SuperconductorMaterials Science

Metallurgy, Fabrication,and Applications

Edited by

Simon FonerFrancis Bitter National Magnet Laboratory

and Plasma Fusion Center, M.I. T.

Cambridge, Massachusetts

and

Brian B. SchwartzDepartment of Physics

Brooklyn College of The City University

of New York

Brooklyn, New York

and

Francis Bitter National Magnet Laboratory

and Plasma Fusion Center, M. I. T.

Cambridge, Massachusetts

PLENUM PRESS • NEW YORK AND LONDON

Published in cooperation with NATO Scientific Affairs Division

CONTENTS

CHAPTER 1 OVERVIEW OF SUPERCONDUCTING

MATERIALS DEVELOPMENT

J. K. Hulm and B. T. Matthias

I. INTRODUCTION 1

II. SUPERCONDUCTING MATERIALS OF THE FIRST KIND 3

A. Discovery 3

B. Magnetic Properties 3

C. Flux Penetration 8

D. Nature of the Superconducting Transition 9

1. Bulk phase transition 11

2. Thin film phase transition 11

E. The Two Fluid Model 13

F. The Microscopic Theory 14

III. SUPERCONDUCTING ALLOYS AND COMPOUNDS,

EARLY WORK 16

A. Introduction 16

B. Critical Temperature Behavior 18

C. Magnetic Field Behavior 21

IV. RAISING T WITH NEW MATERIALS 27c

A. Introduction 27

B. Transition Metal Alloys 30

C. Carbides and Nitrides 35

D. A15 Compounds 37

1. Progress in raising T 37

2. Present T situation°

39c

3. Factors depressing T 41

4. Other features of A15 behavior 43

V. SUPERCONDUCTORS OF THE SECOND KIND 44

xii CONTENTS

A. Introduction 44

B. Another Kind of Superconductor 47

C. Type II Materials 50

VI. UNUSUAL MATERIALS AND FUTURE POSSIBILITIES 53

A. Introduction 53

B. Intercalation Compounds 54

C. Organic Superconductors 56

D. Low Carrier Density Superconductors 56

E. Magnetic Superconductors 57

F. Future Possibilities 57

CHAPTER 2 PRACTICAL SUPERCONDUCTING MATERIALS

M.N. Wilson

I. INTRODUCTION 63

A. Practical Applicationsof Superconducting Materials 63

B. Superconducting Materials in Common Use 65

C. Problems in the Utilization

of Superconducting Materials 67

II. STABILITY: THE GENERAL PROBLEM 68

A. Degradation and Training 68

B. The Disturbance Spectrum 69

C. Mechanical Sources of Disturbance 70

D. Distributed Disturbances 71

E. Point Disturbances 71

F. Composite Conductors 73

III. FLUX JUMPING 74

A. General 74

B. Screening Currents and the

Critical State Model 74

C. Adiabatic Theory of Flux Jumping 76

D. Filamentary Composites 78

E. Dynamic Stability 82

F. Dynamic Stability with Finite

Superconductor Thickness 84

IV. CRYOGENIC STABILIZATION 87

A. Size Effects 87

B. Principles of Cryogenic Stabilization 88

CONTENTS xiii

C. Boiling Heat Transfer 90

D. Resistivity of the Normal Metal 90

E. Heat Conduction Effects 92

F. Effect of Finite Superconductor Size 95

G. Forced Flow Cooling 96

H. Superfluid Helium 100

I. Cryogenic Stabilization in Practice 100

V. AC LOSSES 102

A. The Fundamental Loss Mechanism 102

B. Hysteresis Loss 104

C. Hysteresis Loss with Transport Current 108

D. Filamentary Composites 110

E. Self-Field Losses in Filamentary Composites 114

F. Longitudinal Field Effects 116

G. Combined Losses 119

VI. QUENCHING AND PROTECTION 119

A. The General Problem 119

B. Temperature Rise 120

C. Voltage 122

D. Self-Protecting Magnets 122

E. Other Protection Techniques 123

VII. MEASUREMENT TECHNIQUES 124

A. General 124

B. Measurement of Critical Transport Current 124

C. Measurement of Magnetization 127

D. Measurement at Different Temperatures 130

CHAPTER 3 NIOBIUM-TITANIUM

SUPERCONDUCTING MATERIALS

D.C. Larbalestier

I. INTRODUCTION 133

II. METALLURGICAL AND STRUCTURAL PROPERTIES 134

A. Phases of the Niobium-Titanium System 136

B. Cold-Worked Microstructures 139

C. Elastic and Plastic Mechanical Behavior 152

D. Metallurgical Properties of Related Systems 157

III. PHYSICAL PROPERTIES 159

IV. SUPERCONDUCTING PROPERTIES 162

xiv CONTENTS

A. Basic Properties 162

1. Transition temperatureand upper critical field 162

2. Paramagnetic limitation

and spin-orbit scattering 163

3. Nb-Ti base ternary and quaternary-systems 167

B. The Superconducting Critical Current

Density 173

1. Measurement techniques 173

2. Critical current densities 174

V. INDUSTRIAL AND FABRICATION CONSIDERATIONS 187

VI. FUTURE DEVELOPMENTS AND NEW DIRECTIONS 190

A. Conventional Composites 190

B. Unconventional Developments 192

CHAPTER 4 METALLURGY OF CONTINUOUS

FILAMENTARY A15 SUPERCONDUCTORS

M. Suenaga

I. INTRODUCTION 201

II. HISTORY OF THE "BRONZE PROCESS" 202

A. Early History 202

B. Evolution of the Process 204

1. The Ta diffusion barrier 204

2. The external diffusion process 205

3. The internal tin diffusion process 206

4. Bronze in Nb tubing 208

5. WRAP process 208

6. Other modifications 209

III. METALLURGICAL PRINCIPLES 209

A. Thermodynamic Considerations 209

B. Kinetics 215

1. Growth mechanisms 215

2. Experimental results 221

IV. INFLUENCE OF METALLURGICAL FACTORS

ON SUPERCONDUCTING PROPERTIES 233

A. Strains in Composite Superconductors and

Their Influence on the SuperconductingProperties 234

CONTENTS xv

B. Critical Temperatures 238

1. Effects of heat treatments 238

2. Effects of additives 242

C. Critical-Current Densities and MagneticFields 246

1. Flux pinning (the scaling law) 246

2. Temperature dependence 256

3. Grain size dependence 258

4. Effects of heat treatments and alloying 261

5. What is required for high Jc? 266

V. FUTURE DIRECTIONS

CHAPTER 5 FABRICATION TECHNOLOGY

OF SUPERCONDUCTING MATERIAL

H. Hillmann

I. INTRODUCTION 275

II. TECHNOLOGY OF

SOLID SOLUTION SUPERCONDUCTORS 276

A. Basic Properties of NbTi Alloys 276

B. The influence of thermal treatment

in the region of 873 K 285

C. Mechanical Properties of NbTi Alloys 288

D. Stress-Strain Behavior at Elevated

Temperatures 292

E. Raw Materials and Melting of NbTi 292

F. Melting NbTi Alloys 292

G. Sources of Inhomogeneities and Imperfectionsin the Molten Ingots 295

H. Conductors and Fabrication Parameters 299

I. Extrusion Technology 302

1. Extrusion billets and sealing techniquesfor single and multiextrusion 302

2. Extrusion presses and extrusion

parameters 304

3. Extrusion temperature and preheating 311

4. Extrusion ram speed 311

5. Conductors containing mixed substrate 313

J. Drawing Machinery, Twisting and Current

Optimization 313

K. Current Density Optimization and Propertiesof Monolithic Filamentary Conductors 317

L. The Anisotropy of Rectangularly-ShapedConductors 323

M. Occurrence of the Ti Cu-Phase 328

xvi CONTENTS

III. A15 SOLID SOLUTION CONDUCTORS 333

A. Basic Properties of Nb^Sn and V^Ga 333

B. Principles of Solid State Diffusion 337

C. Fabrication of the Conductors and

Technology of High Sn-Content Bronzes 340

D. Conductor Optimization with Respect to LayerGrowth, Recrystalization, Kirkendall

Effect, Filament Diameter and Filament

Distribution 345

E. Influence of Mechanical Strain on

Electrical Properties 350

F. Remarks About the Measurement of Critical

Current Density of Technical Conductors 360

G. Stabilization and Examples of Technical

Conductors 362

IV. CONDUCTOR ASSEMBLY BY BRAIDING, CABLING,

MECHANICAL STRENGTHENING

AND ADDING STABILIZERS 364

A. Technical Production of Flattened

Cables and Braids 364

B. Hollow Conductors and Fabrication

Principles 368

C. Fabrication of High Current, High

Strength Hollow Conductors 375

1. Strands 379

2. Cr-Ni core with Kapton insulation 379

3. Cabling and Soldering 379

4. Strip for the conduit 379

5. Conductor completion 379

V. FUTURE DIRECTIONS 381

A. Solid Solution Superconductors 381

B. A15 Superconductors 383

CHAPTER 6 ALTERNATIVE FABRICATION

TECHNOLOGIES FOR A15

MULTIFILAMENTARY SUPERCONDUCTORS

R. Roberge

1. INTRODUCTION

II. CONVENTIONAL PROCESS MECHANICAL ASSEMBLY

A. Historical Note

389

390

390

CONTENTS xvii

B. Nb3Sn Technology 390

C. Status 393

D. Need for Alternate Technologies 394

III. IN SITU SOLIDIFICATION 394

A. Introduction 394

B. The Natural Dispersion of the Superconductor 395

1. Phase diagram, solidification process 395

2. Melting and casting techniques 399

C. Transformation into a Filamentary-Superconductor 404

1. Mechanical deformation 404

2. Tin addition 404

3. Diffusion and reaction heat-treatment 407

D. Superconducting Properties 411

1. Overall Jc of Cu-Nb 411

2. Overall Jc of Cu-Sn wires 411

3. Overall Jc of Cu-Nb-Sn versus Nb

concentration 414

4. Overall Jc of Cu-V-Ga 414

E. Mechanical Properties 417

1. Mechanical properties of Cu-Nb-Sn 417

2. Pre-stress model 417

3. Mechanical properties of Cu-V-Ga 420

F. Experimental Observations on Connectivity 422

1. Random distribution 422

2. Filament geometry 423

3. Acid test 427

4. Unified perculation-proximity 430

G. Research in Progress 430

H. Scale-up Technologies 431

IV. POWDER METALLURGY 431

A. Introduction 431

B. Cold Process 432

1. Experimental technique 432

2. Materials selection 432

3. Results 434

4. Potential 437

5. Research in progress 437

C. Hot Process 440

1. Experimental technique 440

2. Results 440

3. Potential 440

D. Infiltration Process 442

1. Experimental technique 442

2. Results 442

xviii CONTENTS

3. Features 442

4. Scale-up technology 444

V. OTHER PROCESSES 444

A. Metastable Solid Solution (Stoichiometric) 444

B. Controlled Precipitation 445

C. Mechanical Alloying 445

D. Modified Jelly Roll 445

E. Energy Research Foundation (ECN) Process 448

VI. CONCLUDING COMMENTARIES

FUTURE DEVELOPMENTS 448

CHAPTER 7 MECHANICAL PROPERTIES AND STRAIN

EFFECTS IN SUPERCONDUCTORS

J. W. Ekin

I. INTRODUCTION 455

A. Sources of Mechanical Loads in Magnets 455

1. During fabrication 455

2. Differential thermal contraction 455

3. The Lorentz force 455

B. Mechanical Properties of Superconductors 456

II. STRESS-STRAIN CHARACTERISTICS 458

A. Micromechanical Model 458

B. Stress-Strain Characteristics for

Practical Conductors 460

III. EFFECT OF UNIAXIAL STRAIN ON J. H0,

and T 464c' c2 c

A. Mechanical-Electrical Interaction 464

B. Jc~e Characteristics for Practical

Superconductors 465

1. Multifilamentary NbTi 465

2. Multifilamentary Nb3Sn 468

3. Multifilamentary V^Ga 470

4. CVD Nb3Ge tape 472

C. Strain Scaling Law - Prediction of J (B,e) 472

1. Scaling of pinning force curves 474

2. Strain scaling law 475

3. Application to practical multifilamen¬

tary Nb3Sn conductors 478

D. General Scaling Law - Prediction of Jc (T,B, e) 479

E. Uniaxial-Strain Criterion for Magnet Design 482

CONTENTS xix

IV. BENDING STRAIN 484

A. Effect of Bending on Jc 484

B. Prediction of Bending-Strain Degradationfrom Uniaxial-Strain Measurements 486

1. Long twist pitch 486

2. Short twist pitch 487

3. Application 489

C. Bending Strain Limits for Magnet Design 490

D. Methods for Minimizing Bending Degradation 492

1. Cabling 492

2. Wind-and-react magnet fabrication 494

V. FATIGUE 495

A. Matrix Degradation 495

1. NbTi 495

2. Nb3Sn 497

B. Micromechanical Model 497

VI. TRAINING 500

A. Stress-Relief Model 501

B. Materials 501

C. Techniques for Minimizing Training 502

1. Crack arrestors 502

2. Bond breakage and friction 504

3. Programmed winding tension 504

4. Magnet shakedown without quenching 504

VII. SUMMARY AND FUTURE RESEARCH NEEDS 505

A. Summary of Material Strain Limits for

Magnet Design 505

B. Future Research Areas 505

CHAPTER 8 PHASE DIAGRAMS

OF SUPERCONDUCTING MATERIALS

R. FlUkiger

I. INTRODUCTION 511

II. EXPERIMENTAL DETERMINATION

OF HIGH TEMPERATURE PHASE DIAGRAMS 512

A. Sample Preparation 513

1. Arc melting 513

2. r.f. melting in water-cooled

crucibles 514

XX CONTENTS

3. r.f. melting in graphite or

ceramic crucibles 514

4. Levitation melting 516

5. Other melting techniques 516

B. Homogenization Heat Treatments 516

C. Direct Observation Methods 520

1. Differential thermal analysis (DTA) 520

2. Thermal analysis on levitating

samples (LTA) 522

3. Electrical resistivity at hightemperatures 526

D. Indirect Observation Methods 528

1. Simultaneous stepwise heating 528

2. Splat cooling of liquid samples 529

3. Argon jet quenching on solid samples 529

4. Superconducting "memory" 530

III. DETERMINATION OF PHASE DIAGRAMS BELOW 300 K 532

A. Factors Influencing the SuperconductingData 532

1. Ordering effects 532

2. Shielding effects 535

B. Low Temperature Specific Heat 536

1. Calorimetric detection of shieldingeffects 536

2. Shielding in multifilamentary Cu-Nb3Snwires 539

3. Calorimetric observation of low

temperature phase transitions 539

C. Electrical Resistivity Below 300 K 544

IV. CRITERIA FOR PHASE STABILITY

AND SUPERCONDUCTIVITY 544

A. The Brewer Plots 544

1. Does Au behave like a transition

element? 547

2. The relative stability of intermetallic

phases 547

3. The A15 phase 548

B. Criteria for Superconductivity 550

V. PHASE FIELDS AND SUPERCONDUCTIVITY IN

BINARY "ELECTRON COMPOUNDS" 554

A. The hep Structure (A3 type) 554

B. The A2 Compounds 554

C. "Atypical" A15 Compounds 556

CONTENTS xxi

1. The V-(Re, Os, Ir, Pt, Au) system 556

2. The electronic structure of electron

compounds: the two-band model 558

3. The Nb-(Os, Ir, Pt, Au) system 560

4. The Cr-(0s, Re, Pt) system 562

5. The Mo-(Re, Os, Ir, Pt) system 562

6. The Ti-system 563

7. Characterization of "atypical"A15 compounds 563

VI. PHASE FIELDS AND SUPERCONDUCTIVITY IN BINARY

AND PSEUDOBINARY "TYPICAL" A15 COMPOUNDS 566

A. The Vv3Au and Nb^3Au systems 566

B. The Systems VgB (B = Ga, Si, Ge, "Al", and

Sn) 567

1. V3Ga 567

2. VgSi and the martensitic transformation 567

3. V3Ge 569

4. "VJU" 569

5. V3Sn 572

C. V.-Based Pseudobinary Compounds 572

1. VgCAu}_xPt3) 572

2. V0 (Ga^xSix) 574

D. Nb3B [B = Ge, Ga, Al, Sn, and Sb) 574

1. Nb-Ge 574

2. Nb-Ga 578

3. Nb-Al 578

4. Nb3Sn 578

5. Nb3Sb 579

E. Nb-Based Pseudobinary Compounds 579

1. Nb-CAu!- Ptx) 579

2. Nb3(Al1_xbx) (B = Ge, Si, Ga, Be, B,

As, ...) 581

F. Mo-Based Binaries and Ternaries 581

1. Mo3Ge and Mo3Si 581

2. Mo3(Ge!-xSix) 581

G. General Correlations for A15 Compounds 581

1. The superconducting transition temper¬ature 583

2. Electronic specific heat 583

3. Type of formation of A15 compounds 583

4. Variation of the lattice parameter in

Nb-based A15-type compounds 586

VII. PHASE FIELDS AND SUPERCONDUCTIVITY IN

RHOMBOHEDRAL Mo CHALCOGENIDES

(CHEVREL PHASES) 587

xxii CONTENTS

A. Binary Mo-S System 590

B. CuxMo6S8 System 592

C. PbxMo6Sg System 592

D. Mo6Seg, C^xMo.Se8, Pb Mo6Se8 595

E. General Correlations for Rhombohedral

Compounds 595

F. Comparison with the A15 Compounds 597

CHAPTER 9 JOSEPHSON JUNCTION ELECTRONICS:

MATERIALS ISSUES AND FABRICATION

TECHNIQUESM.R. Beasley and C.J. Kircher

I. INTRODUCTION 605

II. DEVICE PRINCIPLES AND MATERIALS REQUIREMENTS 607

A. Josephson Junctions: Tunnel Junctions

and Weak-Link Devices 607

1. Tunnel junctions 608

2. Weak-link microbridge Josephson

junctions 613

B. Other Circuit Elements 616

C. Summary of Superconducting Device and

Material Parameters of Importance 618

III. INTEGRATED CIRCUIT FABRICATION 618

A. Junctions with Pb-alloy Electrodes 618

1. Integrated circuit fabrication 618

2. Pb-alloy electrode materials 627

3. Tunnel barrier 631

B. Junctions with Niobium Electrodes 633

C. Comparing Junctions with Nb and

Pb-Alloy Electrodes 636

IV. STABILITY OF FILMS AND DEVICES

DURING CYCLING BETWEEN 350 K AND 4.2 K 638

A. Origin of the Cycling Problem 638

B. Strain Relaxation Mechanisms 641

C. Film and Device Stability 643

D. Choosing a Material for Mechanical

Stability 645

V. ELECTRON TUNNELING

AND TUNNEL BARRIER FORMATION 646

CONTENTS xxiii

A. Theory of Tunneling: Ideal Cases of

Interest 647

B. Complications that Can Occur in

Practical Tunnel Junctions 652

C. Tunnel Barrier Formation 654

1. Grown-oxide barriers 655

2. Deposited barriers 657

VI. ADVANCED MATERIALS AND DEVICES 658

A. Materials of Interest 658

B. Thin-Film Deposition Techniques and

Film Properties 659

C. Advanced Tunneling Devices 663

1. Small Tunnel junctions 663

2. Intermetallic compounds 663

3. Transition metal alloys 670

D. Artificial (Deposited) Barriers 670

E. Weak-Link Microbridges 673

CHAPTER 10 CHEVREL PHASE

HIGH FIELD SUPERCONDUCTORS

R. Chevrel

I. INTRODUCTION 685

II. CHEMISTRY AND STRUCTURE 685

A. Preparation 685

B. Chemistry 686

C. Structure 690

III. PHYSICAL PROPERTIES 697

A. Superconducting Temperatures 697

1. Lattice properties, phonons 697

2. Electronic properties, charge transfer 699

B. Upper Critical Fields 704

C. Magnetism, Coexistence of Magnetismand Superconductivity 706

D. Critical Currents and Applications 707

IV. NEW MATERIALS PROCEEDING FROM THE LINEAR

CONDENSATION OF THE OCTAHEDRAL Mo. CLUSTERS 7106

A. In„tMo,rSe,n Containing Mo. and Mon^3 15 19 6 9clusters 710

B. M2Mo,5Se1 (M = K, Ba, In, Tl) and

M2Mo15Sig (M = K, Rb, Cs)

containing Mofi and Mo clusters 712

xxiv CONTENTS

C. M Mo S (M = K, Tl) 714

D. M^Mox] M^Mo.S (M = K, Rb, Cs),

H2fiofiSe^ (M = In, Tl, Na, K),

M2Mo7Te£ (M = In, Tl, Na, K) with

one-dimensional clusters (Mo^^^oo*

V. CONCLUSION 719

CHAPTER 11 SUPERCONDUCTING PROXIMITY EFFECT

FOR IN SITU AND MODEL LAYERED SYSTEMS

D.K. Finnemore

I. MODEL SYSTEMS 725

II. BOUNDARY CONDITIONS AT THE SUPERCONDUCTING-

NORMAL INTERFACE 726

A. Electron Tunneling 726

B. Thermal Conductivity 726

III. PHONON SPECTRAL FUNCTION, a2F(co) 728

IV. SUPERCURRENTS THROUGH NORMAL BARRIERS 728

A. Thickness Dependence 728

B. Temperature Dependence 728

C. Magnetic Field Dependence 731

V. FLUX ENTRY FIELDS 731

VI. IMPLICATIONS FOR IN SITU COMPOSITES 733

CHAPTER 12 AMORPHOUS SUPERCONDUCTORS

C.C. Tsuei

I. INTRODUCTION 735

A. Preparation Techniques 735

B. Structural Properties 736

C. The Anderson Theorem 738

II. SYSTEMATICS OF T 740c

A. Non-transition Metals 740

B. Transition Metals 742

III. ELECTRON-PHONON INTERACTION 743

CONTENTS xxv

A. The Ratio of Energy Gap to Transition

Temperature (2A(0)/k Tc) 743

B. a2F(w) and X 745

C. Origins of Strong Electron-Photon Inter¬

action 746

1. Amorphous non-TM superconductors 748

2. A15 superconductors 748

IV. CRITICAL FIELDS 750

A. The Upper and Lower Critical Fields 750

B. The Temperature Coefficient of

Critical Fields 751

V. POTENTIAL APPLICATIONS 753

A. High Field Magnets 753

B. Josephson Junctions 754

CHAPTER 13 REVIEWS OF

LARGE SUPERCONDUCTING MACHINES

G. Bogner

I. INTRODUCTION 757

II. TECHNICAL SUPERCONDUCTORS 757

III. SUPERCONDUCTING MAGNETS FOR HIGH ENERGY PHYSICS 758

IV. LEVITATED TRAINS-

ELECTRODYNAMIC LEVITATION SYSTEM 761

V. SUPERCONDUCTING COILS FOR MAGNETIC SEPARATION 766

VI. ROTATING MACHINERY WITH SUPERCONDUCTING WINDINGS 770

A. Generators 770

B. DC Machines 775

VII. SUPERCONDUCTING HIGH POWER CABLES 779

VIII. SUPERCONDUCTING SWITCHES 782

IX. MAGNET SYSTEMS FOR FUSION REACTORS 785

X. SUPERCONDUCTING MAGNETS FOR MHD PLANTS 796

XI. SUPERCONDUCTING MAGNET ENERGY STORAGE (SME STORAGE) 801

xxvi CONTENTS

CHAPTER 14 SUPERCONDUCTIVITY IN CANADA

R. Roberge 809

CHAPTER 15 RESEARCH ACTIVITIES IN

SUPERCONDUCTIVITY IN CHINA

C.-G. Cui and C.-Y. Pang

I. INTRODUCTION 813

II. BACKGROUND 813

III. SUPERCONDUCTING MATERIALS 814

A. NbTi 814

B. Nb3Sn 816

C. V3Ga 817

D. New Materials 817

IV. SUPERCONDUCTING MAGNET SYSTEMS 817

A. Laboratory Magnets 817

B. High Energy Physics 820

C. Controlled Thermonuclear Reaction

Technology 820

D. Superconducting Machines 822

E. Magnetic 822

F. Other Applications 824

V. JOSEPHSON JUNCTION DEVICES 824

A. Voltage Standard 824

B. Magnetometer 825

C. High Frequency Devices 825

CHAPTER 16 EUROPEAN EFFORTS ON

SUPERCONDUCTING MATERIALS

H.C. Freyhardt 827

CHAPTER 17 REVIEW OF NATIONAL EFFORTS IN

MIDDLE EUROPE

H.R. Kirchmayr

I. INTRODUCTION 837

II. AUSTRIA AND SWITZERLAND 837

CONTENTS xxvii

A. Members in Switzerland 837

B. Expenditures Within COST-action 56

in Switzerland 838

1. First phase of the COST-action 56

(1977-1979) 838

2. Second phase of the COST-action 56

(1980-1982) 838

C. Projects in Switzerland 839

D. Members in Austria 840

E. Funding Level in Austria 841

F. Projects in Austria 841

III. CZECHOSLOVAKIA 843

IV. GDR (GERMAN DEMOCRATIC REPUBLIC) 844

V. HUNGARY 844

VI. POLAND 844

CHAPTER 18 RECENT DEVELOPMENTS IN HIGH-FIELD

SUPERCONDUCTORS IN JAPAN

K. Tachikawa

I. INTRODUCTION 847

II. THE DEVELOPMENT OF V3Ga 847

A. Surface Diffusion Process 847

B. Composite Diffusion Process 849

III. IMPROVEMENTS IN HIGH-FIELD CURRENT-CARRYING

CAPACITIES OF COMPOSITE-PROCESSED A15

SUPERCONDUCTORS 849

TV. SUPERCONDUCTING AND MECHANICAL PROPERTIES OF

THE IN SITU PROCESSED V3Ga 852

V. DEVELOPMENTS IN THE V2Hf-BASE C-15 TYPE

SUPERCONDUCTORS 855

VI. DEVELOPMENTS OF MULTIFILAMENTARY A15

CONDUCTORS IN JAPANESE RESEARCH GROUPS

OTHER THAN NRIM 858

CHAPTER 19 PROGRAMS ON SUPERCONDUCTING MATERIALS AND

MINIATURE CRYOCOOLERS IN THE UNITED STATES

R. Brandt, M. Nisenoff and E. Edelsack

xxviii CONTENTS

I. SUMMARY 861

II. INTRODUCTION 861

III. SUPERCONDUCTING MATERIALS 863

A. Bulk Materials 863

1. Liquid Solute Diffusion (LSD) 863

2. Chemical Vapor Deposition (CVD) 865

3. Electron Beam Deposition (EBD) 865

4. Solid State Diffusion (SSD) 865

B. Thin Films 867

IV. SMALL CRYOCOOLERS 883

V. TRENDS 891

A. Bulk Superconducting Materials 891

B. Thin-Film Superconducting Materials 893

C. Small Cryocoolers 896

CHAPTER 20 LARGE-SCALE APPLICATIONS OF

SUPERCONDUCTIVITY IN THE

UNITED STATES: AN OVERVIEW

R.A. Hein and D.U. Gubser

I.'

INTRODUCTION 899

II. LOW FIELD REGIME (H < 2T) 900

A. General Remarks 900

B. Power Transmission Lines 900

1. General Remarks 900

2. Superconducting AC power transmission

lines (SPTL) 901

3. Superconducting DC power transmission

lines 904

C. RF Cavities for Particle Accelerators 905

III. INTERMEDIATE FIELD REGIME (2 < H < 5T) 906

A. General Remarks 906

B. Magnets for High Energy Physics (HEP) 909

C. Rotating Electrical Machines 912

1. DC acyclic (homopolar) motors 912

2. AC machines (generators) 914

D. Energy Storage Magnets 917

CONTENTS xx!x

IV. HIGH FIELD REGIME (H >5T) 921

A. General Remarks 921

B. Magnetohydrodynamics (MHD) 921

C. Magnetically Confined Fusion 923

V. SUPERCONDUCTING MATERIALS 929

VI. HELIUM CONSERVATION 932

VII. MISCELLANEOUS APPLICATIONS 934

A. Electromagnetic Launchers 934

B. Magnetic Separation 934

CHAPTER 21 REPORTS ON SOME SUPERCONDUCTING

MATERIALS COMPANIES IN THE

UNITED STATES

I. AIRCO, INC., CARTERET, NEW JERSEY 07008 939

A. Introduction 939B. Materials Fabrication 939

II. INTERMAGNETICS GENERAL CORPORATION, WATERBURY,CONNECTICUT AND GUILDERLAND, NEW YORK. 942

A. Introduction 942B. Manufactured Materials 942

1. Ductile alloy superconductors 942

2. A15 superconductors 943

3. External bronze process 944C. Conclusions 944

III. SUPERCON, INC. 945

A. Introduction 945B. High Field Superconductors 945

IV. TELEDYNE WAH CHANG CO., ALBANY, OREGON 94697321

A. Introduction 946

B. Material Supply and Manufacturing 946

INDEX949