Quote:
Originally Posted by Fred Brackin
I am not at all sure of this. At least in any practical sense.
Deuterium fusion needs heat to initiate but is 4 times as good at making neutrons (80% of the energy of the reaction) as it is heat. You end up having to sustain the reaction with what's left over after the neutrons and then you have to harness the neutrons too.
This is a fundamental characteristic and there is no guarantee that it is solvable.
He3 fusion might not work out either as it is so much more difficult to initiate but if you do get it started you have much more heat for self-sustenance. Or if used for propulsion you have much more in the form of charged particles for handling magnetically.
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Yeah, and if you have a decent source of He-3 at hand, once you can use both reactions He-3 wins. But if you have to process megatons of Lunar regolith to get it, or go all the way out to Saturn, then suddenly dealing with the neutrons looks less forbidding in comparison.
As Anthony notes, you can use the neutrons to breed tritium from lithium, but you can also use the neutrons themselves to heat a working fluid. It's a headache from an engineering POV, but by no means unsolvable, and breeding tritium gives you more fuel for a deuterium-tritium reaction.
For that matter, I'm not sure He-3 fusion even beats breeder fission realistically (in terms of the THS canon 'reality') if you have to go to Saturn for your He-3.
Added to that is the prospect of a He-3 cartel. In the THS canon, America has a lot of clout through He-3 control, some other powers are looking to mine Uranus or keep working the thin gruel on the Moon to bypass it. Which is believable if He-3 is irreplaceable.
But when you've got endless oceans full of deuterium, and lithium isn't all that rare, suddenly the comparison looks different.