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AAWSAP DIRD, Positron Aerospace Propulsion, March 2010

U.S. Department of War · 2010-03-02 · 35 pages · text from the file's own layer

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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Assuming that 1016 positrons/sec can be realized in the next 10 years, then 150
micrograms could be produced in 6 months to enable a globe-encircling flight of a small
air-breathing turbojet UAV as discussed earlier.
Positron Costs
An independent study has been done to determine future costs of positrons and, for
comparison, antiprotons as well. The results, shown in Table 6, are based on data for
existing sources and proposals for future sources. 60, 61, 62
Table 6. Positron and Antiproton Expected Costs in the Next 10 Years
Source
CERNA
Fermi lab
Trap Injection
Ener
0.01 - 0.1
<0.002
0.1
Filling Rate
sec1
4 X 10
2.8 X 10
When
Now
Now
2011 /1 9
$/JOULE
annihilation
?
333*
0.4/0.004**
* $100 mill ion/year (est. op. cost).
** $5 million/year (est. op. cost, adjusted for inflation )/$100 million/year (est. op. cost).
Two clear results of the study should be noted .
First, measured on a scale of dollars per joule of annihilation energy, positrons cost less
than antiprotons by a factor of 1,000-100,000. Because each antiproton produces 1,836
times more energy per annihilation than a positron, this result appears to defy logic.
However, the laboratory energy threshold for producin g antiprotons is 6,000 times
greater than for positrons, requiring a relatively complex proton synchrotron that is
costly to construct and run. In addition, antiprotons are made at much higher
laboratory energy than positrons and require costly apparatuses to decelerate them to
trapping energies.
On the other hand, because electrons and positrons are relativistic at very low energy,
their electron production and secondary systems are comparatively simple and less
costly to operate and maintain than proton systems. These factors, combined with the
absence of radioactive residue associated with positron annihilation, make positrons the
obvious choice over antiprotons.
Second, the cost of positrons is projected to be $0 .004/J x 180 MJ/μg = $720K/μg.
Hence, the cost of 1 gram is $0 .72T, or 5 percent of the 2008 U.S. gross domestic
product (GDP). A 2000 NASA study63 on which this author collaborated placed the cost
of antiprotons at $64T/g, consistent with the $333/J figure in the second line of Table
5, and roughly six times the 2000 GDP. Unfortunately, this is still being quoted in U.S.
scientific and government communities. The dramatic reduction in the unit cost of
antimatter since 2000 is due to a new emphasis on positrons by the physics
community, and hopefully this paper will help spread that good news.
Earlier, a nonstop flight around the globe by a small positron UAV was described as
equivalent to the 1927 Spirit of St. Louis transatlantic flight of Charles Lindbergh. From
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 35 pages are in the text index: search them above, or from the library's search.