[Spaceships] Orion space drive: launch from underwater?

[Agemegos]

Originally Posted by lwcamp

Brett didn't specify what form of fusion is being used

Indeed not. I'm trying to cover all possible bases. For what it's worth, D-T seems most plausible. But you might use an expensive and bulky aneutronic launch unit to lob the spacecraft to a safe altitude where its cheap and cheerful D-T pulse units would be not to much of a problem.

[Fred Brackin]

Originally Posted by Agemegos

Indeed not. I'm trying to cover all possible bases. For what it's worth, D-T seems most plausible. But you might use an expensive and bulky aneutronic launch unit to lob the spacecraft to a safe altitude where its cheap and cheerful D-T pulse units would be not to much of a problem.

You might use an aneutronic reaction for other purposes. D-T is easiest to ignite but putting out 80% of its' energy in 6the form of neutrons makes it hard to sustain.

Indeed, in late generation thermonuclear warheads you start out with a minimal fission stage induced by neutrons which makes enough heat to cause a very small D-T fusion reaction to make more neutrons for more fission to make enough heat for a large fusion stage and then you put some cheap uranium in the outside casing to make use of those fusion stage neutrons.

You could also insert more fission-fusion stages to make very large bombs.

So fusion-only bombs would have to be significantly different. You would need a lot of energy input to bring the whole fusion mass up to temp and you'd really rather not have all those neutrons carrying off 80% of your energy.

Any reaction other than D-T needs more energy to start the fusion process but keeps much more energy in the fusing plasma. For fusing of large masses aneutronic might require a smaller net energy input.