Plasma is the fourth state of matter and is defined as an ionized gas consisting of positive ions and free electrons. Plasma makes up 99% of the visible universe and can be created by heating a gas to extremely high temperatures. Some key points about plasma include: - Plasma exhibits collective behavior due to interactions between charged particles within the ionized gas. - Debye shielding describes how plasma can shield an electric field due to the formation of oppositely charged particle clouds around disturbances. - Plasma has applications in areas like fusion energy research, lighting, plasma TVs, and in understanding astrophysical phenomena like stars. Controlled nuclear fusion may allow plasma to become a future energy source.

1. PLASMA
Dr. Abhisek Kumar Singh
Department of Physics
G L Bajaj Group of Institutions Mathura
PLASMA - Dr. Abhisek Singh

2. CONTENT
Introduction
History of Plasma
Occurrence of Plasma in Nature
Definition of plasma
Concept of temperature
Debye shielding
How to create plasma
Application
PLASMA - Dr. Abhisek Singh

3. What is matter
• Any substance that has mass and takes up
space by having volume.
• Substances that contain only one type of atom
or volume.
PLASMA - Dr. Abhisek Singh

4. What is PLASMA ?
 Heat a “solid”  It becomes “liquid”
Heat the “liquid”  It becomes “gas”
Heat the “gas”  It becomes “ionized gas” or “Plasma”
 It is also called the “Fourth State of Matter”
First Second Third Fourth
PLASMA - Dr. Abhisek Singh

5. But
• What happens if you raise the temperature to super high level between 1 Thousand
degree centigrade to 1 billons degree centigrade
PLASMA - Dr. Abhisek Singh
𝜋𝑟2
C
0
1000
Will everything just be a gas?

6. Definition of a PLASMA
• Plasma is super heated matter
• Plasma is an ionized gas consisting of positive ion and
free electron
• Plasma is very good conductor of electricity.
• Plasma, like gases have an indefinite shape and
indefinite volume
PLASMA - Dr. Abhisek Singh

7. History of the term “PLASMA”
• The plasma comes from ancient Greek “Molded Substances or
Jelly”
• Plasma was first identified in a
Crookes tube so described by
“Sir William Crookes” in 1879.
(The called it Radiant matter)
• The term plasma was introduced
•as a description of ionized gas by
• “Irving Langmuir”in 1928.
PLASMA - Dr. Abhisek Singh

8. • He used the word “Plasma” in analogy with
blood as the transport of electron from
thermionic filaments reminded Langmuir of
“ the way blood plasma carries red and white
corpuscles”.
PLASMA - Dr. Abhisek Singh

9. Occurrence of plasma in nature
• It has been said that 99% of the matter in the
universe is in plasma state. i.e. In the form of
electrified gas with the atoms dissociated into
positive ions and negative electrons.
• Stellar Interiors, Gaseous Nebulae and much
of Interstellar Hydrogen are plasmas.
PLASMA - Dr. Abhisek Singh

10. PLASMAS IN NATURE
 Plasma in Space
• Stars
• Coronas
• Solar wind
• Star nurseries
• Interstellar Nebulae
• The accretion disks and accretion disk
jets of black holes.
• Space is not empty vacuum. It is actually
filled with plasma that conducts our EM
wave signals. Our Universe is 99.9%
Plasma
https://www.plasmas.org/

11.  Terrestrial Plasmas
• Fire (When hotter than 1500℃)
• Lightning
• The magnetosphere
• The ionosphere
• The plasmasphere
• The polar aurorae
• The polar wind
• Upper atmospheric lightning (e.g. Blue
jets, Blue starters)
• Sprites
https://www.plasmas.org/

12. Plasma on Earth (Artificial)
 Fluorescent lamp
Mercury Lamps
Sodium vapour lamps
Neon Signs
These are all examples of plasma
based light sources
 “Plasma TV” is based on emission of
light from plasma
 “Plasma Lamp” is another example of
plasma light.
PLASMA - Dr. Abhisek Singh

13. Definition of Plasma
• Plasma is a quasi neutral gas of charged and
neutral particles which exhibit collective
behavior.
PLASMA - Dr. Abhisek Singh

14. Collective Behavior
• For ordinary air, the molecules are neutral.
There is no net electromagnetic force on it.
• Plasma has charged particles, they generate
local concentration of positive and negative
charges. They give rise to electric field.
• Motion of charges generate current and
magnetic field .
PLASMA - Dr. Abhisek Singh

15. Quasi-Neutral
• Quasi neutrality of plasma means plasma is
overall neutral.
Number of electron= Number of ions
PLASMA - Dr. Abhisek Singh

16. Gas vs Plasma
PLASMA - Dr. Abhisek Singh

17. Concept of Temperature
• A gas in thermal equilibrium has particles
moving with different velocities.
• Distribution velocities is based on Maxwell
Boltzmann distribution.
• One dimensional Maxwell’s Distribution is,
PLASMA - Dr. Abhisek Singh
  






 KT
mu
A
u
f 2
2
1
exp

18. Where, f(u) is number of particle per cubic meter
with velocity between u and u+du.
Solving this we get,
Average kinetic energy=1/2KT
For 3-dim K.E.=3/2KT
PLASMA - Dr. Abhisek Singh
 
 









du
u
f
du
u
f
mu
Eav
2
2
1

19. • The general result is that average kinetic
energy equals 1/2KT per degree of freedom
PLASMA - Dr. Abhisek Singh
K
T 11600
10
38
.
1
10
6
.
1
23
19



 

J
eV
KT 19
10
6
.
1
1 




20. DEBYE SHIELDING
Plasma has ability to shield out electric
potential applied on it
PLASMA - Dr. Abhisek Singh

21. PLASMA - Dr. Abhisek Singh
• Place two charges metal sphere connected to a
battery in plasma
• These charges sphere attract opposite charges
and a cloud of ions and electron surrounded
the sphere.
• There should be no thermal motion.
•

22. Debye Shielding :
• It is measure of shielding distance
Or thickness of the cloud.
• Debye length
2
/
1
2
)
(
e
n
kT
e
o
D

 
PLASMA - Dr. Abhisek Singh

23. • Three conditions a plasma must satisfy are
• 1.
• 2.
• 3.
PLASMA - Dr. Abhisek Singh

24. HOW TO CREATE PLASMA??
There are many different methods of creating plasmas in the laboratory. The most
commonly known processes are (𝑖) Photoionization and (𝑖𝑖) Electric discharge in
gases.
(𝑖) Photoionization : In that process,
ionization occurs by absorption of incident
photons whose energy is equal to or
greater than the ionization potential of the
absorbing atom. The excess energy of the
photon is transformed into kinetic energy
of the electron-ion pair formed. Ionization
can also be produced by X-rays or gamma
rays, which have much smaller
wavelengths.
https://projects.exeter.ac.uk

25. HOW TO CREATE PLASMA??
(𝑖𝑖) Electric discharge: In a gas discharge, an electric field is applied across the ionized
gas, which accelerates the free electrons to energies sufficiently high to ionize other
atoms by collisions.
When a high speed electron collides with an electron bound to a nucleus, it can give
both electrons enough energy to escape. Thus ionization is occurred.
https://quizlet.com

26. • “Hot" if it is nearly fully ionized
• “Cold" if only a small fraction (for example 1%) of
the gas molecules are ionized
• Even in a "cold" plasma, the electron temperature is
still typically several thousand degrees Celsius.
Hot and Cold Plasmas
PLASMA - Dr. Abhisek Singh

27. Fusion Energy
Potential source of safe, abundant energy.
Astrophysics
Understanding plasmas helps us understand stars
and stellar evolution.
Upper atmospheric dynamics
The upper atmosphere is a plasma.
WHY WE ARE INTERESTED IN PLASMA??

28. APPLICATIONS

29. Much of plasma physics research has been motivated by
the goal of controlled fusion energy.
Fusion energy is a form of nuclear energy which is emitted
when two light nuclei combine to form a single more stable
nuclei.
The sun and stars derive their energy from fusion.
PLASMA IN FUSION ENERGY

30. Plasma
self-heating
Tritium
replenishment
Li
Electricity
Hydrogen
3.5 MeV
14 MeV

31.  It uses a powerful magnetic field to confine plasma in the shape of a torus.
 It is magnetic confinement device developed to contain the hot plasma needed for
producing controlled thermonuclear fusion power
TOKAMAK

32. Plasma Science: Advancing Knowledge in the National Interest (2007), National Research Council,
http://books.nap.edu/openbook.php?record_id=11960&page=9
PLASMA - Dr. Abhisek Singh

33. Interdisciplinarity
(Picture by P. Chen)
PLASMA - Dr. Abhisek Singh

34.  NEW AREA FOR RESEARCH AND DEVELOPMENT
 GREAT FEATURES
 WIDE RANGE OF APPLICATION
 POWERFUL ENERGY SOURCE
FUTURE OF PLASMA PHYSICS

35. PLASMA - Dr. Abhisek Singh