Superconductivity is a quantum phenomenon that manifests itself in materials showing zero electrical resistance below a characteristic temperature resulting in the potential for an electric current to run continually through such a material without the need for a power source. Such materials are used extensively in medical and power applications, e.g. MRI and NMR machines.
Discovering Superconductivity uses a series of practical and investigative activities, which can be used as tutor demonstrations or as student lab exercises.
This highly illustrated text features the following sections:
* Introduction – including a brief history of superconductivity
* Superconductivity – an explanation of the phenomenon and its effects
* Superconducting materials – including High & Low temperature superconductors
* Applications – how superconductivity is used in medical imaging, at CERN and in the Maglev trains
This text will serve as an excellent introduction for students, with or without a physics background, to superconductivity. With a strong practical, experimental emphasis, it provides readers with an overview of the topic preparing them for more advanced texts used in advanced undergraduate and post-graduate courses.
Power Point files of the figures presented within this text are available at: booksupport.wiley.com
A word from the author: ‘The intention of this text is to introduce the reader to the study of superconductivity via a minds-on approach …. The minds-on approach takes this a stage further by requiring the learner to engage with the process to a greater extent.’
Cuprins
List of Figures ix
List of Tables xiii
Preface xv
Acknowledgements xvii
To the Teacher xix
To the Student xxi
SECTION I Introduction 1
1 Resistivity and Conduction in Metals 3
1.1 Introduction 3
1.2 Resistivity 3
1.3 Conduction in Metals 5
1.4 Revisiting Ohm’s Law 7
References 11
2 A Brief History of Superconductivity 13
2.1 Introduction 13
2.2 The Beginning: Kwik Nagenoeg Nul 13
2.3 1933 – Perfect Diamagnetism? 16
2.4 The London Brothers 19
2.5 1957 – The BCS Theory 19
2.6 1962 – The Josephson Effect 21
2.7 1986 – Bednorz and Mu¨ ller and Oxide
Superconductors 22
2.8 2003 – Abrikosov, Ginzburg and Leggett – and
the Future 22
2.9 Getting Cold Enough 24
References 26
SECTION II Superconductivity 29
3 An Explanation of Superconductivity? 31
3.1 Transition Temperature 32
3.2 Two-Fluid Model 34
3.3 Critical Field, Critical Current 36
3.4 Schawlow and Devlin 38
3.5 The London Equation 39
3.6 BCS Theory 41
3.6.1 The Isotope Effect 44
3.6.2 The Energy Gap 44
3.7 An Alternative Approach to the Energy Gap 45
3.7.1 Electron-Electron Attraction 47
References 49
4 The Meissner-Ochsenfeld Effect 51
References 59
5 Diamagnetic Effects 61
5.1 Diamagnetism, Paramagnetism and Ferromagnetism 61
References 67
6 Persistence of Current 69
6.1 Quinn and Ittner 71
References 77
7 Type I and Type II Superconductors 79
7.1 Critical Magnetic Field 79
References 88
8 Flux Pinning 89
8.1 Vortex and Flux Lines 90
8.2 The Original Abrikosov 91
References 95
SECTION III Superconducting materials 97
9 Low-Temperature Superconductors 99
10 Organic Superconductors 101
References 105
11 High-Temperature Superconductors 107
11.1Magnesium Diboride 111
11.2 Transition Temperature of High-
Superconductors 112
References 114
SECTION IV Applications 115
12 Superconducting Wire 117
13 Medical Imaging 121
13.1Magnetic Resonance Imaging (MRI) 121
13.2Magnetoencephalography 122
13.2.1 Neuronal Currents 127
References 128
14 CERN and the LHC 129
References 133
15 Maglev Trains 135
Appendices 139
A The BCS Theory 141
B Flux Penetration 143
C The Josephson Junction and the SQUID 147
D MRI 151
Generating the MRI Signal 151
References 155
E A Note on Superfluidity 157
Index 163
F A Note on Safety 161
Index
Despre autor
Professor Gren Ireson is Professor of Science Education and his research interests include the learning and teaching of particle physics, quantum phenomena and superconductivity.
He teaches an undergraduate certificate course, delivering particle physics, astrophysics and quantum phenomena. For the past seven years he has been involved in pan-European projects developing electronic resources, paper resources, training materials and novel investigations for the learning and teaching of superconductivity. This work, currently ongoing, is based on four EU funded projects.
In addition to delivering this material to undergraduate certificate students the author has delivered the material to advanced school teachers, post graduate scientists [non-physicists] and to students and faculty within the School of Science and Technology at Nottingham Trent University.
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