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AAWSAP DIRD, Aneutronic Fusion Propulsion II, November 2010

U.S. Department of War · 2010-11-01 · 36 pages · text from the file's own layer

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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Chapter 1: Concept Overview
Controlled thermonuclear fusion has been the aspiration for nuclear scientists and
engineers for the last 60 years. During that time, tens of billions of dollars have been
invested in this endeavor with the expected fruition being pushed even further into the
future. When Lyman Spitzer invented the Stellarator in 1951, it was expected to take
only 5 years of concentrated plasma physics experiments to harness the fusion of
hydrogen ions confined by magnetic fields. However, the numerous new instabilities
that arose under increasing higher magnetic confinement pressures have been a
roadblock to the success of controlled fusion.
In 1983, a rediscovery was made by Robert Bussard of a fusion device invented by
Robert Hirsch in his 1966 Ph.D. thesis. The Fusor, as Hirsch named it with his thesis
advisor and famous inventor Philo Farnsworth, simply used spherically concentric
electrodes in a vacuum chamber. When a deuterium gas was supplied to the chamber
and a few-microsecond pulse at 30 kV was applied to the electrodes, D-D fusion
occurred, releasing He and neutrons. Although it released less energy than was needed
to supply the in itia l electric pulse, it provided the evidence for a method to obtain
supplementary heating to ignition of magnetically confined plasmas.
The Fusor led to continued development of what is now called Inertial Electrostatic
Confinement (IEC) devices. Amongst these was the Dense Plasma Focus (DPF), a
plasma production tube invented in 1961, and several other devices. Magnetic
confinement devices utilized the IEC method with imploding layers of lithium or
applying intense beams from either end of a linear magnetic pinch device. This
resurgence of alternate confinement concepts was immediately applied to fusion space
propulsion since it was recognized that there would be an advantage over nuclear
fission propulsion with its costly safety requirements. For mitigating shielding mass and
tritium fuel launch-safety concerns, non-neutron-generating "aneutronic" fusion fuels
were also adopted.
Aneutronic fusion fuels include those isotopes of light elements that when fused
produce no neutrons or a very few from the fusion of daughter products. Although there
are eight such reactions for light nuclei, the most practical for fusion reactors include
the following:
D + 3He ➔ 4 He + p
P + 7Li ➔ 24 He
In Chapter 2, we will review the fusion plasma physics needed to apply these
aneutronic reactions to a confinement device to make a fusion reactor practicable for
propulsion, which is described in Chapter 3. In Chapter 4, the relevance of these
aneutronic fusion propulsion concepts will be reviewed and assessed for aerospace
applications including near-space, orbital, and interplanetary propulsion, as well as the
potential for interstellar use. In Chapter 5, we will summarize the recent national,
international, and privately funded R&D that may expedite development, while in
Chapter 6, we outline an R&D path forward for the aneutronic fusion technologies and
systems needed for the next 50 years. Finally, we provide a summary in Chapter 7 that
that conveys aneutronic fusion propulsion:
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 36 pages are in the text index: search them above, or from the library's search.