Physics:Quantum Plasma (fusion context)

← Back to Plasma and fusion physics

Plasma physics studies ionized gases consisting of charged particles such as electrons and ions. Plasmas are often referred to as the fourth state of matter and are characterized by:

• Collective electromagnetic behavior
• Long-range interactions
• High electrical conductivity

Plasma physics forms the basis for many natural and technological systems, including:

• Stars and astrophysical plasmas
• Laboratory plasmas
• Controlled fusion devices such as tokamaks

Conceptual illustration of plasma physics in a fusion context, showing magnetically confined ionized gas in a tokamak and the collective behavior governed by electromagnetic fields and transport processes.

What is a plasma?

A plasma is a quasi-neutral gas of charged particles that exhibits collective behavior.

Key properties:

• Quasi-neutrality:

$n_e\approx n_i$

• Debye shielding:

${\lambda }_D=\sqrt{\frac{{ϵ}_0{k}_{B}T}{n{e}^2}}$

• Plasma frequency:

${\omega }_p=\sqrt{\frac{n{e}^2}{{ϵ}_{0}m}}$

These properties distinguish plasmas from neutral gases.

Collective behavior

Unlike ordinary gases, plasmas are dominated by electromagnetic interactions.

Important phenomena include:

• Waves (plasma oscillations)
• Instabilities
• Self-organization

The motion of particles is governed by the Lorentz force:

$\mathbf{𝐅}=q(\mathbf{𝐄}+\mathbf{𝐯}\times \mathbf{𝐁})$

This leads to complex collective dynamics.

Kinetic description

Plasmas are typically described using kinetic theory.

The distribution function:

$f(\mathbf{𝐱},\mathbf{𝐯},t)$

evolves according to the Vlasov equation:

$\frac{\partial f}{\partial t}+\mathbf{𝐯}\cdot {\mathrm{\nabla }}_{x}f+\frac{q}{m}(\mathbf{𝐄}+\mathbf{𝐯}\times \mathbf{𝐁})\cdot {\mathrm{\nabla }}_{v}f=0$

This equation describes collisionless plasmas and captures collective effects.

Fluid description

Macroscopic plasma behavior can be described using fluid equations derived from kinetic theory.

Key quantities:

• Density $n$
• Velocity $\mathbf{𝐮}$
• Temperature $T$

These lead to magnetohydrodynamics (MHD), which treats plasma as a conducting fluid.

Magnetically confined plasmas

In fusion research, plasmas are confined using magnetic fields.

The most important configuration is the tokamak:

• Toroidal geometry
• Strong magnetic fields
• High-temperature plasma

Magnetic confinement prevents particles from escaping and allows sustained fusion conditions.

Transport processes

Transport in plasmas determines how particles, momentum, and energy move.

Key processes include:

• Diffusion
• drift motion
• Collisions

Transport can be described by:

• kinetic equations
• Fluid models
• Turbulence models

These processes are essential for understanding plasma confinement and losses.

Edge plasma and scrape-off layer

The outer region of a confined plasma is called the scrape-off layer (SOL).

Characteristics:

• Open magnetic field lines
• Strong gradients
• Interaction with material surfaces

Particles flow along magnetic field lines toward divertor targets, where they are recycled.

This region plays a key role in:

• Heat exhaust
• Particle balance
• plasma-wall interaction

Connection to tokamak edge physics

Edge plasma behavior determines:

• divertor performance
• Recycling of neutrals
• Plasma stability

Detailed modeling of this region requires:

• drift physics
• momentum transport
• Plasma rotation

These effects are studied in:

• Physics:Quantum Tokamak
• Physics:Quantum Tokamak edge physics and recycling asymmetries

Physical interpretation

Plasma physics represents an emergent level of physical description:

• Microscopic level → quantum particles
• Mesoscopic level → distribution functions
• Macroscopic level → fluid behavior

Most plasma models are classical, but their origin lies in quantum statistical mechanics and kinetic theory.

Summary

Plasma physics:

• Studies ionized gases with collective electromagnetic behavior
• Uses kinetic and fluid descriptions
• Explains transport, waves, and instabilities
• Forms the basis of fusion research

It provides the final step connecting quantum theory to large-scale physical systems.

Table of contents (176 articles)

Index

Core theory

1. Foundations
2. Conceptual and interpretations
3. Mathematical structure and systems
4. Atomic and spectroscopy
5. Wavefunctions and modes
6. Quantum dynamics and evolution
7. Measurement and information
8. Quantum information and computing

Matter (by scale)

9. Matter (by scale)

Applications and extensions

10. Quantum optics and experiments
11. Open quantum systems
12. Quantum field theory
13. Statistical mechanics and kinetic theory
14. Condensed matter and solid-state physics
15. Plasma and fusion physics
16. Timeline
17. Advanced and frontier topics

Methods and tools

18. Methods and tools

Full contents

1. Foundations (11)↑

1. Physics:Quantum basics
2. Physics:Quantum Postulates
3. Physics:Quantum Hilbert space
4. Physics:Quantum Observables and operators
5. Physics:Quantum mechanics
6. Physics:Quantum mechanics measurements
7. Physics:Quantum state
8. Physics:Quantum system
9. Physics:Quantum superposition
10. Physics:Quantum probability
11. Physics:Quantum Mathematical Foundations of Quantum Theory

2. Conceptual and interpretations (13)↑

12. Physics:Quantum Interpretations of quantum mechanics
13. Physics:Quantum Wave–particle duality
14. Physics:Quantum Complementarity principle
15. Physics:Quantum Uncertainty principle
16. Physics:Quantum Measurement problem
17. Physics:Quantum Bell's theorem
18. Physics:Quantum Hidden variable theory
19. Physics:Quantum nonlocality
20. Physics:Quantum contextuality
21. Physics:Quantum Darwinism
22. Physics:Quantum A Spooky Action at a Distance
23. Physics:Quantum A Walk Through the Universe
24. Physics:Quantum The Secret of Cohesion and How Waves Hold Matter Together

3. Mathematical structure and systems (13)↑

25. Physics:Quantum Density matrix
26. Physics:Quantum Exactly solvable quantum systems
27. Physics:Quantum Formulas Collection
28. Physics:Quantum A Matter Of Size
29. Physics:Quantum Symmetry in quantum mechanics
30. Physics:Quantum Angular momentum operator
31. Physics:Quantum Runge–Lenz vector
32. Physics:Quantum Approximation Methods
33. Physics:Quantum Matter Elements and Particles
34. Physics:Quantum Dirac equation
35. Physics:Quantum Klein–Gordon equation
36. Physics:Quantum pendulum
37. Physics:Quantum configuration space

4. Atomic and spectroscopy (14)↑

Quantum atomic structure and spectroscopy: orbitals, energy levels, and emission and absorption spectra.

38. Physics:Quantum Atomic structure and spectroscopy
39. Physics:Quantum Hydrogen atom
40. Physics:Quantum number
41. Physics:Quantum Multi-electron atoms
42. Physics:Quantum Fine structure
43. Physics:Quantum Hyperfine structure
44. Physics:Quantum Isotopic shift
45. Physics:Quantum defect
46. Physics:Quantum Zeeman effect
47. Physics:Quantum Stark effect
48. Physics:Quantum Spectral lines and series
49. Physics:Quantum Selection rules
50. Physics:Quantum Fermi's golden rule
51. Physics:Quantum beats

5. Wavefunctions and modes (9)↑

A quantum wavefunction showing probability amplitude in space; the square of its magnitude gives the probability density.

52. Physics:Quantum Wavefunction
53. Physics:Quantum Superposition principle
54. Physics:Quantum Eigenstates and eigenvalues
55. Physics:Quantum Boundary conditions and quantization
56. Physics:Quantum Standing waves and modes
57. Physics:Quantum Normal modes and field quantization
58. Physics:Number of independent spatial modes in a spherical volume
59. Physics:Quantum Density of states
60. Physics:Quantum carpet

6. Quantum dynamics and evolution (17)↑

61. Physics:Quantum Time evolution
62. Physics:Quantum Schrödinger equation
63. Physics:Quantum Time-dependent Schrödinger equation
64. Physics:Quantum Stationary states
65. Physics:Quantum Perturbation theory
66. Physics:Quantum Time-dependent perturbation theory
67. Physics:Quantum Adiabatic theorem
68. Physics:Quantum Scattering theory
69. Physics:Quantum S-matrix
70. Physics:Quantum tunnelling
71. Physics:Quantum speed limit
72. Physics:Quantum revival
73. Physics:Quantum reflection
74. Physics:Quantum oscillations
75. Physics:Quantum jump
76. Physics:Quantum boomerang effect
77. Physics:Quantum chaos

7. Measurement and information (9)↑

78. Physics:Quantum Measurement theory
79. Physics:Quantum Measurement operators
80. Physics:Quantum Projective measurement
81. Physics:Quantum POVM
82. Physics:Quantum Weak measurement
83. Physics:Quantum Measurement collapse
84. Physics:Quantum entanglement
85. Physics:Quantum Zeno effect
86. Physics:Quantum limit

8. Quantum information and computing (10)↑

87. Physics:Quantum information theory
88. Physics:Quantum Qubit
89. Physics:Quantum Entanglement
90. Physics:Quantum Gates and circuits
91. Physics:Quantum Computing Algorithms in the NISQ Era
92. Physics:Quantum Noisy Qubits
93. Physics:Quantum random access code
94. Physics:Quantum pseudo-telepathy
95. Physics:Quantum network
96. Physics:Quantum money

9. Quantum optics and experiments (5)↑

Experimental quantum physics: qubits, dilution refrigerators, quantum communication, and laboratory systems.

97. Physics:Quantum Nonlinear King plot anomaly in calcium isotope spectroscopy
98. Physics:Quantum optics beam splitter experiments
99. Physics:Quantum Ultra fast lasers
100. Physics:Quantum Experimental quantum physics
101. Physics:Quantum optics
Template:Quantum optics operators

10. Open quantum systems (9)↑

102. Physics:Quantum Open systems
103. Physics:Quantum Master equation
104. Physics:Quantum Lindblad equation
105. Physics:Quantum Decoherence
106. Physics:Quantum dissipation
107. Physics:Quantum Markov semigroup
108. Physics:Quantum Markovian dynamics
109. Physics:Quantum Non-Markovian dynamics
110. Physics:Quantum Trajectories

11. Quantum field theory (19)↑

Structural dependency map of quantum field theory.

111. Physics:Quantum field theory (QFT) basics
112. Physics:Quantum field theory (QFT) core
113. Physics:Quantum Fields and Particles
114. Physics:Quantum Second quantization
115. Physics:Quantum Harmonic Oscillator field modes
116. Physics:Quantum Creation and annihilation operators
117. Physics:Quantum vacuum fluctuations
118. Physics:Quantum Propagators in quantum field theory
119. Physics:Quantum Feynman diagrams
120. Physics:Quantum Path integral formulation
121. Physics:Quantum Renormalization in field theory
122. Physics:Quantum Renormalization group
123. Physics:Quantum Field Theory Gauge symmetry
124. Physics:Quantum Non-Abelian gauge theory
125. Physics:Quantum Electrodynamics (QED)
126. Physics:Quantum chromodynamics (QCD)
127. Physics:Quantum Electroweak theory
128. Physics:Quantum Standard Model
129. Physics:Quantum triviality

12. Statistical mechanics and kinetic theory (9)↑

130. Physics:Quantum Statistical mechanics
131. Physics:Quantum Partition function
132. Physics:Quantum Distribution functions
133. Physics:Quantum Liouville equation
134. Physics:Quantum Kinetic theory
135. Physics:Quantum Boltzmann equation
136. Physics:Quantum BBGKY hierarchy
137. Physics:Quantum Relaxation and thermalization
138. Physics:Quantum Thermodynamics

13. Condensed matter and solid-state physics (13)↑

139. Physics:Quantum Band structure
140. Physics:Quantum Fermi surfaces
141. Physics:Quantum Semiconductor physics
142. Physics:Quantum Phonons
143. Physics:Quantum Electron-phonon interaction
144. Physics:Quantum Superconductivity
145. Physics:Quantum Topological phases of matter
146. Physics:Quantum well
147. Physics:Quantum spin liquid
148. Physics:Quantum spin Hall effect
149. Physics:Quantum phase transition
150. Physics:Quantum critical point
151. Physics:Quantum dot

14. Plasma and fusion physics (8)↑

Conceptual illustration of plasma physics in a fusion context, showing magnetically confined ionized gas in a tokamak and the collective behavior governed by electromagnetic fields and transport processes.

152. Physics:Quantum Fusion reactions and Lawson criterion
153. Physics:Quantum Plasma (fusion context)
154. Physics:Quantum Magnetic confinement fusion
155. Physics:Quantum Inertial confinement fusion
156. Physics:Quantum Plasma instabilities and turbulence
157. Physics:Quantum Tokamak core plasma
158. Physics:Quantum Tokamak edge physics and recycling asymmetries
159. Physics:Quantum Stellarator

15. Timeline (8)↑

160. Physics:Quantum mechanics/Timeline
161. Physics:Quantum mechanics/Timeline/Pre-quantum era
162. Physics:Quantum mechanics/Timeline/Old quantum theory
163. Physics:Quantum mechanics/Timeline/Modern quantum mechanics
164. Physics:Quantum mechanics/Timeline/Quantum field theory era
165. Physics:Quantum mechanics/Timeline/Quantum information era
166. Physics:Quantum mechanics/Timeline/Quantum technology era
167. Physics:Quantum mechanics/Timeline/Quiz

16. Advanced and frontier topics (9)↑

168. Physics:Quantum topology
169. Physics:Quantum battery
170. Physics:Quantum Supersymmetry
171. Physics:Quantum Black hole thermodynamics
172. Physics:Quantum Holographic principle
173. Physics:Quantum gravity
174. Physics:Quantum De Sitter invariant special relativity
175. Physics:Quantum Doubly special relativity
176. Physics:Quantum arithmetic geometry

References

Author: Harold Foppele