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This Defense Intelligence Reference Document, prepared in fiscal year 2010 by the Defense Intelligence Agency's Defense Warning Office under the Advanced Aerospace Weapon System Applications (AAWSA) Program, reviews aneutronic fusion as a way to propel spacecraft. It compares chemical, ion, fission, fusion and antimatter propulsion, and it also covers radiation shielding and relativistic rocket calculations. It looks at research needs over the next 30 years for missions from low Earth orbit to Mars, Jupiter and Alpha Centauri.
From the source:Release of 2026-09-18 Incident: 11/1/10, 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 surveys aneutronic fusion as a possible advanced space-propulsion method, focusing on fusion reactions that release most of their energy in charged particles rather than neutrons and therefore offer potential advantages over more neutron-intensive fusion concepts, especially in radiation shielding, direct energy conversion, and thrust generation. The report reviews the underlying rocket physics, compares candidate fusion fuels and ignition conditions, and gives particular attention to proton-boron and related schemes, while also discussing Bussard’s concepts and other fusion projects as representative development paths. It also makes clear that the central obstacle remains ignition and sustained net-energy fusion under practical conditions, and it notes additional problems such as x-ray energy losses from the hot plasma, extreme temperature requirements, and the gap between theoretical specific impulse and what proposed systems had demonstrated experimentally. Overall, the document presents aneutronic fusion propulsion as an attractive long-range concept for deep-space travel, but one whose practical realization still depended on major unresolved advances in fusion engineering.
“Anderson”1 page
UNCLASSIFIED/ /PO lt Of f l@IAL WS& &NkY Appendix C: Antimatter Annihilation Rocket •'• . positron antiproton stable antihydrogen atom Figure 16. Antihydrogen Atom. Using data from Table 3, the only propu lsion system that can generate higher l sp than fusion will be due to antimatter annihilation. By using the Relativistic Rocket Worksheet in Appendix D, it is possible to decrease the time to reach Proxima Centauri to on ly 18.5 years by accelerating at 0.05 g to reach 43% of the speed of light. By using antihydrogen, two annihilation mechanisms are possible: • Electron-positron annihilation releases one energetic gamma ray (1.022 MeV) or, in the presence of a nucleus, two 0.511 - MeV gamma rays . There is no effective way to reflect gamma rays, but they can be absorbed with suitable shield ing and their energy converted into heat. Research into designs that convert gamma ray heat into propulsion or electrica l power should proceed over the next 10 to 20 years. • Proton -antiproton annihilation releases charged and neutral pions, which decay after about 0.026 microseconds into charged muons and neutrinos. The charged pions can be used to directly generate thrust or to make electricity if they are directed by electromagnets. Unfortunately, 40% of the pions will be neutral and quickly decay into gamma radiation, which are lost from the system or absorbed in the rocket chamber wall and generate heat. Muons also decay into charged particles (electrons and positrons), along with neutrinos. Neutrinos and antineutrinos, along with their energy, are lost from the system. Novel rocket designs that capture gamma radiation with a tungsten insert allow the waste heat to be used to accelerate a propellant, such as hydrogen, to generate additional thrust. This system was proposed by Robert Frisbee and Ulrich Walter and deserves further study. 24 Efficient ways to redirect the energy of gamma rays into thrust should be a major focus of research. Antimatter propulsion is fairly straightforward since ignition is not a problem. By mixing hydrogen with antihydrogen, annihilation begins immediately. Antimatter UNCLASSIFIED/fF&A &FFI&I:.l.k W&li &NkY 36
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