Date: Tue, 23 Feb 1999 08:59:41 -0500
Debye length:
The electric field of an isolated charged particle diminishes as the
square
of the distance from the particle. In a plasma, however, this field is
modified because the electrons are free to move into the vicinity of
positive
ions and away from other electrons. The field of each isolated particle
is
thus partially shielded by its immediate neighbors. Over a sufficiently
large
distance--wherein the fields of many individual charges are able to
cancel
each other--this shielding becomes complete. This distance, called a
Debye
length, is a measure of the distance over which an individual charged
particle can exert an effect. Volumes greater in radius than a Debye
length
must be approximately neutral. The Debye length is equal to (6.9 times
the
square root of (T/n))centimeters, where T is the temperature of the
electrons
in Kelvins and n(e) is the number of electrons per cubic centimeter. For
a
body of particles to behave as a plasma, its dimensions must be large
compared to the Debye length.
For Further Information:
HISTORICAL SKETCH OF AVON, OHIO, TO 1974
Schools of Avon, Ohio
From: Burch Seymour
To: velikov@onelist.com