C.M.Braams, P.E.Stott "Nuclear fusion"

Institute of Physics Publishing Bristol and Philadelphia 2002

Preface
Prologue

1 The road to Geneva
1.1 The scientific roots
1.1.1 Fusion energy in stars
1.1.2 Fusion reactions on Earth
1.1.3 The origins of plasma physics
1.2 In and out of secrecy
1.2.1 Programmes taking shape
1.2.2 Looking behind the curtain
1.2.3 The road to travel

2 Geneva 1958
2.1 Fast linear pinches or Z-pinches
2.2 Steady-state mirror confinement
2.3 Pulsed mirrors and theta pinches
2.4 Stellarators
2.5 Toroidal pinches
2.6 RF fields and other subjects
2.7 Looking back at Geneva

3 Open systems
3.1 Simple mirror machines
3.1.1 Mirror loss
3.1.2 The quest for burnout
3.1.3 MHD stability
3.1.4 Velocity-space instabilities in mirror machines
3.2 Tandem mirrors
3.3 Z-pinch and plasma focus
3.4 Theta pinches
3.5 Unconventional schemes
3.6 The status of open systems

4 Pulsed toroidal systems and alternative lines
4.1 High-beta stellarators
4.2 Stabilized and reversed-field pinches
4.3 Screw pinches
4.4 Field-reversed configurations and spheromaks
4.5 Internal-ring devices
4.6 Unconventional toroidal schemes
4.7 Status of alternative toroidal systems

5 Stellarators versus tokamaks
5.1 Stellarators: Bohm diffusion or not?
5.2 Tokamaks: from Geneva to Novosibirsk
5.3 Diagnosing the plasma
5.4 Stellarators trailing tokamaks

6 The dash to tokamaks
6.1 The tokamak goes abroad
6.2 Neutral beam heating
6.3 Disruptions and density limits
6.4 Sawteeth
6.5 Passing through purgatory
6.6 Hydrogen recycling and refuelling
6.7 Divertors
6.8 Neoclassical theory
6.9 Empirical scalings

7 The next generation
7.1 New machines
7.2 Radio-frequency heating
7.3 Non-inductive current drive
7.4 The switch to carbon
7.5 Beta limits
7.6 Confinement degradation
7.7 TheH-mode
7.8 Attempts to understand confinement
7.9 Transport codes

8 The era of the big tokamaks
8.1 Building the big tokamaks
8.1.1 JET—the Joint European Torus
8.1.2 TFTR—the Tokamak Fusion Test Reactor
8.1.3 JT-60
8.2 Operation and results
8.2.1 Heating the big tokamaks
8.2.2 Keeping clean
8.2.3 Pushing to higher performance
8.2.4 Real fusion power at last
8.2.5 The end of the era
8.3 Improving the tokamak
8.3.1 Reactor-relevant divertor physics
8.3.2 Advanced tokamak scenarios
8.3.3 Spherical tokamaks
8.4 Towards ignition

9 Towards a fusion reactor
9.1 First thoughts
9.2 Second thoughts
9.3 Pioneering studies
9.4 Drawing fire
9.5 Economic and social aspects of fusion
9.6 Joining forces for the 'next step'
9.7 ITER
9.7.1 The ITER EDA design
9.7.2 The physics basis
9.7.3 Decision and indecision
9.7.4 Back to the drawing board

10 Epilogue
References
Symbols
Glossary
Index

Physicists who first cast an eye on the problem of the peaceful use of thermonuclear energy, around the middle of the twentieth century, soon realized that to try something and see what might happen would get them nowhere until they understood more of plasma physics. But although plasmas occur widely in nature, indeed most of the known matter in the universe is in the plasma state, this area of physics had been largely neglected. When relativity and quantum mechanics had presented themselves in the early years of the twentieth century as the areas where the greatest advances in physics were to be made, the unexplored land between Newtonian mechanics and Maxwellian electromagnetism was simply overlooked. Astronomers and gas discharge physicists were the first to become aware of this omission and to take steps to correct it and, when the thermonuclear problem came up, they were among the first to bring their expertise to bear on the subject. In the course of the 1950s this developed into a recognized new branch of physics and as this unfolded, controlled thermonuclear research, or fusion research as it came to be known, evolved from basic to applied plasma physics. As it turned out, of all the magnetic field configurations investigated for their capability to confine a hot plasma, the tokamak became the leading contender, to the point where we can now proceed to the construction of a test reactor and to contemplate the next step: a prototype commercial reactor. In this book, we attempt to sketch the different paths followed by fusion research from initial ignorance to present understanding, be it the understanding of why a particular scheme would not work, or why it was more profitable to concentrate, at least for the time being, on the mainstream—tokamak development. The authors have been actively involved in these events from 1957 to 1987 (CMB) and from 1962 to the present time (PES). We do not regard ourselves as historians, but we hope that our account will help future historians as well as scientists in other fields to find their way through this difficult terrain. We also hope that our present and former colleagues will, when reading the book, recall the excitement with which all of us witnessed what went on in this challenging field of discovery. And most of all we wish to help those new in the field or preparing to enter it, to see it in a broad perspective and to realize that the course of fusion will not have been run even when the first demonstration reactor has come into operation.

In the course of writing this book we have drawn on the vast volume of published material relating to fusion in scientific journals and elsewhere, as well as on unpublished material and on the reminiscences of our colleagues. We have tried to give an accurate and balanced account of the development of fusion research that reflects the relative importance of the various lines that have been pursued and gives credit to the contributions from the many institutions in the countries that have engaged themselves in fusion research. However, compressing half a century of research into a book of manageable length has not been an easy task, so inevitably there will be issues, topics and contributions that some readers might feel deserved more detailed treatment.

We would like to thank all of our colleagues who have helped and advised us in many ways. In particular we are indebted to Folker Engelmann, Masami Fujiwara, Viktor Golant, the late Igor Golovin, Evgeniy Gusakov, Ian Hutchinson, Atsuo Iiyoshi, Sigeru Mori, Vyacheslav Strelkov, Masaji Yoshikawa and Kenneth Young who took a great deal of time and trouble to read an early draft of the book and who gave constructive criticism and valuable suggestions for its improvement. We are grateful also to Rosario Bartiromo, Michael Bell, Bas Braams, Hardo Bruhns, Niek Lopes Cardozo, Chris Carpenter, James Drake, Umberto Finzi, Alan Gibson, Richard Gill, Giinther Grieger, Hans-Jiirgen Hartfuss, Richard Hawryluk, Bick Hooper, John How, Jan Hugill, Otto Kardaun, Winfried Kernbichler, Bo Lehnert, Anthony Leonard, Jonathan Lister, James Luxon, Akko Maas, the late Charles Maisonnier, Dale Meade, Tobin Munsat, Katsunori Muraoka, Per Nielsen, Noud Oomens, Ronald Parker, Carol Phillips, Kseniya Razumova, Jan Rem, Michael Roberts, Chris Schiiller, Richard Siemon, Shigeru Sudo, Tatsuo Sugie, Vladimir Tereshin, Paul Thomas, Vladimir Voitsenya, Friedrich Wagner, Hans Wilhelmsson, Horst Wobig, Alan Wootton and many others who have helped us to check specific points of detail, generously provided figures and assisted in other ways. A special thanks to John Navas, Simon Laurenson and the staff of Institute of Physics Publishing for their patience and encouragement. We would like to thank Piet van Kuyk and Wim Tukker who produced or edited most of the figures.

CMB acknowledges the hospitality he enjoyed at the FOM Institute 'Rijnhuizen', The Netherlands after his retirement and the support he received from its scientific staff and its technical and administrative services.

The content of this book and the views expressed therein are the sole responsibility of the authors and do not necessarily represent the views of the European Commission or its services.