AAWSAP DIRD, Positron Aerospace Propulsion, March 2010

This Defense Intelligence Reference Document was prepared by the Defense Intelligence Agency's Defense Warning Office and dated 2 March 2010. It is one of a series of advanced technology reports produced under the Advanced Aerospace Weapon System Applications program. It looks at using positrons as fuel for air-breathing turbojets, ramjet-assisted missiles, single-stage reusable vehicles and rockets for a manned Mars mission, and it also covers positron production, costs and storage. It concludes that a first positron-powered flight around the globe could be possible within 10 years.

From the source:Release of 2026-09-18 Incident: 3/2/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD examines positrons as a possible fuel for advanced aerospace propulsion, arguing that antimatter offers extraordinary energy density and could, in principle, support applications ranging from long-endurance aircraft and missiles to single-stage launch vehicles, onboard power systems, and crewed Mars missions. At the same time, it makes clear that the concept depends on resolving major unsolved problems in producing positrons in sufficient quantities and storing them safely for long periods, and much of the document’s discussion of flight systems and Mars missions remains conceptual rather than closely tied to demonstrated engineering practice. Its overall conclusion is that positron propulsion is theoretically attractive, but remains highly speculative as a practical technology because its core production and storage requirements remain unsolved.

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Lifetime shortening owing to cyclotron
extremely low density and excellent
thermal insulating properties. It is
composed of strands of SiO2 (silica)
grains suspended in a gel that has been
dried and expanded by injection of gases 5-Tesla Magnetic Field and 100 V/ cm Electric Field
(1 a.u. = 0.052 nm) {courtesy University ofto a very-low-density configuration of Bielefeld, Germany) 74
large voids within an irregular lattice of
silica strands (Figure 22). Silica aerogel is
available commercially with typically 20-nanometer average voids. Recent research has
produced silica aerogel with up to 1-micrometer void sizes.
Experiments in Japan and at Positronics
Research LLC33 with low-energy positrons
in silica aerogel show a high efficiency
(~35 percent) for making Ps through the
interaction of the positron with silica
grains. High radiation exposure from
positrons implanted in the material result
in it becoming "paramagnetic,"
permanently at low temperatures, with a
high density of "dangling bonds"
containing very loosely bound electrons
that explains the high efficiency for Ps
formation. It therefore serves a dual role
as source and storage medium for Ps.
What lifetimes might be expected working Figure 22. TEM of Silica Aerogel {courtesy
with this material? Lawrence Berkeley Laboratory)
The Ps decay rate in a porous material is given by: 75
'A = k'/(R - r') + 'A + 11T q (2)
Figure 21. Computer Simulation of Ps Atoms in a
radiation of the electron and positron
gyrating in the magnetic field are not
included in this model. Because this
process is proportional to B2, magnetic
fields should be small-less than 0.1 Tesla
based on our computations of the effect.
This, in turn, renders the atom very large,
with up to 1-micrometer elongation. If
this can be verified in the laboratory, the
first of the two conditions laid out in the
previous section will be satisfied.
Next, it is important to identify a storage
medium with the largest possible voids.
Silica aerogel is a promising material that
was developed by NASA because of its
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