Earth Science: Geology, the Environment, and the Universe

Chapter 3: Matter and Atomic Structure

Problem of the Week

In What State Do You Exist?

If you were to stand on a corner of a busy street and ask passers-by the following question, "In what states can matter exist?" would most folks, probably answer, "Oh, that’s easy, there are three, solids, liquids, and gases." What would be your response to their answer? Right or wrong?

They would be wrong. From what we know, there are four states of matter: solids, liquids, gases, and plasmas. Solids, liquids and gases are very familiar in our lives, but matter, as plasmas, is a relatively new idea. Plasmas have been in existence since the very beginnings of the solar system. They exist at very high temperatures and consist of freely moving electrons, which have been stripped from the nuclei of atoms, and ions.

Plasmas are much more common than you would think. "In fact, ninety-nine percent of the universe is in some form of a plasma state, including lightning, very hot flames, nebulas, the Sun, and other stars."

"Courtesy of SOHO consortium. SOHO
is a project of international cooperation between ESA and
NASA." The gases on the sun exist as plasmas."

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Here on Earth we see plasmas as lightning, in lighting devices like neon signs, and in the Aurora Borealis. What really makes plasmas special though, is their potential, earthly role in the production of a virtually inexhaustible source of energy through the process of nuclear fusion.

Plasmas are the key to nuclear fusion, which can be simply defined as the combination of lighter atomic nuclei into heavier nuclei, resulting in the release of energy. Scientists believe that the fuel for the fusion process is hydrogen, an element found in abundance on Earth, in the form of water. In order for fusion reactions to occur, the particles must be hot enough (temperature), in sufficient number (density), and well contained (confinement time). The intense gravitational forces present in stars provide these conditions and plasmas exist there naturally. Intense research is currently being conducted to sustain nuclear fusion on Earth. The results could lead to a reduction in energy problems.

What is the Problem?

Read again the conditions that are required for fusion to occur:

1. Check out the following Web site to find out the temperatures required in order for fusion to occur: (Shockwave plugin is required.) How hot? http://ippex.pppl.gov/ippex/MODULE_5
   /Forces/FUSION_VS_TEMP.HTML
   
   
2. Fusion is such an efficient way to produce energy. Make some educated guesses as to why we aren't using it on Earth now.
   
   
3. Review again, the conditions that must be present to maintain a fusion reaction; besides the problems with temperature, are the other two conditions reproducible on earth? What do you think? Why or why not?

Hopefully this Problem of the Week has whet your appetite and you want to know more about plasmas, fusion, and the important research being done to harness the power of the stars here on Earth. Check out these "student friendly" and fun Websites and activities to find out more.

1. About Fusion – a tutorial, which explains the process of fusion and fusion research.
   
   
2. Fusion Energy– each link takes you to an interactive activity that allows you to investigate the forces involved in making fusion happen.