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From: (Jordin Kare)
Subject: Re: Stable Plasma Electron Torid
Date: Tue, 25 Apr 2000 03:17:52 GMT

In article <8e0t7f$4eo$>, (George
William Herbert) wrote:

> P RidgeRn <> wrote:
> >>*If* they can make the electron spiral torus work as advertised as
> >>an energy storage system, thrust will not be a problem.  ...

> >That is my point exactly.This technology needs full funding and rapid
> >developement because it will open space to human colonization.
> If and only if it can be developed to perform to something
> like the claimed value.

> Again, and this is repeating an earlier criticism I made
> in the group and remains unanswered, the best lab reported
> plasma lifetimes so far for this method are 600 milliseconds
> (0.6 second)
> The author of that study claims without anything like sufficient
> justification that the plasma lifetime *should* be close to
> infinite and doesn't really know why it's only 0.6 sec at best.
> That is inadequate.

Indeed, having skimmed the cited report available on the Web, I note that
the author claims:

"*Analysis indicates* [emphasis mine -- jtk]] the stable plasma will
recover from perturbations and will remain stable.  There is no known or
obvious normal occurrence that will lead to instability"

Anyone who has worked with plasmas knows that instabilities are the rule
rather than the exception, and that if low-order instabilities (which are
easy to analyze) are suppressed, then high-order instabilities will
promptly emerge.   The proposed energy storage is based on containing an
*enormously* strong toroidal magnetic field ("...most of the energy is
contained in the internal magnetic field that has no mass.") with no
plausible basis for stably containing the field pressure.

There are a lot of people out there who don't
> really completely understand plasma physics but are dabbling in
> it and making some unreasonable claims.  This appears by all
> accounts to be another one.

I am reminded of any number of past claims about fusion systems which
"just needed to be scaled up" to produce copious fusion power, including
many proposed by competent -- or at least highly credentialed -- plasma
physicists and engineers.  I'm still waiting....

I am also strongly reminded of an earlier attempt (don't recall if it was
WWI or WWII at this point) to use "stable torii"   It's well known that
smoke rings" (toroidal vortices of air, if you leave out the smoke) are
stable, and can be projected with enough force to blow out a candle across
the room.  The typical "smoke ring generator" is a cylindrical container
with a hole in one end and a piston or moving membrane on the other  --
aka a coffee can with a hole in the lid.  (This remains a staple of
gee-whiz classroom demonstrations and grade-4-to-6 science experiment
books, and I've seen toy "vortex pistols" that would do a good job
knocking down playing-card houses from several yards away.)  So, "Gee, all
we have to do is scale this up and we can shoot down airplanes with it."
Analysis was undoubtedly done to show the idea was sound, and as I recall
it received some military funding.  And as we all know, smoke ring
antiaircraft batteries have been in use worldwide ever since.  The
similarity to the current work is left as an exercise for the reader.

I suppose I'm getting old and curmudgeonly, but I'll be *very* surprised
if we hear much more about this idea.

Jordin Kare

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