[ExI] lockheed's fusion video

Adrian Tymes atymes at gmail.com
Wed Oct 22 02:27:51 UTC 2014

On Tue, Oct 21, 2014 at 6:21 PM, spike <spike66 at att.net> wrote:

> *From:* extropy-chat [mailto:extropy-chat-bounces at lists.extropy.org] *On
> Behalf Of *Adrian Tymes
> *Sent:* Tuesday, October 21, 2014 5:37 PM
> *To:* ExI chat list
> *Subject:* Re: [ExI] lockheed's fusion video
> On Tue, Oct 21, 2014 at 11:37 AM, spike <spike66 at att.net> wrote:
> >>…The creators of the Tokamak when faced with this problem, went the
> only way I can think of: they made the reaction vessel huge, to increase
> the surface area of that inner surface, the first surface a hot neutron
> sees.
> >…There are other, more efficient ways to increase the surface area -
> especially the ratio of surface area to volume, to mass of plasma, or to
> number of neutrons, all of which ratios go down if you go big.
> (Volume/mass/molar count at given density scale with the cube of linear
> dimension, while surface area only scales with the square.)  Or did you
> mean to decrease the surface area's ratio?...
> Imagine you find a way to fuse 3H and a 2H.  Regardless of how you contain
> that, neutrons fly out.  Magnetic fields cannot contain those, not now, not
> in the future.  The first solid surface they hit absorbs some of those
> neutrons.
You miss my point.  "Go huge" increases the surface area less than the
amount of stuff passing through that surface area.  It seems possibly

Also, while I know it to be true, I wonder what the main reasons are why
magnetic containment can not pull this off.  What are the primary
difficulties encountered?

But I am focusing on what was once considered a secondary problem with
> fusion reactors, after we figure out how to sustain the reaction: that the
> pressure vessel degrades from neutron bombardment.
> Has anyone here heard of some magic trick to deal with that neutron
> problem?  Is there another metal capable of making a competent structure
> which can absorb neutrons, then decay to something else which can maintain
> the structure?

That would in theory seem impossible, without mass replacement.  Whatever
material it decays into, will then be hit with more neutrons - and more,
and more, until it decays into something that can no longer accept neutrons.

Molten lead could in theory handle this - siphon part of it off, separate
out the decayed fraction, replace with new led, and inject it in - but
you'd need a way of handling the structure.  Perhaps centrifugal pressure
could keep the molten lead in a roughly hollow-sphere shape, or at least
enough rings that the solid structure containing this molten lead would be
minimally exposed.

Alternately, some design where the shell is made of movable panels (as
pictured in the Portal series, especially Portal 2), such that you could
move one out of the way once it is saturated or used up but have others
behind it so as to not lose sufficient containment.  (Just...whatever you
do, and no matter how innocuous a joke it seems, do not name the software
in charge of this "GLaDOS".)
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