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Antimatter Sail: Focus on Storage

An antimatter sail, as described yesterday in the work of Gerald Jackson and Steve Howe, is an exciting idea particularly because it relies on only small amounts of antimatter, tapping its energies to create fission in a uranium-enriched sail. Thus the uranium is the fuel and the antimatter, as Jackson says, is the ‘spark plug.’ We reduce the needed amount of antimatter and define what the new Kickstarter campaign calls “…the first proposed antimatter-based propulsion system that is within the near-term ability of the human race to produce.”

The antimatter sail produces fission by allowing antimatter, stored probably as antihydrogen, to drift across to the sail, and as we saw yesterday, the potential for velocities up to 5 percent of lightspeed mean that such a sail could be deployed on interstellar missions. Proxima Centauri naturally emerges as a target, but Jackson and Howe’s work is not a result of recent interest in that star and its one known planet. The 2002 study in which they describe the antimatter sail was originally created for a probe to 250 AU (a Kuiper Belt and heliopause mission), drawing on work on a 10 kg instrument payload that was done at the Jet Propulsion Laboratory.

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Image: Antiproton striking the depleted uranium coating on a carbon sail. Credit: Gerald Jackson/Hbar Technologies.

The just launched Kickstarter campaign is to re-think that earlier work in the context of an unmanned mission to a nearby solar system. Among the specific campaign goals is to create a detailed design for long-lived antimatter storage, a key issue in any such concept. After all, we have to store the antimatter in such a way that it does not annihilate with the normal matter surrounding it. We’ve known that this can be done for some time. In fact, it was back in 1984 that physicist Hans Dehmelt demonstrated how to hold a single positron in a cylinder using electric and magnetic fields. Dehmelt gave his device the name ‘Penning trap,’ a nod to Frans Penning, a Dutch physicist who saw that a magnetic field could steer electrons into tight orbits.

Dehmelt would go on to be awarded the Nobel Prize in Physics in 1989 for co-developing the Penning trap technique with Wolfgang Pauli (each shared one-half of the prize). By adjusting the voltage and strength of the magnetic field, the Penning trap would become a viable way to store tiny amounts of antimatter.

But as antimatter storage has become feasible, problems grow as we begin storing more and more of the stuff. Try to contain large amounts of positrons or antiprotons and their like charges repel. Thus large quantities of antimatter — and compared to current levels of production, we need large quantities indeed — experience repulsive forces between them that quickly become stronger than the magnetic container can handle. Soon the magnetic ‘bottle’ begins to leak and the antiparticles are destroyed.

In his book Antimatter (Oxford University Press, 2010), Frank Close notes that even a millionth of the amount of antimatter needed for a Mars trip would create tons of electric force on the walls of the tank. That’s a daunting thought, and this is for a nearby target, although Close isn’t thinking in terms of the antimatter sail concept, which minimizes the amount of antimatter needed. Even so, high-capacity storage of antimatter has to be addressed.

What Jackson and Howe have been looking at for their antimatter sail involves storing the antimatter in the form of antihydrogen (a positron orbiting an antiproton). Here we’re at the heart of the original work the duo did for NASA’s Institute for Advanced Concepts, from which the antimatter sail took root. A key goal of the new Kickstarter campaign is to produce a design report describing how to build an antihydrogen storage bottle that can be used aboard a spacecraft. Their extensive experience with the issues makes Jackson and Howe an ideal team to push spacecraft antimatter storage forward.

I’m looking back at the original NIAC report Steve Howe prepared for NASA, which envisions storing antihydrogen in the form of frozen pellets rather than in traps, the idea being to use integrated circuit chips of the kind we have become familiar with through today’s microprocessors. We would deploy the same kind of etching technology to create a series of tunnels on each chip, with wells at periodic intervals where the antihydrogen pellets would be held. Changing the voltage allows pellets to move down these tunnels from well to well.

Remember the concept here: The antimatter, as it emerges from the storage device (held some 12 meters behind the sail) is then accelerated so that it drifts out into contact with the sail. But Jackson and Howe’s thinking is clearly evolving on this matter. The plan discussed on the Kickstarter site is to create an antihydrogen storage bottle based on methods Robert Millikan and Harvey Fletcher used in the early 20th Century to measure the charge of the electron. As this involved observing charged oil droplets between two metal electrodes, its uses may supercede the kind of chip technology originally envisioned. And further research, Jackson says, may actually involve antilithium rather than antihydrogen as the optimum form of antimatter.

A key requirement, of course, is portability — this is a storage method that has to be applicable to spacecraft. At Hbar Technologies’ headquarters, Jackson and Howe have the first portable storage bottle for such uses, one able to store positrons or antiprotons at liquid helium temperatures in a hard vacuum. Jackson’s experience with storage also extends to the design and construction of particle accelerator storage rings. Forcing storage technology forward is the need to house amounts of antimatter too large to store as charged elementary particles.

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Image: Original portable antimatter storage bottle built by Penn State University and JPL.

I’ve focused on storage, but it’s clear that a lot of things have to go right to get to an interstellar antimatter sail. Key parameters for the Kickstarter effort are to drill down further on antimatter storage issues while at the same time describing renewed antiproton production possibilities at Fermi National Accelerator Laboratory. The effort will recast the original study by way of firming up or adjusting earlier parameters in sail physics and engineering. The thrust-test apparatus developed through the NIAC grant will be upgraded and test facilities identified; here I would imagine experiments involving uranium-laden foils and antiproton interactions. Jackson and Howe also want to design an antihydrogen experiment to be funded in a later campaign.

To me, the possibility of a renewed and improved antiproton process at Fermilab is quite interesting, as we’ve seen what minute amounts our technologies are currently able to generate. In addition to an investigation like this, I would imagine Jackson and Howe will want to look at James Bickford’s ideas on natural antimatter production within the Solar System (see, for example, Antimatter Acquisition: Harvesting in Space, or search the archives here for more).

Bickford argues that space harvesting of antimatter is five orders of magnitude more cost effective than producing antimatter on Earth, an idea Jackson and Howe may want to contest if the highly restricted antimatter yields at Fermilab can be adjusted and improved. For more, see the Kickstarter page for this effort and keep an eye on Jackson and Howe’s Antimatter Drive site. The page there is not yet populated, but the intent is to archive all previous work on the antimatter sail, including a great deal of continuing studies on these storage concepts.

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Comments on this entry are closed.

  • Brett October 18, 2016, 15:42

    Do we have to store it as anti-hydrogen or anti-lithium? Could we, for example, make anti-iron? I don’t know how difficult that would be, but it would be much easier to store with magnets.

    • Eniac October 20, 2016, 21:59

      It would be REALLY difficult. We cannot even make regular lithium from protons and electrons. It would require proton/proton fusion, which is very difficult. Forget about the anti-version.

  • Bill Higgins-- Beam Jockey October 18, 2016, 23:58

    Hans Dehmelt received one-quarter of the Nobel Prize in Physics for 1989, as did Wolfgang Paul (1913-1993), whose name is similar to that of another famous physicist. Wikipedia explains, “He humorously referred to Wolfgang Pauli as his imaginary part.”

    I’m afraid I don’t have time to explain so complex a joke.

    Anyway, the remaining half of the 1989 physics prize went to Norman F. Ramsey.

  • Sean Meaney October 19, 2016, 5:48

    Could have just had a large shell of uranium and filled the hollow with antiprotons. A Reflex furnace if you will.

  • ljk October 19, 2016, 10:31

    NASA’s JPL looks to boost power from nuclear batteries

    Curt Godwin

    October 19, 2016

    Radioisotope thermoelectric generators (RTGs) have been the power source for many of the most ambitious exploration missions in NASA’s history, powering spacecraft in areas too remote, or too impractical, for solar panels to provide sufficient electricity. A new development to this power-generating workhorse may soon substantially improve the capabilities of the RTG, possibly benefiting both interplanetary missions and daily life here on Earth.

    In an Oct. 13, 2016, release, NASA’s Jet Propulsion Laboratory (JPL) outlined the potential to increase the efficiency of the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG), and make it hardier in the process.

    “NASA needs reliable long-term power systems to advance exploration of the solar system,” said Jean-Pierre Fleurial, supervisor for the thermal energy conversion research and advancement group at JPL.

    Full article here:

    http://www.spaceflightinsider.com/space-centers/jet-propulsion-laboratory/nasas-jpl-looks-to-boost-power-from-nuclear-batteries/

    To quote:

    To that end, JPL engineers look to make use of a class of materials known as skutterudites. These minerals have the electrical conductivity of a metal while maintaining the thermal insulation characteristics of glass.

    Skutterudites hold the promise of increasing the available power to a spacecraft by nearly 50 percent at the end of its 17 year design life, as compared with current MMRTGs.

    “We needed to design high temperature compounds with the best mix of electrical and heat transfer properties,” said Sabah Bux, a technologist at JPL who works on thermoelectric materials. “Skutterudites, with their complex structures composed of heavy atoms like antimony, allow us to do that.”

    • Antonio October 21, 2016, 16:17

      Let’s hope this doesn’t end like NASA’s research on ASRGs.

      • ljk October 24, 2016, 9:28

        What is ASRG?

  • Michael October 20, 2016, 3:16

    I once though of using a porous ball of fission material that was fission initiated by a trickle feed of neutrons to release decay products. The decay products would then due to the temperature of the porous ball make their way out onto the surface of a sail to again to undergo decay to release fission fragments for propulsion. It seems to me that anti-mater is to volatile to contain and use effectively.

  • Jeff Wright October 21, 2016, 17:44

    Rather like Johndale Solem’s MEDUSA
    ——————————————————publiusr

  • ljk October 25, 2016, 9:04

    October 24, 2016

    Positron Dynamics near term work to proving out antimatter catalyzed deuterium fusion propulsion with over 100,000 ISP

    Nextbigfuture has interviewed Ryan Weed, CEO of Positron Dynamics. Positron Dynamics is developing antimatter catalyzed fusion propulsion which they will first demonstrate in a cubesat launch. They are getting around the still mostly unsolved difficulties of storing antimatter. They are doing this by using Sodium 22 isotopes.

    Positron Dynamics has previously received a lot of press coverage when it was funded by the Thiel Breakthrough foundation to work on antimatter.

    Last year the Positron Dynamics plan was to fly an antimatter cubesat in 2019 and they are still on track towards that goal.

    Full article here:

    http://www.nextbigfuture.com/2016/10/positron-dynamics-near-term-work-to.html

  • Robert G November 8, 2016, 15:46

    Posting this on a slightly old thread, maybe handy for anybody doing a bit of a dig on this subject to find.

    http://home.cern/about/updates/2016/11/asacusa-improves-measurement-antiproton-mass

    Some people at CERN have been producing cooled helium where one of the electrons is replaced by an antiproton. The remaining, regular, electron interacts with the surrounding regular matter, and it seems that the result is stable. I’ve no idea how well this would work for long term storage, but it is certainly a thing that has been done.

    • Robert G November 17, 2016, 20:26

      My mistake. Having reread this properly and dug slightly deeper, ‘stable’ means for a few tens of microseconds. Long enough for spectroscopy, but not for space travel.

      Still, it set me thinking. The antiproton is presumably in an ‘s’ orbital which is at a maximum at the nucleus (giving a relatively short lifetime). I wonder if there is a way with a laser (perhaps with circularly or helically polarised light?) to impart orbital angular momentum and kick it into a ‘p’ orbital? ‘P’ orbital wavefunctions have a node at their centre so the antiproton would be spending no time there, presumably extending lifetime. I think you might also need a second laser corresponding to a transition to a higher energy ‘p’ orbital – saturate on this frequency so stimulated emission matches stimulated absorption and maybe you could pin the population to a 50/50 mix between two ‘p’ states.