Safe Storage of Antimatter?

[Maquise]

Has there been any consideration/work on a system for the safe, long term storage of antimatter that doesn’t explode when unplugged? It seems like that would be necessary to actually use it as a viable fuel.

I had an idea, and was wondering if there is any theoretical way to electromagnetically isolate an atom in a chemical structure.

[Radar]

Has there been any consideration/work on a system for the safe, long term storage of antimatter that doesn’t explode when unplugged? It seems like that would be necessary to actually use it as a viable fuel.

I had an idea, and was wondering if there is any theoretical way to electromagnetically isolate an atom in a chemical structure.

Since any magnetic trap is inherently unstable I do not think it would be possible to create a passive containment for antimatter. As for storing it in some chamical structures, aside from the instability problem, there is also the issue of proximity. If the trapping molecule in question is close enough to meaningfully interact with the antimatter, then it is close enough to go up in a blaze of glory. The heavier the antiparticles, the easier it would be to deal with them (since they will be that much slower), but I do not know of any reasonable solution.

What kind of idea do you have in mind?

[Jay R]

Antimatter can be safely stored in an antimatter vessel of the proper size and shape.


[The storage of an antimatter vessel is left as an exercise for the reader.]

[Khedrac]

It seems like that would be necessary to actually use it as a viable fuel.

The first step for making antimatter into a viable fuel is finding a way of producing it - and since this is always likely to be very energy expensive, then short of the sci-fi trope of a wormhole to an antimatter universe which can be mined, then the energy source for making the antimatter is likely to be the better fuel than the antimatter. Until you can bypass this issue, then a mathod of storage is irrelevant and unlikely to have many people researching it.

Now, if antimatter become useful for something else (e.g. weapons) then a stable storage system will become attractive and gain more research, but until then there's little point in the research.

[gomipile]

then the energy source for making the antimatter is likely to be the better fuel than the antimatter.

Most proposals I've seen suggest using heavy and bulky energy sources like solar panels to produce antimatter, which would hopefully be a relatively energy dense fuel after the containment system is factored in.

Solar panels wouldn't be too useful as an energy source on an interstellar journey. Or even while exploring our own Oort cloud.

[Lvl 2 Expert]

The first step for making antimatter into a viable fuel is finding a way of producing it - and since this is always likely to be very energy expensive, then short of the sci-fi trope of a wormhole to an antimatter universe which can be mined, then the energy source for making the antimatter is likely to be the better fuel than the antimatter. Until you can bypass this issue, then a mathod of storage is irrelevant and unlikely to have many people researching it.

Now, if antimatter become useful for something else (e.g. weapons) then a stable storage system will become attractive and gain more research, but until then there's little point in the research.

Antimatter would be useful for high density energy storage, for example on an interstellar spacecraft. Because fuel adds weight, a light fuel is an efficient fuel, and this adds up fast. I did some back of an envelope calculations ones, and while I'm pretty sure they were wrong, my outcome was that even hydrogen as a fuel for nuclear fusion would not be dense enough to reasonably get to 0.1C (100mC) and back. Antimatter is the best option, provided there is a decent way to make it and a good way to store it. (For spacecraft in particular there's an alternative in the form of beaming energy to it with lasers or such, but that has its own problems. Even the tightest laser beams become diffuse sooner than we'd think, and one of the more promising methods of capturing the energy, solar sails, can't really use the effect unless there's a second laser at their destination.)

Magnetism probably works if we can control what kind of antimatter we end up with well enough. We can build magnetic installations to float something like a frog just fine. The antimatter needs to clump together (very well, better than a frog does) yet have a minor charge overall (not too much, or it repels itself and becomes unstable). I don't know if working with permanent magnets is feasible, but some combination of superconductive magnets and backup systems to keep the cooling system powered at all times should be functional enough, right?

Another option that often comes up is trapping the antimatter per particle. Not with a magnetic installation for each particle, because that murders all efficiency, but by encasing them in fullerenes or similar. I don't know how that's supposed to keep the antimatter from touching their encasing, it seems kind of pointless, but it's a thing people speculate about.

[Anymage]

If this is slightly harder sci-fi, the first thought is that you don't need to worry about turning the containment device off. Since you'll be generating energy to keep your spaceship moving, you might as well direct some of that energy back into the containment field. (Space stations and other ports where you'd stop to refuel likely are around stars or other massive energy sources, and can similarly count on a reliable stream of energy to keep their containment fields working.) Yeah, you're kind of hosed in the event of serious damage or malfunction to your engine. There are lots of ways that damage or malfunction can leave you hosed in deep space.

Alternately, antiparticles only annihilate their normal particle pair. If an electron and an antiproton touched, nothing too exciting would happen. You'd have to make a special handwavium that isn't made out of normal atomic material. But since antimatter drives and being able to travel interstellar distances in reasonable time frames are already more likely to show up in softer sci-fi already, a bit of handwavium won't break too much.

[warty goblin]

Alternately, antiparticles only annihilate their normal particle pair. If an electron and an antiproton touched, nothing too exciting would happen. You'd have to make a special handwavium that isn't made out of normal atomic material. But since antimatter drives and being able to travel interstellar distances in reasonable time frames are already more likely to show up in softer sci-fi already, a bit of handwavium won't break too much.

That would suggest that you could keep anti-hydrogen contained in a handy neutronium bottle. Of course since the bottle itself would be stupidly heavy and, absent a pocket neutron star, have a tendency to violently explode, this probably isn't that much better than just uncontained antimatter. Not to mention you'd better hope like hell you didn't accidentally get a bit of anti-deuterium in your Bottle of High Energy Death.

[Excession]

I wonder if it would be possible to trap an anti-proton or an anti-alpha particle inside a buckyball. Perhaps the negatively charged antiparticle would be repelled by the electrons enough that it wouldn't be able to reach the nuclei and react.

More likely it would just push the electrons out of the way I guess.

[Radar]

I wonder if it would be possible to trap an anti-proton or an anti-alpha particle inside a buckyball. Perhaps the negatively charged antiparticle would be repelled by the electrons enough that it wouldn't be able to reach the nuclei and react.

More likely it would just push the electrons out of the way I guess.

The problem is even worse: since electrons are evenly spaced around the antiparticle inside, the net force is 0.

[halfeye]

Alternately, antiparticles only annihilate their normal particle pair. If an electron and an antiproton touched, nothing too exciting would happen.

Is that right? I mean for one, an anti-proton has the same charge as an electron, so they would typically repel. For another, when you take it down to quarks, don't anti and positive have different quarks which would react whatever the containing particle was?

[Battleship789]

The problem is even worse: since electrons are evenly spaced around the antiparticle inside, the net force is 0.

True, but if the antiparticle is disturbed from the exact center, the force from the electrons should repel the antiparticle into some periodic motion that would prevent the antiparticle from colliding.

[Radar]

True, but if the antiparticle is disturbed from the exact center, the force from the electrons should repel the antiparticle into some periodic motion that would prevent the antiparticle from colliding.

You may think that, but the answer is still no - as long as the aniparticle is inside, the forces will cancel out anyway. There will be only some fluctuations due to fact that a bucky ball is not a uniformly charged sphere, but those fluctuations can push out just as likely as push in. You are probably wondering, how could that be?

Short answer is Gauss's law, which gives us an easy way to calculate electric field in or out of symmetric objects. A good trap needs to push the antiparticle toward the center from any possible direction, so the electric field would have to always point in the direction of the center of the sphere (for positive antiparticles) or away from it (for negative ones). From Gauss law we know we would have to have a charge at the center of the trap to generate such a field. Otherwise such a field configuration is impossible.

You may also think of it this way: electric forces decrease with square of the distance. So close to a surface they will surely be higher, but at the same time the effective area, which gives a meaningful contribution to the total force is not very large, since anything further away will have its force directed almost parallel to the inside surface of the trap, so it will cancel out with an identical vector from the other side. At the same time, if we look at the far away surface of the trap, force from each individual charge there will be smaller, but the area from which those forces point roughly in the same direction is larger by a factor of distance squared leading to amplification of the net effect and exactly canceling out the influence of the wall near the particle.

[Battleship789]

You may think that, but the answer is still no - as long as the aniparticle is inside, the forces will cancel out anyway. There will be only some fluctuations due to fact that a bucky ball is not a uniformly charged sphere, but those fluctuations can push out just as likely as push in. You are probably wondering, how could that be?

Short answer is Gauss's law, which gives us an easy way to calculate electric field in or out of symmetric objects. A good trap needs to push the antiparticle toward the center from any possible direction, so the electric field would have to always point in the direction of the center of the sphere (for positive antiparticles) or away from it (for negative ones). From Gauss law we know we would have to have a charge at the center of the trap to generate such a field. Otherwise such a field configuration is impossible.

You may also think of it this way: electric forces decrease with square of the distance. So close to a surface they will surely be higher, but at the same time the effective area, which gives a meaningful contribution to the total force is not very large, since anything further away will have its force directed almost parallel to the inside surface of the trap, so it will cancel out with an identical vector from the other side. At the same time, if we look at the far away surface of the trap, force from each individual charge there will be smaller, but the area from which those forces point roughly in the same direction is larger by a factor of distance squared leading to amplification of the net effect and exactly canceling out the influence of the wall near the particle.

Hmm, the buckyball itself is electrically neutral, so if we have a negatively charged antiparticle inside the net charge of the system is negative. Thus, the exterior of the buckyball would need to be negatively charged, with a positively charged interior, for the field lines to properly connect (because a buckyball can be idealized as a perfect conductor). Oh, and that will cause the field inside the buckyball to be zero. Makes sense.

[Radar]

Hmm, the buckyball itself is electrically neutral, so if we have a negatively charged antiparticle inside the net charge of the system is negative. Thus, the exterior of the buckyball would need to be negatively charged, with a positively charged interior, for the field lines to properly connect (because a buckyball can be idealized as a perfect conductor). Oh, and that will cause the field inside the buckyball to be zero. Makes sense.

Yay for physics!

Bottom line is, to trap passively a negatively charged antiparticle, you would need a positive charge exactly, where you want the antiparticle to stay. Since this postive charge needs to be anchored (and not just floating inside empty bucky ball), it needs to be in contact with the rest of the trap thus the point about separating matter from antimatter becomes moot.

The only short-range repulsion I am aware of comes from mixing electron clouds between atoms, but this is not usable here, since we cannot let antimatter this close to anything.

[Excession]

The problem is even worse: since electrons are evenly spaced around the antiparticle inside, the net force is 0.

That is a good point, which I had not thought of.

[gomipile]

They're not very mass-efficient, but I'm surprised no one has mentioned Penning traps.

[Squire Doodad]

Out of curiousity, what would happen if you kept antimatter in a vacuum with a magnetic charge keeping it in a stable orbit inside the vacuum?

It might explode if it hits the walls, but if it doesn't hit the walls in the first place that isn't an issue.

[Radar]

Out of curiousity, what would happen if you kept antimatter in a vacuum with a magnetic charge keeping it in a stable orbit inside the vacuum?

It might explode if it hits the walls, but if it doesn't hit the walls in the first place that isn't an issue.

As far as we know, there is no independent magnetic charge. If you mean a constant magnetic field, then it would only hold the particle in the plane perpendicular to the magnetic field. Any movement along the field would be free. You can fix that by looping the field, so the particles rotate quickly perpendicular to the spin and slowly along the field. This bending however causes instability, so you sill have leaks. Essentially you face the same problems all the fusion reactor engeneers are dealing with whether you go for a tokamak or stellarator field configuration.

[gomipile]

Penning traps essentially do that with small amounts of charged antimatter particles. They use a combination of a static magnetic field and electric field.

They work, but they are very limited in capacity, because all of the antimatter particles have the same charge as each other, so they expand into a bigger cloud the more of them there are in the trap.

[Radar]

Penning traps essentially do that with small amounts of charged antimatter particles. They use a combination of a static magnetic field and electric field.

They work, but they are very limited in capacity, because all of the antimatter particles have the same charge as each other, so they expand into a bigger cloud the more of them there are in the trap.

And this is why for large scale storage you need a different design. Unless somehow you can miniaturize Penning traps enough to become viable. Ideally one would store electrically neutral antiatoms, since scaling would be easier, but then there is an issue of pretty low interaction with outside EM field.

[Tvtyrant]

If we figure out how to make wormholes, and move the ends, you could just put the anti-matter in deep space and attach it to the ship via wormhole. As it falls in due to the ships gravity it powers the ship.

[gomipile]

If we figure out how to make wormholes, and move the ends, you could just put the anti-matter in deep space and attach it to the ship via wormhole. As it falls in due to the ships gravity it powers the ship.

At which point, the point of discussing antimatter as fuel is irrelevant. To exaggerate, one could use wood fired steam power instead if wormholes are available in that way.