HTS4 Fusion Conductor Workshop Karlsruhe, 26./27.5.2011 Overview of HTS conductors and MgB 2 wires René Flükiger University of Geneva (GAP) & CERN (TE-MSC) Geneva Switzerland 1
Outlook * Overview: recent progress on various conductor types * Y or R.E. based coated conductors * Conductors produced by P/M techniques: - Bi-2223, Bi-2212 (very brief) -MgB 2 wires * Problems to be solved * Conclusions 2
REBaCuO systems Preparation and properties Data obtained from literature and directly from the authors. Some data from an overview of Alan Wolsky, IEA, 2010 3
Requirements to a REBaCuO tape Current density * Carry optimized current in REBaCuO (dopants) Mechanical * Substrate strong enough at high temperature to stand the formation of REBaCuO * Tape as a whole strong and flexible enough to be wound into cable and coils at 300 K * Tape must withstand longitudinal and transverse stresses during operation Electrical stability * Carry excess current in Ag layer and in in Al, Cu,. outer layers Thermal stability * Enable heat transfer to the coolant AC losses * Modify architecture to minimize AC losses (Roebel, striations) 4
REBaCuO tape of SEI (Sumitomo) «Clad type»: Reel-to reel PLD process, 30 mm wide Substrate: RABITS (Rolling Assisted Biaxial Texturing) 2 m J c = 250 A/cm-w Strength : 500 MPa ~ 1 m 120 m 0.2 m M. Ohya et al., «AC loss characteristics of RE123 Superconducting Cable», ASC 2010 5
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Layer: 0.8 m Courtesy S. Fleshler, AMSC HTS4 Fusion Conductors, Karlsruhe 2011 8
REBaCUO tape of SuperPower 2G wire based on IBAD MgO and MOCVD process < 0.1 mm D. Hazelton et al., ASC 2010 9
Selvamanickam et al. 10
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Doping with BaZrO 3 : complete absence of reaction with REBaCuO BaZr0 3 : the solution for the crucible corrosion problem during the single crystal growth of High-T c superconductors R.E.Ba 2 Cu 3 0 7- (R.E. = Y, Pr) (A. Erb, E. Walker, R. Flükiger, Physica C 245 (1995) 245-251) BaZr0 3 : melting point of about 2600 C, smaller thermal expansion coefficient than ZrO 2, better thermal shock resistance than ZrO 2. Cubic perovskite structure Density : 6.242 g/cm 3 Broken BaZrO 3 crucible after a crystal growth experiment. Neither a reaction layer nor remaining flux can be observed on the BaZr0 3 crucible walls. 12
REBaCuO tape of Fujikura Igarashi et al., Fujikura Technical Review, Jan. 2009 13
600 m long large Ic C.C. 800 700 I c (max.) = 698 A Ic(77 K) (A) 600 500 400 300 200 100 0 77K 0T High uniformity in I c profile for Long, thick GdBCO film GdBCO film 3 4μm Measured every 70 cm at the criterion of 1.0 V / cm 100 200 300 400 500 600 Position (m) Recently achieved Ic=572A / 816m Feb. 11 14
I c B T property for 600A class C.C. Measured by Prof. Kiss group of Kyushu University collaborated with Florida State Univ. & Tohoku Univ. I c [A/cm-width] ~1,120A/cm @5T 1,000 100 2.5 m-thick-gdbco/ibad CC by Fujikura Co. ~300A/cm @5T,50K 50K 625A/cm @15T 20K 65K 77K B//c 10 0 5 10 15 20 25 30 35 magnetic field [T] 4K 414A/cm @31T Field 15 Curren
REBaCuO tape of SuNAM e beam evaporation e beam evaporation e beam evaporation Oh, S.S. et al, SuST, 21(2008)034003 16
SuNAM: Recent results Hastelloy, IBAD-MgO, > 100 meters SmBCO : for research: EDDC (evaporation using a drum in dual chambers) for production: RCE (reactive coevaporation) 600 500 400 I C (A) 300 200 100 0 0 100 200 300 400 Length (m) 17
REBaCO tape of Bruker A. Usoskin, MRS 2010, April 2010 18
Summary: Fabrication width, production rate SEI: Fabrication width 30 mm, No indication about production rate AMSC: Fabrication width 40 mm, Goal: 100 mm width, lengths: > 500 m > 1 000 km/year of 4 mm tape SuperPower: Fabrication width 12 mm, Lengths: 1 400 m July 2010: > 150 km/year (?) Fujikura: Fabrication width 10 mm, lengths: > 1 000 m 2009: PLD/CeO 2 (60 m/h), IBAD MgO ( 1,000 m/h), Y 2 O 3 (500m/h), Al 2 O 3 (150 m/h), GdBaCuO (15 m/h) SuNAM: Fabrication width 12 mm, lengths: > 100 m (planned: 2 000 m) Nov. 2009: Homoepitactic (70m/h),LMO buffer (50 m/h) Goal: 2,000 km/year (assuming 100% yield) Bruker: Fabrication width 40 mm, lengths: 100 m (planned: > 1 000 m) Goal: line speed (ABAD) 30 m/h and PLD (70 m/h) 19
Summary: Many ways lead to REBaCuO coated conductor tapes Coating with liquid (metal organic deposition, MOD (AMSC) Adsorb vapors (metal organic chemical vapor deposition, MOCVD (SuperPower) Adsorb metal atoms from vacuum (pulsed laser deposition), PLD (electron beam evaporation):rce (Bruker, SEI) (SuNAM) 20
What remains to be done? Higher J c values: * higher homogeneity over whole length * thicker layers * enhanced pinning by nano-additives * reduced anisotropy by nano-additives 21
Higher critical current density Optimization of deposition parameters M. Igarishi et al., EUCAS 2009 (Fujikura) 22
Higher critical current density Enhanced layer thickness Fujikura reports 6 m thick layer with 1 040 A/cm-w (Deposition time not reported) M. Igarishi et al., EUCAS 2009 (Fujikura) 23
Higher critical current density Enhancement of J c for fields out-of plane: the minimum J c is the decisive one for applications Further progress still to expect SuperPower, 77K/1T AMSC, 77K, 1 T V. Selvamanickam and J. Deckow, DOE Peer Review 2010 M. Rupich, J. McCall, C. Thieme, DOE Peer Review, 2010 24
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Reduction of AC losses * Roebel technique, * Striations, * Roebel + striations 26
Effect of tensile stress on J c 27
Effect of tensile stress on J c 4.2 K AMSC tape; measured on a Walters spiral irr = 0.51 % D. Uglietti, B. Seeber, V. Abächerli, W.L. Carter, R. Flükiger, SuST, 19(2006)869 Effect of transverse stress: unknown 28
Bending strain strength of Cu laminated IBAD/PLD tapes I c measurement, straight at 77K (I co ) fix to bending tool at R.T. Ic measurement at 77K Cu :0.1mm Substrate:0.1mm Ic/Ic0 1.2 1.0 0.8 0.6 0.4 0.5% Strain: (assuming Cu plastic Deformation) Cu: outside Hastelloy :inside R[mm] 0.2 0.0 tensile compressive 0 2 4 6 8 10 12 14 16 18 20 tensile Bending radius R[mm] Hastelloy :outside Cu: inside compressive I c /I co >0.95 tensile:r > 11mm compressive:r > 5mm 29
The system Bi-2223 Data from K.I. Sato, Sumitomo 30
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Problem: Micrometer holes in Ag sheath of Bi-2223 tapes Ag sheath of Bi-2223 tape, after reaction 34
The system Bi-2212 Recent results of D. Larbalestier et al. (Tallahassee): Application of cold isostatic pressure on Bi-2212 wires 35
// Bi-2212 wire: Oxford Instruments J c doubled after CIP treatment New data of D. Larbalestier (Peter Lee plot) 36
The system MgB 2 Large applications: * LINK (CERN) * Poloidal field coils? * Ignitor? 37
Improved J c and B irr by Cold Densification in long lengths of in situ MgB 2 wires Coworkers at University of Geneva: Shahriar A. Hossain Wire preparation, densification Miloslav Kulich Carmine Senatore Physical measurements, specific heat 38
Binary Fe/MgB 2 wire 1.0 mm 1.0 mm Drawn to a square cross section After cold densification Densification pressures for MgB 2 wires: 1 1.5 GPa R. Flükiger, M.S.A. Hossain, C. Senatore, SuST 22(2009)095004 39
Mechanism of densification effects in MgB 2 wires MgB 2 is a forgiving material: No cracks at limit between unpressed and pressed filament 40
Monofilamentary MgB 2 wires with malic acid additives Highest values known so far for in situ MgB 2 wires 41
Densification of Multifilamentary MgB 2 wires M.S.A. Hossain, C. Senatore, M. Rindfleisch, R. Flükiger, SuST, 24(2011), in press 42
Sheath P Wire cross Filament Fill Mass Relative Vickers Material (GPa) section cross factor Density mass micro- (mm x mm) Section (%) (Mg+2B) density hardness (mm 2 ) (g/cm 3 ) (%) (GPa) Monel/Nb/Cu 0 0.61 x 1.00 0.0957 15.5 1.015 51 1.4 Monel/Nb/Cu 1.5 x 1.01 0.0829 14.3 1.413 69 3.6 43
Homogeneous areal change of all densified filaments 44
4.2 K 45
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The exponential n factor: strong enhancement 47
Densification of long MgB 2 wire lengths Two independent hydraulic systems: 40t/16t Control of the 4 anvils: * independent pressure set * independent time of pressure Very high exerted pressures: 1 1.5 GPa (several times higher than an extrusion machine) Pressure sequence: 2.3 s Traveling distance between pressing steps: 14 mm Pressing length: 70 mm Total densified length (estimated): 300 m/day Densified lengths of 1 km / day: possible after modifications 48
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HTS4 Fusion Conductors, Karlsruhe 2011 50
Monofilamentary MgB 2 wire (malic acid added, Hyper Tech) 51
Conclusions (MgB 2 ) * J c of in situ wires: enhanced by a factor 2.3 * There is still a potential for improvement of J c. Max. J c (4.2K) expected at 15 T 10 6 Matsumoto / Thin Film Hässler / Tape Hossain / Rectangular wire Togano / IMD wire J c [A/cm 2 ] 10 5 10 4 // 4.2 K // Nb 3 Sn 10 3 // 4 8 12 16 20 24 28 B [T] * To improve: thermal stabilization Applicable on any P/M system: *Bi-2212 (under work) *Future s.c. systems 52