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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.
“Anderson”2 pages
UNCLASSIFIED/ J'FOR OFFI@IAl W&lii 9PU.Y either space charge or magnetic energy considerations, the storage limit is tens of picograms, 7-8 orders of magnitude short of 100 micrograms, where practical uses of positrons begin to emerge, as illustrated earlier. The second approach is confinement of neutral Ps atoms in manufactured porous media of either regular lattices of atoms, such as polymers, or irregular strands of insulator material encapsulating voids, such as silica aerogel. 69, 70 Regardless of void size, Ps atoms ultimately annihilate with electrons attached to atoms on the boundaries of voids by the so-called "pickoff" process. Therefore, large, observable lifetimes require materials with extraordinarily large voids. FORMATION OF POSITRONIUM IN POROUS MEDIA Positrons are injected into a porous material at low energy (~100 keV) to ensure that they stop and form a Ps atom over a distance of a few millimeters. 7 1 The positron rapidly loses its energy by collisions with electrons attached to atoms in the material. As it nears 6.8 electronvolts (eV)-the binding energy of the ground state of Ps-it captures a weakly bound electron and forms Ps. It diffuses through the material, and over about 1 nanosecond, its energy is rendered to the room temperature of the material, 0.025 eV. This is called thermalization. The quantum mechanical model of Psis remarkably similar to the hydrogen atom. The major difference is that Ps spontaneously annihilates, whereas hydrogen is stable. The "self-annihilation" of Ps due to overlap of electron and positron wave functions results in extremely short lifetimes, as noted earlier. Lifetimes against "self-annihilation" can be demonstrably increased if the following two conditions are met: (1) a way is found to isolate the electron wave function from the positron wave function, and (2) materials provide voids large enough to allow detection of lifetimes well beyond 142 nanoseconds (ns). A high vacuum is required to avoid Ps annihilation on gas molecules within the voids. The following describes how Positronics Research LLC has approached these issues in the laboratory. 72 LONG-TERM STORAGE OF POSITRONIUM Under crossed magnetic and electric fields, Ps assumes a doubly oblate shape (Figure 21), with the electron and positron separated by hundreds of nanometers to tens of micrometers, depending on the size of the fields.7 3 Computation of lifetimes against quantum mechanical barrier penetration reveals lifetimes in excess of 1 year over a large range of magnetic and electric fields. UNCLASSIFIED/ ,<FOA OFFICI t L !l&li 0PIL¥ Figure 20. A Positron Forms Ps on the Edge of a Void, Thermalizes, and Becomes Trapped in a Void Before Annihilating (courtesy University of Michigan) 25
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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.