm yttria ~ 1  m YBCO 2  m Ag 40  m Cu And coated conductors of YBCO which approximate single crystals by the mile……. 27

Market Demand

Larbalestier - NHMFL EAC Mtg., July 22-23, 2014 – confidential – do not distribute Slide 29 Maeda and Yanagisawa IEEE TAS 24, (2014) Outcome: Bi-2223 insert gave signals equivalent to LTS magnet By contrast, great difficulty stabilizing and shimming the REBCO magnet Non-linear, hysteretic effects in REBCO coil Quite different shielding current patterns in multi- and single filament conductors RIKEN experience with 2223 and REBCO in their 500 MHz solution NMR system (100 MHz HTS MHz LTS) Screening Currents in HTS Tapes

Larbalestier - NHMFL EAC Mtg., July 22-23, 2014 – confidential – do not distribute Slide 30 Prior to 2012, all HTS Conductors (Bi-2223, REBCO) were Tapes Delivered in Reacted Form 30 Bi-2212 upended this paradigm, delivering the highest conductor current density in round-wire The first HTS conductor to look like an LTS conductor Conductor must be wound, then reacted Big advantage – very flexible architecture, multifilament, twisted form Big disadvantage – reaction complexity 2212 (25% sc) REBCO coated conductor (1% sc) 2012 with bar over-pressure (OP)

…even though HTS greatly extends properties at 4K… Courtesy Peter Lee J E floor for practicality

Magnet R&D Issues 32 Conductor Magnet Field Engineering Electrical Insulation Mechanical Engineering Safety and Protection Cryogenics

LTSW2013, 4/11/2013A. Ballarino The essential role of the superconductors in the search for higher energy J eng  400 A/mm 2 Nb-Ti up to 8 T Nb 3 Sn up to13 T HTS up to 20 T Proceedings of MT-23 HTS: more than 1500 tons procurement by 2030  Concept and models now 33

Magnet R&D Issues 34 Conductor Magnet Field Engineering Electrical Insulation Mechanical Engineering Safety and Protection Cryogenics

Magnet R&D Issues 35 Conductor Magnet Field Engineering Electrical Insulation Mechanical Engineering Safety and Protection Cryogenics

Mechanical Engineering…  Forces ~B 2  Energy ~B 2  Virial Theorem M~E/σ 36

Magnet R&D Issues 37 Conductor Magnet Field Engineering Electrical Insulation Mechanical Engineering Safety and Protection Cryogenics

High field does not improve propagation but reduces stability margin L. Ye, F. Hunte and J. Schwartz, SuST (8 pp) (2013)

Cost Considerations

Raw Materials Cost 2014 Wire type Raw materials cost $/kg Materials $/m P- factor Price $/m Comments NbTi LHC-type 0.8 mm diam NbTi alloy 280 OFHC 11.5 Barrier (.60) Based on Cooley (2005) -Nb cost increased 2.7x (USGS MCS 2014) -Cu cost increased 2.3x (USGS MCS 2014) -P-factor well established Nb 3 Sn RRP-type 0.8 mm diam NbTa alloy 785 OFHC 11.5 Barrier Based on Cooley (2005) -Nb cost increased 2.7x (USGS MCS 2014) -Cu cost increased 2.3x (USGS MCS 2014) -P-factor reduced for increased product maturity YBCO 40Superpower 2014 Bi mm diam Ag alloy 640 powder Based on Cooley (2005) -Ag cost increased 3.7x (silverprice.org) -Powder price unchanged

J E (B) Data Used for Price/Performance Comparison Larbalestier, et al. Nat. Mat /nmat3887

Price/Performance 2014 (Ag $20/oz.)

Price/Performance with Ag at $30/oz. Ag at $30/oz Ag at $20/oz

Price/Performance with Ag at $5/oz Ag at $5/oz Ag at $30/oz

Raw Materials Cost 2014 Wire type Raw materials cost $/kg Materials $/m P- factor Price $/m Comments NbTi LHC-type 0.8 mm diam NbTi alloy 280 OFHC 11.5 Barrier (.60) Based on Cooley (2005) -Nb cost increased 2.7x (USGS MCS 2014) -Cu cost increased 2.3x (USGS MCS 2014) -P-factor well established Nb 3 Sn RRP-type 0.8 mm diam NbTa alloy 785 OFHC 11.5 Barrier Based on Cooley (2005) -Nb cost increased 2.7x (USGS MCS 2014) -Cu cost increased 2.3x (USGS MCS 2014) -P-factor reduced for increased product maturity YBCO 40Superpower 2014 Bi mm diam Ag alloy 640 powder Based on Cooley (2005) -Ag cost increased 3.7x (silverprice.org) -Powder price unchanged Bi Use RRP fabrication cost (+$7.50/meter)

Ag at $20/oz with RRP Fabrication Cost $20 Ag & RRP fab cost

Price/Performance with Ag at $5/oz Ag at $5/oz Ag at $30/oz

The Business of Science ® © Oxford Instruments 2014 (ASC 2004) Beyond Nb 3 Sn: Bi-2212 wire …even if development has been slower than it might have been The difference from Nb 3 Sn? A lesser market pull The promise of 2212 has long been apparent… Voids – the signs have been there for some time

The Business of Science ® © Oxford Instruments 2014 (ASC 2010) Progress, but “pushing” only goes so far… (ASC 2006) Steady conductor improvement Steady device improvement But limited opportunities… → Missing that virtuous circle (MT-2011)

The Business of Science ® © Oxford Instruments – now ready to be “pulled”? Conductor development situation now similar to Nb 3 Sn in the early 2000’s Performance may be good enough today to break into “real” applications – we now need that market pull 2212: the workhorse material for cutting edge magnets at ASC 2024?