From: bds@rzg.mpg.de (Bruce Scott TOK)
Newsgroups: sci.physics.plasma
Subject: Re: cold and hot plasma ?
Organization: Rechenzentrum der Max-Planck-Gesellschaft in Garching
References: <896njl$jtn$1@jupiter.cs.uml.edu>


In article <896njl$jtn$1@jupiter.cs.uml.edu>,
kileak <sguille@lucent.com> wrote:
>
>
>kileak a écrit dans le message ...
>>hello guys !
>>i'm newwbie here and i have a question.
>>1-what is the difference between a "cold" and a "hot" plasma ???
>>2-what do you think of the demonstration at:
>>http://members.xoom.com/jlnlabs/html/oa_plasmoid.htm
>>is the glowing cloud created in the glass a real hot plasma ??

This appears to be some sort of UFO story... (``This simple and basic
experiment is one of the main part of the working principle of an
enhanced EHD Plasma reactor used in some advanced flying crafts'')

Anyway, there appears to be a real experiment, but to me it looks like
something chemical, with no evidence for a plasma. I'd be convinced if
you measured electric and/or magnetic field fluctuations, or
temperatures high enough to ionise the constituent atoms.

By our standards (magnetic confinement experiments), a hot plasma is one
in which electrical resistivity has little or no effect on instabilities
and associated turbulence. In practical terms, this means temperatures
above 100 or 200 electron volts, or about 1 or 2 milllion degrees
Kelvin. Others use the standard of full ionisation, which can mean
higher or lower temperatures than this, depending on how the plasma is
generated (i.e., the electron density). A tokamak edge plasma is fully
ionised above about 30 eV.

Concerning ball lightning, see the recent article in _Nature_ (within
the last 3-5 weeks), claiming to have a chemical energy explanation for
the phenomenon.

--
cu,
Bruce

drift wave turbulence: http://www.rzg.mpg.de/~bds/