National Helium Shortage & The Polywell

Discuss how polywell fusion works; share theoretical questions and answers.

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mattman
Posts: 459
Joined: Tue May 27, 2008 11:14 pm

National Helium Shortage & The Polywell

Post by mattman »

Hello All,

The world is currently heading towards a worldwide helium shortage. The stuff cost upward of 9 dollars for 100 grams. Its getting so bad, oil companies are trying to mine the stuff. Do you think the polywell or fusor could be used to generate helium? Making helium is allot easier than making net power. A couple of questions:

1. What fusion reaction generate helium? (D&D, D&T, T&T, ect...)
2. What is the cheapest feed stock for this reaction? (I expect normal hydrogen).
3. What is the ideal voltage for the Hydrogen + Hydrogen --> Helium reaction?
4. How many electrons would you need to hold to get this voltage?
5. Whats field pressure would you need for that cloud?
6. Are you near the Brillouin limit?
7. If you used a fusor (it is easier to hit the voltage), what would your yield be?


Here is the VC pitch. You show a plot of the national hydrogen and helium price. You point to the price differential. You say to the investor: "this is where we get paid."

hanelyp
Posts: 2261
Joined: Fri Oct 26, 2007 8:50 pm

Re: National Helium Shortage & The Polywell

Post by hanelyp »

Every fusion reaction I see worth serious consideration for power production produces He-4 as a primary end product. Presuming we had a viable fusion power reactor the question becomes the cost of equipment to separate helium from the vacuum pump outlet. A deuterium reactor would already have separation equipment to recover H-2, H-3, and He-3. A pB-11 reactor pump outlet would be mostly H-1, He-4, boron hydrides (easily condensed out), and whatever outgasses/leaks.

The only reaction I see for producing He-4 where the feed stock isn't grossly more costly than helium is pB-11, which would take a very large amount of energy if you can't get close to net power production.

from http://en.wikipedia.org/wiki/Helium
Most terrestrial helium present today is created by the natural radioactive decay of heavy radioactive elements (thorium and uranium, although there are other examples), as the alpha particles emitted by such decays consist of helium-4 nuclei. This radiogenic helium is trapped with natural gas in concentrations up to 7% by volume, from which it is extracted commercially by a low-temperature separation process called fractional distillation.
Which suggests some nuclear wastes might be a source if the helium crunch ever got that bad, which I don't expect.
The daylight is uncomfortably bright for eyes so long in the dark.

D Tibbets
Posts: 2775
Joined: Thu Jun 26, 2008 6:52 am

Re: National Helium Shortage & The Polywell

Post by D Tibbets »

Helium, specifically Helium4 is found in almost all natural gas. There are different amounts present. In some wells in Texas to Kansas I believe helium makes up several percent of the harvested gas. This is where almost all of our natural helium comes from and a lot has been stock piled and these stored supplies are dwindling. Once they are gone the cost will increase because less concentrated natural gas sources will need to be used. But, the reserves are correspondingly huge, though the final cost will be greater. I do not know the average helium content in fracking natural gas fields.

Helium also comes from fusion of hydrogen. The D-T reaction produces Helium 4. D-D reactions produces helium3 half the time. Helium 3 is a potential fusion fuel also and has been discussed here. If D-D Polywell, etc. works then the produced helium3 (along with produced tritium) can be used to boost output, or used in a separate D-He3 reactor- which is "aneutronic" and might be useful in reactors where neutron production needs to be minimized. Examples would be ship or spaceship reactors. If there is an adequate D-D reactor proliferation, all of the Helium3 needed for aneutronic ship reactors could be available without mining it on the Moon. If the Polywell, etc can be made to work with PB11 then Helium3 is not needed as the proton Boron11 reaction is far superior to the D-He3 reaction from a neutron exposure standpoint.


In either case the He3 or He4 produced in fusion reactors would be relatively very tiny amounts compared to Helium4 production from natural gas wells.
For comparison. If a power plant burns 1 million pounds of natural gas per day, the helium harvested from that natural gas may be ~ 100 to 10,000 pounds. A fusion plant producing helium at the same delivered power capacity would be producing helium at perhaps ~ 1-10 pounds per day. The cost of extracting and purifying this helium in such small quantities would result in very high costs. This would be justifiable for producing He3 fusion fuel. The cost is worth it, but for general helium production, extracting it from even poor natural gas sources would be much cheaper.

PS: Making helium4 by fusing p-p (hydrogen1 isotopes) is what happens in the Sun. But to do this in a reactor on Earth is perhaps ~ a billion billion times harder than fusing deuterium- deuterium. It aint gonna happen. The fusion crossection for D-D is ~ 10^-25 Barns, for P-P it is ~ 10^-45 Barns . Things change some when you get hotter than the Suns core (~ 15,000,000 degrees C or ~ 1500 eV) and the CNO catalized hydrogen fusion picks up, but at best you are several orders of magnitude behind D-D fusion .


Dan Tibbets
To error is human... and I'm very human.

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