Antimatter: Finding the Fuel

by Paul Gilster on May 17, 2012

In Stephen Baxter’s wonderful novel Ark (Roc, 2010), a team of scientists works desperately to come up with an interstellar spacecraft while epic floods threaten the Earth. The backdrop gives Baxter the chance to work through many of our current ideas about propulsion, from starships riding a wave of nuclear explosions (Orion) to antimatter possibilities and on into Alcubierre warp drive territory. I won’t give away the solution, but will say that it partly involves antimatter used in an unorthodox way, and because Baxter’s is a near-term Earth, there simply isn’t enough antimatter to go around. That means getting to Jupiter first to harvest it.

Antimatter in space is an idea that James Bickford (Draper Laboratory) analyzed in a Phase II study for NASA’s Institute for Advanced Concepts, for he had realized that high-energy galactic cosmic rays interacting with the interstellar medium (and also with the upper atmospheres of planets in the Solar System) produce antimatter. In fact, Bickford’s calculations showed that about a kilogram of antiprotons enter the Solar System every second, though little of this reaches the Earth. To harvest some of this incoming antimatter, you need a planet with a strong magnetic field, so Jupiter is a natural bet for Baxter’s scientists, who go there to forage.

The odd thing, though, is that Saturn is actually a better source of antimatter than Jupiter, with 250 micrograms produced by reactions in the rings and injected into the magnetosphere every year. Bickford’s work showed that the process by which galactic cosmic rays produce antimatter isn’t as effective around Jupiter because its magnetic field shields the Jovian atmosphere and lowers the flux. A much larger flux reaches the atmosphere of Saturn. But Bickford also believed that our own Earth would be a good antimatter source, leading to the idea of using a plasma magnet — the scientist discusses using high temperature superconductors to form two pairs of 100-meter RF coils to manage this. The result is a kind of magnetic scoop that could trap antiparticles found in our planet’s radiation belts.

Image: Among sources of naturally occurring antimatter in our Solar System, Saturn may be the most useful. Credit: James Bickford.

Why go to the trouble of collecting antimatter from space? Because antimatter production on the order of one-trillionth of a gram per year, which is about what we can get out of today’s accelerator labs through high-energy particle collisions, isn’t enough to power up a lightbulb for more than a few seconds. Moreover, at today’s prices the stuff costs about $100 trillion per gram. This is why Robert Forward, who used to circulate an antimatter newsletter among colleagues and wrote extensively about its possibilities, proposed that one day we would build antimatter factories in space. Build a large enough solar-powered array and you could, he thought, come up with something on the order of a gram of antimatter per day.

Remember that as little as ten micrograms of antimatter might power a 100-ton payload on a one-year mission to Jupiter and you can see that one gram of antimatter a day is a bountiful supply. But Forward’s antimatter collector array was huge, 100 kilometers to the side, and well beyond today’s engineering. Thus the interest generated by the PAMELA satellite (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) last year when it picked up more antiprotons in the region known as the South Atlantic Anomaly than had been expected.

This South Atlantic Anomaly is where the inner Van Allen radiation belt makes its closest approach to the Earth’s surface, which in turn creates a higher flux of energetic particles there. The PAMELA work showed that Bickford’s original NIAC analysis was correct — antimatter is indeed being produced near the Earth. Bickford went on to suggest that we could collect some 25 nanograms per day using his magnetic scoop, a process that if successful would prove orders of magnitude more cost effective than creating antimatter here on Earth.

So would Baxter’s doughty crew be able to harvest their antimatter much closer to home than Jupiter or Saturn? Maybe not. A new paper by Ronan Keane (Western Reserve Academy) and Wei-Ming Zhang (Kent State University) comes into play here. The authors have developed new thinking on antimatter propulsion, specifically on the magnetic nozzles that would be required to make it work. It’s important work and tomorrow I want to get into the propulsion aspects of it, but for today I note their comment on the PAMELA findings and antimatter. Here’s a quote:

The recent PAMELA discovery, in which the observed antiproton flux is three orders of magnitude above the antiproton background from cosmic rays, paves the way for possible harvesting of antimatter in space. Theoretical studies suggest that the magnetosphere of much larger planets like Jupiter would be even better for this purpose. If feasible, harvesting antimatter in space would completely bypass the obstacle of low energy efficiency when an accelerator is used to produce antimatter, and thus could offer a solution to the main difficulties stressed by the skeptics.

The problem with this — and this has been noted by The Physics arXiv Blog and Jennifer Ouellette in recent days — is that PAMELA could come up with only 28 antiprotons over the course of 850 days of data acquisition. There is no question that Bickford is right in seeing how antimatter can be produced locally. In fact, the paper on the PAMELA work says this: “The flux exceeds the galactic CR antiproton flux by three orders of magnitude at the current solar minimum, thereby constituting the most abundant antiproton source near the Earth.” But does the process produce enough antimatter to make local harvesting a serious possibility?

We need to learn more, obviously, and it’s worth noting, as Keane and Zhang do in their paper, that the Alpha Magnetic Spectrometer was installed on the International Space Station in mid-2011, giving us a much enhanced ability to detect and measure antiparticles in Earth orbit. Antimatter harvesting within the Solar System appears to be a workable concept, but if we’re going to need to go to the gas giants to make it happen, we’re obviously pushing back the time frame on collecting significant quantities that could be used in future propulsion systems.

More on this tomorrow, when we’ll look further at Keane and Zhang’s ideas on antimatter engines and what could make them possible. Their paper is “Beamed Core Antimatter Propulsion: Engine Design and Optimization,” submitted to the Journal of the British Interplanetary Society (preprint). The PAMELA work is Adriani et al., “The discovery of geomagnetically trapped cosmic ray antiprotons,” Astrophysical Journal Letters Vol. 37, No. 2, L29 (abstract / preprint). For a cluster of Bickford references, see Antimatter Source Near the Earth, published here last August.

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Greg May 17, 2012 at 10:07

Isn’t the true issue with accelerator made antimatter that the collection method is not very efficient? If I remember it correctly, Forward proposed that it maybe possible to create “antimatter factories” that had a much higher efficiency increasing to micrograms of collected antimatter per year.

Paper Clip May 17, 2012 at 11:58

So is this McGuffinite?

Alex Tolley May 17, 2012 at 12:19

Could the intense magnetic fields of sunspots be used to aid harvesting of antimatter?

Mike Lockmoore May 17, 2012 at 12:26

I’m a big fan of Baxter, but I was deeply frustrated and disappointed with the earlier _Flood_, the prequel of _Ark_. I found almost all of the characters in _Flood_ to be implausible in terms of their backstory or behaviors, or both, and in almost all cases, very unlikeable.

On top of that, the global flood scenario, which seems completely implausible to me, was only treated in a scientifically hand-waving way, very unlike Baxter in earlier novels. I mean, if we are to appreciate the flood, at least come up with a more interesting mechanism for it! You have a science degree, man!

Lastly, a lot of the prose in the first half of the book or so focuses in minute detail on the flooding events in a lot of specific places in Britain. I suppose if you are British, you might get a kick out of reading about how various well-known places fare in a global flood, but it got to be a very tiresome slog for me.

So, even though I knew _Ark_ was out, I have not read it yet.

OK, now that I have that rant off my chest, I’m heartened to hear that _Ark_ actually has some interesting science and technology to present the reader. Maybe I should try to forget I ever read _Flood_ and try to read _Ark_ with an open mind?

Paul Gilster May 17, 2012 at 13:02

Mike, I haven’t read Flood, so can’t comment on it, but I did enjoy Ark quite a bit.

Steve Bowers May 17, 2012 at 13:16

Here’s my image of an antimatter harvester in orbit around Saturn;
http://www.orionsarm.com/eg-article/4ba0f009dffe1

Adam May 17, 2012 at 16:34

The next step in making antimatter will be via pair production in intense laser photon fields. Electron-positron pair-production is close to viable and while proton-antiproton creation is 1836 times more challenging energy-wise the physics is reasonably well known.
A problem with the Keane/Zhang analysis is that it’s giving us an average particle ejection speed. What’s not accounted for is the energy-mass loss via uncharged particles – that dramatically reduces the effective specific impulse, which is the figure of merit in assessing rocket performance. The average pion speed between the old antimatter annihilation studies and this more recent modelling means a significantly lower average energy per particle as well, which impacts significantly on the specific impulse. From what I can glean from the new paper the specific impulse (times g) is about 0.28c.

bill May 17, 2012 at 17:57

In response to a series of comments on my proposal to tie together the concept of a USS Enterprise under a Centauri dreams blog two days ago I have this to say to some of those individuals who felt that such a concept would be counterproductive. With regards to the gentleman who wrote the following:

“Two items: I am wary of building a Worldship or any kind of interstellar vessel based primarily on the need for humans to escape Earth due to some impending global-scale disaster. Do you think the people who cannot escape our planet are just going to sit idly by while a starship is being made for a select few? ”

I would say this; that I am proposing an interstellar vehicle not under the idea that this be built due to an impending world catastrophe but rather that the vehicle be put forth as a idea to the general public to further safeguard and expand the knowledge of human beings. Notice that this idea is suggesting that we are not engaged in a life-and-death struggle but rather are looking to try to expand the boundaries of knowledge and exploration. I am not in any way shape or form suggesting that the Earth is going to have a cataclysm happen now or anywhere in the near future, rather if , something should happen we would have already taken serious precautions. As regards to the comment that how is this supposed to happen when we are having trouble setting up conferences to simply talk over the ideas. If you had read my previous comment you would see that I had suggested we tie this in with the iconic TV show Star Trek which captures the public imagination. Doing so is a selling point and we have to face facts that if we are going to get any type of action taken on these matters than we will have to find a way to get people interested. My personal belief is that the government or governments of the world have no intention of going into outer space. They simply just have too much going on right now and possibly forever to allow them to have the time and luxury of looking at something that would be viewed as pie-in-the-sky.

If such a enterprise (no pun intended) should actually be attempted then a dedicated involvement by a non-governmental enterprise might, just might, be of sufficient attraction and interest to allow us to harness antimatter as I explained previously. I do not see how in terms of cost and efficiency than any other fuel source could be expected to do the job and as I stated before and antimatter factory in space orbiting our Sun would have use of unlimited free energy to generate the required amounts. Is it expensive? Of course it’s going to be expensive anything new and experimental always has research and developmental costs associated with it, that’s just part of the game. But don’t forget that once a system is established it can be used repeatedly to do anything regarding space travel. However you slice it I believe that this is the way to approach the problem. As for it being a one-way trip for the crew these people would want to accept this as part of the deal of going and they would consider themselves pioneers and explores. Allowing the vehicle to achieve one tenth the speed of light or so would permit them to reach targets within hopefully their respective lifetimes. The bottom line in all this is that enthusiasm is a powerful force to generate innovation and intensified effort.

Brett Bellmore May 18, 2012 at 7:04

I think the real question here is not whether magnetic traps in space would be more efficient at manufacturing anti-matter than CERN. Existing particle accelerators weren’t designed for efficiency in anti-matter production, they were designed for scientific research.

The real question is whether they’d be more efficient than a machine designed for no other purpose than manufacturing anti-matter. Given the numbers I’ve seen, I find that hard to believe.

ljk May 18, 2012 at 10:19

bill said on May 17, 2012 at 17:57:

“As regards to the comment that how is this supposed to happen when we are having trouble setting up conferences to simply talk over the ideas. If you had read my previous comment you would see that I had suggested we tie this in with the iconic TV show Star Trek which captures the public imagination. Doing so is a selling point and we have to face facts that if we are going to get any type of action taken on these matters than we will have to find a way to get people interested.”

LJK replies:

As a long-time Star Trek fan going back to the Original Series when it first aired on my parents’ black-and-white no cable and no videotape or DVR capability television set, let me give you my impression of most other Star Trek fans and their perception by the general public.

Not all but a lot of them are interested in Star Trek primarily as a soap opera with science fiction elements. Sit them down for a lesson in real astronomy or how an actual starship would operate and they won’t be hanging around for long.

I was interested in Star Trek as a kid *because* of my initial interest in real astronomy and space travel. It was a quite a shock to learn that my friends who were also ST fans were not into those aspects of the series beyond their fictional portrayal. As I said, they were into the characters and entertainment the same way fans of regular soap operas were into their series. They often got annoyed when I would point out something in an episode that could not happen in reality.

That latest ST film from 2009 is a case in point. I found it to be terrible in just about every way, including and especially the depiction of science and technology. It was almost a mockery to the Original Series and its intentions, which included being a vehicle for Gene Roddenberry to get real-world contemporary social issues aired on television in the guise of science fiction, which most producers then and now viewed as silly old “kids stuff”.

Judging from the money that film raked in and the public reactions of many fans, they didn’t seem to care whether a supernova would be powerful enough to wipe out half the galaxy or if FTL technology would ever be possible. They just wanted to be entertained with familiar characters (and I admit they did choose the cast fairly well).

I know Star Trek is not a science documentary, but that is where a lot of people get their “education” on space and science from, whether we like the idea or not.

So when I saw this sudden pronouncement by some guy who says “Hey, let’s make a real Starship Enterprise!” I was torn between its potential cleverness and the probable reality that the minute the public realizes that real science and physics would be involved, the enthusiasm would dwindle faster than a Denebian Slime Devil population once the food in its habitats on Regulus V starts running out.

FYI – Same thing happened when Star Wars first came out in 1977. There was an initial increase in attendance at college astronomy courses, until they found out there were very few space battles and Wookies in the real Universe.

And as you said, the governments are not going to fund this and the rich guys who might are already financially focused on planetoid mining. I also found it a bit ironic that the guy who wants us to build a fleet of Enterprises was almost shut down by an overwhelmed early 21st Century server system.

So if the real space program isn’t going to grab the public interest – and there ARE interesting things going on besides the Space Shuttle, which I never found as compelling as Apollo et al – how will one based on a science fiction television series that isn’t even in vogue with the current generation with no obvious means of funding or resources going to do any better?

ljk May 18, 2012 at 10:50

To swing this back around to the topic of this article, antimatter may be amazingly powerful, but so much is involved in turning it into starship fuel that I do not want to wait around for it if we ever want interstellar travel to be a reality, especially in this century.

The places on Earth that do manufacture antimatter make ridiculously small
amounts that quickly disappear. The cost of these tiny samples is even more absurd. “Mining” it from space, whether in Earth orbit or the rings of Saturn, will involve humanity needing to be well settled in the Sol system in the first place – and we already know what a Catch-22 situation that has become.

FYI – That is what concerned me about Daedalus from the first time I learned about that BIS star probe: Not the fusion drive itself but what we would have to do to get the helium-3 fuel by mining the atmosphere of Jupiter. The original paper assumed from the perspective of the 1970s that we might be ready to start building Daedalus in the 2050s. Yeah, right. I am still waiting to see what Icarus can do in the fusion department that does not require us having to go all the way to Jupiter to get fuel.

Maybe the private space industry will turn everything around. I will gladly retire my pessimism about our future in space if so.

If we want to get to Alpha Centauri real soon with current and very near-term real technology, then Orion is the way to go. It was initially proven feasible back in the early 1960s (go see the test model at the Smithsonian Air and Space Museum in Washington, D.C.). We still have plenty of nuclear bombs. We have several nations with major space launch infrastructures. We still have very remote regions on Earth in which to test and launch Orion in.

The things that are holding up Orion are neither technical nor in violation of the laws of physics. And personally I would find the idea of launching a vessel to the stars riding the multiple explosions of hydrogen bombs which would pointedly not be used for destroying cities quite exciting and compelling.

By the way, I know there are more elegant and sophisticated ways to get to the stars than Orion. But nearly all of them involve the settlement of the Sol system and technologies that we will not have for decades if not longer. And if Gott is right about the window of opportunity for humanity to move into the wider Milky Way galaxy, we literally cannot afford to wait around and hope for our children to come up with warp drive or something equivalent.

bill May 18, 2012 at 19:16

@ljk

The strange thing is you and I are both on the same page and I absolutely concur with everything that you said concerning the general public in its perception of Star Trek or whatever science fiction story is playing at the particular moment. People, simply do not care nor wish to learn anything deeper than their momentary desires and wants. This is in no way belittling or ridiculing anyone anywhere it’s just simply a statement of fact that the general publics attention span and depth is not equivalent to those who are willing to learn and further their knowledge.

I am in no way advocating that we teach the general public any type of science or any type of depth of knowledge, rather I just merely suggest that we keep them modestly informed about the goings-on and we attempt to make a plea our pledge what have you to assess the degree of interest in contributing to the idea of interstellar travel. The publics interest will wax and wane as they go about their daily lives, our interest here is simply to provide them essentially with ‘entertainment’ for the price of hopefully being contributors in this great adventure.

ljk May 18, 2012 at 22:43

Remember the 1995 film Apollo 13? The public and networks were already getting bored with what began as only the third attempt to place humans on the Moon in 1970.

http://www.youtube.com/watch?v=cbPJZb8ZWWo

Granted the public back then was being led to believe that manned flights to the Moon would soon become common, but still it is worrisome that the attention of the masses to something so rare and historic can shift so quickly.

Even if a spaceship resembling the USS Enterprise was built, it would have to be operated in a real fashion, without all the drama seen on Star Trek. In fact that is how space travel is going to be for a long while, with astronauts having enough drama just trying to keep the ship aimed properly and working in one piece. That is what the public needs to understand and appreciate.

Adam Crowl May 19, 2012 at 7:25

Larry,
Orion was *not* capable of interstellar, as originally envisaged. All the work was done on a fission pulse system.
Then, in 1968, Dyson pondered what the limits of the concept might be. If we could make *pure* deuterium fusion devices, then couple them to a 100,000 ton space-ship with 25% efficiency, we *might* get an exhaust velocity of 15,000 km/s and a cruise speed of *maybe* 3% light-speed.

Do you know how to make a pure fusion device? The trick is no one does. At best our pulse system *might* get 1,500 km/s, using fusion-boosted fission devices. That’s amazing performance in the Solar System, but it’s maybe ~440 years to Alpha Centauri with a mass-ratio of ~55 or so. Not sure anyone will be keen on putting the required many thousands of tons of weapons-grade fissionables into orbit.

Brett Bellmore May 19, 2012 at 14:40

Ironically, one of the uses proposed for antimatter is triggering fusion reactions…

Eniac May 19, 2012 at 22:03

If we are hoping for antimatter, let us also hope that there will never be suitcase-sized containment systems for milligram amounts….

Brett Bellmore May 20, 2012 at 16:58

Storage of substantial amounts of anti-hydrogen as plasma or charged particles is obviously infeasible, due to terrible ratios between the ‘tankage’ and the stored anti-matter, and leakage rates. So forget that.

The freezing point of anti-hydrogen is presumably the same as that of hydrogen: 14K. At which temperature it has a pretty substantial vapor pressure. You need to get to some seriously cryogenic temperatures to store anti-hydrogen without a disastrously high rate of evaporation. In a space craft this might not be an issue, with a big hunk of anti-hydrogen it wouldn’t be evaporating off the surface faster than you’d be using it.

But I think it does preclude storing anti-hydrogen in something chip sized, (Which might otherwise be feasible.) unless you have higher elements with negligible vapor pressures to make a tiny tank out of.

IMO, creation of some modest quantity of higher anti-elements to make “tanks” out of is probably a critical requirement for storing enough anti-matter for interstellar propulsion. And you probably don’t have to worry about small anti-matter bombs until we’ve got enough power that interplanetary range death rays are a more pressing concern.

stephen May 20, 2012 at 17:34

I’d like to mention the idea that nuclei with large atomic numbers–greater than 173, according to one calculation–would spontaneously pull positrons (or electron-positron pairs?) out of the vacuum.
How much would a neutron star really resemble an atomic nucleus? Maybe neutron stars might be generating positrons?

Holger May 20, 2012 at 18:44

Brett Bellmore:
Why do you (apparently) consider storage of neutral anti-hydrogen as more feasible than storage of charged antimatter? Progress on the storage of individual particles seems to suggest the opposite. Even apart from the evaporation problem, I see no way to store macroscopic amounts of neutral antimatter on Earth: A solid chunk of antimatter would just “drop to the ground” of its container and start annihilating, wouldn’t it? To prevent it from “falling” by purely mechanical means seems to me to be much more difficult than to contain charged antimatter electromagnetically

The easiest way to store large amounts of antimatter that I can think of would be to store it in a high orbit around the Earth (where there is near vacuum and zero gravity), ideally in a container of higher antimatter that does not evaporate at space temperatures.

ljk May 21, 2012 at 9:21

Well, Adam, then there is still hope for an Orion starship being a relatively short-duration Worldship, one that could get a crew to the nearest star systems in centuries rather than millennia. At least it would cut down the chances for an onboard society going south. And they will have an available weapon system should they run into any problems out there.

And of course Orion will still do very well for the Sol system, assuming people can get past its propulsion source.

No, I am not giving up on Orion, it is too cool an idea. Plus it is about the only interstellar vessel we can build NOW.

Holger May 21, 2012 at 13:39

PS to my above comment:
I suppose I can answer my question myself (at least partially): A solid piece of antihydrogen that is “almost neutral”, say missing only 0.1% of its positrons, can still be contained electromagnetically just like pure antiprotons, but can of course be kept much more compact.

But I have another question to Brett: How high (in terms of the atomic number) does one have to go to find a material with low enough vapor pressure? I suppose solids at room temperature may do, so anti-lithium (or anti-carbon/ anti-(carbon hydrates)) would work for the tanks?

Eniac May 21, 2012 at 22:14

I see no way to create “higher” antimatter. It will be difficult enough to get antiprotons and protons to form antihydrogen in large amounts. Pretty much the only way it could be stored is cryogenically in solid form. Levitated electromagnetically in utravacuum. Or floating free in deep space, protected by a sunshade and kept at the equilibrium temperature of deep space (4K, if I am not mistaken?). Someone needs to calculate if the heat generated by the influx of solar wind or ISM particles can be safely radiated at 4K, or alternatively will lead to progressive and eventually catastrophic warming. I suspect the latter, unfortunately, might be the case, since radiation cooling is horribly ineffective at 4K. Another tricky part is when it comes to “mining” the antimatter from the reservoir and somehow transporting it to the engine. I cannot come up with a good way to accomplish this without premature and catastrophic recombination.

Also, for a ship to get anywhere the antimatter “snowball” will have to be pushed without touching it. It is not clear that the magnetic properties of solid hydrogen at 4K will provide enough of a handle to allow significant acceleration. Electrostatics will certainly not suffice when talking about large objects like this.

There are so many really hard engineering problems here that I am quite certain that antimatter propulsion is not going to be what first takes us to the stars.

Brett Bellmore May 23, 2012 at 6:54

Holger: My objection to storage of bare antiprotons, or anti-plasma, is simply that the mechanisms for storage must necessarily outweigh the antimatter by a huge ratio. The only reason you’re messing around with antimatter in the first place is the energy density it potentially represents. If your “tank” has to outweigh the fuel by a factor of a thousand, you might as well forget antimatter, and carry deuterium.

Based on vapor pressures, the lowest element you could use to suppress evaporation would be lithium. Beryllium would also be a candidate. Both would be technically challenging to create by nucleosythesis from anti-hydrogen, but probably not as challenging as the original anti-hydrogen.

Eniac May 23, 2012 at 23:45

Brett:

Both would be technically challenging to create by nucleosythesis from anti-hydrogen, but probably not as challenging as the original anti-hydrogen.

I beg to differ. It will be enormously challenging to fuse anti-protons into anything bigger. The cross-section is minuscule, and the losses would be gigantic. Making anti-hydrogen is a piece of cake in comparison.

You are right about the container weight issue, which is why I think a 4K snowball is the only halfway reasonable method. If at 4K the vapor pressure is too high, or the heating by incoming particles cannot be removed by radiative cooling, things look dire indeed.

Brett Bellmore May 25, 2012 at 7:07

Making the required amounts of antimatter requires power on a literally astronomical scale. Nucleosythesis, while difficult, is at least exothermic. That’s my basis for saying it’s less difficult. Granted, the initial step of P-P fusion would be challenging, but is there any reason you couldn’t catalyze it using muons? That you’d be putting more energy into muon production than you got out of the fusion would be of little concern, you’d already expended a thousand times as much making the anti-protons. Once you had anti-deuterium, the route to lithium or beryllium is straightforward.

My point concerning the vapor pressure had to do with concern about the possibility of building a suitcase sized containment for significant amounts of antimatter; Hard to detect antimatter bombs, IOW. While the rate of evaporation off of a 4K anti-hydrogen snowball would preclude anything like that, it doesn’t exceed the rate at which a starship would be using the antimatter, so is less of an issue for the starship.

Eniac May 26, 2012 at 0:12

is there any reason you couldn’t catalyze it using muons?

Yes, even muons are not going to let you fuse more than a very minute fraction of the already very precious antiprotons.

Once you had anti-deuterium, the route to lithium or beryllium is straightforward.

Straightforward? You lose many orders of magnitude at every step. The economics just do not work out. If every atom of anti-lithium requires 10^10 antiprotons to make, its synthesis may as well be plain impossible. That the few reactions you can get are exothermal really does not help you at all.

If you were to start with anti-deuterium and anti-tritium, you might imagine a Tokamak style reactor with an anti-plasma to create anti-helium. But anti-lithium? Not likely. And starting from anti-protons? Absolutely not. Accelerators are not a solution, because they can provide few encounters before scattering, which makes the waste ratio very large.

Eniac May 26, 2012 at 0:22

Another thought: Some have asserted that current accelerators are not made for antimatter production. I do not think that is true. The Large Hadron Collider relies on antiprotons being fed in, and the magnitude of the antiproton current is likely to be the limiting factor on how many collisions you get, which in turn is the focus of the entire investment. It stands to reason, therefore, that the antiproton production and storage facilities at CERN are state of the art in producing as many antiprotons as possible, with few, if any, other concerns at cross-purpose.

Brett Bellmore May 27, 2012 at 8:33

Eniac, barring a rapid transition to a K2 type civilization, or the discovery of a straightforward way of “flipping” matter into antimatter, I don’t believe we’re ever going to be making enough of it for use as an interstellar rocket propellant. For a K2 civilization, manufacturing a few hundred pounds of anti-Berylium probably wouldn’t be problematic. And who knows what a civilization capable of editing fundamental particles could do?

Honestly, I think the future of interstellar propulsion, if it has a future, is mass beam propulsion. The problems are very straightforward, compared to use of antimatter, and the energy requirements substantially lower for similar performance.

michael doser August 2, 2012 at 4:50

“The Large Hadron Collider relies on antiprotons being fed in, and the magnitude of the antiproton current is likely to be the limiting factor on how many collisions you get, which in turn is the focus of the entire investment. It stands to reason, therefore, that the antiproton production and storage facilities at CERN are state of the art in producing as many antiprotons as possible, with few, if any, other concerns at cross-purpose.”

Actually, the LHC collides protons, not protons and antiprotons; that’s the Tevatron you’re thinking of, and indeed, Fermilab has a higher production rate of antiprotons than CERN, partly because it can start with higher energy antiprotons (since it will then accelerate them to even higher energies) than CERN (which needs to decelerate them to lower energies for antihydrogen studies). FAIR (with its possible extension FLAIR) has an even higher production cross section than CERN, and will represent the state of the art in a few years, but even there, the production rate is “only” a factor of 100 higher than at CERN, essentially by using a higher proton flux for production, and improving the antiproton collection efficiency.

Nate September 29, 2012 at 7:56

I’m not all that good at science, just interested, so forgive me of this is a dumb question.

I see some comments about the feasability of storing antimatter aboard a space ship so it may be used as fuel to power said ship.
My question is this: Is it impossible to make an “antimatter factory” *on board* of the ship that would make more of the desired fuel as the journey goes on? Making fuel when the ship needs more, rather than making it all in advance and facing the risk of running out.

Hope someone smarter can indulge.

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