High Field DC Magnet Technology David Larbalestier and Mark Bird National High Magnetic Field Laboratory Florida State University, Tallahassee FL 32310 NSF Site Visit Review December 6-8, 2011
2006 MagLab Renewal Proposal was based on technology needed to address COHMAG opportunities New magnets for neutron and x ray scattering should be built New grand magnet challenges: 30T NMR (All Superconducting) 60T Hybrid (Resistive + Superconducting ) 100T Long Pulse (Resistive) Agencies supporting MR research should also support magnet and probe technologies How better to achieve these goals: All required materials in conductor forms that were not available in 2004 or 2006! The renewal was thus on evaluating and developing coil-relevant conductor forms of Bi-2212, MgB 2 and YBCO.the involved communities [users and magnet builders] should cooperate to establish a consortium whose objective would be to address the fundamental materials science and engineering problems that will have to be solved.. COHMAG report p. 109
Outline of my talk What has happened since COHMAG? What we are planning in the next 5 years? How are we addressing COHMAG goals and are new goals appropriate? it? DC resistive magnets (Pulsed magnets Chuck Mielke) All superconducting magnets DC hybrid resistive/supercon ducting magnets
Resistive magnet history at MagLab ID Task Name 1 Start Date 9/14 2 1st 27-T Magnet 3 2nd 27-T Magnet 4 Dedication 5 3rd 27-T Magnet 6 4th 27-T Magnet 7 1st 30-T Magnet 8 2nd 30-T Magnet 9 1st 24.5-T, 50-ppm Magnet 10 1st 33-T Magnet 11 NASA 12 NRIM 13 Keck 14 Large Bore 15 2nd 33-T Magnet 16 27-T, 50-mm Magnet 17 33-T II 18 45-T Hybrid 19 Insert Only: 32.5-T 20 44-T Record 21 45-T Record 22 Outsert Damaged 23 New Insert 24 Nijmegen 25 31-T, 50-mm 26 35-T, 32-mm 27 28-T, 50 ppm 28 25 T Split 29 Cell 2: 31 T, 50 ppm 92 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 6/22 9/19 10/1 1/17 1/30 3/18 4/27 7/25 2/5 World Records! 6/24 11/11 2/27 6/3 9/9 World Records! 6/1 6/6 5/17 12/11 6/26 7/10 2/1 The MagLab has designed and built the world s most powerful resistive magnets which serve ~400 users/year at MagLab. PARAMETERS Mechanical Stress ~90% of yield (650 MPa) Current Density ~ 700 A/mm 2 Florida-Bitter: Elongated holes in staggered grid reduce stress & increase efficiency 40%. 4/10 Power Density ~ 13 W/mm 3 Heat Flux ~ 7 W/mm 2. 4/7 12/12 8/2 World Records! 4 6/30 8/4
25 T SPLIT RESISTIVE MAGNET 4 ports of 45 Invented new Florida Split-Helix technology to wrap coils around vacuum space. ld (T) Fiel 30 Grenoble 25 20 15 10 MIT HZB VM-1 Tallahassee HZB Hybrid 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Solid Angle (steradians) At the mid-plane: 51% vacuum space. 10% steel. 584 tons of magnetic compression. 220 l/s of cooling water. 160 ka of current. MagLab split magnet provides 56% higher field than nexthighest-field split magnet worldwide. Rotation configuration needed to allow Faraday geometry. 5
World-Record 35 T, 20 MW Florida-Bitter magnet at MagLab. 2.7 m 36 T, 24 MW Polyhelix magnet under development in Grenoble. Resistive Magnet Development 2013-2018 1.4 m France, Netherlands and China are making major investments in dc fields and will soon surpass or match present MagLab capabilities. 38 T, 24 MW Florida-Bitter magnet under development in Nijmegen. 2.1 m MagLab Florida-Bitter technology continues to be more efficient than competition. The proposed new 28 MW resistive magnets will allow the MagLab to triple access to ~40 T fields and utilize the 41 T, 28 MW 56 MW power supply upgrades Florida-Bitter previously funded by Florida. magnet proposed for MagLab.
HTS conductors can transform superconducting magnet technology A decisive break from Nb Ti and Nb 3 Sn 120 J c is always limited by proximity to H c2 100 Bruker achieved (2009) 1 GHz (23.5T at ~1.5K) in a Nb Ti/Nb 3 Sn NMR 80 magnet A magnificent but asymptotic 60 advance! HTS removes the H c2 or H irr restriction 40 butimposes newones Stress 20 Quench protection A young and still primitive conductor 0 technology with conductor materials much more complex than Nb Ti or Nb 3 Sn Irre eversibility Field F (T) Bi-2212 RW YBCO ( ) Nb 3 Sn Bi-2223 ( ) Nb-Ti 0 20 40 60 80 Temperature (K) Nb 3 Sn is limited to ~18 T in saddle magnets and ~ 24 T in solenoid magnets 100 T H c2 conductors are potentially transformational for magnet technology
The HTS conductor choices Bi 2223 multifilament tapes Bi-2223 tapes exhaustively studied for power applications 30-77K: Now mature lower Je than 2212 and YBCO Bi-2212 round wire ~ 1mm dia. REBCO coated conductor tapes 4-12 mm wide by ~ 0.1 mm thick 20μm Cu 50μm Hastelloy substrate 20μm Cu 2 μm Ag 1 μm HTS ~ 30 nm LMO ~ 30 nm Homo-epi MgO ~ 10 nm IBAD MgO
Short sample current densities of Bi 2212 and YBCO exceed Nb 3 Sn above about 20T 3 REBCO is strongly anisotropic while all others are isotropic! But champion short sample properties do not always extend to coil lengths
2006 2012: round wire 2212 revival Restarted collaboration with OST aiming at round wire conductors Showed capability of small coils 1T in 31T, 2T in 20T Started to understand why J c was both highly variable and best mark unimproved since 2005 Formed the VHFSMC collaboration with DOE HEP labs and contractors and industry uncovered some of the key variables controlling J c in this complex material Now developing an integrated conductor and insulation technology at winding density of 200 A/mm 2 to enable 30T NMR and 5-10 ka cables for accelerator Larbalestier magnets - SciMag NRC DOE-HEP Panel : Washington collaboration DC, March 12, 2012 1.1T in 31T 12.7 μm
2007 2012: REBCO coil development Partnered with SuperPower to assess the capability of REBCO coated conductors for magnets 27 T (2007), 33T (2009), 35.5T (2011) with REBCO Used coated conductors as design basis for a 32T user magnet Wrote funded MRI proposal to NSF in 2009 now in construction Partnered with other key players to drive conductor technology Muon Accelerator Project for US HEP CERN LHC Energy upgrade with HTS cables (EUCARD2) we are the US point of contact through our leadership of the US HEP HTS collaborations on 2212 EUCARD2 European proposal p for REBCO and 2212 cables has reviewed well Need NIH interest to drive NMR technology 27 T 28 T 34 T 35.4 T, layer wound in one 760 MPa 120 m piece 2007 2009 2008 2010 2011 >500 m coil in 2012 REBCO coated conductors available now in 50-150 m lengths we have pushed the limits in support of a conservative Larbalestier - SciMag32 NRC T Panel user : Washington magnet DC, March design 12, 2012 and for future big magnets
NHMFL 32 T: The first HTS user magnet High field 24/7 use Low operating cost Breakthrough from current 18/20 T level HTS Technology choices REBCO Coated conductor, single strand Conservative design with margin Focused project team Reliability is key Supported by broader, aggressive R&D program Close interaction with conductor vendor The first ever all superconducting magnet with B >24T Key technological choices made Now: full-featured test coils 2013: User operations HTS/LTS hybrid (LTS outsert from industry) 32 T, 4.2 K, 32 mm bore Standard physics homogeneity Dilution refrigerator : <20 mk
HTS coil stress and energy challenges Byear b 2003 2008 2008 b BSCCO B A +B HTS =B total J ave Stress [MPa] Stress [MPa] [T] [A/mm 2 ] J ave xbb A xrr max J e xb A xr max 20+5=25 T(tape) 20+2=22 T(wire) 31+1=31 T (wire) b2007 YBCO- SP 19+7.8=26.8 T 259 215 382 89 92 80 125 69 47 175 109 89 b 2008 YBCO-NHMFL 31+2.8=33.8 T 460 245 324 2009 YBCO -SP 20+7.2=27.2 211 185 314 b 2009 YBCO-NHMFL (strain limited) 20+0.1= 20.1 241 392 ~611 φ 163 mm 35 30 open symbols: BSCCO solid symbols: ReBCO 600 500 B CF [T] 25 20 15 peak field trend peak winding J 400 300 200 100 J m 2 ave [A/mm ] φ 39 mm Bi 2212 φ 38 mm 10 0 1990 1995 2000 2005 2010 Larbalestier year [-] - SciMag NRC Panel : Washington DC, March 12, 2012 YBCO SP 2007 φ 87 mm
HTS cables are essential for large coils Bi-2212 Rutherford cable Applications for HTS cables Scale of DC Hybrids at NHMFL REBCO Coated conductor 4 x 4 mm Twisted cable 5or12mm ROEBEL cable CORC cable on round core 6 + mm Spiraled cable Oak Ridge SNS Zeemans magnet CERN DEMO (post-iter) Muon collider etc 6 &12 tapes @ 20 T,4.2 K : OK February 2012: Successful test of 4 ka CORC REBCO cable in 20 T background Cables keep inductance small, allowing fast ramp and safe quench
2 nd Gene eration 1 st Gen 3 rd Gen Constru uction Magnet Total Field (T) First Ops Outsert Field (T) Energy (MJ) Technology MIT I 20 1972 5.8 ventilated, cryostable? McGill 25 1972 15 Oxford I 16 25 1973 6.5 Stabilized NbTi Moscow 25 1973 6.3 4 Ventilated multifilamentary strip Nijmegen I 25 30 1977 8.5 Ventilated, cryostable MIT II 25 30 1981 7.5 3.5 Ventilated, cryostable Sendai I 20 1983 8 1 no ventilation Sendai II 24 1984 8 5 Sendai III 31 1985 12 19 Nijmegen II 30 1985 10.5 10 Ventilated, cryostable Grenoble I 31 1987 11 22 Ventilated Hefei I 20 1992 7 1.4 Adiabatic MIT III 34 35 1991 13 21 Quasi adiabatic Tsukuba 31 37 1995 15 63 fully stable monolithic NHMFL I 45 1999 14.2 100 CICC Sendai iiv 23 2003 6 2 Cryogen free Sendai V 30 2005 11 8 Cryogen free NHMFL II 36 41 2014 13 52 CICC Grenoble II 42+ 20 8.5 76 Quench Shield, RCOCC Nijmegen III 45 2016 12 40 CICC Hefei II 40 2013 11 CICC Berlin 25 2013 13 52 CICC Resistive- Superconducting Hybrid Magnets High-Field Resistive Inner Coils. Low-power SC outer coils. 17 built to-date. MagLab pioneered Cable- In-Conduit Conductor CICC for hybrids. 4 of 5 hybrid projects underway today use CICC. The MagLab has developed: Most user-friendly and productive hybrid in history Unique facilities for testing CICCs. Tested CICCs extensively. Conductors. Coil-fabrication technology.
MagLab Series Connected Hybrid (LTS) Magnets Proposed SCH high-field insert will give 41 T using only 13 MW (40% reduction from present). 3 Magnets, 3 Funding Sources, 1 Outsert Conductor set 1.7 m All superconducting LTS outsert/hts insert favored now MagLab Tallahassee, FL 36T 13 MW 1ppm NMR Funded by NSF Helmholtz Center Berlin (HZB) Berlin, Germany 25-30 T 4-8 MW Neutron Scattering Helmholtz Foundation Spallation Neutron Source (SNS) at ORNL 25-30T 0 MW Neutron Scattering Proposal Submitted to NSF & DOE All use 14 T Nb 3 Sn superconducting outsert magnet
COHMAG Challenge: 60 T Hybrid needs HTS cable Existing 45 T, 30 MW Cu 50 T, 14 MW Concept 60 T, 14 MW Concept (Desired by Tsukuba, Sendai, Grenoble, Nijmegen) 1 m LTS CICC HTS CICC LTS CICC 1.1 m HTS CICC LTS CICC 1.6 m 0.84 m Field (T) 1.1 m >45 T class Concepts Worldwide Power (MW) Outsert Field (T) Energy (MJ) Sendai/Tsukuba 47 15 20 94 Grenoble 50 24 13 Nijmegen 50 28 Tallahassee 50 14 28 220 Tallahassee 60 14 43 600 1.6 m MagLab bdeveloping 50 T Conductor concept for use on 3 continents. Development of HTS & LTS cables, coil technology, and test facility essential for a 50 60 T hybrid.
LTS (Nb3Sn) and HTS CIC Conductors (dimensions in mm) Series Connected 30 Hybrid Nb3Sn High Field 28.7 45 T Hybrid Nb3Sn Coil A 16.3 10 ka, 14 T 60 T Hybrid Concept REBCO 80 ka, 43 T 50 8 50.8 50 T Hybrid Concept REBCO 30 ka, 28 T ITER CS Nb3Sn 45 ka, 13 T HTS conductors could be REBCO or 2212 cables 45
Conductor and Test Coil technologies are intimately linked Coils, R&D Test tbeds 27T with SuperPower 35.5 T REBCO NHMFL 15T BNL/PBL Conductors HTS Magnet YBCO Systems 2212 32 T, 30 T NMR, SMES, hybrid magnets Base support Muon Colliders, LHC energy upgrade. EUCARD2 The SBIR and CDP (Conductor Development Program within DOE-HEP) have maintained a strong industrial component need replacement for lost DOE-EERE support for utility applications DOE Office of Science (BES, Fusion, HEP, NP) use.
Could an Fe base superconductor compete too? 2 ) J c (A/cm 10 6 10 5 K doped Ba-122 10 4 10 3 Co doped Ba-122 10 2 Sm-1111 10 1 FeSe 0 5 10 15 Magnetic Field (T) μ 0 H ( T ) 100 80 60 40 K doped BaFe2 As2 Low anisotropy and very high Hc2 H//c H//ab Single crystal MgB 20 2 Bulk Nb 3 Sn 0 0 10 20 30 40 T ( K ) μ 0 H/T c ( T/K ) 1.0 0.8 0.6 0.4 0.2 Bulk H//ab Single Crystal 0.0 0.85 0.90 0.95 1.00 T/T c Recent untextured bulk polycrystals and wire forms show J c >10 3 A/mm 2 and 3 times higher H c2 than Nb 3 Sn High Jc only seen in fine grain samples a b Weiss et al. under review 100 nm 5 nm
SUMMARY MagLab achievements Resistive: 14 record magnets serve ~400 MagLab users/year. Florida technology is now used at 5 of the 6 largest labs worldwide. 28 MW upgrades will allow tripling of access to 40 T. Hybrid Outserts: Nb 3 Sn CICC are now being used for 5 of 6 resistive/superconducting hybrids under development worldwide. 50 60 T hybrids using LTS/HTS outserts being considered at 5 labs using MagLab concept designs HTS Magnets & Materials: MagLab s HTS effort spans YBCO and Bi2212 conductor and coil technology development Integrated with commercial, government and international partners. 32 T user magnet, should lead the way to 30 T NMR Cable technology development vital to accelerator magnets and for x ray and neutron scattering Major collaborations provide basis for COHMAG desired consortium.
10 year outlook summary HTS magnet technology vitally dependent on conductors Relatively mature for DC and pulsed resistive magnets HTS conductors are in scale up phase now but base conductor support historically done by DOE (HEP and EERE) is now very much at risk Cuprate HTS conductors have allowed almost 50% more field than LTS (35 vs. 24T so far) 40 50 T feasible too Conductor technology is still primitive (too short, not fully multifilament), cable concepts being evaluated now Bettergrain boundaries would be hugely helpful Other users are building HTS into their long range plans LHC at CERN, Muon Collider, high field NMR, cryocooled lab magnets