Antimatter - fuse it into an easier to handle form

[SomeGuy12]

How feasible would it be to do the following?

1. Create antimatter with spontaneous pair production. As I understand it, you just build big honking lasers and crisscross the beams in free space. Matter will spontaneously form if the light intensity is too high where the beams cross, and you then just collect the antiprotons and positrons. This is supposed to theoretically be moderately efficient, though I'm not sure what the practical efficiency limits for this method are. 1% efficiency would be enough to be practical, I think.

2. Trap the antimatter and form it into anti-hydrogen. You just shove the antiprotons and positrons into the same trap, anti-hydrogen forms spontaneously.

3. Force the antihydrogen to fuse. Never touch it with any physical apparatus. The first fusion step is the hardest.

4. Keep on a series a fusion steps until you either reach anti-iron (a long way there), or more practically, you hit something that is a Type 1 superconductor. Lithium works, though 0.0004 K is a bit too touchy. Beryllium, 0.023 K, might be feasible.

5. Now, to store it on the starship, you just need a series of canisters with magnets, even permanent magnets in the walls. The superconductor rejects the magnetic field lines and will levitate in the middle. Just have to keep it cold.

6. You move one of the cannisters down to the main engine. A lasers vaporizes a tiny fleck from the bottom of the superconductor and you use laser tweezers to move the fleck into the engine without touching the walls, ever. This bit might be tricky...

7. The engine uses big honking magnets, and you just dispose of the positrons by dumping them overboard after accelerating them to high velocity, and you combine the anti-lithium with ordinary lithium. The resulting annihilation creates 20% or so pions which your repel with magnets. Rest of the energy you try to let either escape into space or it impinges on the engine. So you want the engine to have lots of gaps for light to escape. It would probably resemble a very thin, light latticework, with the engine on a big cable or long boom to separate it from the spacecraft. Would still need big honking radiator wings.

Could this end up being a feasible idea, assuming you had incredible engineering capability (like tens of thousands of geniuses and centuries, or an AI equivalent) and orbital facilities to develop the systems?

Edited October 17, 2015 by SomeGuy12

[Gaarst]

1. Done

2. Done for a few atoms

3. Not done yet in a controlled way with normal matter. There is active research on it for clean nuclear energy

4. Never done outside a star AFAIK

5. Could be done

6. Tricky indeed, I don't really know if that's feasible

7. Pulse propulsion was considered for a time (Orion project, also exists in KSP) with nuclear bombs. So it could work.

Somewhere in the future it might be feasible. I don't know if it will be worth the trouble though: who knows, we might have discovered FTL drive then...

[Shpaget]

How feasible would it be to do the following?

2. Trap the antimatter and form it into anti-hydrogen. You just shove the antiprotons and positrons into the same trap, anti-hydrogen forms spontaneously.

How? As soon as the atom forms, it loses charge and you can no longer contain it in a magnetic/electric field.

[SomeGuy12]

Laser tweezers are one way that works on neutral atoms.

[Nuke]

3. Not done yet in a controlled way with normal matter. There is active research on it for clean nuclear energy

fusion has been done in controlled environments. the catch is it took more energy than it created. a farnsworth fusor for example gets a lot of fusions, its just all the energy ends up going into melting the grid so it can never break even (hence the polywell). they even fuse some rather heavy elements in attempts to create and study super heavy elements. you could fuse antimatter but if your resulting nucleus gets knocked out of containment, its going to annihilate.