AAWSAP DIRD, Aneutronic Fusion Propulsion II, November 2010

This Defense Intelligence Reference Document, dated 1 November 2010, was prepared by the Defense Intelligence Agency's Defense Warning Office under the Advanced Aerospace Weapons System Applications program. It reviews fusion plasma physics, confinement methods and propulsion concepts that use aneutronic fusion fuels such as hydrogen and boron-11. It concludes that pulsed DPF or IEC thrusters may replace satellite ion thrusters in the near term. It also finds that aneutronic fusion propulsion will not be practical beyond the solar system without breakthrough propulsion physics.

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 revisits aneutronic fusion propulsion in a more systems-oriented manner, arguing that fusion concepts using low-neutron fuels such as proton-boron or helium-3 could become attractive for space propulsion because they reduce shielding burdens and may support direct conversion of charged-particle energy into thrust or onboard power. The report reviews the relevant fusion plasma physics and focuses on several candidate confinement approaches, then connects those concepts to possible applications in near-space, orbital, and interplanetary propulsion. It presents the most plausible nearer-term use as very high-power electric or plasma propulsion for satellites and deep-space missions rather than atmospheric flight or interstellar travel, while emphasizing that major obstacles remain in ignition, sustained confinement, system mass, power handling, fuel storage, launch integration, and end-to-end engineering.

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Figure 15. Thrust-to-Weight Ratio and Exhaust Velocity Regimes for Various
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INTERSTELLAR
The ability of fusion propulsion to carry payloads or travelers t o a habitable star tens of
light-years away will be limited by the amount of fusion fuel it can transport or gather
along its route. A simple calculation of the amount of energy to move a space-shuttle
sized veh icle (100 Mg) to the nearest star, Alpha Centauri, indicates a minimum
amount of energy in the mass equivalent of 106 kg. However, in 1960 Robert Bussard
proposed the use of magnetic fields to scoop interstellar hydrogen to fue l a fusion
rocket to propel a spacecra~ now know as the Bussard Ram Jet (shown in Figure 16). 20
Although interstellar hydrogen does not fuse, Bussard proposed the use of the stellar
carbon-nitrogen-oxygen (CNO) cycle in which carbon is used as a catalyst to burn
hydrogen through the strong nuclear reaction. However, the size of the scoops and the
fusion power required to maintain them makes this concept unlikely to be realized.
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