This book serves as an introduction to boundary plasma physics, providing an accessible entry point to the topic of plasma exhaust in magnetic confinement devices. While it delivers a concise, rigorous, and comprehensive account of all the major scientific topics relevant to those working on the subject, it also remains accessible and easy to consult due to its modular and compact structure. Beginning with the basic kinetic and fluid descriptions of plasma, and advancing through plasma-surface interactions, filamentary transport and plasma detachment, to conclude with a discussion of divertor configurations, this book represents a necessary and timely addition to the literature on the fast-growing field of boundary plasma physics. It will appeal to experienced theoreticians or experimentalists looking to enter the field as well as graduate students wishing to learn about it.
Author(s): Fulvio Militello
Series: Springer Series on Atomic, Optical, and Plasma Physics, 123
Publisher: Springer
Year: 2022
Language: English
Pages: 533
City: Cham
Preface
Acknowledgements
Contents
1 Introduction
1.1 Essential Elements of Fusion Physics
1.2 The Plasma Exhaust Problem
1.3 Boundary Physics at a Glance
1.4 Goals and Synopsis
References
2 Plasma Equations
2.1 Forces and Dynamics
2.2 Kinetic Description
2.2.1 Liouville Equation and Probability Distributions
2.2.2 Boltzmann and Vlasov Equation
2.3 A Basic Discussion of Plasma Collision Operators
2.3.1 From Collisions to Collision Operators
2.3.2 Boltzmann's H-Theorem, or a Short History of Irreversibility
2.3.3 Simplifying Things: The BGK Operator
2.4 Fluid Description
2.4.1 Density Equation
2.4.2 Momentum Equation
2.4.3 Energy Equation
2.5 Implication of Non-relativistic Dynamics
2.6 Closures, Orderings and Reduced Models
2.6.1 Braginskii Equations
2.6.2 MHD
2.6.3 Drift-Ordered Equations
2.6.4 Geometry in Reduced 2D Systems
References
Further Reading
3 Sheath Physics
3.1 The Langmuir (or Debye) Sheath
3.2 Debye Shielding
3.3 A Quick Review of Wall Models
3.4 Wall with Perpendicular Magnetic Field or Non MagnetisedPlasma
3.4.1 Fluid Sheath Model and Existence Conditions
3.4.2 Particle Fluxes and Electrical Phenomena in the Sheath
3.4.3 Collisional Presheath
3.4.4 Kinetic Treatment of the Sheath
3.4.5 Bohm Criterion for Plasmas with Multiple Ions
3.4.6 Sheath Energy Transmission: Formerly (and Wrongly) Known as Heat Transmission
3.5 Wall with Inclined Magnetic Fields and Magnetic Pre-sheath
3.5.1 Bohm Criterion for Shallow Angles and Magnetic Pre-sheath
3.5.2 Electric Potential and Dependence on the Incidence Angle
3.5.3 Effect of Fluid Drifts
3.5.4 Very Shallow Angles and Role of Collisions
References
Further Reading
4 Atomic, Molecular and Plasma-Surface Physics
4.1 A Few Useful Concepts and Reaction Terminology
4.2 Basic Model with Atomic Hydrogen
4.2.1 Electron-Neutrals Interactions
4.2.2 Ion-Neutral Interactions
4.2.3 Other Interactions Between the Electrons,Ions, and Atoms
4.3 Molecular Interactions
4.4 Impurities
4.5 Plasma-Surface Interactions
4.5.1 Reflection, Trapping and Desorption
4.5.2 Wall Recycling
4.5.3 Sputtering
4.5.4 Electron Emission
References
Further Reading
5 Basic Exhaust Concepts
5.1 Magnetic Geometry and Its Connection with the BoundaryPlasma
5.2 Protecting the Plasma Facing Structures
5.3 Elementary Estimates of Scrape-Off Layer Width
5.4 Simple Geometrical Effects—Flux Expansion and Tile Tilting
5.4.1 Poloidal and Toroidal Flux Expansion
5.4.2 Target Tilting
5.4.3 Total Flux Expansion and Magnetic Projection of the Areas
5.4.4 Further Observations on the Geometrical Effects
5.5 Divertor Regimes: The Two Point Model
5.5.1 Derivation of the Two Point Model
5.5.2 General Solutions of the Two Point Model
5.5.3 Collisionality and Its Role in the Two Point Model
5.5.4 Applications of the Two Point Model: Divertor Regimes
5.5.5 Extended Two Point Model
5.6 Flux Formulation and Parallel Profiles in the Boundary Plasma
5.6.1 Neutrals and Particle Sources
5.6.2 Particle Flux
5.6.3 Energy Flux and Temperature Profile
5.6.4 Target Conditions
5.6.5 Upstream Conditions
5.6.6 Mach Number, Velocity and Density Profiles
5.6.7 Electric Potential
5.7 Divertor Asymmetry in Low to Intermediate Collisionality
References
Further Reading
6 Radiation and Detachment
6.1 Plasma/Neutral Processes at Large Collisionality and Low Temperature
6.1.1 Model Equations for High Collisionality Cold Plasmas
6.1.2 A Closer Look at the Energy Transfer Mechanisms in a Cold Pure Plasmas
6.2 Impurity Radiation and Associated Models
6.3 Divertor Asymmetry at High Collisionality or Radiation
6.4 Detachment
6.4.1 Particle Flux Balance
6.4.2 Routes to Detachment: A Qualitative Discussion
6.4.3 Role of Pressure Losses and Recombination
6.4.4 Partial Detachment and Detachment Onset
6.4.5 Deep Detachment: Detachment Window and Stability
6.5 MARFEs and Stable X-Point Radiation
References
7 Filamentary Transport
7.1 Basic Filament Physics and Observations
7.1.1 Filament Propagation
7.2 Filaments at the Outer Midplane
7.2.1 Filament Generation
7.2.2 Filament Interactions (or Lack Thereof)
7.2.3 Parallel Dynamics of the Upstream Filaments
7.2.4 Filaments at the X-Point
7.2.5 Response of Filaments to Different SOL Conditions
7.3 Filaments in the Divertor Region
7.4 The Nature of Boundary Turbulence
7.4.1 Important Statistical Concepts and Tools
7.4.2 Randomness and Structure in Temporal Fluctuations
7.4.3 Diffusion and Spatial Fluctuations
7.5 Statistical Models of Filamentary Transport and UpstreamProfiles
7.5.1 Profiles, Background and Fluctuations
7.5.2 Phenomenology of the Upstream Profiles
7.5.3 Statistical Framework
7.6 Heat Fluxes at the Divertor Target: Wagner-Eich Function
References
Further Reading
8 Conventional and Alternative Divertors
8.1 Single Null Divertor: The ITER Solution
8.2 Alternative Divertor Designs
8.2.1 Why They Are Needed
8.2.2 Beneficial Features in Divertor Design
8.3 The X-Divertor
8.4 The Super-X Divertor
8.5 Double Null Divertor
8.6 The Snowflake Divertor and X-Point Target Divertor
8.7 Liquid Metals as Plasma Facing Components
8.8 What Will the Future Bring?
References
Further Reading
Appendix A
A.1 Of Vectors and Tensors
A.2 Viscous Forces in all Their Glory
References
Index
