This document discusses plasma, the fourth state of matter. It provides a history of plasma research, beginning with Sir William Crookes discovering plasma in 1879. It describes the key properties of plasma, including that it is electrically conductive and dominated by electric and magnetic fields. Plasma exists in conditions where the Debye length is small compared to size and it is electrically neutral. Over 99% of the observable universe exists as plasma. Examples of plasma discussed include lightning, aurora borealis, space plasmas, and artificial plasmas like fluorescent lights. The document also covers different plasma types based on temperature, equilibrium, neutrality, and particle size.

1. BABY HAPPY MODERN PG COLLEGE,
HANUMANGARH
Submitted to-
Department of physics
Submitted by-
Pooja swami
M.Sc. Previous
Physics
Introduction of Plasma

2. CONTENTS-
History
Four state of matter
Plasma 4th state of matter
Properties of plasma
Condition for plasma existence
Debye sphere
Quasi neutrality of plasma
The plasma universe
Difference between plasma and gas
Types of plasma
• On the basis of existence
• On the basis of temperature
• On the basis of equilibrium
• On the basis of neutrality
• On the basis of particle’s size
 Fluid model of plasma
 Uses of plasma
 Examples of plasma
• Terrestrial plasma
• Space and astrophysical plasma
• Artificial plasma
 Reference

3. HISTORY-
 was the first to “discover” plasma in 1879, in crooks tube .
 Called it “ radiant matter “ .
Sir William crooks
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4. CONTI...
 Took trips to the north pole where he studies auroras made theories about electric
current and plasma carried from sun to earth .
 His theories were ridiculed in his time .
 Birkeland currents named after him.
Kristian birkeland
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5. CONTI…
 coined the term plasma because it reminded him of blood plasma(1927) .
 Recognized the waves forms in plasma – called “ Langmuir waves “ .
 Developed Langmuir probe for exploring properties of plasma .
 Made first plasma welder.
Irving Langmuir
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6. CONTI…
 Played a central role in the development of modern plasma physics .
 Won noble prize in 1970 for his work with plasma .
Hannes Alfven
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7. FOUR STATE OF MATTER
Solid
Liquid
Gas
Plasma
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8. PLASMA 4TH STATE OF MATTER
 Plasma is a state of matter in which an ionized gaseous
substance become highly electrically conductive to the
point that long range electric and magnetic field
dominates the behavior of matter .
 The world plasma comes from ancient Greek meaning
“moldable substance “ or “ jelly “.
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9. PROPERTIES OF PLASMA
Fourth state of matter , plasma mostly doesn’t naturally exist on the earth ‘s surface under normal conditions.
It is artificially generated from natural gases.
Plasma is an electrically neutral medium of unbound positive and negative particles (i.e. overall charge of
plasma is zero ).
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10. CONDITION FOR PLASMA EXISTENCE
The Debye length must be small compared to the linear extent of the plasma i.e. D<<L .
The plasma is approximately neutral i.e. ni = ne.
 There must be a large number of electrons in the Debye sphere i.e.
4/3ΠD3ne>>1
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11. DEBYE SPHERE
The assumption of a large number of particles is a further criterion for the
existence of plasma . The large number of particles provides the smooth
decrease in the field required for the detection of Debye length D . The
requirement is insured if the no. of particles within a sphere of radius
equals to Debye length D is known as Debye sphere .
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12. QUASI NEUTRALITY OF PLASMA
The criterion of quasi neutrality is not independent criterion. Meaning of quasi neutrality for plasma is that
number of negative ions in plasma should be equal to the number of positive ions i.e.
ni = ne
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13. THE PLASMA UNIVERSE
 About 99% of the matter in the observable universe is in the plasma state .
 In our solar system ,the sun , the interplanetary medium , the magneto spheres and
ionospheres of the earth and the other planets , as well as the ionospheres of the comets
and certain planetary moons all consist of plasmas .
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14. DIFFERENCE BETWEEN PLASMA AND GAS
PLASMA GAS
 Electrical conductivity of plasma is usually very high
,the conductivity of plasma may be treated as infinite
.
 In plasma number of independently acting species are
two or three :electrons , ions, proton and neutrons .
 Plasma interact collectively at long ranges through
the electric and magnetic forces .
 Electrical conductivity of gases are very low until it
break down into plasma at electric field above 30kv
per cm.
 Independently acting species in plasma is one i.e. all
gas particle .
 Gas interacts binary two particle collision is observed
generally in gas .
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15. CONTI…
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16. PLASMON PATICLE
A plasmon is a quantum of plasma oscillation. Just as light (an optical oscillation) consists of photons, the
plasma oscillation consists of plasmons. The plasmon can be considered as a quasiparticle since it arises
from the quantization of plasma oscillations, just like phonons are quantization of mechanical vibrations.
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17. TYPES OF PLASMA
 ON THE BASIS OF EXISTANCE
Natural plasma Artificial plasma
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18. ON THE BASIS OF TEMPREATURE
Hot plasma Cold plasma Ultra cold plasma
 Really hot i.e. temperature is of order
15x107 kelvin .
 Not really cold temperature of cold
plasma is almost equals to room
temperature .
Temperature is equals to 1 kelvin.
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19. ON THE BASIS OF EQUILIBRIUM
Thermal plasma Non thermal plasma
 In thermal plasma electrons are in thermal
equilibrium with ion and neutral gas particles .
 Ti = Te
 In non thermal plasma electron are much
hotter than ion so they comes into equilibrium
among themselves .
 Te >>Ti>>Tn
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20.  ON THE BASIS OF NEUTRALITY
Neutral plasma Non –neutral plasma
Plasma having its net charge
approximately zero is called neutral
plasma .
e.g. neon signs , fluorescent lamps .
A plasma with a significant excess of a charge
density is called non neutral plasma .
e.g. cathode rays , positron plasma ,charged
particle beams etc.
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21.  ON THE BASIS OF PARTICLE’S SIZE
Dusty plasma Grain plasma
A dust plasma contains tiny
charged particles of dust . The dust
particle acquire high charges and
interact with each other .
A plasma contains larger particles is called
grain plasma .
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22. FLUID MODEL OF PLASMA
Fluid model of plasma describes plasma in terms of smoothed quantities ,like density
and averaged velocities around each position . A more general description is the two
fluid plasma (figure) . Where the ions and electrons are describes separately. Fluid
models are often accurate when collisionality sufficiently high .
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23. USES OF PLASMA
 Surface treatments as plasma coating
 Metal cutting and welding
 Metallurgy
 Fluorescent lamps
 In fields of research
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24. EXAMPLES OF PLASMA
 Terrestrial plasma
• Lightning
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25. Aurora borealis
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26.  Space and Astrophysical plasma
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27.  Artificial plasma
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28. REFERENCE
Plasma Physics by S.N. sen
www.googleco.in
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