Gettysburg College
Plasma Physics

The Picketts Charge Plasma Device

What is Plasma?

Plasma is the fourth state of matter.  Although the definition of plasma is often simplified to being an "ionized gas," the true definition of plasma is more complex than this, for some ionization is common in almost every gas.  Plasma can be defined more accurately and scientifically as "a quasineutral gas of charged and neutral particles which exhibits collective behavior" (Chen, 3).  In simplified terms, plasma is a gas that can conduct electricity.

Plasma is the most common state of matter; it is believed to comprise more than 99% of our visible universe.  Every time we witness a bolt of lightning or gaze in awe at (or see photographs of) the Aurora Borealis, we are observing plasma on Earth.  The truth, however, is that we seem to live in the 1% of our universe where naturally occurring plasma is quite rare.  Lightning and the Aurora Borealis are just two of the very few examples of naturally occurring plasma on this planet.  Plasma is relatively rare on Earth because very high temperatures are often necessary for plasma formation.  In fact, at extremely high temperatures, all matter is in the plasma state.  This is true because heat causes atoms of a neutral gas to speed up, thus increasing the probability and occurrences of collisions; when atoms collide, electrons can be liberated from their parent atom.  The result is the creation of a charged gas (plasma).  This condition for plasma formation explains why plasmas are commonly found in astronomical bodies with temperatures of millions of degrees, as well as why they are rare on Earth.
Very high temperature is not the only condition that is conducive to plasma formation.  Gas also ionizes when it is rarefied; when a gas is rarefied, freed electrons virtually never encounter an ion with which it can rejoin.  Plasma can also be formed when an exterior source of energy, like an electromagnetic field, is so strong that it tears electrons free from originally neutral atoms.  The conversion of a neutral gas into a plasma can occur extremely quickly. (The Pervasive Plasma State).

Why Study Plasma?

There are numerous everyday uses for plasmas.  For example, fluorescent lights and neon signs work because of plasma.  Circuit features on microprocessor chips in computers also contain plasma.  Even the exhaust that is emitted during rocket launches is actually plasma, not gas.  Plasma is also used to manufacture industrial diamonds and superconducting films.

It may be the solution to our energy problems. While the Earth's natural supplies of coal, oil, and natural gas are being depleted, and the burning of fossil fuels creates harmful pollution, fusion is raising the hopes of many scientists.  After all, the deuterium in the Earth's oceans is sufficient, through fusion, to energize the world for millions of years at little or no cost to our environment.  And plasma is key in fusion.  This is true because fusion occurs when the atomic nuclei of light elements are combined to create heavier nuclei.  This nuclear reaction results in the release of enormous quantities of energy.  But for fusion to occur, three conditions must be met.  The particles must be hot enough, in sufficient number (density), and well contained (confinement time).  All three of these conditions are observed when matter is in the plasma state.  Research in plasma physics could help make fusion reactors part of our future. 

Studying plasma will hopefully unlock the secrets of space weather and allow scientists to forecast space weather more accurately.  Since stars, nebula, and other galaxies are primarily plasma, studying plasma will hopefully answer many of the lurking questions about such topics as how stars are created and how they die.



Plasma Research at Gettysburg College:




Facilities and Development


Student Research




Gettysburg College and Physics Department


Early Team Photos




Tim Good’s Homepage

Links to General Information about Plasma:

Links to Our Collaborators' Work:


West Virginia University - Mark Koepke


University of Iowa - Frederick Skiff

Plasma Research at Other Colleges & Universities:


Columbia University


Massachusetts Institute of Technology (MIT)


Princeton University


University of California Irvine


The University of Texas at Austin


University of Iowa


West Virginia University


International List of Plasma Research Facilities/Projects

Space Weather Links: