imported>WikiHarold: Repair Quantum Collection B backlink template

2026-05-08T20:01:55Z

Repair Quantum Collection B backlink template

← Older revision	Revision as of 20:01, 8 May 2026
(No difference)

imported>WikiHarold: Repair Quantum Collection B backlink template

2026-05-08T20:01:55Z

Repair Quantum Collection B backlink template

New page

{{Quantum book backlink|Plasma and fusion physics}}
Plasma physics studies [[Physics:Quantum matter/plasma|ionized gases]] consisting of charged particles such as [[Physics:Quantum atoms/electron|electrons]] and [[Physics:Quantum atoms/ion|ion]]s.
Plasmas are often referred to as the fourth state of matter and are characterized by:
* Collective electromagnetic behavior
* Long-range interactions
* High electrical [[Physics:Quantum Transport theory|conductivity]]
Plasma physics forms the basis for many natural and technological systems, including:
* Stars and astrophysical plasmas
* Laboratory plasmas
* Controlled fusion devices such as [[Physics:Quantum Tokamak|tokamak]]s<ref name="chen">F. F. Chen, ''Introduction to Plasma Physics and Controlled Fusion''.</ref>

[[File:Plasmaphysica in a tokamak reactor-2.jpg|thumb|300px|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.<ref name="chen" />

Key properties:

* Quasi-neutrality:
<math>
n_e \approx n_i
</math>

* Debye shielding:
<math>
\lambda_D = \sqrt{\frac{\epsilon_0 k_B T}{n e^2}}
</math>

* Plasma frequency:
<math>
\omega_p = \sqrt{\frac{n e^2}{\epsilon_0 m}}
</math>

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:

<math>
\mathbf{F} = q(\mathbf{E} + \mathbf{v} \times \mathbf{B})
</math>

This leads to complex collective dynamics.<ref name="chen" />

== Kinetic description ==
Plasmas are typically described using [[Physics:Quantum kinetic theory|kinetic theory]].

The distribution function:

<math>
f(\mathbf{x}, \mathbf{v}, t)
</math>

evolves according to the [[Physics:Quantum Vlasov equation|Vlasov equation]]:

<math>
\frac{\partial f}{\partial t} + \mathbf{v} \cdot \nabla_x f + \frac{q}{m}(\mathbf{E} + \mathbf{v} \times \mathbf{B}) \cdot \nabla_v f = 0
</math>

This equation describes collisionless plasmas and captures collective effects.<ref name="nicholson">D. R. Nicholson, ''Introduction to Plasma Theory''.</ref>

== Fluid description ==
Macroscopic plasma behavior can be described using fluid equations derived from [[Physics:Quantum kinetic theory|kinetic theory]].

Key quantities:

* Density <math>n</math>
* Velocity <math>\mathbf{u}</math>
* Temperature <math>T</math>

These lead to [[Physics:Quantum Magnetohydrodynamics|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 [[Physics:Quantum Tokamak|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
* [[Physics:Quantum Drift physics|drift motion]]
* Collisions

Transport can be described by:

* [[Physics:Quantum kinetic theory|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
* [[Physics:Quantum Plasma-wall interaction|plasma-wall interaction]]

== Connection to tokamak edge physics ==
'''Edge plasma behavior determines:'''

* [[Physics:Quantum Tokamak#Divertor performance|divertor performance]]
* Recycling of neutrals
* Plasma stability

Detailed modeling of this region requires:

* [[Physics:Quantum Drift physics|drift physics]]
* [[Physics:Quantum Transport theory|momentum transport]]
* Plasma rotation

These effects are studied in:

* [[Physics:Quantum Tokamak]]
* [[Physics:Quantum Tokamak edge physics and recycling asymmetries]]<ref name="emdee">Emdee, E. D. et al., ''Combined Influence of Rotation and Scrape-Off Layer Drifts on Recycling Asymmetries in Tokamak Plasmas''.</ref>

== 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.

=See also=
{{#invoke:PhysicsQC|tocHeadingAndList|Physics:Quantum basics/See also}}

=References=
{{reflist|3}}
{{Author|Harold Foppele}}

{{Sourceattribution|Plasma physics (fusion context)|1}}

Physics:Quantum Plasma (fusion context) - Revision history

imported>WikiHarold: Repair Quantum Collection B backlink template

imported>WikiHarold: Repair Quantum Collection B backlink template