🚀 go-pugleaf

In article <1991Nov12.125104.16722@cs.rochester.edu> dietz@cs.rochester.edu (Paul Dietz) writes:
>In article <24270@wraxall.inmos.co.uk> des@frogland.inmos.co.uk (David Shepherd) writes:
>
>>however, are all these claims of a limitless energy supply being
>>overplayed? at the (excellent) open day at JET in the summer one
>>of the leaflets/films said that the power would be produced by sheathing
>>a fusion reactor in lithium, which would itself fuse with high energy
>>deuterium (?) nuclei flying out of the reaction and that the heat
>>from this would be used to generate electricity.  .. . 
>
>The claims certainly are overplayed.  And, if the reactor is too hot to go
>into for 4 months after a 2 megajoule pulse, what's going to happen if
>a commercial reactor producing 3000 MW (th) continuously should break
>down?  I have this image of ITER becoming a major embarassment.

>Known reserves of lithium are a small subset of the amount of lithium
>in the crust  .. . 

>The lithium is transmuted by neutrons, btw.  The (n,t) reaction on 6Li does
>produce some additional heat, but most the energy is from d+t fusion reactions
>in the plasma, carried to the blanket by the neutrons.

>I wonder why JET didn't do a D + 3He experiment (or did they?).

The reactivity of D-He(3) is too low at the luke warm temperatures of
a projected operating tokamak.  One would like to have a temperature 
around 72 KeV to optimize the charge particle production (minimize 
neutron output), but at least half that temperature is needed to ignite.  
That is the <T> and not the "temperature" in the kinetic wash of the
injected particle beams.  

Basically, D-He(3) is an ideal first burn fusion fuel because it has
much reduced particle wall loading and generates a greatly reduced 
radioactive inventory.  The fact that a tokamak can not achieve a burn
from the outset with such a fuel spells big problems for the the world
governments driven fusion program as meeting a workable device. 

I think it's high time we punted the tokamak and started over with 
much cleaner concepts that feature much better engineering profile, 
shorter development time and low capitalization.  To keep the program 
from becoming another flagship white elephant, industry should lead 
and put up half the money to keep them honest (and have enough stake 
that they would dump losers after a few years as opposed to decades 
or centuries??)   The tokamak started around 1963 and optimistic 
predictions put its commercialization not far from 2063 (if ever). 

>	Paul F. Dietz 	dietz@cs.rochester.edu

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