The neutron drive

A big problem with nucular energy - and nucular torchships - is the neutron problem. Neutrons're uncharged so you don't control them. In the D+T fusion reaction, they're 79% of the energy... wasted; 5% with classic He-3. And then they butt into other isotopes, making them unstable depending on what isotopes. Unstable means: radioactive. Last The Feb. 4th/5th night, having woken up at 3 AM, I stumbled on a discussion from Google Plus, if you remember that, on directing the neutrons.

I haven't seen much on that since the posting time, 2018.

The upshot is, neutrons can be directed at emission ... if the atoms which burst them out were directed. That is done in MRI machines. The complaint here is that you need a VERY BIG machine if you're going to be aligning sufficient neutrons to overcome, say, 10 km/s of deltaV (i.e. low orbit).

Now, the reaction won't last so, neither might the magnets. Maybe feed the magnets at the launch-pad, externally. Maybe divert some of the outgoing energy to keep the magnets runnin'.

If we can use Hydrogen-Three instead of Helium-Three, first off, the cost is slightly lower (unless orbiting Uranus) since the latter comes out of the former's decay. Although at 0.087c tritium exhaust is a bit slower than helium's 0.089c. Let's call that a draw.

More to the point for tritium the "Lawson factor" is a sixteenth lower, so is ignited that much easier. Might not need to blow up a nuke to start it! Assuming we're in space, we orbit the launchpad and feed it with solar. For deceleration in space, if we can't aerobrake: there's that antiproton reaction. Note that with a 12.32 year half-life, tritium doesn't store too great so is for inner-planet work only.

Either way such a neutron / fusion boost looks a fine way to generate some hardcore initial thrust, maybe also for deceleration at the destination. I'm thinking an Orion with less fissionable material. Its "fallout" would mostly be neutrons aimed where you want 'em. D+T is assuredly on the table tho' mainly for space, still. And the D+He-3, with slightly better exhaust velocity, should scale up which under undirected fusion it wouldn't. That might be a plan for Earth. Which I'd never say for any implementation of Thermal.

If from Earth you launch from something you want to harvest that fallout from, and at a safe distance. Say: an uninhabited ice-field. Dig a deep hole in that ice first if you're paranoid. The "side effect" would mainly be a lot of tritium and deuterium ice, which you then get to scavenge and re-sell; and oxygen-18, which you pass to the flourine-18 market.

SUPERMIRROR 2/5 10:15 PM: via NicoNicoNekomancer, Neutron optics. Polish up some Titanium and/or nickel or silicon in space, neutrons will bounce off it. I like this idea for stage-two, when the neutrons are fewer. Or maybe you align the neutrons to head toward the payload and bounce them all out to the same direction. Anything is better than having them ping-pong about the chamber causing trouble.

BUMP 2/6: I'm rereading the articles more closely, and rethinking this.

SPIN 8/12: Bruhaug n' Kish.