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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.
“Low Earth orbit”4 pages
UNCLASSIFIED/ ,'1"1!11'- l!ll"l"ll!lllit l!l!i! 811LIJ components. Alternatively, solar collectors or closed-loop nuclear reactors could be employed. To improve ablation efficiency, annihilation gamma rays must be wavelength shifted (WLS) by passing them through a high-Z WLS material. The material of choice, lead, also serves as the shell of the Ps pellet. The pellet vaporizes into high-energy plasma, and the WLS photons propagate to the pressure plate. Silicon carbide ablation material has been adopted from the antiproton catalyzed microfission/fusion concept40 , 41 developed at Penn State University by the author and coworkers. Photon energy distributions are shifted through 2 cm of lead to 1-10 keV from 511 keV with 85 percent efficiency. Performance depends primarily on the energy of the WLS photons and the energy per pellet. At 8 keV, lsp is in the range 1,200-3,000 sec. Thrust is 40-145 kN, the latter at a pellet injection rate of 1 hertz. The total quantity of positrons consumed for a one-way trip to Mars over this range of lsp is 15-40 mg with 50 percent of gamma rays striking the plate and a 85 percent WLS efficiency. POSITRON ROCKET SYSTEM COMPARISON A side-by-side comparison of three positron rocket propulsion concepts is presented in Table 5 for a one-way transit to Mars using f::N = 3. 7 km/sec. 17 Table 5. Comparison of Three Positron Propulsion Concepts for Mars Mission lsp Thrust e+ mass Special Notes Solid-Core 650 - 920 sec 72 kN. small class • Wall and nozzle temperature • 6-9 mg (100% efficiency) • Continuous burn • Multiple engines may be possible • Hot-bleed line possible Future work • Efficiency study Gas-Core Sanger Ablation 1000 - 2500 sec 1200 - 3000 sec 130 kN (1000 atm) 40-145kN(1 Hz) • Wall and nozzle • Positron density temperature per pellet • H Ionization • < 25 mg (85% • 15-40mg efficiency) (42.5% efficiency) • Pulsed burn • Pulsed burn • Multiple engines • Multiple engines may be possible may be possible • Hot-bleed line • No direct onboard possible power • Engine can be • Engine can be throttled throttled • Efficiency study • Further WLS and • Lower pressure possible? radiation transport study UNCLASSIFIED/ ,CFQA: QFFIGIPk ll&'i Qllk¥
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Report, from the dia 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.