High Field Magnets Perspectives from High Energy Physics. Dr. Glen Crawford Director, Research and Technology R&D DOE Office of High Energy Physics

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1 High Field Magnets Perspectives from High Energy Physics Dr. Glen Crawford Director, Research and Technology R&D DOE Office of High Energy Physics

2 What is High Energy Physics? The High Energy Physics (HEP) program mission is to understand how the universe works at its most fundamental level. We do this by: Discovering the most elementary constituents of matter and energy, Probing the interactions between them, And exploring the basic nature of space and time. To do this we typically build large particle accelerators and large detectors. Both of these require advanced magnets. To this end HEP maintains an infrastructure of equipment and people to design and fabricate these magnets. When necessary we support the development of state of the art superconducting materials 2

3 How Do We Want to Get There? At the Energy Frontier, powerful accelerators are used to create new particles; At the Intensity Frontier, intense particle beams and highly sensitive detectors study events that occur rarely in nature; and At the Cosmic Frontier, ground and space-based experiments and telescopes offer new insight and information about the nature of dark matter and dark energy, and discover new phenomena. 3

4 Introduction For the physical sciences, particularly High Energy Physics and Fusion science, the availability of advanced magnet systems has been an enabling technology. To manipulate and control charged particle beams To analyze reactions We are presently operating at the state of the art in our accelerators, detectors and fusion reactors. Tevatron, RHIC, LHC, ITER As a field of research and application we are one of the largest consumers of superconducting materials and magnets R&D to maximize the physics reach of the technology Production and operation at industrial scale 4

5 Current HEP Accelerator Facilities Neutrino Program NSF s proposed Underground Lab. DUSEL 1300 km NOvA (off-axis) Chicago MINOS (on-axis) 735 km MiniBooNE SciBooNE MINERvA Large Hadron Collider Geneva, Switzerland Fermilab Tevatron Batavia, Illinois 5

6 What do HEP magnet builders want? The highest critical field and current density Fabricability into wires with flexible architectures High transport current to minimize inductance Low cost/performance ratio Small environmental footprint High strength Ability to wind as is Long length Low ramping losses and magnet protection Industrial scalability What do we have now.? 6

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8 LHC Magnet Statistics 8000 Superconducting NbTi Magnets Bending Dipoles (7 T) Focusing Quadrupoles Correcting Magnets HTS leads 40,000 tons of material cooled to 2 K, operated in a DC fashion (magnets ramp a few times a week) 8

9 CMS Detector CMS Solenoid: 14 m diameter; 13 m long; 4 T central field 9

10 ATLAS Detector ATLAS Toroid at LHC. Diameter=20 meters. Length=25 meters. 10

11 HEP State-of-the-Art All existing machines use Low Temperature Superconductors NbTi Ductile alloy easy to work with Lowest cost practical superconducting material Commodity item used in MRI magnets (several thousand magnets per year) Relatively low critical temperature T c and critical magnetic field B c2 (9.8 K and K) Nb 3 Sn Brittle compound difficult to work with and must be formed by heat treatment after magnet fabrication. Higher cost than NbTi (x 4-5) Small worldwide production relative to NbTi (NMR, Lab research magnets) Higher critical temperature T c and critical magnetic field B c2 (18.2 K and K) React-and-Wind versus Wind-and-React 11

12 Improvement in SC conductor

13 Improvement in Accelerator Dipole Magnets? Bi YBCO Nb 3 Sn NbTi Tevatron A combination of laboratory and industrial development. 13

14 US LARP Long Nb3Sn Quadrupole Main Features: Aperture = 90 mm Magnet length = 3.7 m Gradient = 200+ T/m Objective: -Demonstrate Nb 3 Sn magnet scale-up -Long shell-type coils -Long shell-based structure (bladder & keys) LQS01 SSL 4.3 K First test Current Gradient Peak Field 13.9 ka 242 T/meter 12.4 T Stored Energy 473 kj/meter

15 Future HEP Needs Upgrade of the Large Hadron Collider (luminosity, energy) Higher fields beyond NbTi (both quads and dipoles) Radiation Resistance Performance Issues Insulation Cooling Issues Muon Accelerators (neutrino factory, high energy collider) Very high fields, current densities e.g., cooling solenoids with B > 20-30T Ramped ring magnets with highest possible fields Harsh radiation environment (muons in beam decay!) Large stored energy 15

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17 High Temperature Superconductors: New Enabling Technology? We need to develop superconducting magnets which take advantage of this fantastic new operating space Current HEP operating space 17

18 HTS greatly extends properties at 4K YBCO B Tape Plane J E (A/mm²) MgB 2 Nb-Ti 18+1 MgB 2 /Nb/Cu/Monel Courtesy M. Tomsic, 2007 Maximal J E for entire LHC Nb-Ti strand production (CERN- T. Boutboul '07) YBCO B Tape Plane RRP Nb 3 Sn Bronze Nb 3 Sn Compiled from ASC'02 and ICMC'03 papers (J. Parrell OI-ST) Applied Field (T) 2212 J E floor for practicality 4543 filament High Sn Bronze-16wt.%Sn- 0.3wt%Ti (Miyazaki- MT18-IEEE 04) 427 filament strand with Ag alloy outer sheath tested at NHMFL YBCO Insert Tape (B Tape Plane) YBCO Insert Tape (B Tape Plane) MgB 2 19Fil 24% Fill (HyperTech) 2212 OI-ST 28% Ceramic Filaments NbTi LHC Production 38%SC (4.2 K) Nb 3 Sn RRP Internal Sn (OI-ST) Courtesy Peter Lee SuperPower tape used in record breaking NHMFL insert coil 2007 Nb 3 Sn High Sn Bronze Cu:Non-Cu

19 Nb47Ti (OST) Bi-2223 (AMSC) Internal Sn Nb 3 Sn (OST) Bi-2212 (OST) YBCO coated conductors next Preferred conductor features: Multifilament Round or lightly aspected shape with no Jc anisotropy Capability to wind in unreacted form while conductor fragility is minimized MgB 2 (Hypertech) 19

20 Very few HTS magnets so far why? High conductor cost Complex structure Challenging to work with Low overall J c (J e and J winding ) Bi-2223, but round wire Bi is better Wires and tapes are still primitive compared to Nb-Ti and Nb3Sn Typical commercial batch lengths for YBCO are currently m Stability and quench protection? Mechanical stress at high fields a major concern What s needed to make HTS more attractive? Clear domain where LTS cannot compete Properties that are clearly superior to LTS 40µm Cu 2µm Ag ~ 1µm YBCO ~ 30nm LMO ~ 30nm Homo-epi MgO ~ 10nm IBAD MgO ~ 7nm yttria ~ 80nm alumina 50µm substrate 40µm Cu Cartoon (not to scale!) of YBCO sandwich 20

21 Recent MAP-related HTS Efforts Progress towards a demonstration of a final stage cooling solenoid: Demonstrated 15+ T (16+ T on coil) ~25 mm insert HTS solenoid BNL/PBL YBCO Design Highest field ever in HTS-only solenoid (by ~1.5 ) Preparing for a test with HTS insert in NC solenoid at NHFML >30 T BSCCO-2212 Cable - Transport measurements show that FNAL cable attains 105% J c of that of the single-strand 21 I c (4.2 K) (A) x B (T) single-strand 6-around-1 cable Multi-strand cable utilizing chemically compatible alloy and oxide layer to minimize cracks

22 Rutherford and Roebel cables for large magnets Rutherford cable (flattened, fully transposed cable) works well for round wire 2212 Major task of the HEP collaboration YBCO tape cannot be Rutherford cabled but cabling by the Roebel method is possible Under evaluation by Karlsruhe and General Cable and IRL (NZ) Predicted perp. field Ic of 15 strand, 5 mm wide Roebel YBCO cable parallel 5-7 times higher YBCO Nick Long (IRL) and Andrew Priest (General Cable NZ) Bi-2212 Arno Godeke, Magnet Group, LBNL 22

23 Existing Facilities for High Field Magnet and Materials R&D HTS conductors LTS HTS NbTi HTS Nb 3 Sn HTS HTS Nb 3 Sn LTS HTS 23

24 Model HEP R&D Program for HTS Applications What would it take to Demonstrate a relevant HTS conductor and magnet technology in five years? Leveraging and continuing the program for the development of HTS conductor and magnet technology based on development of high J c strands for HEP applications. A university materials program $600k/yr High strength materials development $500k/yr Industrial support $600k/yr Cable development $350k/yr Small coil development $600k/yr Total $2.5M/yr Program provides significant orders for industry that has been an important component of development and also provides conductor for coil fabrication and development. 24

25 Summary DOE/HEP is an important stakeholder in high-field magnet research High-end customer with particular needs (highest field, current density) but generally pragmatic approach due to cost and scale. We contribute to the R&D effort in our part of parameter space We benefit from research infrastructure at NHFML, universities, industry Strong track record in developing LTS conductors and magnets (NbTi, Nb3Sn) Current magnet technology may be near its limits for HEP applications LARP Nb3Sn quads for LHC upgrades and then? Future energy frontier machines will be driven by LHC results, but buildable options are limited Future: high-temperature superconductors operated at low T? Promise of very high field with good current density But: materials, technology development in early days. HTS production very labor-intensive high cost 5-10(+) year timescale to go from good conductor to accelerator magnets 25

26 Backup Slides

27 The Tevatron The confluence of leadership, skills and technology with industrial overtones in a pure research environment

28 Bi-2223 for HTS Current Leads Bi-2223 CL conductors standard OPIT wire production industrial production process established AgAuMg matrix for superior mechanical properties reduced thermal conductivity Matrix content between 60 % and 70 % Je (77K, s.f.) up to > 150 A/mm² room temperature strength > 90 MPa Tape stacking for high current CL components Up to now > 20 km of HTS CL tape produced by Bruker HTS Up to now > 1000 HTS stacks produced by Bruker HTS HTS CL components Courtesy Bruker EST HTS CL for laboratory magnets and future MRI High current HTS CLs for CERN LHC and Fusion 28

29 How about round wires? YBCO B _ Tape Plane YBCO B Tape Plane 1000 NbTi RRP Nb 3 Sn J E (A/mm²) MgB 2 Bronze Nb 3 Sn Applied Field (T) YBCO Insert Tape (B Tape Plane) YBCO Insert Tape (Bperp TP) MgB2 19Fil 24% Fill HyperT 2212 OI-ST 28% SC (PMM030224) NbTi LHC 38%SC (4.2 K) Nb3Sn RRP OI-ST Nb3Sn High Sn Bronze Cu:Non 0.3 YBCO stands above all even though it is 1% of the cross-section, not the 30% of Bi-2212 But, Bi-2212 can be strongly overdoped to get its carrier density up 30

30 Bi-2212 is of particular interest to HEP: it can lead to a Rutherford cable HTS has 3 times the critical field (<100T) of Nb 3 Sn (~28T) Irreversibility Field (T) Nb 3 Sn Nb-Ti Bi-2212 RW MgB 2 ( ) Bi-2223 ( ) Temperature (K) YBCO ( ) ARRA program started in June