J. Wesson "Tokamaks"

THIRD EDITION. © CLARENDON PRESS-OXFORD, 2004

Units and symbols

1 Fusion

1.1 Fusion and tokamaks
1.2 Fusion reactions
1.3 Thermonuclear fusion
1.4 Power balance
1.5 Ignition
1.6 Tokamaks
1.7 Tokamak reactor
1.8 Fuel resources
1.9 Tokamak economics
1.10 Tokamak research

2 Plasma physics

2.1 Tokamak plasma
2.2 Debye shielding
2.3 Plasma frequency
2.4 Lannor orbits
2.5 Particle motion along В
2.6 Particle drifts
2.7 Adiabatic invariants
2.8 Collisions
2.9 Kinetic equations
2.10 Fokker-Planck equation
2.11 Gyro-averaged kinetic equations
2.12 Fokker-Planck equation for a plasma
2.13 Fokker-Planck coefficients for Maxwellian distributions
2.14 Relaxation processes
2.15 Collision times
2.16 Resistivity
2.17 Runaway electrons
2.18 Electromagnetism
2.19 Fluid equations
2.20 Magnetohydrodynamics
2.21 Physics of plasma fluid
2.22 Plasma diamagnetism
2.23 Braginskii equations
2.24 Plasma waves
2.25 Landau damping

3 Equilibrium

3.1 Tokamak equilibrium
3.2 Flux functions
3.3 Grad-Shafranov equation
3.4 Safety factor q
3.5 Beta
3.6 Large aspect-ratio
3.7 Shafranov shift
3.8 Vacuum magnetic field
3.9 Electric fields
3.10 Particle orbits
3.11 Particle trapping
3.12 Trapped particle orbits
3.13 Plasma rotation
3.14 Current drive

4 Confinement

4.1 Tokamak confinement
4.2 Resistive plasma diffusion
4.3 Diffusion in a cylinder
4.4 Prirsch-Schlttter current
4.5 Pnrsch-SchlUter diffusion
4.6 Banana regime transport
4.7 Plateau transport
4.8 Ware pinch effect
4.9 Bootstrap current
4.10 Neoclassical resistivity
4.11 Ripple transport
4.12 Confinement modes and scaling expressions
4.13 H-modes
4.14 Internal transport barriers
4.15 Scaling laws
4.16 Transport coefficients
4.17 Fluctuations
4.18 Turbulence-induced transport
4.19 Radial electric field shear and transport
4.20 Candidate modes
4.21 Turbulence simulations, critical gradients, and temperature pedestals
4.22 Impurity transport
4.23 Experimental discoveries
4.24 Radiation losses
4.25 Impurity radiation

5 Heating

5.1 Heating
5.2 Ohmic heating
5.3 Neutral beam injection
5.4 Neutral beam heating
5.5 Neutral beam production
5.6 Radio frequency heating
5.7 Physics of radio frequency heating
5.8 Ion cyclotron resonance heating
5.9 Lower hybrid resonance heating
5.10 Electron cyclotron resonance heating
6 Mhd stability
6.1 Mhd stability
6.2 Stability theory
6.3 Growth rates
6.4 Energy principle
6.5 Tokamak instabilities
6.6 Large aspect-ratio tokamak
6.7 Kink instability
6.8 Tearing modes
6.9 Tearing stability
6.10 Internal kink
6.11 Resistive m = 1 modes
6.12 Localized modes
6.13 Ballooning modes
6.14 Ballooning stability
6.15 Axisymmetric modes
6.16 betta limit

7 Instabilities

7.1 Instabilities
7.2 Magnetic islands
7.3 Tearing modes
7.4 Mimov instabilities
7.5 Current penetration
7.6 Sawtooth oscillations
7.7 Disruptions
7.8 Causes of disruptions
7.9 Physics of disruptions
7.10 Mode locking
7.11 Error field instability
7.12 Vertical instability
7.13 Ergodicity
7.14 Fishbone instability
7.15 Toroidal Alfven eigenmodes
7.16 MARFEs
7.17 ELMs
7.18 Operational overview

8 Microinstabilities

8.1 Microinstabilities
8.2 Electron drift wave
8.3 Passing particle instabilities
8.4 Trapped particle instabilities
8.5 Micro-tearing modes
9 Plasma-surface interactions
9.1 Plasma-surface interactions
9.2 The plasma sheath
9.3 The scrape-off layer
9.4 Recycling
9.5 Atomic and molecular processes
9.6 Wall conditioning
9.7 Sputtering
9.8 Arcing
9.9 Limiters
9.10 Divertors
9.11 Heat flux, evaporation, and heat transfer
9.12 The behaviour of tritium

10 Diagnostics

10.1 Tokamak diagnostics
10.2 Magnetic measurements
10.3 Interferometry
10.4 Reflectometry
10.5 Measurement of electron temperature
10.6 Ion temperature and the ion distribution function
10.7 Radiation from plasmas
10.8 Total radiation measurements
10.9 Langmuir probes
10.10 Measurements of fluctuations
10.11 Determination of the q-profile

11 Tokamak experiments

11.1 Tokamak experiments
11.2 T-3
11.3 ST
11.4 JFT-2
11.5 Alcator A, Alcator C, and Alcator C-Mod
11.6 TFR
11.7 DITE
11.8 PLT
11.9 T-10
11.10 ISX
11.11 FT and FT Upgrade
11.12 Doublet-III
11.13 ASDEX
11.14 TEXT
11.15 TEXTOR
11.16 Tore Supra
11.17 COMPASS
11.18 RTP
11.19 START, MAST, and NSTX
11.20 TCV
11.21 Tokamak parameters

12 Large Tokamaks

12.1 Large Tokamaks
12.2 TFTR
12.3 JET
12.4 JT-60/JT-60U
12.5 DIII-D
12.6 ASDEX Upgrade

13 The future

13.1 Status
13.2 Strategy
13.3 Reactor requirements
13.4 ITER
13.5 Prospects

14 Appendix

14.1 Vector relations
14.2 Differential operators
14.3 Units—conversions
14.4 Physical constants
14.5 Coulomb logarithm
14.6 Collision times
14.7 Lengths
14.8 Frequencies
14.9 Velocities
14.10 Resistivity
14.11 Chang-Hinton fomula for Xi
14.12 Bootstrap current
14.13 Confinement scaling relations
14.14 Plasma shape
14.15 Formulae
14.16 Symbols

Index

When I worked on toroidal devices in the early days of fusion research the plasma temperatures achieved were around lOeV and the confinement times were perhaps 100 microseconds. In the next thirty years there was steady progress and at the publication of the first edition of this book in 1987 the temperatures in large tokamaks were several keV and a confinement time of one second had been reached.

By then the tokamak had become the predominant device in the attempt to achieve a useful power source from thermonuclear fusion. The accompanying increase in research activity and general interest in tokamaks led to the need for an introductory account of the subject and it was the aim of the first edition to provide such an introduction.

In the subsequent decade up to publication of the second edition the subject was trans- formed again. There were now areas where the experimental behaviour could be understood in terms of accepted theory, which was encouraging. There had also been substantial research on large tokamaks leading to the long awaited achievement of significant amounts of fusion power. Inevitably this brought us face to face with the problems involved in design- ing and building a tokamak reactor. The aim of the second edition was to describe these advances, and it is perhaps a measure of the developments in the subject that the second edition was twice the size of the first. When the time came for a reprint the opportunity was taken of bringing the book up to date in this third edition. In the intervening period the emphasis has been on preparing the ground for an experimental reactor but there have also been significant advances in our understanding of the plasma behaviour, for example, the wider experience of internal transport barriers, the appreciation of the role of tearing modes driven by neoclassical effects, and insights from turbulence simulations.

Despite the increasing complexity of the subject it is hoped that the book will still prove useful to those entering the subject, to specialists within tokamak research who wish to acquire knowledge of other areas in the subject, and to those outside tokamak research who would like to learn something of the principal concepts, methods, and problems involved. A further aim is to provide a handbook of equations, formulas, and data which the research worker frequently needs.

I regard it as an honour to have worked with the distinguished physicists who are my co-authors. Their spirit of cooperation has made the endeavour a pleasure.

I am grateful to my wife Olive for her support during the time-consuming preparation of the manuscript. I would like to thank Carol Simmons, Birgitta Croysdale, and Ingrid Farrelly who typed the earlier editions and Lynda Lee who has been unfailingly helpful in the preparation of this edition. I must further thank Stuart Morris who produced most of the figures and Chad Heys who helped with the many new figures required for the present edition. I am also grateful to Graham O'Connor for his careful reading of the text and for the resulting corrections.

Finally, I would like to dedicate this book to my friends and colleagues in the world- wide community of fusion physicists. They have set a splendid example of international collaboration for others to follow.