Fusion Reactors & Moon Helium: Is Helium a Better Option?

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Discussion Overview

The discussion centers around the potential of helium, specifically helium-3, as a fuel alternative for fusion reactors compared to current proposed fuels. Participants explore the feasibility, abundance, and challenges associated with helium-3, particularly in the context of its extraction from the Moon and its fusion properties.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • Some participants argue that helium is more difficult to fuse than hydrogen due to higher electric repulsion, despite helium-3's potential for aneutronic fusion that does not produce neutrons.
  • Others suggest that the challenges of extracting helium-3 from the Moon may outweigh the issues related to radioactivity from other fusion fuels.
  • One participant questions the abundance and extraction difficulties of helium-3 on Earth, suggesting that if it became economically valuable, supply solutions would likely emerge without lunar mining.
  • Another participant notes that while terrestrial helium-3 is scarce, it can be produced from the decay of tritium, which has historical production from thermonuclear systems.
  • There is a mention of lithium as a potentially better option for fusion propulsion, particularly in relation to direct fusion propulsion after fission processes.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and practicality of using helium-3 for fusion reactors, with no consensus reached on whether it is a better option than current fuels. The discussion remains unresolved regarding the best approach to fusion fuel selection.

Contextual Notes

Participants highlight limitations in the availability of helium-3 on Earth and the challenges associated with its extraction from lunar sources. The discussion also reflects uncertainty about the economic viability of helium-3 compared to other fusion fuels.

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Aquamarine said:
Is helium a better alternative then the current proposed fuels for fusion reactors?

http://www.space.com/scienceastronomy/helium3_000630.html
http://www.asi.org/adb/02/09/he3-intro.html

Aquamarine,

Helium would be more difficult to fuse than Hydrogen - there's more
electric repulsion with Helium than with Hydrogen. We also have more
Hydrogen than Helium readily available.

The one item in favor of Helium, is that if one uses Helium-3 [ available
on the Moon ], then the fusion reaction is "aneutronic" - it doesn't produce
neutrons - so it doesn't make other materials radioactive.

However, radioactivity is not an insurmountable problem - it can be
readily dealt with. The problems associate with getting Helium-3 from
the Moon, and bringing it back will probably dwarf the problems with
radioactivity.

Dr. Gregory Greenman
Physicist
 
You know, nothing in either of the links Aquamarine gave tells us about the abundance (or difficulty of extracting) of He3 here on Earth (other than as a by-product of human activities). No doubt it's available here on Earth (otherwise, how would physicists have done experiments into its superfluid nature, for example?), and no doubt a minor component of the helium that's part of natural gas deposits. I suspect that if He3 were to become economically valuable, all kinds of entrepreneurs would find ways to supply the demand ... without having to go to the Moon to mine it!
 
Although the natural abundance of He-3 is very low (0.0137% in terrestrial sources), it can be obtained in relatively large amounts, as the product of the radioactive decay of tritium, which has been made for thermonuclear systems.

Of the tritium produced in the ten years following WWII (1945-1955), all of that, which has survived, has been through at least 4 half-lives, so more than 94% of it is now He-3. Of course, much of that may have already been used in experiments.
 
He3 is an isotope heavilly bombarded on the lunar surface from solar waves (rays) which are tritated (not referring to water). This component can be used for propellant production however, lithium (which is almost abundent beaneath earth) is a more greater option.

- thus Li 6 - D is applicable for direct fusion propulsion, only after fission - because of thermal laws (millions of degrees).
D can be made from regular water - 1 in 6000 atoms are exising Dueterium /D.
 

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