Date: 7/7/94
From: sshankar@tcad34.Berkeley.EDU (Sadasivan Shankar)
Newsgroups: sci.physics.plasma
Subject: What precisely is plasma ?

Hello,
I will start the posting with a couple of questions.

1. Why is plasma different from gas phase of matter ?

2. What are the most specific characteristics of a plasma ?

I think that will be an appropriate way to start discussion on
this newsgroup.

S.SHankar
Intel

[Note from Moderator:
These are excellent questions - hopefully, many responses
will be motivated by them.
Francis Chen, Intro. to Plasma Physics, Plenum Pr., 1974
"A plasma is a quasineutral gas of charged and neutral
particles which exhibits collective behavior"
[however, lab experiments are now done with non-neutral plasmas]
T. Boyd and J. Sanderson, Plasma Dynamics, Barnes & Noble, 1969
"A plasma is any state of matter which contains enough free,
charged particles for its dynamical behavior to be dominated by
electromagnetic forces."
[however, reference is made to quark "plasmas"]
These references and more recent texts by Krall & Trivelpiece, Nicholson
and others provide information on specific characteristics of a plasma.
George Parks, for example, states that "A plasma possesses properties that
arise from both the individual interactions of the charged particles and
those that come from the 'collective' behavior of particles. This
behavior arises from many particles interacting simultaneously through
the long-range Coulomb potential. The collective interactions are best
described by the concepts of statistical physics." (G. Parks, Physics of
Space Plasmas, Addison-Wesley, 1991, p. 21). Chapter two of this reference
is one example of a concise summary of plasmas and their defining
characteristics.]