Fusion Message Board

In this space, visitors are invited to post any comments, questions, or skeptical observations about Philo T. Farnsworth's contributions to the field of Nuclear Fusion research.

Subject: Re: Deuterium refining
Date: Aug 19, 08:39 am
Poster: Richard Hull

On Aug 19, 08:39 am, Richard Hull wrote:

>>We fusor freaks have enough tough rows to hoe without trying to home brew cheap industrial gases.
>>The actual process of calibrated leaking in D2 gas is a major hurdle for the amateur not already familiar with the art.
>>Richard Hull
>This is my first post - Let me say "well done". The information on Farnsworth and the Fusor is very interesting and well presented.
>One comment following on the D2 notes - As you know the "hot" fusion team demonstrated proof of concept with 80 tons of D2 in the first thermonuclear device. Later weaponized versions relied on H, D, and T combined with 6Li and 7Li. The lithium salts providing a solid, compact form of the fusion fuels. Li also provide in situ T in a high neutron flux environment. I know LiH is commercially available, and LiD may be available from Aldrich - Question 1: could an Li - H or D salt be used a fuel to boost a Farnsworth Fusor? One immediate benefit: as a solid it would not compromise the vacuum.
>Question 2 - How do you convert n/s, or neutron flux units into common energy units (Joules or BTU/Hr) and compare those numbers to energy input. I'm trying to envision the power extraction side of a steady state Fusor.
>JK Smith


The use of the solid lithium fuels in a fusor has not been investigated to my knowledge. It has been thought of by some reserachers, but most of the fusors in this modern era are on line as simple neutron sources. How to implement the Lithium fuel into the reaction is the big question.

The precise location in the fusor of the maximum fusion area is now being debated. If in the center, (which I doubt), then any incursion by solids there would interrupt the smooth field gradients which the fusor relies on.

I'll have to ponder that one.

Finally, you asked about power out tabulations. This is a real toughy due to the multiplicity of reactions in the chamber. The pure neutron energy would be related to the electron volt energies of the particles and we have a mixed bag, but most folk work off of the 3.45mev neutron products although there are fast ions in the mix too. and other reactions which might push out neutrons in the 17 mev range on occasion.

The electron volt is equal to 1.6 X10E-19 joules. A 3.5mev neutron would contain about
5.6 X10E-13 joules of energy and a small amateur fusor might be capable of let's say 10E6 neutrons/second. That means its total output in a specific neutron energy range would be 10E-6 to 10E-7 joules. That is one millionth of a watt-second. The average power input needed to do that would be about 30kv X 20ma or about 600 watts! that is a net loss of energy! or 600 million times more energy in than out!
this simplistic analogy is not even close to reality as we left out about 60 other variables and didn't figure in circuit losses in about 50 other places and used only the lowest energy neutron production for calculation, but even with a million fold improvement in efficiency we would still need 600 times more energy in than we get out.

Sounds awful defeatist doesn't it? Well it is part of the nuclear fusion game. The interesting point is that the big boys aren't faring much better after 40 years at it and billions spent.

The best they can do with inertial confinement is terawatt laser blast frozen D-T pellets and create a mini-hydrogen blast in a jar once every 20 seconds or so. I feel they are not scientifically forthcoming about all their energy inputs when they make us believe they have gone over break even for milliseconds.

Most of the folks I have talked with are looking at "direct conversion" from some sort of P-B11 dual alpha particle collection scheme or reaction. Still, this seems years off.

Richard Hull