plasma (physics)

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Plasma ()πλάσμα
, Henry George Liddell, Robert Scott, ''A Greek English Lexicon'', on Perseus
is one of the
four fundamental states of matter In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and Plasma (physics), plasma. Many intermediate states are known to exist, such as ...
. It contains a significant portion of charged particles – ions and/or
electron The electron ( or ) is a subatomic particle with a negative one elementary charge, elementary electric charge. Electrons belong to the first generation (particle physics), generation of the lepton particle family, and are generally thought t ...
s. The presence of these charged particles is what primarily sets plasma apart from the other fundamental states of matter. It is the most abundant form of ordinary matter in the
universe The universe is all of space and time and their contents, including planets, stars, galaxy, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmology, cosmological description of the development of ...
, being mostly associated with
star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
s, including the
Sun The Sun is the star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other st ...
. It extends to the rarefied intracluster medium and possibly to intergalactic regions. Plasma can be artificially generated by heating a neutral gas or subjecting it to a strong
electromagnetic field An electromagnetic field (also EM field or EMF) is a classical (i.e. non-quantum) field (physics), field produced by (stationary or moving) electric charges. It is the field described by classical electrodynamics (a classical field theory) and is ...
. The presence of charged particles makes plasma electrically conductive, with the dynamics of individual particles and macroscopic plasma motion governed by collective electromagnetic fields and very sensitive to externally applied fields. The response of plasma to electromagnetic fields is used in many modern devices and technologies, such as plasma televisions or plasma etching. Depending on temperature and density, a certain number of neutral particles may also be present, in which case plasma is called
partially ionized The degree of ionization (also known as ''ionization yield'' in the literature) refers to the proportion of neutral particles, such as those in a gas or aqueous solution, that are Ionization, ionized. For electrolytes, it could be understood as ...
.
Neon sign In the signage industry, neon signs are electric signs lighted by long luminous gas-discharge tubes that contain rarefied neon or other gases. They are the most common use for neon lighting, which was first demonstrated in a modern form in Decem ...
s and
lightning Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...
are examples of partially ionized plasmas. Unlike the
phase transition In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic State of ...
s between the other three states of matter, the transition to plasma is not well defined and is a matter of interpretation and context. Whether a given degree of ionization suffices to call a substance 'plasma' depends on the specific phenomenon being considered.

# Early history

Plasma was first identified in laboratory by
Sir William Crookes Sir William Crookes (; 17 June 1832 – 4 April 1919) was a British chemist and physicist who attended the Royal College of Chemistry, now part of Imperial College London, and worked on spectroscopy. He was a pioneer of vacuum tubes, inventing t ...
. Crookes presented a
lecture A lecture (from Latin ''lēctūra'' “reading” ) is an oral presentation intended to present information or teach people about a particular subject, for example by a university or college teacher. Lectures are used to convey critical inform ...
on what he called "radiant matter" to the
British Association for the Advancement of Science The British Science Association (BSA) is a charity and learned society founded in 1831 to aid in the promotion and development of science. Until 2009 it was known as the British Association for the Advancement of Science (BA). The current Ch ...
, in Sheffield, on Friday, 22 August 1879. Systematic studies of plasma began with the research of
Irving Langmuir Irving Langmuir (; January 31, 1881 – August 16, 1957) was an American chemist, physicist, and engineer. He was awarded the Nobel Prize in Chemistry in 1932 for his work in surface chemistry. Langmuir's most famous publication is the 1919 art ...
and his colleagues in the 1920s. Langmuir also introduced the term "plasma" as a description of ionized gas in 1928:
Lewi Tonks Lewi Tonks (1897–1971) was an American quantum mechanics, quantum physicist noted for his discovery (with Marvin D. Girardeau) of the Tonks–Girardeau gas. Tonks was employed by General Electric for most of his working life, researching microwa ...
and Harold Mott-Smith, both of whom worked with Langmuir in the 1920s, recall that Langmuir first used the term by analogy with the
blood plasma Blood plasma is a light Amber (color), amber-colored liquid component of blood in which blood cells are absent, but contains Blood protein, proteins and other constituents of whole blood in Suspension (chemistry), suspension. It makes up about ...
. Mott-Smith recalls, in particular, that the transport of electrons from thermionic filaments reminded Langmuir of "the way blood plasma carries red and white corpuscles and germs."

# Definitions

## The fourth state of matter

Plasma is called the ''fourth
state of matter In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and Plasma (physics), plasma. Many intermediate states are known to exist, such as ...
'' after
solid Solid is one of the State of matter#Four fundamental states, four fundamental states of matter (the others being liquid, gas, and Plasma (physics), plasma). The molecules in a solid are closely packed together and contain the least amount o ...
,
liquid A liquid is a nearly Compressibility, incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of State of matter#Four fundamental states, the four fund ...
, and
gas Gas is one of the four fundamental states of matter In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and Plasma (physics), pl ...
. It is a state of matter in which an ionized substance becomes highly
electrically conductive Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current An electric current is a stream of charged particles, su ...
to the point that long-range electric and magnetic fields dominate its behaviour. Plasma is typically an electrically quasineutral medium of unbound positive and negative particles (i.e. the overall charge of a plasma is roughly zero). Although these particles are unbound, they are not "free" in the sense of not experiencing forces. Moving charged particles generate electric currents, and any movement of a charged plasma particle affects and is affected by the fields created by the other charges. In turn this governs collective behaviour with many degrees of variation. Plasma is distinct from the other states of matter. In particular, describing a low-density plasma as merely an "ionized gas" is wrong and misleading, even though it is similar to the gas phase in that both assume no definite shape or volume. The following table summarizes some principal differences:

## Ideal plasma

Three factors define an ideal plasma: *The plasma approximation: The plasma approximation applies when the plasma parameter Λ, representing the number of charge carriers within the Debye sphere is much higher than unity. It can be readily shown that this criterion is equivalent to smallness of the ratio of the plasma electrostatic and thermal energy densities. Such plasmas are called weakly coupled. *Bulk interactions: The
Debye length In plasmas and electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electron The electron ( or ) is a subatomic particle with a negative one elemen ...
is much smaller than the physical size of the plasma. This criterion means that interactions in the bulk of the plasma are more important than those at its edges, where boundary effects may take place. When this criterion is satisfied, the plasma is quasineutral. *Collisionlessness: The electron plasma frequency (measuring
plasma oscillation Plasma oscillations, also known as Langmuir waves (after Irving Langmuir), are rapid oscillations of the electron density in conducting media such as Plasma (physics), plasmas or metals in the ultraviolet region. The oscillations can be described as ...
s of the electrons) is much larger than the electron–neutral collision frequency. When this condition is valid, electrostatic interactions dominate over the processes of ordinary gas kinetics. Such plasmas are called collisionless.

## Non-neutral plasma

The strength and range of the electric force and the good conductivity of plasmas usually ensure that the densities of positive and negative charges in any sizeable region are equal ("quasineutrality"). A plasma with a significant excess of charge density, or, in the extreme case, is composed of a single species, is called a non-neutral plasma. In such a plasma, electric fields play a dominant role. Examples are charged
particle beam A particle beam is a stream of charged particle, charged or neutral particles. In particle accelerators, these particles can move with a velocity close to the speed of light. There is a difference between the creation and control of charged parti ...
s, an electron cloud in a
Penning trap A Penning trap is a device for the storage of charged particle In physics, a charged particle is a particle with an electric charge. It may be an ion, such as a molecule or atom with a surplus or deficit of electrons relative to protons. It can ...
and positron plasmas.

## Dusty plasma

A dusty plasma contains tiny charged particles of dust (typically found in space). The dust particles acquire high charges and interact with each other. A plasma that contains larger particles is called grain plasma. Under laboratory conditions, dusty plasmas are also called ''complex plasmas''.

# Properties and parameters

## Density and ionization degree

For plasma to exist,
ionization Ionization, or Ionisation is the process by which an atom Every atom is composed of a atomic nucleus, nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the mos ...
is necessary. The term "plasma density" by itself usually refers to the electron density $n_e$, that is, the number of charge-contributing electrons per unit volume. The degree of ionization $\alpha$ is defined as fraction of neutral particles that are ionized: $\alpha = \frac,$ where $n_i$ is the ion density and $n_n$ the neutral density (in number of particles per unit volume). In the case of fully ionized matter, $\alpha = 1$. Because of the quasineutrality of plasma, the electron and ion densities are related by $n_e = \langle Z_i\rangle n_i$, where $\langle Z_i\rangle$ is the average ion charge (in units of the
elementary charge The elementary charge, usually denoted by is the electric charge carried by a single proton or, equivalently, the magnitude of the negative electric charge carried by a single electron, which has charge −1 . This elementary charge is a fundame ...
).

## Temperature

Plasma temperature, commonly measured in
kelvin The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its metric prefix, prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based eng ...
or
electronvolt In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an Voltage, electric potential difference of one volt i ...
s, is a measure of the thermal kinetic energy per particle. High temperatures are usually needed to sustain ionization, which is a defining feature of a plasma. The degree of plasma ionization is determined by the electron temperature relative to the
ionization energy Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged a ...
(and more weakly by the density). In
thermal equilibrium Two physical systems are in thermal equilibrium if there is no net flow of thermal energy between them when they are connected by a path permeable to heat. Thermal equilibrium obeys the zeroth law of thermodynamics. A system is said to be i ...
, the relationship is given by the Saha equation. At low temperatures, ions and electrons tend to recombine into bound states—atoms—and the plasma will eventually become a gas. In most cases, the electrons and heavy plasma particles (ions and neutral atoms) separately have a relatively well-defined temperature; that is, their energy distribution function is close to a Maxwellian even in the presence of strong
electric Electricity is the set of physics, physical Phenomenon, phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagne ...
or
magnetic Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles ...
fields. However, because of the large difference in mass between electrons and ions, their temperatures may be different, sometimes significantly so. This is especially common in weakly ionized technological plasmas, where the ions are often near the
ambient temperature Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...
while electrons reach thousands of kelvin. The opposite case is the
z-pinch In fusion power research, the Z-pinch (zeta pinch) is a type of Plasma (physics), plasma confinement system that uses an electric current in the plasma to generate a magnetic field that compresses it (see Pinch (plasma physics), pinch). These s ...
plasma where the ion temperature may exceed that of electrons.

## Plasma potential

Since plasmas are very good
electrical conductor In physics and electrical engineering, a conductor is an object or type of material that allows the flow of Electric charge, charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric ...
s, electric potentials play an important role. The average potential in the space between charged particles, independent of how it can be measured, is called the "plasma potential", or the "space potential". If an electrode is inserted into a plasma, its potential will generally lie considerably below the plasma potential due to what is termed a Debye sheath. The good electrical conductivity of plasmas makes their electric fields very small. This results in the important concept of "quasineutrality", which says the density of negative charges is approximately equal to the density of positive charges over large volumes of the plasma ($n_e = \langle Z\rangle n_i$), but on the scale of the
Debye length In plasmas and electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electron The electron ( or ) is a subatomic particle with a negative one elemen ...
, there can be charge imbalance. In the special case that '' double layers'' are formed, the charge separation can extend some tens of Debye lengths. The magnitude of the potentials and electric fields must be determined by means other than simply finding the net
charge density In electromagnetism, charge density is the amount of electric charge per unit length, surface area, or volume. Volume charge density (symbolized by the Greek letter ρ) is the quantity of charge per unit volume, measured in the Systeme Internat ...
. A common example is to assume that the electrons satisfy the Boltzmann relation: $n_e \propto e^.$ Differentiating this relation provides a means to calculate the electric field from the density: $\vec = (k_BT_e/e)(\nabla n_e/n_e).$ It is possible to produce a plasma that is not quasineutral. An electron beam, for example, has only negative charges. The density of a non-neutral plasma must generally be very low, or it must be very small, otherwise, it will be dissipated by the repulsive
electrostatic force Coulomb's inverse-square law, or simply Coulomb's law, is an experimental scientific law, law of physics that quantifies the amount of force between two stationary, electric charge, electrically charged particles. The electric force between char ...
.

## Magnetization

The existence of charged particles causes the plasma to generate, and be affected by,
magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to t ...
s. Plasma with a magnetic field strong enough to influence the motion of the charged particles is said to be magnetized. A common quantitative criterion is that a particle on average completes at least one gyration around the magnetic-field line before making a collision, i.e., $\nu_ / \nu_ > 1$, where $\nu_$ is the electron gyrofrequency and $\nu_$ is the electron collision rate. It is often the case that the electrons are magnetized while the ions are not. Magnetized plasmas are ''
anisotropic Anisotropy () is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy Isotropy is uniformity in all orientations; it is derived . Precise definitions depend on ...
'', meaning that their properties in the direction parallel to the magnetic field are different from those perpendicular to it. While electric fields in plasmas are usually small due to the plasma high conductivity, the electric field associated with a plasma moving with velocity $\mathbf$ in the magnetic field $\mathbf$ is given by the usual Lorentz formula $\mathbf = -\mathbf\times\mathbf$, and is not affected by Debye shielding.

# Mathematical descriptions

To completely describe the state of a plasma, all of the particle locations and velocities that describe the electromagnetic field in the plasma region would need to be written down. However, it is generally not practical or necessary to keep track of all the particles in a plasma. Therefore, plasma physicists commonly use less detailed descriptions, of which there are two main types:

## Fluid model

Fluid models describe plasmas in terms of smoothed quantities, like density and averaged velocity around each position (see
Plasma parameters Plasma parameters define various characteristics of a Plasma (physics), plasma, an electrically conductive collection of charged particles that responds ''collectively'' to electromagnetic forces. Plasma typically takes the form of neutral gas-li ...
). One simple fluid model,
magnetohydrodynamics Magnetohydrodynamics (MHD; also called magneto-fluid dynamics or hydro­magnetics) is the study of the magnetic properties and behaviour of electrically conducting fluids. Examples of such magneto­fluids include Plasma (physics), plasmas ...
, treats the plasma as a single fluid governed by a combination of
Maxwell's equations Maxwell's equations, or Maxwell–Heaviside equations, are a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, and electric circuits. Th ...
and the
Navier–Stokes equations In physics, the Navier–Stokes equations ( ) are partial differential equations which describe the motion of viscous fluid substances, named after French engineer and physicist Claude-Louis Navier and Anglo-Irish physicist and mathematician Sir G ...
. A more general description is the two-fluid plasma, where the ions and electrons are described separately. Fluid models are often accurate when collisionality is sufficiently high to keep the plasma velocity distribution close to a
Maxwell–Boltzmann distribution In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its motion and behavior through Spacetime, space and time, and the related entities of energy and force. "Physical science ...
. Because fluid models usually describe the plasma in terms of a single flow at a certain temperature at each spatial location, they can neither capture velocity space structures like beams or double layers, nor resolve wave-particle effects.

## Kinetic model

Kinetic models describe the particle velocity distribution function at each point in the plasma and therefore do not need to assume a
Maxwell–Boltzmann distribution In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its motion and behavior through Spacetime, space and time, and the related entities of energy and force. "Physical science ...
. A kinetic description is often necessary for collisionless plasmas. There are two common approaches to kinetic description of a plasma. One is based on representing the smoothed distribution function on a grid in velocity and position. The other, known as the
particle-in-cell In plasma physics Plasma () 1, where \nu_ is the electron gyrofrequency and \nu_ is the electron collision rate. It is often the case that the electrons are magnetized while the ions are not. Magnetized plasmas are ''anisotropic'', meaning tha ...
(PIC) technique, includes kinetic information by following the trajectories of a large number of individual particles. Kinetic models are generally more computationally intensive than fluid models. The Vlasov equation may be used to describe the dynamics of a system of charged particles interacting with an electromagnetic field. In magnetized plasmas, a gyrokinetic approach can substantially reduce the computational expense of a fully kinetic simulation.

# Plasma science and technology

Plasmas are the object of study of the academic field of ''plasma science'' or ''plasma physics'', including sub-disciplines such as space plasma physics. It currently involves the following fields of active research and features across many journals, whose interest includes: *Plasma theory **
Plasma equilibria and stability The stability of a plasma is an important consideration in the study of plasma physics. When a system containing a Plasma (physics), plasma is at Mechanical equilibrium, equilibrium, it is possible for certain parts of the plasma to be disturbed b ...
**Plasma interactions with waves and beams **
Guiding center In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its motion and behavior through Spacetime, space and time, and the related entities of energy and force. "Physical science i ...
**
Adiabatic invariant A property of a physical system, such as the entropy of a gas, that stays approximately constant when changes occur slowly is called an adiabatic invariant. By this it is meant that if a system is varied between two end points, as the time for the ...
** Debye sheath **
Coulomb collision A Coulomb collision is a binary elastic collision between two charged particles interacting through their own electric field. As with any inverse-square law, the resulting trajectories of the colliding particles is a Hyperbola, hyperbolic Keplerian ...
*Plasmas in nature ** Astrophysical plasma ** Northern and southern (polar) lights **The Earth's
ionosphere The ionosphere () is the ionization, ionized part of the upper atmosphere of Earth, from about to height above sea level, above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionize ...
**
Interplanetary medium The interplanetary medium (IPM) or interplanetary space consists of the mass and energy which fills the Solar System, and through which all the larger Solar System bodies, such as planets, dwarf planets, asteroids, and comets, move. The IPM sto ...
**Planetary
magnetosphere In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior Dynamo ...
s **
Space plasma The interplanetary medium (IPM) or interplanetary space consists of the mass and energy which fills the Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding ...
*Industrial plasmas ** Plasma chemistry ** Plasma processing ** Plasma spray **
Plasma display A plasma display panel (PDP) is a type of flat panel display that uses small cells containing Plasma (physics), plasma: ionized gas that responds to electric fields. Plasma televisions were the first large (over 32 inches diagonal) flat panel displ ...
**Plasma sources ** Dusty plasmas *
Plasma diagnostics Plasma diagnostics are a pool of methods, instruments, and experimental techniques used to measure properties of a plasma Plasma or plasm may refer to: Science * Plasma (physics) Plasma () 1, where \nu_ is the electron gyrofrequency and \nu_ ...
**
Thomson scattering Thomson scattering is the elastic scattering of electromagnetic radiation by a free charged particle, as described by classical electromagnetism. It is the low-energy limit of Compton scattering: the particle's kinetic energy and photon frequency ...
**
Langmuir probe A Langmuir probe is a device used to determine the electron temperature, electron density, and electric potential of a Plasma (physics), plasma. It works by inserting one or more electrodes into a plasma, with a constant or time-varying electric p ...
** Ball-pen probe ** Faraday cup **
Spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectrum, electromagnetic spectra that result from the interaction between Electromagnetism, electromagnetic radiation and matter as a function of the wavelengt ...
**
Interferometry Interferometry is a technique which uses the ''interference (wave propagation), interference'' of Superposition principle, superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important inves ...
** Ionospheric heating **
Incoherent scatter Incoherent scattering is a type of scattering phenomenon in physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its motion and behavior through Spacetime, space and time, and the r ...
radar *Plasma applications ** Dielectric barrier discharge **
Enhanced oil recovery Enhanced oil recovery (abbreviated EOR), also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. EOR can extract 30% to 60% or more of a reservoir's oil, compared to 20% to 40% using E ...
**
Fusion power Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion, nuclear fusion reactions. In a fusion process, two lighter atomic nucleus, atomic nuclei combine to form a heavier nucleus, whi ...
**Plasma Actuator (e.g. Serpentine geometry plasma actuator) ***
Magnetic fusion energy Magnetic confinement fusion is an approach to generate thermonuclear fusion power that uses magnetic fields to confine fusion fuel in the form of a plasma (physics), plasma. Magnetic confinement is one of two major branches of Plasma_(physics)#MH ...
(MFE) — ****
Tokamak A tokamak (; russian: токамáк; otk, 𐱃𐰸𐰢𐰴, Toḳamaḳ) is a device which uses a powerful magnetic field to confine plasma (physics), plasma in the shape of a torus. The tokamak is one of several types of magnetic confinemen ...
****
Stellarator A stellarator is a Plasma (physics), plasma device that relies primarily on external magnets to confine a plasma. Scientists researching magnetic confinement fusion aim to use stellarator devices as a vessel for nuclear fusion reactions. The n ...
**** Reversed field pinch ****
Magnetic mirror A magnetic mirror, known as a magnetic trap (магнитный захват) in Russia and briefly as a pyrotron in the US, is a type of magnetic confinement, magnetic confinement device used in fusion power to trap high temperature plasma (phys ...
****
Dense plasma focus A dense plasma focus (DPF) is a type of plasma Plasma or plasm may refer to: Science * Plasma (physics) Plasma () 1, where \nu_ is the electron gyrofrequency and \nu_ is the electron collision rate. It is often the case that the electrons ar ...
***
Inertial confinement fusion Inertial confinement fusion (ICF) is a fusion energy process that initiates nuclear fusion Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic parti ...
(ICF) ***
Plasma weapon A directed-energy weapon (DEW) is a ranged weapon A ranged weapon is any weapon that can engage targets beyond hand-to-hand distance, i.e. at distances greater than the physical reach of the user holding the weapon itself. The act of using ...
s **
Ion implantation Ion implantation is a low-temperature process by which ions of one element are accelerated into a solid target, thereby changing the physical, chemical, or electrical properties of the target. Ion implantation is used in semiconductor device fa ...
**
Ion thruster An ion thruster, ion drive, or ion engine is a form of electrically powered spacecraft propulsion, electric propulsion used for spacecraft propulsion. It creates thrust by accelerating ions using electricity. An ion thruster ionizes a neutr ...
**
MAGPIE Magpies are birds of the Corvidae family. Like other members of their family, they are widely considered to be intelligent creatures. The Eurasian magpie, for instance, is thought to rank among the world's Animal cognition, most intelligent crea ...
(Implosion experiments) ** Plasma ashing ** Spark-ignition engines: enhancing ignition at a single point (from the spark plug) with a broad-front multi-channel discharge in plasma. **Food processing *** Nonthermal plasma or "cold plasma" ** Plasma arc waste disposal, recycling. ** Plasma acceleration ** Plasma medicine (e. g. Dentistry) ** Plasma window Plasmas can appear in nature in various forms and locations, summarised in the following table:

## Space and astrophysics

Plasmas are by far the most common phase of ordinary matter in the universe, both by mass and by volume. Above the Earth's surface, the ionosphere is a plasma, and the magnetosphere contains plasma. Within our Solar System,
interplanetary space Interplanetary may refer to: * Interplanetary space, the space between the planets of the Solar System *Interplanetary spaceflight Interplanetary spaceflight or interplanetary travel is the Human spaceflight, crewed or Uncrewed spacecraft, unc ...
is filled with the plasma expelled via the
solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...
, extending from the Sun's surface out to the heliopause. Furthermore, all the distant
star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
s, and much of
interstellar space Outer space, commonly shortened to space, is the expanse that exists beyond Earth and Earth atmosphere, its atmosphere and between astronomical object, celestial bodies. Outer space is not completely empty—it is a Ultra-high vacuum, near-per ...
or
intergalactic space Outer space, commonly shortened to space, is the expanse that exists beyond Earth and Earth atmosphere, its atmosphere and between astronomical object, celestial bodies. Outer space is not completely empty—it is a Ultra-high vacuum, near-per ...
is also likely filled with plasma, albeit at very low densities. Astrophysical plasmas are also observed in
accretion disk An accretion disk is a structure (often a circumstellar disk) formed by diffuse material in orbit In celestial mechanics, an orbit is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of ...
s around stars or compact objects like
white dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's fain ...
s,
neutron star A neutron star is the Gravitational collapse, collapsed Stellar structure, core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially Metallicity, metal-rich. Except fo ...
s, or
black holes A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...
in close
binary star A binary star is a system of two star, stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separa ...
systems. Plasma is associated with ejection of material in astrophysical jets, which have been observed with accreting black holes or in active
galaxies A galaxy is a system of stars, stellar remnants, interstellar medium, interstellar gas, cosmic dust, dust, dark matter, bound together by gravity. The word is derived from the Ancient Greek, Greek ' (), literally 'milky', a reference to the ...
like M87's jet that possibly extends out to 5,000 light-years.

## Artificial plasmas

Most artificial plasmas are generated by the application of electric and/or magnetic fields through a gas. Plasma generated in a laboratory setting and for industrial use can be generally categorized by: *The type of power source used to generate the plasma—DC, AC (typically with
radio frequency Radio frequency (RF) is the oscillation rate of an Alternating current, alternating electric current or voltage or of a Magnetic field, magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around ...
(RF)) and microwave *The pressure they operate at—vacuum pressure (< 10 mTorr or 1 Pa), moderate pressure (≈1 Torr or 100 Pa), atmospheric pressure (760 Torr or 100 kPa) *The degree of ionization within the plasma—fully, partially, or weakly ionized *The temperature relationships within the plasma—thermal plasma ($T_e = T_i = T_$), non-thermal or "cold" plasma ($T_e \gg T_i = T_$) *The electrode configuration used to generate the plasma *The magnetization of the particles within the plasma—magnetized (both ion and electrons are trapped in Larmor orbits by the magnetic field), partially magnetized (the electrons but not the ions are trapped by the magnetic field), non-magnetized (the magnetic field is too weak to trap the particles in orbits but may generate
Lorentz force In physics (specifically in electromagnetism) the Lorentz force (or electromagnetic force) is the combination of electric and magnetic force on a point charge due to electromagnetic fields. A particle of charge moving with a velocity in an elect ...
s)

### Generation of artificial plasma

Just like the many uses of plasma, there are several means for its generation. However, one principle is common to all of them: there must be energy input to produce and sustain it. For this case, plasma is generated when an
electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving par ...
is applied across a
dielectric gas A dielectric gas, or insulating gas, is a dielectric In electromagnetism, a dielectric (or dielectric medium) is an Insulator (electricity), electrical insulator that can be Polarisability, polarised by an applied electric field. When a diele ...
or fluid (an electrically non-conducting material) as can be seen in the adjacent image, which shows a
discharge tube A gas-filled tube, also commonly known as a discharge tube or formerly as a Julius Plücker, Plücker tube, is an arrangement of electrodes in a gas within an dielectric, insulating, temperature-resistant envelope. Gas-filled tubes exploit phen ...
as a simple example ( DC used for simplicity). The
potential difference Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential The electric potential (also called the ''electric field potential'', potential drop, the electrostat ...
and subsequent
electric field An electric field (sometimes E-field) is the field (physics), physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the ...
pull the bound electrons (negative) toward the
anode An anode is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic is ...
(positive electrode) while the
cathode A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in ...
(negative electrode) pulls the nucleus. As the
voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), w ...
increases, the current stresses the material (by
electric polarization In classical electromagnetism, polarization density (or electric polarization, or simply polarization) is the vector field that expresses the density of permanent or induced electric dipole moments in a dielectric material. When a dielectric is p ...
) beyond its dielectric limit (termed strength) into a stage of
electrical breakdown Electrical breakdown or dielectric breakdown is a process that occurs when an electrical insulating material, subjected to a high enough voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference ...
, marked by an
electric spark An electric spark is an abrupt electrical discharge that occurs when a sufficiently high electric field creates an Ionization, ionized, Electric current, electrically conductive channel through a normally-insulating medium, often air or other ga ...
, where the material transforms from being an insulator into a conductor (as it becomes increasingly
ionized Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged a ...
). The underlying process is the Townsend avalanche, where collisions between electrons and neutral gas atoms create more ions and electrons (as can be seen in the figure on the right). The first impact of an electron on an atom results in one ion and two electrons. Therefore, the number of charged particles increases rapidly (in the millions) only "after about 20 successive sets of collisions", mainly due to a small mean free path (average distance travelled between collisions).

### =Electric arc

= With ample current density and ionization, this forms a luminous
electric arc An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (p ...
(a continuous electric discharge similar to
lightning Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...
) between the electrodes.
Electrical resistance The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its Multiplicative inverse, reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares s ...
along the continuous electric arc creates
heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...
, which dissociates more gas molecules and ionizes the resulting atoms (where degree of ionization is determined by temperature), and as per the sequence:
solid Solid is one of the State of matter#Four fundamental states, four fundamental states of matter (the others being liquid, gas, and Plasma (physics), plasma). The molecules in a solid are closely packed together and contain the least amount o ...
-
liquid A liquid is a nearly Compressibility, incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of State of matter#Four fundamental states, the four fund ...
-
gas Gas is one of the four fundamental states of matter In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and Plasma (physics), pl ...
-plasma, the gas is gradually turned into a thermal plasma. A thermal plasma is in
thermal equilibrium Two physical systems are in thermal equilibrium if there is no net flow of thermal energy between them when they are connected by a path permeable to heat. Thermal equilibrium obeys the zeroth law of thermodynamics. A system is said to be i ...
, which is to say that the temperature is relatively homogeneous throughout the heavy particles (i.e. atoms, molecules and ions) and electrons. This is so because when thermal plasmas are generated,
electrical energy Electrical energy is energy related to forces on electrically charged particles and the movement of electrically charged particles (often electrons in wires, but not always). This energy is supplied by the combination of electric current and electr ...
is given to electrons, which, due to their great mobility and large numbers, are able to disperse it rapidly and by
elastic collision In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its motion and behavior through Spacetime, space and time, and the related entities of energy and force. "Physical scien ...
(without energy loss) to the heavy particles.Note that non-thermal, or non-equilibrium plasmas are not as ionized and have lower energy densities, and thus the temperature is not dispersed evenly among the particles, where some heavy ones remain "cold".

### Examples of industrial/commercial plasma

Because of their sizable temperature and density ranges, plasmas find applications in many fields of research, technology and industry. For example, in: industrial and extractive
metallurgy Metallurgy is a domain of Materials science, materials science and engineering that studies the physical and chemical behavior of metallic Chemical element, elements, their Inter-metallic alloy, inter-metallic compounds, and their mixtures, which ...
, surface treatments such as plasma spraying (coating),
etching Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in Intaglio (printmaking), intaglio (incised) in the metal. In modern manufacturing, other chemicals may ...
in microelectronics, metal cutting and
welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as b ...
; as well as in everyday vehicle exhaust cleanup and
fluorescent Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...
/
luminescent Luminescence is spontaneous emission Spontaneous emission is the process in which a Quantum mechanics, quantum mechanical system (such as a molecule, an atom or a subatomic particle) transits from an excited state, excited energy state to a lo ...
lamps, fuel ignition, while even playing a part in supersonic combustion engines for
aerospace engineering Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: Aeronautics, aeronautical engineering and Astronautics, astronautical engineering. A ...
.

### =Low-pressure discharges

= *''
Glow discharge A glow discharge is a Plasma (physics), plasma formed by the passage of electric current through a gas. It is often created by applying a voltage between two electrodes in a glass tube containing a low-pressure gas. When the voltage exceeds a val ...
plasmas'': non-thermal plasmas generated by the application of DC or low frequency RF (<100 kHz) electric field to the gap between two metal electrodes. Probably the most common plasma; this is the type of plasma generated within
fluorescent light A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet, ult ...
tubes. *''
Capacitively coupled plasma A capacitively coupled plasma (CCP) is one of the most common types of industrial plasma sources. It essentially consists of two metal electrodes separated by a small distance, placed in a reactor. The gas pressure in the reactor can be lower than ...
(CCP)'': similar to glow discharge plasmas, but generated with high frequency RF electric fields, typically 13.56 MHz. These differ from glow discharges in that the sheaths are much less intense. These are widely used in the microfabrication and integrated circuit manufacturing industries for plasma etching and plasma enhanced chemical vapor deposition. *'' Cascaded arc plasma source'': a device to produce low temperature (≈1eV) high density plasmas (HDP). *''
Inductively coupled plasma An inductively coupled plasma (ICP) or transformer coupled plasma (TCP) is a type of plasma (physics), plasma source in which the energy is supplied by electric currents which are produced by electromagnetic induction, that is, by time-varying magn ...
(ICP)'': similar to a CCP and with similar applications but the electrode consists of a coil wrapped around the chamber where plasma is formed. *'' Wave heated plasma'': similar to CCP and ICP in that it is typically RF (or microwave). Examples include helicon discharge and electron cyclotron resonance (ECR).

### =Atmospheric pressure

= *'' Arc discharge:'' this is a high power thermal discharge of very high temperature (≈10,000 K). It can be generated using various power supplies. It is commonly used in metallurgical processes. For example, it is used to smelt minerals containing Al2O3 to produce
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substan ...
. *''
Corona discharge A corona discharge is an electrical discharge caused by the ionization of a fluid such as air surrounding a conductor (material), conductor carrying a high voltage. It represents a local region where the air (or other fluid) has undergone e ...
:'' this is a non-thermal discharge generated by the application of high voltage to sharp electrode tips. It is commonly used in
ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic Allotropy, allotrope , breaking down i ...
generators and particle precipitators. *'' Dielectric barrier discharge (DBD):'' this is a non-thermal discharge generated by the application of high voltages across small gaps wherein a non-conducting coating prevents the transition of the plasma discharge into an arc. It is often mislabeled 'Corona' discharge in industry and has similar application to corona discharges. A common usage of this discharge is in a plasma actuator for vehicle drag reduction. It is also widely used in the web treatment of fabrics. The application of the discharge to synthetic fabrics and plastics functionalizes the surface and allows for paints, glues and similar materials to adhere. The dielectric barrier discharge was used in the mid-1990s to show that low temperature atmospheric pressure plasma is effective in inactivating bacterial cells. This work and later experiments using mammalian cells led to the establishment of a new field of research known as plasma medicine. The dielectric barrier discharge configuration was also used in the design of low temperature plasma jets. These plasma jets are produced by fast propagating guided ionization waves known as plasma bullets. *'' Capacitive discharge:'' this is a nonthermal plasma generated by the application of RF power (e.g., 13.56 MHz) to one powered electrode, with a grounded electrode held at a small separation distance on the order of 1 cm. Such discharges are commonly stabilized using a noble gas such as helium or argon. *" Piezoelectric direct discharge plasma:" is a nonthermal plasma generated at the high-side of a piezoelectric transformer (PT). This generation variant is particularly suited for high efficient and compact devices where a separate high voltage power supply is not desired.

### MHD converters

A world effort was triggered in the 1960s to study
magnetohydrodynamic converter __NOTOC__ A magnetohydrodynamic converter (MHD converter) is an Electromagnetism, electromagnetic machine with no moving parts involving magnetohydrodynamics, the study of the kinetics (physics), kinetics of Electrical resistivity and conductivity, ...
s in order to bring MHD power conversion to market with commercial power plants of a new kind, converting the
kinetic energy In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its motion and behavior through Spacetime, space and time, and the related entities of energy and force. "Physical sci ...
of a high velocity plasma into
electricity Electricity is the set of physics, physical Phenomenon, phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagne ...
with no
moving parts Machine A machine is a physical system using Power (physics), power to apply Force, forces and control Motion, movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but ...
at a high
efficiency Efficiency is the often measurable ability to avoid wasting materials, energy, efforts, money, and time in doing something or in producing a desired result. In a more general sense, it is the ability to do things well, successfully, and without ...
. Research was also conducted in the field of supersonic and hypersonic aerodynamics to study plasma interaction with magnetic fields to eventually achieve passive and even active flow control around vehicles or projectiles, in order to soften and mitigate
shock wave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound The speed of sound is the distance travelled per unit of time by a sound wave as it propaga ...
s, lower thermal transfer and reduce drag. Such ionized gases used in "plasma technology" ("technological" or "engineered" plasmas) are usually ''weakly ionized gases'' in the sense that only a tiny fraction of the gas molecules are ionized. These kinds of weakly ionized gases are also nonthermal "cold" plasmas. In the presence of magnetics fields, the study of such magnetized nonthermal weakly ionized gases involves resistive magnetohydrodynamics with low
magnetic Reynolds number In magnetohydrodynamics, the magnetic Reynolds number (Rm) is a dimensionless quantity that estimates the relative effects of advection or Induction equation, induction of a magnetic field by the motion of a conducting medium to the magnetic diffus ...
, a challenging field of plasma physics where calculations require dyadic tensors in a 7-dimensional
phase space In Dynamical systems theory, dynamical system theory, a phase space is a Space (mathematics), space in which all possible states of a system are represented, with each possible state corresponding to one unique point in the phase space. F ...
. When used in combination with a high Hall parameter, a critical value triggers the problematic electrothermal instability which limited these technological developments.

# Complex plasma phenomena

Although the underlying equations governing plasmas are relatively simple, plasma behaviour is extraordinarily varied and subtle: the emergence of unexpected behaviour from a simple model is a typical feature of a
complex system A complex system is a system composed of many components which may interaction, interact with each other. Examples of complex systems are Earth's global climate, organisms, the human brain, infrastructure such as power grid, transportation or com ...
. Such systems lie in some sense on the boundary between ordered and disordered behaviour and cannot typically be described either by simple, smooth, mathematical functions, or by pure randomness. The spontaneous formation of interesting spatial features on a wide range of length scales is one manifestation of plasma complexity. The features are interesting, for example, because they are very sharp, spatially intermittent (the distance between features is much larger than the features themselves), or have a
fractal In mathematics, a fractal is a geometric shape containing detailed structure at arbitrarily small scales, usually having a fractal dimension strictly exceeding the topological dimension. Many fractals appear similar at various scales, as illus ...
form. Many of these features were first studied in the laboratory, and have subsequently been recognized throughout the universe. Examples of complexity and complex structures in plasmas include:

## Filamentation

Striations or string-like structures, also known as Birkeland currents, are seen in many plasmas, like the plasma ball, the
aurora An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in polar regions of Earth, high-latitude regions (around the Arctic and Antarctic). Auroras display ...
,
lightning Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...
,
electric arc An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (p ...
s,
solar flares A solar flare is an intense localized eruption of electromagnetic radiation in the Sun's Stellar atmosphere, atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, ...
, and
supernova remnant A supernova remnant (SNR) is the structure resulting from the explosion of a star in a supernova. The supernova remnant is bounded by an expanding shock wave, and consists of ejected material expanding from the explosion, and the interstellar mat ...
s. They are sometimes associated with larger current densities, and the interaction with the magnetic field can form a magnetic rope structure. (See also
Plasma pinch A pinch (or: Bennett pinch (after Willard Harrison Bennett), electromagnetic pinch, magnetic pinch, pinch effect, or plasma pinch.) is the compression of an electrically conducting Electrical filament, filament by magnetic forces, or a device tha ...
) Filamentation also refers to the self-focusing of a high power laser pulse. At high powers, the nonlinear part of the
index of refraction In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, or ...
becomes important and causes a higher index of refraction in the center of the laser beam, where the laser is brighter than at the edges, causing a feedback that focuses the laser even more. The tighter focused laser has a higher peak brightness (irradiance) that forms a plasma. The plasma has an index of refraction lower than one, and causes a defocusing of the laser beam. The interplay of the focusing index of refraction, and the defocusing plasma makes the formation of a long filament of plasma that can be
micrometers The micrometre (American and British English spelling differences#-re, -er, international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American and British English spelling differences# ...
to kilometers in length. One interesting aspect of the filamentation generated plasma is the relatively low ion density due to defocusing effects of the ionized electrons. (See also
Filament propagation In nonlinear optics, filament propagation is propagation of a beam of light through a medium without diffraction. This is possible because the Kerr effect causes an index of refraction change in the medium, resulting in self-focusing of the beam. F ...
)

## Impermeable plasma

Impermeable plasma is a type of thermal plasma which acts like an impermeable solid with respect to gas or cold plasma and can be physically pushed. Interaction of cold gas and thermal plasma was briefly studied by a group led by
Hannes Alfvén Hannes Olof Gösta Alfvén (; 30 May 1908 – 2 April 1995) was a Swedish electrical engineer, plasma physicist and winner of the 1970 Nobel Prize in Physics ) , image = Nobel Prize.png , alt = A golden medallion with an emb ...
in 1960s and 1970s for its possible applications in insulation of fusion plasma from the reactor walls. However, later it was found that the external magnetic fields in this configuration could induce kink instabilities in the plasma and subsequently lead to an unexpectedly high heat loss to the walls. In 2013, a group of materials scientists reported that they have successfully generated stable impermeable plasma with no magnetic confinement using only an ultrahigh-pressure blanket of cold gas. While spectroscopic data on the characteristics of plasma were claimed to be difficult to obtain due to the high pressure, the passive effect of plasma on
synthesis Synthesis or synthesize may refer to: Science Chemistry and biochemistry *Chemical synthesis, the execution of chemical reactions to form a more complex molecule from chemical precursors **Organic synthesis, the chemical synthesis of organi ...
of different nanostructures clearly suggested the effective confinement. They also showed that upon maintaining the impermeability for a few tens of seconds, screening of
ions An ion () is an atom or molecule with a net electric charge, electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be po ...
at the plasma-gas interface could give rise to a strong secondary mode of heating (known as viscous heating) leading to different kinetics of reactions and formation of complex
nanomaterials * Nanomaterials describe, in principle, materials of which a single unit is sized (in at least one dimension) between 1 and 100 nm (the usual definition of Nanoscopic scale, nanoscale). Nanomaterials research takes a materials science-base ...
.

# Gallery

File:HallThruster 2.jpg,
Hall-effect thruster In spacecraft propulsion, a Hall-effect thruster (HET) is a type of ion thruster in which the propellant is accelerated by an electric field. Hall-effect thrusters (based on the discovery by Edwin Hall) are sometimes referred to as Hall thruster ...
File:Wispy 'Plasma Dancer' on the limb of the Sun.ogv, Solar plasma File:Plasma Spraying Process.jpg, Plasma spraying File:MAST plasma image.jpg, Plasma in a
tokamak A tokamak (; russian: токамáк; otk, 𐱃𐰸𐰢𐰴, Toḳamaḳ) is a device which uses a powerful magnetic field to confine plasma (physics), plasma in the shape of a torus. The tokamak is one of several types of magnetic confinemen ...
File:Argon Plasma.jpg, Laboratory plasma

* Ambipolar diffusion * Electric field screening *
Electrically powered spacecraft propulsion Spacecraft electric propulsion (or just electric propulsion) is a type of spacecraft propulsion technique that uses electrostatic or electromagnetic fields to accelerate mass to high speed and thus generate thrust to modify the velocity of a sp ...
* Hannes Alfvén Prize * IEEE Nuclear and Plasma Sciences Society * List of plasma physicists *
List of plasma physics articles This is a list of plasma physics topics. A * Ablation * Abradable coating * Abraham–Lorentz force * Absorption band * Accretion disk * Active galactic nucleus * Adiabatic invariant * ADITYA (tokamak) * Aeronomy * Afterglow plasma * Airglow ...
* LULI *
Magnetohydrodynamic converter __NOTOC__ A magnetohydrodynamic converter (MHD converter) is an Electromagnetism, electromagnetic machine with no moving parts involving magnetohydrodynamics, the study of the kinetics (physics), kinetics of Electrical resistivity and conductivity, ...
*
Nikola Tesla Nikola Tesla ( ; ,"Tesla"
''Random House Webster's Unabridged Dictionary''.
; 1856 – 7 January 1943 ...
* Plasma nitriding *
Plasma propulsion engine A plasma propulsion engine is a type of electric propulsion that generates thrust from a quasi-neutral plasma (physics), plasma. This is in contrast with ion thruster engines, which generate thrust through extracting an ion current from the Plas ...
* Plasma surface interaction * Publications in plasma physics * Quark-gluon plasma *
Space physics Space physics, also known as solar-terrestrial physics or space-plasma physics, is the study of Plasma (physics), plasmas as they occur naturally in the Earth's Near space, upper atmosphere (aeronomy) and within the Solar System. As such, it encompa ...
* Total electron content