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This unclassified Defense Intelligence Reference Document from the Defense Intelligence Agency is dated 2 March 2010. It was produced in FY 2009 under the Advanced Aerospace Weapon System Applications (AAWSA) Program. The report reviews work on using positrons as aerospace fuel. It covers air-breathing turbojet and ramjet engines, unmanned aircraft, missiles, single-stage reusable vehicles, positron rockets and a crewed Mars mission, along with how positrons could be produced and stored. It concludes that a first positron-powered flight around the globe could be possible within 10 years.
“The Times”8 pages
UNCLASSIFIED/ ,'P81l 8PPll!l*L tl!II!! t!IHLY Lifetime shortening owing to cyclotron 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 extremely low density and excellent thermal insulating properties. It is composed of strands of SiO2 (silica) ;.: ,,·l B E----_,; I i, l., , ,, -., ' ' --: -- i' a. u. grains suspended in a gel that has been dried and expanded by injection of gases to a very-low-density configuration of large voids within an irregular lattice of silica strands (Figure 22). Silica aerogel is Figure 21. Computer Simulation of Ps Atoms in a 5-Tesla Magnetic Field and 100 V/cm Electric Field (1 a.u. = 0.052 nm) (courtesy University of Bielefeld, Germany) 74 available commercially with typically 20-nanometer average voids. produced silica aerogel with up to 1-micrometer void sizes. Recent research has Experiments in Japan and at Positronics Research LLC 33 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 /.. = k'/(R - r') + /.. + /.. T q 26 UNCLASSIFIED/ ,<EiOAt OEiEiIQI.«1k W&li &•~LY ( 2)
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Report, from the dia collection. The PDF is mirrored here; the original link is under it. 35 pages are in the text index: search them above, or from the library's search.