[ExI] lockheed's fusion video

[spike]

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.  That material becomes neutron rich, which makes is subject to fission.  Lead is really good stuff, because it fissions down to bismuth, but neither lead nor bismuth work as a pressure vessel.  You need some kind of serious metal for that, such as steel.  Unless something has changed since my misspent youth in college physics, which I do admit has been tragically many years ago, when neutron rich iron isotopes undergo fission, they form cobalt, which is lousy as a structural material.  

So we could have a steel inner surface which degrades and a lead alloy of some sort which carries away the heat and fission by beta decay to bismuth (as my creaky memory is saying (I need to check that.))  But that steel inner surface still needs to be recycled often.

>…Also, is there a discrete surface?  My impression was that plasmas don't have surface tension the way liquids do…

 

That part I don’t know.  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?

 

spike

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