PLASMA

SHERIN WAEL

D.ISAM AL-ASHQER

What is plasma?

• (from Greek πλάσμα, is one of the four fundamental states of matter. It comprises the major component of the Sun. Heating a gas may ionize its molecules or atoms thus turning it into a plasma, which contains charged particles: positive ions and negative electrons.

what is plasma?

(from Greek πλάσμα, is one of the four fundamental states of mater. It comprises the major component of the sun. Heating a gas may ionize its molecules or atoms thus turning it into a plasma, which contains charged particles: positive ions and negative electrons. And this cause the plasma to conduct electrisity and affected to the electromagnatic field.

Plasma history

Sir William Crookes was the first to discover plasma in 1879,In a Crookes tube , and called it ‘’radiant matter’’. Then The nature of the Crookes tube “cathode ray" matter was subsequently identified by British physicist thomson in 1897.

• The term "plasma" was coined by Irving Langmuir in 1928,  perhaps because the glowing discharge molds itself to the shape of the Crooks tube .

• Langmuir described his observations as:

• Except near the electrodes, where there are sheaths containing very few electrons, the ionized gas contains ions and electrons in about equal numbers so that the resultant space charge is very small. We shall use the name plasma to describe this region containing balanced charges of ions and electrons.

Plasma has 99% of the universe matter between stars and galaxies.

• Plasma has 99% of the cosmos matter between stars and galaxies (mass and size)…

• Jupiter planet and plasma; this planet contains 99% of plasma of its size, and 1% mass.

• Common forms of plasma:A- Artificially produced;1. Plasma displays, including TVs. 2. Inside fluorescent lamp (low energy lightining.(neon signs).

3. Rocket exhaust . 4.fusion energy research . .

5. Plasma ball (sometimes called a plasma sphere or plasma globe.

6. laser-produced plasmas (LPP), found when high power lasers interact with materials.

B. Terrestrial plasmas:1. lightning. 2.sprites.

3.The ionosphere. 4. The polar aurorae.

C. Space and astrophysical plasmas:1. The sun and other stars. 2. the solar wind.

3. The interplanetary medium 4. The Jupiter flux tube.(space between planets).

Non thermal or cold plasmas

• Stable at cooler temperatures.• Being used in medicine and food packing.• Acts as a sterilizing agent.

Plasma definition(with details):1. The plasma approximation: Charged particles must be close enough

together that each particle influences many nearby charged particles, rather than just interacting with the closest particle ((these collective effects are a distinguishing feature of a plasma)).The plasma approximation is valid when the number of charge carriers within the sphere of influence (called the Debye sphere whose radius is the depye screening length) of a particular particle is higher than unity to provide collective behavior of the charged particles. The average number of particles in the Debye sphere is given by the plasma parameter, "Λ" (the Greek letter lambda).

2. Bulk interactions: The Debye screening length (defined above) is short compared to 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.

3. Plasma frequency: The electron plasma frequency (measuring plasma oscillations of the electrons) is large compared to the electron-neutral collision frequency (measuring frequency of collisions between electrons and neutral particles). When this condition is valid, electrostatic interactions dominate over the processes of ordinary gas kinetics.

• Debye length: is the measure of a charge carrier's net electrostatic effect in solution, and how far those electrostatic effects persist.

• Debye sphere is a volume whose radius is the Debye length, in which there is a sphere of influence, and outside of which charges are electrically screened.

• In space, electrons have a small density, so debye length has avery small magnitude, like the solar wind and between stars.

Debye length in a plasma

λD is the Debye length,

ε0 is the permittivity of free space,

kB is the Boltzman constant,

qe is the charge of an electron,

Te and Ti are the temperatures of the electrons and ions, respectively,

ne is the density of electrons,

nij is the density of atomic species i, with positive ionic charge jqe

Characteristics of plasma

* Forms filaments, cells, sheaths * High intensity electric current flowing through plasma takes on spiral shape (Birkeland Current) * Forms double layer sheaths at outer boundaries of plasmas of different characters– high electric charge between double layers * Forms cells of different voltages, temperatures, density and chemical properties

four states of matter

solid

liquid

gas

plasma

gas

1st State of Matter?

- Technically, plasma should be called the 1st state of matter, as it is what all the other states arise from.

- may make up 99.99 % of the entire universe.

Types of plasma :• 1- Ultracold plasma:Ultracold plasmas are created in a magneto-optical trap (MOT) by trapping and

cooling neutral atoms, to temperatures of 1 mK or lower, and then using another laser to ionize the atoms by giving each of the outermost electrons just enough energy to escape the electrical attraction of its parent ion.

2- 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 beams, an electron cloud in a penning trap and positron plasmas.

• 3- Dusty plasma and grain 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.

!Plasma is everywhere!• The Hubble telescope and other space probes have been

providing us with lots of information about plasma in the last decade.

• Plasma can be easily produced in a lab, and its behavior is scalable

• Numerous technologies make use of plasma• People have known about it for over 130 years!

Plasma formation:Degree of ionization:• For plasma to exist, ionization is necessary. The term "plasma density"

by itself usually refers to the "electron density", that is, the number of free electrons per unit volume. The degree of ionization of a plasma is the proportion of atoms that have lost or gained electrons, and is controlled mostly by the temperature, Even a partially ionized gas in which as little as 1% of the particles are ionized can have the characteristics of a plasma.

The degree of ionization, α,

Where ni is the number density of ions,

na is the number density of neutral atoms.

• Temperatures:Plasma temperature is commonly measured in kelvin or electronvolts.

informally, a measure of the thermal kinetic energy per particle. Very high temperatures are usually needed to sustain ionization, The degree of plasma ionization is determined by the "electron temperature" relative to the ionization energy (and more weakly by the density). At low temperatures, ions and electrons tend to recombine into bound states atoms and the plasma will eventually become a gas.

Potentials:Since plasmas are very good electrical conductors, electric potentials play

an important role. The potential as it exists on average in the space between charged particles, independent of the question of how it can be measured, is called the "plasma potential", or the "space potential“.

Differentiating this relation provides a means to calculate the electric field from the density

Magnetization

• 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 before making a collision, i.e., ωce/νcoll > 1

where ωce is the "electron gyrofrequency" and νcoll is the "electron collision rate". It is often the case that the electrons are magnetized while the ions are not. Magnetized plasmas are isotropic, 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 high conductivity, the electric field associated with a plasma moving in a magnetic field is given by E = −v × B (where E is the electric field, v is the velocity, and B is the magnetic field), and is not affected by debye shielding.

References

Plasma-universe.comElectric-cosmos.orgWikipedia

Scott, Donald, The Electric SkyThornhill, Wallace, The Electric UniverseAlfred, Jay, Our Invisible Bodies.

• The vedios connection:• الفيديو االول

http://www.youtube.com/watch?v=wBWChj1lWhg

الثاني الفيديو

http://www.youtube.com/watch?v=K1jZUCIZKbE