antihydrogen & chip-scale refrigerators

Date: Apr 24, 2005

antihydrogen & chip-scale refrigerators

Date: Apr 25, 2005

Hmmm. It would be interesting to know how much H-bar (anti-hydrogen) they think they can store.

If even something the size of a sugar cube could store a micro-gram of antihydrogen, this would represent the energy equivalent of about 1.3 gallons of gasoline. A cubic meter of active storage medium could store the equivalent of a gram of antimatter, or the energy equivalent of about two Nagasaki sized atomic bombs.

Such an energy storage system possibly could make propulsion more efficient. Who knows.

Still, a microgram of antihydrogen is a heck of a lot! This represents nearly 180 MJ of energy, provided of course it can be synthesized, stored and then annhilated in a controlled manor. No one has demonstrated any of these features yet with a significant quantity of H-bar. Lots of work to do yet before antimatter becomes the rocket 'fuel' of choice!

Date: Apr 25, 2005

Stable muonic atoms

Date: Apr 25, 2005

RE: antihydrogen & chip-scale refrigerators

Date: Apr 25, 2005

What do you mean by "quantum repulsion"? I have difficulties to figure out how you could trap an anti-hydrogen and keep it from annihilating with the box that contains it.

Date: Apr 25, 2005

sorry about the cryptic reference -- I will have to dig it up, to provide more details.

from what I recall though, it was simply a case of lining the container walls with a material that would present a like-charge to the antiprotons (antihydrogen) within.

Maybe a physical chemist on this discussion board can describe it more accurately, but it appears that nitrogen atoms in the 2p0 ground state have an electron 'orbital' that sticks out one side (a polar atom ?). So if you line the walls with all these things having their -ve charge aligned radially inwards, then any -vely charged protons (for example) floating inside, will be repelled from the wall.

Does this make sense ? .....like I said, I will have to revisit the original paper to confirm.

Date: Apr 26, 2005

How. Then we are not talking about anti-hydrogen, but rather anti-protons.

I see a few phonomena that would sooner or later kill the anti-protons, but I have no idea of the time scales.

1) even if you isolate it perfectly, the anti-proton can actually annihilate with a proton which is outside the box, through tunnel-effect.

2) nothing is free of radiation, especially in space. A positive muon or positron could be captured by the anti-proton, making it neutral and hit the walls. A collision with a high-energy neutron or proton could also induce the annihilation.

3) if only a few of the anti-protons annihilate in some way, it will increase the temperature and cause more annihilations.

Date: Apr 26, 2005

It seems to me that because of quantum tunneling 'leakage' that perhaps the only way to store antiprotons would be some kind of 'zero dimensional' quantum trap. What I mean by 'zero dimensional' is actually a misnomer--it is in effect just a tiny box in which a few antiprotrons could be placed. The box would of necessity be arranged so that the interior forms a stable potential well (how this could be done, I don't know. Perhaps by using specially doped semi-conductors and then using more or less conventional photolithography techniques to manufacture the boxes.) In this way, the storage boxes would actually be a part of a manufactured substrate.

Still, it seems like a pretty inefficient way to store something. Even with billions of 'cells' the amount of antiprotrons stored would be tiny. And then there's still the issue of manufacturing antiprotons and capturing (cooling) them within the cells.

Even if a significant quantities of antihydrogen were to be stored in something analagous in size to a sugar cube (say a microgram) this still represents a rather dangerous potential energy hazard. What happens if such a device were accidentially dropped? Would impact fracturing of the semiconductor lattices release a significant amount of antihydrogen? Could the energy release caused the annhilation of the leakage cause disruption of the rest of the lattice cells? I don't know, but it seems uncomfortably likely that a catrsophic explosion could result.

Advice: don't drop your saturated antiproton storage crystal on the floor!

Date: Apr 26, 2005

correct me if I'm wrong, but I wouldn't worry too much about quantum tunneling 'leakage.'

I think this effect may be significant at the nuclear scale (ie. sub-atomic & sub-molecular), but not so for a single-layer of N2 molecules...

As for for the fragility of the storage devices, I'm actually thinking they'd be less like the size of a sugar-cube, and more like a nanostructure ("nano-fridge") -- perhaps several thousand nanometers on a side. Dropping such a thing would not cause it to crack (hitting it with a hammer might). Uninterruptible power supply would of course be 'de rigeur.'

Date: Apr 26, 2005

A rellatively simple way of cooling the stuff already exists. The method used for making Bose Condensates is to fire a properly phased laser beam head-on into an oncoming cloud of atoms, or as we would have it, anti-hydrogen. (and yes, that is what it is called even tho it only has the nucleus tho it doesn't make sense to me with that one)

Also, possible quantum tunnelling distances vary depending on the material being tunnelled through, the energy and mass patterns between the points, (though not necessarilly what a ruller would find as being between) and some other things that I don't remember. A 2 or 3 years ago one of the famous sci/tech colleges came up with a magnetic double bottle that managed to stop QT and successfully hold amazingly large amounts of anti-matter in a container that outwardly was approximately the size, shape, and collor of a vacuum thermos. lol

Date: Apr 26, 2005

Yeah -- Bose Condensate should work.... but doesn't it require temperatures much closer to zero-K ? ....also, can it be scaled up to microgram quantities, or is it just good for the few-thousand atoms (or less ?) typical of lab experiments ?

Date: Apr 27, 2005

Euh, I think the bose-condensate works only for bosons, thus in our case anti-hydrogen atoms, and we are back to the problem that they are neutral and thus difficult to confine.

Quantum tunneling can have a non-negligible probability to happen at larger distances if the cross section for the reaction is huge, and I think it must be the case for proton-antiproton annihilation. But I do not know to which extent.

Date: Apr 27, 2005

Yeah, I'd have to agree. Quantum tunneling can be significant--look at JFET's (Junction Field Effect Transistors) which are engineered to produce significant quantum tunneling currents in order to operate as amplifiers.

Sorry Jaro, I wasn't very clear at all about the 'sugar cube' sized box. I meant to say that it was composed of an array of nanometer scale 'boxes' which would act as tiny 'wells' in which anti-protons could be stored. I have no idea how to get them in there or how to get them out. But leakage ought to be fairly low, because there would be relatively little intereactions between anti-protons. However, a Bose-Einstein Condensate I suppose would allow for a coherent 'ball' of antiprotons all in approximately the same to state to be trapped within a potential well. A three dimensional crystal substrate doped with your para-Nitrogen might do--however I have no idea how to make it. I'd sure hate to get a microgram of antihydrogen in a trap only to find out (too late)--at the 'Pearly Gates'--that the trap wasn't good enough!

As for storing neutral antihydrogen, I can't say. As a gas, there would be plenty of leakage opportunities I would think. As a liquid--the same. As a solid--possibly doable, but it would have to be really cold to reduce its vapor pressure. I think it would be the gas molecules that may be primary leakage problem....

Date: Apr 28, 2005

Maybe, tho I was suggesting the methods used in the making of the Bose-Einstein Condensates as a cooling method rather than a storage method. BEC's are under either 0.1 K or 0.01 K (can't remember which) so they are plenty cold enough, and they work with full fledged atoms. (specifically hydrogen) I remembered about them because of some laser development that occured as a side note at one of the schools that was trying to research them.
The laser method of making the condensate is to send a jet of gas in one direction, and then to hit it in a head-on collision with a (very) high power laser beam to cause it to lose all forward momentum. Since the gas was already moving in a single direction, you also don't have sideways movement, (much) at which point the gas becomes super cold.
And if the laser burst is of high enough power, short enough duration, and tight enough frequency control, they don't even leave the electrons in the target cloud energised. Tho if you do it slightly diffferently you strip the electrons from the atoms and simultaneously accelerate those same electrons to near c in the dirrection the that the vector components provide. (which is basically the same as the laser was aming)

Date: May 5, 2005

Ashley, I think you mean the Penning Trap.

From what I recall, a jacket of liquid hydrogen cooled by liquid helium surrounds an electromagnetic bottle. In this bottle, antimatter is oscillated back and forth in an hour-glass pattern.

You'd do better to check with Pennsylvania State University, where the Penning Trap is being developed. My memory is not completely trustworthy. They developed the PennTrap in conjunction with their ICAN-II spacecraft design, with a unique propulsion system of "Anti[proton] Catalysed Microfission/fusion". Of course, the antimatter is not a catalyst but it does start a nuclear reaction in deuterium or uranium atoms. The interesting thing is that, with only a few micrograms of antimatter, one could go to Mars in a rather short amount of time compared to conventional propulsion methods.

Date: May 5, 2005

pry be a good idea at that. I was just trying to remember, but I hadn't actually been interested enough at the time to pay atention, so couldn't even remember the name of the thing. lol