Plasma: The Fourth State of Matter

By: McCall Robinson & Megan Reeves

What is plasma?An electrically

neutral, highly ionized gas composed of ions, electrons, and neutral particles. It is NOT the same plasma that is found in blood.

Who discovered plasma?Irving Langmuir was the first scientist to give a

complete and appropriate theory of ionized gases, and was also the first on using the name 'Plasma' to refer to this new medium or state of matter. This happened by 1920's, when some other scientists were also studying ionized gases. By that time other physicists realized the presence and importance of ionized gases in outer space, as well as the role they play in nuclear fusion reactions in star nuclei, increasing the relevance of Plasma Physics on understanding nature.

Irving Langmuir

Where can plasma be found?Plasma is what makes up stars, solar

wind, nebulae, and everything in between planets and stars. This type of plasma is called Space and Astrophysical plasma.

Terrestrial plasmas are the plasmas that make up lightening and the Aurora Borealis

Plasma can also be found in Plasma TVs, fluorescent lamps, and neon signs.

Early plasma researchLangmuir worked for the General electric

company where he worked with electric devices based on ionized gases.

These studies led to research of cool and dense plasma

From these studies braches of plasma research started to expand in different directions.

Three of the most important things that developed for this research were the discovery of the ionosphere, a better understanding of astrophysical plasma, and interest in nuclear fusion.

The IonosphereThe ionosphere is a very weak ionized plasma

just above the Earth’s atmosphere. It is made by the reactions of solar wind and

solar radiation with the Earth's atmosphere and geomagnetic field.

Astrophysical PlasmaAstrophysical plasma is the plasma that

makes up the stars, the sun, and everything in between.

The properties of this plasma are studied in astrophysics.

Astrophysical plasmas are influenced by magnetic fields. Since they’re electrically neutral, electric fields play less of a role and any charge is readily neutralized.

The StarsThe stars are really just gigantic,

shining balls of plasma held together by gravity.

 Plasma in the stars and in the space between them make up over 99% of the visible universe and most of that which is not even visible.

The SunOur Sun is almost entirely an ionized ball

made of plasma which consists of electrons and ions, in which there is barely any gas at all. The movement of the plasma produces strong magnetic fields and corresponding electric currents.

Even though it’s quite common to hear the Sun being referred to as a gaseous body, a more specific description is that it is made of plasma. In this case, the plasma consists of hydrogen and helium ions, together with the electrons that were liberated when those ions were produced

LightningLightning strikes when the molecules in air

change from a gas to plasma. Air molecules are quite stable, so this change takes a lot of energy.

Plasma is also used in tubes to simulate lightening.

The Aurora Borealis The Sun is the source of the auroras. A "cloud" of

plasma is given off from the Sun. This stream of plasma is known as a solar wind. As the solar wind interacts with the outer edge of the Earth's magnetic field, the particles are "shocked" into flowing around the Earth. Some of the particles are trapped by the earth's magnetic field. They follow the magnetic lines of force down to the ionosphere where the particles react the gases in it, causing them to glow. The colors match up to the different gases in the ionosphere. Oxygen atoms give off red and green light, depending on how high they are in the ionosphere. Nitrogen molecules give off blue and violet light.

Artificial plasmasArtificially made plasmas have many practical

uses.Most artificial plasmas are generated by the

application of magnetic and electric fields. Plasma can be generated in a laboratory setting and for industrial use.

Plasma TVsThey are called Plasma televisions because the pixels rely on plasma cells, or basically what are commonly known as fluorescent lamps. 

Neon SignsPlasma is also found inside of neon signs. Just

like a fluorescent light, neon signs are glass tubes filled with gas. When the sign is turned on, electricity flows throughout the tube. The electricity charges the neon gas and creates plasma inside of the tube. The plasma glows a special color depending on the kind of gas that is inside. 

Jobs with plasmaMany welders work with plasma. There is a

special welding process called arc welding. Arc welding uses electric energy to produce the high energies needed to join pieces of metal.

NASA also uses plasma. Ion rockets use plasma fuels for trips through space. Ion rockets use the electric power to expel charged ion particles.

Arc Welding Ion Rocket

The future of plasmaMuch research is going into the advancement

of plasma TVs. They are trying to develop more specialty features and a higher quality picture.

New developments of plasma are going on everyday even studies in using plasma in dentistry.

Scientists hope to someday generate electric power by using plasmas to control the process of nuclear fusion.