From: bds@rzg.mpg.de (Bruce Scott TOK)
Newsgroups: sci.physics.plasma
Subject: Re: Silly Plasma Fusion idea
Organization: Rechenzentrum der Max-Planck-Gesellschaft in Garching
References: <896ncp$ub5$1@jupiter.cs.uml.edu>



In article <896ncp$ub5$1@jupiter.cs.uml.edu>,
Steven Dobbs <steven.dobbs@cableinet.co.uk> wrote:
>
>could there be a way to make plasma fusion happen more easily? like
>when designing experiments, I imagine that a certain amount of
>analytical work is done in designing a fusion experiment, and the
>aparatus then reflects the analytical work - its just that its
>sometime difficult or impossible to analyse real world situations.

This is very true... even too complicated for state of the art numerical
simulations. Many of the surprises, both good and bad, have come
empirically (eg, H Mode, confinement saturation with density, electron
pre-heating of target fuel pellets) and have only been explained, or not
explained, by all the analytical and numerical work thereafter.

> Plasma fusion becomes unstable due to to instabilities that form -
>could there be 'magic' solutions to this, such as complicated
>mag-field containment oscilations, laser/ion beam patterns that would
>in someway cause instabilities to dissipate?

There are both global and local instablities. In a magnetised plasma,
the latter are what do transport; the former cause disruptions. There
have however been semi-magical solutions, following from the sensitivity
of the local instabilities to such things as magnetic geometry and a
sheared electric field (hence ExB rotation) profile. In the plasma
edge, following increasingly well-coupled computation and experiment,
the special shaping of the plasma boundary and a special region called
the divertor have been important. These things provide much of the
remaining hopes for feasible reactors.

--
cu,
Bruce

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