Re: DON'T LOSE time and money around the fusion energy illusion and the lunar-helium-3 dream!!!

On 30 Aug, 15:46, Joe Strout <j...@xxxxxxxxxx> wrote:
In article <1188469582.879910.76...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Ian Parker <ianpark...@xxxxxxxxx> wrote:

I have been thinking about this. I will agree that one should have an
open mind about the method of fusion. I think we should understand why
the Tokomak and magnetic containment has such a dominant position. It
is not suficient simply to heat the plasma, the plasma must be hot
long enough for useful power to be extracted. This is where inertial
metods, and as I understand it your method of containment is inertial,
break down.

I'm not sure what "your method" you're talking about, but IEC fusion
doesn't depend on heat at all, and that's the key point.

When you're using a thermalized plasma for fusion, you've got two
problems right off the bat:

1. The fuel ions are thermalized, meaning that they have a distribution
of energies. Put another way, at any given moment, most pairs of ions
will not have enough energy to fuse (since generally the temperatures
needed for this approach are so high that we can just barely achieve
them anyway). So this greatly reduces the probability of fusion when
two particles bump into each other.

2. The fuel ions are travelling in completely random directions. This
also greatly reduces the probability of fusion when two particles bump
into each other, since most of the time, you'll have something more like
a glancing collision than a head-on one.

One of the key insights of the IEC approach is that it is NOT using heat
to make ions fuse; instead, it is accelerating them together, much like
any other particle accelerator. Rather than flying around randomly,
fuel ions are accelerated electrostatically towards the focus at the
center. So whenever two ions bump into each other, they have the right
energy to fuse (curing problem 1); and because they're all being
accelerating towards the center, there is a higher probability of a
direct collision (partially curing problem 2).

So when referring to IEC fusion, don't talk about the temperature of the
plasma -- that's an inappropriate measure. Talk about the ion energy
(or velocity) instead.

A great deal of research has been devoted to getting a stable plasma
in a tokomak so that the density/temperature/containment parameter
looks good.

Yes, and a great deal more research will be done for decades to come, no
doubt. I'm not trying to take down tokamaks; some great physics comes
from them. But they're taking a very difficult approach to the problem,
and are unlikely to have much relevance to actual energy production. If
we'd spent even 10% of what's been spent on tokamak research on more
sensible approaches, we probably would have fusion power by now.

It would seem that what you are advocating isd a single pass. You
cannot get an appreciable percentage of atoms fusing on a single
encounter. If you have a hot plasma the atoms are travelling in random
directions - true, but they have a large number of collisions per
second. If you have 2 directed beams you cannot be certain of a hit,
still less of a square on hit.

You must vusualize an array of skittles placed a distance apart and me
aiming at them! Certain to miss.


- Ian Parker

.

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