Subject: Re: what's this fuss about ITER
From: Arthur Carlson TOK
Date: 02 Jan 1997 09:32:02 +0100
jac@ibms46.scri.fsu.edu (Jim Carr) writes:
> The first question that comes to my mind is, how well do those
> codes do with the current generation of experiments? Do they
> extrapolate well backwards (to earlier machines) and between JET
> and PPPL tests?
What I have heard is that Dorland and Kotschenreuther do well
predicting profile information from many, but not all, machines and
regimes, but not necessarily better than a number of other
theories. They have not applied their theory systematically to the
global confinement data base which is the basis of predicting ITER
performance. There are some reasons that this is not entirely
straightforward to do, but until it has been done many scientists
will remain skeptical of the quantitative predictive ability of their
theory.
> The second question is, where do they get (or test) the parameterization
> of the interactions between the bremstrahlung photons and the plasma?
Bremsstrahlung photons do not interact appreciably with tokamak
plasmas. They just heat the walls.
--
To study, to finish, to publish. -- Benjamin Franklin
Dr. Arthur Carlson
Max Planck Institute for Plasma Physics
Garching, Germany
carlson@ipp-garching.mpg.de
http://www.rzg.mpg.de/~awc/home.html
As usual, if I am caught or killed, the Institute
will disavow any knowledge of my actions.
Subject: Re: Japan achieves fusion breakeven!
From: pusch@mcs.anl.gov (Gordon D. Pusch)
Date: 02 Jan 1997 07:44:04 -0600
In article <32CAEFC9.3DE@elec.canterbury.ac.nz> "R.G. Lynn"
writes:
> Gordon D. Pusch wrote:
>
> > What has happened is: some theorist calculated that =IF= the current
> > theory is correct, and =IF= they'd used 50/50 D/T instead of pure D,
> > then (according to theory), the device *should* have released one-half
> > of one percent more energy than it consumed. The preceeding contains
> > so many weasle-words that it clearly is describing at best a *footnote*
> > in =potential= history, not history-in-the-making.
> < snip >
>
> It's 5%, not half of one percent.
Yeah, yeah, yeah, I realized that =AFTER= I posted... :-(
Nevertherless, 5% is not *much* to write home about --- given the
uncertainties and generally ``post hoc'' nature of plasma physics,
I'd be not at ALL surprised if in hindsight we find that said
hypothetical 5% ``gain'' gets eaten up by unanticipated plasma-
instabilities and/or loss-mechanisms...
> I would bet that with this type of result they will be pushing
> towards trying to do a D-T shot at the stated conditions as soon as
> possible because it would be a big feather in the cap for Japan,
> perhaps it could also help spark a bit more interest in funding
> fusion programs amongst the various relevant bean counters.
Depends on many other factors --- remember that JET didn't try a
D/T shot until they were in immanent danger of shutdown, because
they weren't set up to handle an irradiated and contaminated machine.
If the Japanese machine isn't set up for remote handling, a 50/50 D/T
shot might very well be the last shot they could =EVER= perform for a
=LONG= time... :-( What good is a ``feathered cap,'' if you can NEVER
wear said cap again ???
-- Gordon D. Pusch
But I don't speak for ANL or the DOE, and they *sure* don't speak for =ME=...
Subject: Fission plant meltdown info wanted
From: cdean73352@aol.com (CDean73352)
Date: 3 Jan 1997 03:47:58 GMT
Could someone who actually knows, please explain if possible what happens
when a nuclear reactor melts down. It would seem to me that a
heterogeneous is required for the nuclear process to occur. However, when
the core melts down; the core should become a molten mass of material at
the bottom of the reactor.
Three Mile Island was a partial meltdown, and showed that even after the
core started to meltdown - the nuclear process could be brought back under
control and eventually stopped.
I'm curious as to what would occur at the bottom of the reactor during a
total meltdown (reactions, gases formed, etc.) .
Thanks,
Carl
