"John W. McKelliget" <John_McKelliget@uml.edu>
Subject: CHARTER, WHAT IS A PLASMA?
Organization: University of Massachusetts - Lowell
Expires: 01 January 2000
Welcome to the sci.physics.plasma newsgroup.
This is a monthly posting intended to introduce you to the
newsgroup and to plasmas in general.
2. sci.physics.plasma Archive
3. Role of Moderator
4. Current Moderator
5. Previous Moderator
8. What is a Plasma?
9. Plasma Related Links
In November 1999 15 articles were approved for posting to
2. SCI.PHYSICS.PLASMA ARCHIVE:
These, and all previous postings to the newsgroup, can be found in
the sci.physics.plasma archive at
3. ROLE OF MODERATOR:
sci.physics.plasma is a moderated newsgroup.
All postings are sent to the moderator who checks to see that the
posting conforms to the newsgroup's charter. The moderator is not an
editor or censor and should not be considered at fault for any incorrect
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4. CURRENT MODERATOR: (since July 1996)
John W. McKelliget
Dept. of Mechanical Engineering
University of Massachusetts
Lowell, MA 01854
5. PREVIOUS MODERATOR AND NEWSGROUP INITIATOR:
sci.physics.plasma was initiated by Tim Eastman (firstname.lastname@example.org) in
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7. CHARTER: NEWSGROUP for Plasma Science and Technology
Plasmas are as rich as any other state of matter in terms of distinct
processes and they encompass distinguishable scales ranging from the
atomic to the galactic. Opportunities in plasma science and technology
reflect this breadth in phenomena and scales; one recent list contains
close to 200 subject areas and more than 90 applications areas including
thin-film diamond deposition, toxic waste disposal, plasma arcs for
steel processing, laser self-focusing, fusion for energy production, gas
and arc lamps, cutting and welding, and semiconductor production.
The Plasma Science and Technology research community seeks an increased
dialogue among its multifarious constituencies. The NEWSGROUP for Plasma
Science and Technology is intended as a community forum for sharing new
developments and bringing researchers together for potential new
collaborations. The newsgroup also provides a forum for public outreach
and education. Postings from students and the general public are
welcome as we all help one another in learning more about the "fourth
state of matter" and its enormous range
8. WHAT IS A PLASMA?:
The loosest definition of a plasma is that it is an electrically
conducting gas. At normal temperatures and pressures gases are usually
very good electrical insulators. This is because the electrons in the
gas are tightly bound inside gas atoms and are not free to move in
response to externally applied electric or magnetic fields.
Under certain conditions, however, some or all of the electrons can be
removed from their parent atoms, a process called ionization. The gas
then consists of a mixture of negatively charged electrons, positively
charged atoms, called ions, and un-ionized neutrally charged atoms. Now
the electrons and ions are free to move under the action of applied
electromagnetic fields and the gas can conduct electricity. Due to
their much smaller mass the electrons respond to the applied fields much
more readily than the ions and, consequently, carry most of the
current. Since electrons and ions are produced in pairs and have
opposite charges most of the plasma remains electrically neutral.
There are three principal methods for ionizing a gas. The first, called
field ionization, involves applying an extremely high electrical field
that acts on the electrons in a neutral atom and essentially disrupts
the atom. The second, called thermal ionization, involves raising the
temperature of the gas until collisions knock electrons out of the
atoms. Thus, a plasma does not have to be "hot", although some are
extremely so. The third method involves bombarding the gas with
high energy radiation or other sub-atomic particles.
Because the properties of a plasma are so very diferent from those of a
neutral gas the plasma state is sometimes called " the fourth state of
In practice the plasma state covers an extremely large range of
temperature and pressure, from the gas in the fluorescent lamps in your
house to the fusion reactions in the center of the sun. Although you
may have to search for a plasma in your daily life, most of the visible
matter in the universe is in the plasma state.
Technological applications of plasmas include: fluorescent lights,
welding arcs, steelmaking furnaces, experimental fusion reactors,
semiconductor processing, flat panel displays,
photovoltaics, solar coatings, architectural coatings,
and hazardous waste processing.
9. PLASMA RELATED LINKS:
"The Plasma State" an essay commisioned by the American Physical Society
Division of Plasma Physics
Plasma science & technology homepage
Extensive additional plasma material can be found at
Listings of upcoming plasma conferences can be found at the following