Feasibility of my antipproton battery

[Pete at Home]

Say some alien friends of mine have a relatively cheap way of gathering antiprotons from Jupiter's rings.  Seems like they could easily be contained within a powerful electric field since their charge is negative.  Could a battery be constructed where a trickle of proton-antiproton emissions sustain the eontaining field, as well as powering a city or spacecraft?

IIRC a gram of antiprotons being let loose at once to collide with matter would produce a triple hiroshima burst.  I suppose that an exact antimatter replica of Putin (let's call it anti-putin) could take out the planet and wrack substantial havoc on the solar system.

I cant find anywhere what the exact byproducts of proton-antiproton annihilation, although elecdtron/positron annihilation is known to produce two gamma photons, which afaik is not very user-friendly.

[Fenring]

Antimatter storage already exists, we just don't have a lot of it since it's hard to produce. We don't mine it in nature since it can't co-exist in areas densely packed with matter.

As for how to design such a battery, I guess take a trip to main engineering on the USS Enterprise Don't forget your crystals.

[Pete at Home]

I've got half the rough design, I think.

Collect the anti-protons from space, using charged fields to collect and store them away from matter.

I'm just not sure how to trickle them out and how to deal with the meson byproducts.

[Fenring]

Collect the anti-protons from space

?

[NobleHunter]

How do you turn the matter/antimatter reaction into electricity? Using it to boil water seems a tad inefficient.

There's antimatter from cosmic rays (I think?) near Earth, too, so you wouldn't need to go all the way to Jupiter.

I think you're over-estimating the power wrt the anti-Putin. Antimatter is good for big booms but not quite that good. I spent some time trying to figure out what would happen if an anti-matter gatherer was left in orbit if humans went extinct. There needed to be a lot of antimatter before it matched the dinosaur killing impact.

[Wayward Son]

Heinlein once wrote that an anti-matter bomb would be to an atomic bomb like the hydrogen bomb is to a kitchen match.

IIRC, nuclear fission converts about 2 percent of its mass into energy, while an anti-matter bomb converts 100 percent.  So you're dealing with a lot more than triple a Hiromisha burst.

But, as you noted, it's not in a very useful form of energy, being light.  Electron/positron are a form of matter/anti-matter, so I would expect that their annihilation would be the same as for any other type of matter/anti-matter.  And catching gamma rays is a bitch, as they tend to blast through just about everything.

So, no, I don't see a way to directly convert matter/anti-matter annihilation into electricity.  You probably should put that on the back burner for now.

Unless, of course, you can find someone smarter than me (which isn't all that difficult).

[LetterRip]

It would work, basically you use antimatter matter collisions to generate a lot of heat, and use the heat to generate steam or vaporize something.  This is then used to either turn a turbine or for propulsion, or both (have your turbine be in the path through your exhaust nozzle).

Being in space complicates things since often you want to be able to reject the heat - easy to do on earth with cooling towers, etc. lots of convenient thermal mass around that is colder than what you have heated up.  In space you would probably have to dump it into some thermal mass that you have brought along for that purpose.

[Seriati]

Wayward, it is 100% or effective 200%?  Doesn't the anti-matter also get converted into energy?

[Fenring]

Just like with nuclear power antimatter has the potential to be used as a bomb or as a power source. But unlike nuclear power we don't have access to much antimatter as fuel, meaning its only practical use is as a one-off massive bomb. No thanks. Once we can artificially generate sizeable quantities of it it will be feasible; for now we can only produce a little.

[Wayward Son]

Wayward, it is 100% or effective 200%?  Doesn't the anti-matter also get converted into energy?

It depends how you count it.  Anti-matter has mass, just like regular matter, so if you consider the total mass of the system (both atoms), it's 100%.  If you only count the mass of the regular matter, you would double it.  But, yes, both the matter and anti-matter get converted into energy.

For fission, you only have (had?) one atom to begin with, so there's much less confusion.

[Pete at Home]

How do you turn the matter/antimatter reaction into electricity? Using it to boil water seems a tad inefficient.

There's antimatter from cosmic rays (I think?) near Earth, too, so you wouldn't need to go all the way to Jupiter.

I think you're over-estimating the power wrt the anti-Putin. Antimatter is good for big booms but not quite that good. I spent some time trying to figure out what would happen if an anti-matter gatherer was left in orbit if humans went extinct. There needed to be a lot of antimatter before it matched the dinosaur killing impact.

A single kilo of antimatter would be the equivalent of a tsar bomb, and if you check out the explosio0n on that 50 megaton, i dont think it's exaggerated to suppose that a putin sized mass of, say, anti-silicone, weighing about 100 kg, could breach the core and knock us out of orbit.

[Wayward Son]

It would work, basically you use antimatter matter collisions to generate a lot of heat, and use the heat to generate steam or vaporize something.  This is then used to either turn a turbine or for propulsion, or both (have your turbine be in the path through your exhaust nozzle).

Being in space complicates things since often you want to be able to reject the heat - easy to do on earth with cooling towers, etc. lots of convenient thermal mass around that is colder than what you have heated up.  In space you would probably have to dump it into some thermal mass that you have brought along for that purpose.

That would work, but I doubt there's a material that would make it practical for space travel, much less for a "battery."

In order to generate heat, the material would have to absorb the gamma radiation.  According to this this site, for "typical" gamma radiation (from nuclear fission, which is probably not as energetic as matter/anti-matter annihilation), you need about 1.3 feet of lead to reduce the radiation by a factor of 1 billion--that which you (apparently) need for it to be relatively safe for humans.  That's pretty heavy.  And lead is not well suited for transferring heat, IIRC, since it has a relatively low melting point.  Of course, the equivalent mass of steel might work, but heating that much steel might take a while.

[Pete at Home]

Collect the anti-protons from space

?

There's. Evidence that some scattered antiprotonss drift along in Jupiter's rings.  You can scoop and contain charged antimatter within charged electric fiields.  Antiprotons and electrons still repell each other, having the same charge.

While eledctron and positrons annihilate to gamma upon collision, protons and antiprotons are likely to leave meson debris and less than 100% conversion.

[Wayward Son]

While eledctron and positrons annihilate to gamma upon collision, protons and antiprotons are likely to leave meson debris and less than 100% conversion.

Yeah, you're right, at least according to Wikipedia. But with the enormously higher mass of the proton, I'd still be rather wary of standing close to the gamma radiation.

[NobleHunter]

A single kilo of antimatter would be the equivalent of a tsar bomb, and if you check out the explosio0n on that 50 megaton, i dont think it's exaggerated to suppose that a putin sized mass of, say, anti-silicone, weighing about 100 kg, could breach the core and knock us out of orbit.

https://en.wikipedia.org/wiki/TNT_equivalent

If 1kg = 50 megatons, then 100kg = 5000 megatons or 5 gigatons. (just showing my math, I'm only a history major). That puts it several orders of magnitude less than Chicxulub, so not a planet killer. But still very bad.

[TheDeamon]

According to this this site, for "typical" gamma radiation (from nuclear fission, which is probably not as energetic as matter/anti-matter annihilation), you need about 1.3 feet of lead to reduce the radiation by a factor of 1 billion--that which you (apparently) need for it to be relatively safe for humans.  That's pretty heavy.  And lead is not well suited for transferring heat, IIRC, since it has a relatively low melting point.  Of course, the equivalent mass of steel might work, but heating that much steel might take a while.

You don't use the lead in (significant amounts for) the primary containment chamber, you use whatever materials are best suited for containing the reaction for that purpose. You use the lead in the secondary/tertiary containment chambers to make sure the gamma rays don't progress further.