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To: Technogeeb
With it (and ordinary deuterium easily extracted from seawater) fusion becomes almost trivial.

Uh...no. D-T fusion is actually easier to achieve, D-H3 makes for a simpler reactor. We are nowhere near achieving the breakeven point for either.

76 posted on 10/14/2003 1:22:11 PM PDT by hopespringseternal
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To: hopespringseternal
Uh...no. D-T fusion is actually easier to achieve, D-H3 makes for a simpler reactor.

No. D-T is D-H3 (H3 is tritium. Or did you mean D-He3?). In any case, D-T fusion is "easier to achieve" only from the standpoint of the coulomb forces (and associated temperatures) involved (essentially about 10keV vs. 50keV), and ignores the real-world engineering issues. In a D-T reaction, most of your energy comes out as neutrons; not only making it almost worthless for power production, but complicating other engineering problems as well (thermal loss, shielding issues, radioactivity of containment system, etc). With D-He3 fusion, a lot of the engineering problems of D-T fusion are significantly reduced since it is mostly aneutronic (there is some unintended neutron production from "side" reactions, but there are theoretical ways to eliminate these as an issue). While He3-D fusion can't be achieved in a conventional Tokamak, there are other (high plasma beta) designs where breakeven He3-D fusion should be theoretically achievable. Because the energy produced in He3-D can more easily sustain the reaction (far more so than the neutrons of a D-T reaction), an He3-D reactor should have a superior Lawson value, and thus provides the only long-term solution to the fusion problem, something D-T fusion will never do. Except as a laboratory curiousity, D-T fusion is a waste of time.

We are nowhere near achieving the breakeven point for either.

Not true. We could build a working He3-D fusion reactor with what we know right now (assuming we had the He3, which we won't since it appears we're going to give it all to the Chinese); it would just have to be so large (in order to have a sufficiently high Lawson value) that it would be economically unfeasible considering the current price of alternatives. Environmentalists would also probably be annoyed by the ignition mechanism...

But even if that were true (and from an economic standpoint, I will grant you that for the moment it is), that argument would be irrelevant. We didn't have practical gasoline engines a century ago either, but that doesn't make the oil of Saudi Arabia now worth any less. We KNOW that that the Lunar He3 is valuable (or at least, is inevitably going to be valuable), and there isn't any reason why we shouldn't try to claim it, or at the very least keep another nation from monopolizing it.

80 posted on 10/14/2003 3:30:43 PM PDT by Technogeeb
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