ByAziz Companiwala

1.Introduction2.Who Found plasma?3. Plasma CharacteristicsCharacteristics 3.1 Temperatures 3.2 Cold Hot Plasma3.3 Potentials 3.4 Comparison of plasma and gas

phases 3.5 Critical ionization velocity 4 Types of Plasma4.1 Ultracold plasma 4.2 Non-neutral plasma 4.3 Dusty plasma and grain plasma

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5 Magnets can Move Plasmas 6 Can Plasmas Be Controlled?7 Applications

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What Is Plasma?What Is Plasma? A hot ionized gasA hot ionized gas

The ‘fourth state of matter’The ‘fourth state of matter’

Unlike gases, solids, or liquids, plasma does Unlike gases, solids, or liquids, plasma does

not contain moleculesnot contain molecules

Instead, it is a gas that is composed of ionsInstead, it is a gas that is composed of ions

Composes more than 99% of the known Composes more than 99% of the known

visible universevisible universe

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So What’s In It?So What’s In It? Some, or all, of the electrons in the outer Some, or all, of the electrons in the outer

orbitals have been stripped awayorbitals have been stripped away

The result is a collection of ions and The result is a collection of ions and electrons, which are no longer bound electrons, which are no longer bound togethertogether

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What Did That Mean?What Did That Mean?

Because the particles are not Because the particles are not neutral:neutral: Plasma behaves differently then regular Plasma behaves differently then regular

gasesgases For instance, in the presence of For instance, in the presence of

electromagnetic fieldselectromagnetic fields

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Who Found It?Who Found It?

First discovered by First discovered by

Sir William Crookes, in 1879Sir William Crookes, in 1879

But it wasn’t called But it wasn’t called

‘‘plasma’ until 1928, when plasma’ until 1928, when

Irving Langmuir coined the termIrving Langmuir coined the term

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Characteristics:Characteristics: TemperatureTemperature

Defines two kinds of plasma: Cold and HotDefines two kinds of plasma: Cold and Hot

Refers to the electron temperatureRefers to the electron temperature

Plasma temperature is commonly measured in kelvins or electronvolts, Plasma temperature is commonly measured in kelvins or electronvolts,

and is an informal measure of the thermal kinetic energy per particle.and is an informal measure of the thermal kinetic energy per particle.

Ion temperature may be very different (lower)Ion temperature may be very different (lower)

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Cold PlasmaCold Plasma Isn’t really coldIsn’t really cold

Typical electron temperatures for cold plasmas are Typical electron temperatures for cold plasmas are

in the thousands of degreesin the thousands of degrees

Only a small fraction of the gas molecules are Only a small fraction of the gas molecules are

ionized (degree of ionization)ionized (degree of ionization)

Usually on the order of 1%Usually on the order of 1%

Often created using strong electric fieldsOften created using strong electric fields

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CoolCoolWhere Can I Find Cold Plasma?Where Can I Find Cold Plasma?

Fluorescent LightsFluorescent Lights

Strobe LightsStrobe Lights

Experimental Experimental Fusion Research Fusion Research DevicesDevices

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Hot PlasmaHot Plasma

Really hotReally hot

Like the Sun (15,000,000° C at the core)Like the Sun (15,000,000° C at the core)

The molecules are nearly if not fully The molecules are nearly if not fully

ionizedionized

Created by heating the molecules to Created by heating the molecules to

extremely high temperaturesextremely high temperatures

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ScorchingScorchingWhere Can I Find Hot Plasma?Where Can I Find Hot Plasma?

In Nature, actuallyIn Nature, actually The Sun and other starsThe Sun and other stars LightningLightning The Aurora Borealis (Colourfull light that appears in The Aurora Borealis (Colourfull light that appears in

Northern sky at dawn) Northern sky at dawn)

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Characteristics:Characteristics: PotentialsPotentials

Since plasmas are very good conductors, Since plasmas are very good conductors, electric potentials play an important role. electric potentials play an important role. The potential as it exists on average in the The potential as it exists on average in the space between charged particles, space between charged particles, independent of the question of how it can independent of the question of how it can be measured, is called the "plasma be measured, is called the "plasma potential" or the "space potential".potential" or the "space potential".

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Characteristics:Characteristics: PotentialsPotentials

The magnitude of the potentials and The magnitude of the potentials and electric fields must be determined by electric fields must be determined by means other than simply finding the means other than simply finding the net charge density. A common net charge density. A common example is to assume that the example is to assume that the electrons satisfy the "electrons satisfy the "Boltzmann relation””

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Comparison of plasma and Comparison of plasma and gas phasesgas phases

Plasma is distinct from other lower-Plasma is distinct from other lower-energy states of matter.energy states of matter.

Although it is closely related to the Although it is closely related to the gas phase,but it differs in a number gas phase,but it differs in a number of ways, including the followingof ways, including the following::

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PropertyProperty GasGas PlasmaPlasma

Electrical Electrical ConductiviConductivityty

Very lowVery low Air is an Air is an excellent excellent insulator until it insulator until it breaks down into breaks down into plasma at plasma at electric field electric field strengths above strengths above 30 kilovolts per 30 kilovolts per centimeter.centimeter.

Usually very Usually very highhigh For many For many purposes the purposes the conductivity of a conductivity of a plasma may be plasma may be treated as treated as infinite. infinite.

IndependentIndependently acting ly acting speciesspecies

BinaryBinary Two-particle Two-particle collisions are collisions are the rule, three-the rule, three-body collisions body collisions extremely rare.extremely rare.

CollectiveCollectiveWaves, or Waves, or organised motion organised motion of plasma, are of plasma, are very important very important because the because the particles can particles can interact at long interact at long ranges through ranges through the electric and the electric and magnetic forces. magnetic forces.

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Critical ionization Critical ionization velocityvelocity

Critical ionization velocityCritical ionization velocity (CIV, also called (CIV, also called Critical velocityCritical velocity, CV) is the relative velocity , CV) is the relative velocity between a neutral gas and plasma (an ionized between a neutral gas and plasma (an ionized gas), at which the neutral gas will start to ionize. gas), at which the neutral gas will start to ionize. If more energy is supplied, the velocity of the If more energy is supplied, the velocity of the atoms or molecules will not exceed the critical atoms or molecules will not exceed the critical ionization velocity until the gas becomes almost ionization velocity until the gas becomes almost

fully ionized.fully ionized. Critical ionization velocity experiment onboard space shuttleDiscovery (STS-39), releasing a plume of nitrous oxide gas

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Types of PlasmaTypes of PlasmaINDEX

Types of PlasmaTypes of Plasma

Ultracold plasmaUltracold plasma It is possible to create ultracold plasmas, by using It is possible to create ultracold plasmas, by using

lasers to trap and cool neutral atoms to lasers to trap and cool neutral atoms to temperatures of 1 mK or lower. Another laser temperatures of 1 mK or lower. Another laser then ionizes the atoms by giving each of the then ionizes the atoms by giving each of the outermost electrons just enough energy to outermost electrons just enough energy to escape the electrical attraction of its parent ion.escape the electrical attraction of its parent ion.

The key point about ultracold plasmas is that by The key point about ultracold plasmas is that by manipulating the atoms with lasers, the kinetic manipulating the atoms with lasers, the kinetic energy of the liberated electrons can be energy of the liberated electrons can be controlled controlled

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Types of PlasmaTypes of Plasma

Non-neutral plasmaNon-neutral plasma The strength and range of the electric force The strength and range of the electric force

and the good conductivity of plasmas and the good conductivity of plasmas usually ensure that the density of positive usually ensure that the density of positive and negative charges in any sizeable region and negative charges in any sizeable region are equal ("are equal ("quasineutrality"). A plasma "). A plasma which has a significant excess of charge which has a significant excess of charge density or which is, in the extreme case, density or which is, in the extreme case, composed of only a single species, is called composed of only a single species, is called a non-neutral plasma. In such a plasma, a non-neutral plasma. In such a plasma, electric fields play a dominant role. electric fields play a dominant role. Examples are charged Examples are charged particle beams, and , and positron plasmas positron plasmas

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Types of PlasmaTypes of Plasma

Dusty plasma and grain plasmaDusty plasma and grain plasma A dusty plasma is one containing tiny charged A dusty plasma is one containing tiny charged

particles of dust (typically found in space) which particles of dust (typically found in space) which also behaves like a plasma. A plasma containing also behaves like a plasma. A plasma containing larger particles is called a grain plasma.larger particles is called a grain plasma.

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Magnets can Move Magnets can Move Plasmas?Plasmas?

Plasma does a great job of conducting electricity. Plasma does a great job of conducting electricity. Since magnets can affect matter that conducts Since magnets can affect matter that conducts electricity, magnets influence plasma in much the electricity, magnets influence plasma in much the same way they work on an iron bar-they can same way they work on an iron bar-they can move it without even touching it.move it without even touching it.

Very powerful electromagnets are used to control Very powerful electromagnets are used to control the plasma in a the plasma in a Tokamak. These magnets, along These magnets, along with a powerful electrical current of up to several with a powerful electrical current of up to several million amps, create a kind of “magnetic bottle” million amps, create a kind of “magnetic bottle” that confines the plasma to a doughnut shape, or that confines the plasma to a doughnut shape, or torus.

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Can Plasmas Be Can Plasmas Be Controlled?Controlled?

For over 50 years, scientists and engineers in For over 50 years, scientists and engineers in many different countries have tried to create a many different countries have tried to create a fusion reactor that produces more energy than it fusion reactor that produces more energy than it consumes. All atoms have a dense nucleus (made consumes. All atoms have a dense nucleus (made up of protons and neutrons - orange and black or up of protons and neutrons - orange and black or red and blue spheres in the figures below). red and blue spheres in the figures below). Fission and fusion reactions are two ways a Fission and fusion reactions are two ways a nucleus changes. nucleus changes.

Fission produces lighter elements from heavier ones.

Fusion makes heavierelements from lighter ones.

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Application Of PlasmaApplication Of Plasma

Benefits at HomeBenefits at Home

High efficiency lighting; manufacturing of High efficiency lighting; manufacturing of semiconductors for home computers, TVs semiconductors for home computers, TVs and electronics; flat-panel displays; and and electronics; flat-panel displays; and surface treatment of synthetic cloth for surface treatment of synthetic cloth for dye adhesion.dye adhesion.

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Application Of PlasmaApplication Of Plasma

Business ApplicationsBusiness Applications

Plasma enhanced chemistry; surface Plasma enhanced chemistry; surface cleaning; processing of plastics; gas cleaning; processing of plastics; gas treatment; spraying of materials; chemical treatment; spraying of materials; chemical analysis; high-efficiency lighting, etc…analysis; high-efficiency lighting, etc…

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Application Of PlasmaApplication Of Plasma

Plasma LightingPlasma LightingThe most prevalent man-made plasmas on our The most prevalent man-made plasmas on our planet are the plasmas in lamps. There are planet are the plasmas in lamps. There are primarily two types of plasma-based light primarily two types of plasma-based light sources, fluorescent lamps and high-intensity arc sources, fluorescent lamps and high-intensity arc lamps. Fluorescent lamps find widespread use in lamps. Fluorescent lamps find widespread use in homes, industry and commercial settings.homes, industry and commercial settings.

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DefinitionDefinition A A particle beamparticle beam is an accelerated stream of is an accelerated stream of

charged particles or neutrons (often moving at charged particles or neutrons (often moving at very near the speed of light) which may be very near the speed of light) which may be directed by magnets and focused by electrostatic directed by magnets and focused by electrostatic lenses {Anlenses {An electrostatic lenselectrostatic lens is a device that is a device that assists in the transport of charged particles. }, assists in the transport of charged particles. }, although they may also be self-focusing although they may also be self-focusing

Quasi-neutralityQuasi-neutrality ((quasiquasi, from the Latin, "as if", , from the Latin, "as if", "resembling") describes the apparent charge "resembling") describes the apparent charge neutrality of a plasma overall, while at smaller neutrality of a plasma overall, while at smaller scales, the positive and negative charges making scales, the positive and negative charges making up the plasma, may give rise to charged regions up the plasma, may give rise to charged regions and electric fields. and electric fields.

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DefinitionDefinition AA tokamaktokamak is a machine producing ais a machine producing a toroidal toroidal

magneticmagnetic field for confining a plasmafield for confining a plasma. . It is one of It is one of several types of magnetic confinement devices, several types of magnetic confinement devices, and it is one of the most-researched candidates and it is one of the most-researched candidates for producing controlled thermonuclear fusion for producing controlled thermonuclear fusion power.power.

TorodialTorodial In geometry, a In geometry, a torustorus (pl. (pl. toritori) is a surface of ) is a surface of

revolution generated by revolving a circle in three revolution generated by revolving a circle in three dimensional space about an axis coplanar with dimensional space about an axis coplanar with and not touching the circleand not touching the circle

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DefinitionDefinition

In a plasma, the In a plasma, the Boltzmann relationBoltzmann relation connects the electron density connects the electron density nne to the e to the plasma potential φpl as follows:plasma potential φpl as follows:

nne = e = nn0 exp(eφpl/0 exp(eφpl/kkBBTTe) e) The reference for the potential is taken to The reference for the potential is taken to

be a position where the electron density is be a position where the electron density is nn00

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