Several connected mini topics.
- Given that boron proton fusion works in the polywell, I'm assuming that 3He-3He fusion will also work.
- There have been several mentions of a resonance energy in boron-proton fusion cross section. Very handy given a near mono-energetic plasma, except that collisions will be coming from a wide range of angles. Mostly, I think, broadly centered around 90 degrees in the machine centered frame. This means that in the collision center of momentum frame the particle will have a wide range of energies, not good when depending on a narrow resonance energy.
- Natural boron is roughly 20% boron 10, rather than the boron 11 desired for the boron proton reaction. Making an educated guess, fusion of boron 10 and a proton would produce 2 4He and 1 3He. So the ash of using natural boron in your reactor would contain 6-7% 3He, desirable fuel. But using un-enriched boron makes the reaction harder, assuming reaction cross section for 10B and 11B is the same.
Boron, isotopes, 3He
I think it is D + He3 fusion. That will give a lot of neutrons due to D-D side reactions.
Five 9s pure B11 is commercially available for semiconductor production.
Since collisions at 90 deg have about 50% less energy (center of mass) you will not get many reactions at that angle, especially if you operate in the resonance region.
B10 is not a fusion fuel. Why do I say this? After some 50 years of study of fusion fuel possibilities no one mentions it as even a side reaction.
Five 9s pure B11 is commercially available for semiconductor production.
Since collisions at 90 deg have about 50% less energy (center of mass) you will not get many reactions at that angle, especially if you operate in the resonance region.
B10 is not a fusion fuel. Why do I say this? After some 50 years of study of fusion fuel possibilities no one mentions it as even a side reaction.
He3-He3 fusion is a documented aneutronic reaction, but like boron-proton more difficult than the reactions involving deuterium.
The boron-proton collisions at an angle would produce few reactions, but still scatter, with all the losses that produces.
I agree that boron 10 is probably not a viable fusion fuel by itself, and accordingly would be poorly documented regarding reaction cross section and such. but the He3 breeding angle still interests me.
The boron-proton collisions at an angle would produce few reactions, but still scatter, with all the losses that produces.
I agree that boron 10 is probably not a viable fusion fuel by itself, and accordingly would be poorly documented regarding reaction cross section and such. but the He3 breeding angle still interests me.
Nah, they're going for the same reason we went there.DavidWillard wrote:Coincidentally, the moon's lunar soil has lots of He-3 absorbed by the solar wind.
It's been proposed as a mission reason to go back to the moon for fuel.
Why do you think the Chinese want a lunar base so bad?
The economics of lunar mining are insane; we won't see it till someone figures out a way get stuff out of this gravity well without chemical rockets.
Agreed on both points.TallDave wrote:
Nah, they're going for the same reason we went there.
The economics of lunar mining are insane; we won't see it till someone figures out a way get stuff out of this gravity well without chemical rockets.
There may be a source of Helium-3 as a biproduct of Geothermal energy production. Apparenty primordial helium-three exists in the Earth's mantle and can be used to help determine where to drill for Geothermal Hotspots. Maybe there will be a source of He3 as a result of Geothermal Energy production. If so, we could gain experience with D-He3 to eventually be used where B-eleven is in short or expensive supply.
http://www.lbl.gov/Science-Articles/Arc ... nergy.html
I was just thinking this morning that a great reason to go to the moon is for fabrication. There are lots of things that can be built better in vacuum. Imagine whole factories of robots building stuff on the surface of the moon. In pretty close to a perfect vacuum. E-beam welding would be a cinch! It'd be pretty darn easy to build a clean room too - no air to carry particles around.
The economics still has to justify it though.
The economics still has to justify it though.
There is enough B11 in deposits in Turkey and the USA for 100,000 years at current rates of energy use. Dr. B said there was enough in the oceans for millions of years. Assuming 10% depletion of the oceans that would be another several 100K years worth. Even if earth energy usage went up 10X that is still at least 10K years worth. More than enough time to find more in the solar system.Helius wrote:Agreed on both points.TallDave wrote:
Nah, they're going for the same reason we went there.
The economics of lunar mining are insane; we won't see it till someone figures out a way get stuff out of this gravity well without chemical rockets.
There may be a source of Helium-3 as a biproduct of Geothermal energy production. Apparenty primordial helium-three exists in the Earth's mantle and can be used to help determine where to drill for Geothermal Hotspots. Maybe there will be a source of He3 as a result of Geothermal Energy production. If so, we could gain experience with D-He3 to eventually be used where B-eleven is in short or expensive supply.
http://www.lbl.gov/Science-Articles/Arc ... nergy.html