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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.
UNCLASSIFIED//POlt Offl@IAL WS& &NkY these methods are discussed below. Fusion reactors for the production of electricity have been a goal for over 50 years, yet no method has yet achieved "break even," where the amount of energy generated by fusion exceeds the energy required to initiate the fusion process. Fusion methods are often compared based on their abil ity to "break even." GRAVITATIONAL CONFINEMENT To initiate fusion, ions of hydrogen or its isotopes must be heated to high enough temperatures to increase the likelihood of a fusion reaction occurring during a collision. Another method is to increase the pressure of an ionized gas to a point where the number of collisions increase with an enhanced possibility of a fusion collision . This is the mechanism that stars employ to initiate fusion; for example, if the object were completely composed of deuterium, the minimum mass needed to generate gravitational pressures sufficient to initiate fusion would be equivalent to the mass of the planet Jupiter. MAGNETIC CONFINEMENT FUSION (MCF) Deuterium and other ions follow lines of magnetic flux, and tokamaks have been used to form a magnetic field in the shape of a torus to contain a plasma containing ions for fusion. Tokamaks contain powerful electromagnets that generate the magnetic field. Secondary electromagnets induce an electric current into the plasma to heat it to ignition temperature (ohmic heating). Other methods have been employed to heat the plasma, includi ng the introduction of radiofrequency energy, magnetic compression, and neutral beam injection. INERTIAL CONFINEMENT FUSION (ICF) The Teller-Ulam thermonuclear bomb was an example of inertial confinement where x ray rad iation pressure from a fission explosion is used to compress a mixture of deuterium and tritium to initiate fusion. The National Ignition Facility in Livermore, California, is an example of a laser-based ICF system. In this facility, a 287,000-lb, 10-meter-diameter target vacuum chamber is equipped with a small metal cylinder, or holraum, that contains a 2-mm pellet of D-T gas or "ice." An assembly of powerful lasers simultaneously fire 4 megajoules of infrared energy into a device that converts this energy into ultraviolet (UV) energy. The UV energy impacts the holra um, generating x-rays and rapidly heating the holraum. This induces an implosion t hat creates extremely hig h pressures and temperatures in the D-T pellet, initiating nuclear fusion. Less than 10% of the initial energy is imparted to the holraum. This is a pulsed system where multiple holraums and pellets would be required to sustain energy output. Other methods can be used to momentarily confine a plasma containing deuterium and tritium to initiate fusion. For example, instead of lasers, ion beams, electron beams, and conventional explosives could be employed. Several systems based on electron accelerators have also been used .. The Farnsworth-Hirsch fusor and the Polywell are examples of two tabletop devices used to demonstrate fusion. Another accelerator desig n is called t he Dense Plasma Focus (DPF), where a pulsed accelerator drives a magnetic field within a diffuse mixture of deuterium and tritium gas to the top of an anode. When the moving magnetic field reaches the top of the anode, UNCLASSIFIED/fF&A &FFI&I:.l.k W&li &NkY 16
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 50 pages are in the text index: search them above, or from the library's search.