DOW-UAP-D145: Aneutronic Fusion Propulsion, Part I - Rocket Physics, Proton-Boron Fuel and a 127-Year Trip to Proxima Centauri

Source file: DOW-UAP-D145_AAWSAP-DIRD-Aneutronic-Fusion-Propulsion-I-November-1-2010.pdf Originating agency: Defense Intelligence Agency (DIA), Technology Warning Division (DWO-4), Defense Warning Office, under the AAWSAP program Document type: Defense Intelligence Reference Document (DIRD), "Defense Futures" series; control number DIA-08-1011-003 (the prefix is faint on the cover scan) Date: 1 November 2010 (information cutoff date, ICOD: 20 July 2010) Classification: UNCLASSIFIED//FOR OFFICIAL USE ONLY (the FOUO caveat is struck through on the interior pages; the cover banner is faded; made public in 2026) Page count: 50 VIRIN: 260918-D-D0360-1134 PURSUE Release: 6

Summary

Release 6 contains two DIRDs with exactly the same title, "Aneutronic Fusion Propulsion," both dated 1 November 2010. The "I" and "II" labels were added in the release to tell them apart. This is Part I: its control number is DIA-08-1011-003 and it was written by a single author, AAP Person 83. The companion, DOW-UAP-D146 (DIA-08-1011-004), was written by three different authors and takes a distinctly systems-oriented approach.

"Aneutronic fusion" is a catch-all for nuclear fusion reactions in which most of the energy is released in charged particles, such as protons and helium nuclei, rather than neutrons. The advantage for a spacecraft is twofold: the crew is easier to shield, because neutrons penetrate deep into matter and charged particles do not; and charged-particle energy can be steered by magnetic fields into thrust or converted directly into electricity. The price is much higher ignition temperatures.

The paper is built like a textbook, in seven chapters and five appendices: theory (rocket equations, specific impulse, shielding, fission rockets), fusion rocket design, aneutronic schemes, antimatter, existing projects, "Speculation on Research Needs Over the Next 30 Years," and conclusions. The appendices cover relativistic rockets, an aneutronic fusion rocket, an antimatter rocket, and a full calculation worksheet for a mission to Proxima Centauri. There are 16 figures and three tables. The paper does not mention UFOs or UAP.

Research Article

Why chemical rockets are not enough

The introduction frames the problem: chemical rockets must carry enormous quantities of fuel. The author reviews existing alternatives, including the thermal fission rocket. Between 1956 and 1971 such rockets were built and tested at the Nevada Test Site under Project Rover; 72 reactor tests culminated in a 12-minute run of the Phoebus-2A NERVA reactor, which generated over 4 gigawatts of thermal power. But radioactive contaminants in the exhaust, the paper says, make the technology impossible to use for launching payloads from Earth.

Chapter 1 explains the basics for a non-specialist. In space there is no air to push against, so a rocket must carry its own "reaction mass." There are two ways to raise thrust: eject more mass, which means carrying more fuel, or eject it faster, up to the light-speed limit. Hence the paper's central metric, specific impulse (Isp), measured in seconds. Table 1 (page 11) compares: the upper stages of the Saturn V reached 421 seconds, the best chemical rocket tested (fluorine-lithium-hydrogen) 542, a nuclear thermal rocket 850, an ion thruster 3,000 and VASIMR 30,000. The author notes the trade-off: as exhaust velocity rises, energy efficiency (thrust per unit power) falls. "The point here is that for spaceflight to anywhere other than near destinations, our present rocket technology is insufficient."

The shielding section supplies the numbers that explain why neutrons are the problem. A person in the United States receives about 3.5 millisieverts a year; in space, outside Earth's magnetic field, about 250. An acute dose of 2,000 millisieverts causes significant medical problems and 5,000 is usually fatal. Launching lead shielding costs about $10,000 per pound. And a fusion reactor adds its own neutron flux. "A simpler solution," the author writes, is to use fusion schemes that do not generate neutrons at all (page 17). Chapter 1 ends with fission-rocket history: on at least one occasion in the NERVA tests, pieces of radioactive material were ejected over a small area of the test site and had to be retrieved by hand, and the Soviet spy satellite Cosmos 954 crashed with its onboard reactor into the Arctic region of Canada on 24 January 1978, at a cleanup cost of over $6 million.

From "ordinary" fusion to aneutronic fusion

Chapter 2 starts with the easiest reaction to ignite, deuterium-tritium (D-T): 17.6 MeV, of which 14.1 MeV goes to the neutron and 3.5 MeV to the helium nucleus. The neutron penetrates deep into lead or steel; the helium nucleus stops almost at once, and its energy can be harvested by a magnetohydrodynamic (MHD) generator that separates ions and electrons in a magnetic field and produces electricity directly (Figure 5). According to Figure 8, D-T becomes probable around 5 keV (about 10 million kelvin), D-D around 10 keV and deuterium-helium-3 around 30 keV (300 million kelvin). Even so, the author stresses, after more than 50 years no method has reached "break even," the point where fusion yields more energy than it takes to ignite.

The survey of ignition methods is specific: gravitational confinement (a star of pure deuterium would need the mass of Jupiter); magnetic confinement in tokamaks; inertial confinement, with a description of the National Ignition Facility at Livermore: a 287,000-pound, 10-meter-diameter target chamber, a 2-mm D-T pellet and 4 megajoules of laser energy, less than 10% of which reaches the hohlraum; and the Dense Plasma Focus, which even at 10 pulses per second with full energy capture would, by the author's calculation, yield only 280 watts. Results from fusion in deuterium-loaded metals are called "very poor," and those from cavitation (bubble) fusion "low."

Chapter 3 is the core of the paper. Figure 9 lists eight aneutronic reactions, including deuterium-helium-3 (a 14.7 MeV proton and a 3.6 MeV helium nucleus), helium-3 with helium-3, proton-lithium-6 and proton-boron-11, which yields three helium nuclei and 8.7 MeV (Figure 10). Helium-3 is rare on Earth; the paper estimates that over one million tons of it exist in lunar regolith. That makes boron-11, which is 80.1% of natural boron, and lithium-6 (7.5% of lithium) the practical candidates. The author uses the 1955 "Lawson criteria" as a basis for comparison: 34 for D-T, 0.43 for D-He3, 0.005 for p-Li6 and 0.014 for p-B11. But the ion temperatures required for p-Li6 and p-B11 are 800 and 300 keV, against 50 keV for D-T. A further problem is bremsstrahlung ("braking radiation"): x-rays emitted when electrons from the plasma strike the chamber walls, cooling the plasma.

Antimatter, projects and Bussard's QED engine

Chapter 4, a short one, serves as a benchmark. Antimatter is the densest fuel: specific impulse normalized to light speed (Isp/c) is 1 for electron-positron annihilation and 0.60 for proton-antiproton, against 0.119 for fusion and 0.04 for fission. Up to 10 to the 12th power antiprotons have already been stored in magnetic traps for days at a time.

Chapter 5 reviews projects. General Atomics' Project Orion of the late 1950s, nuclear explosions against a pusher plate, with specific impulse up to 100,000 seconds and a Mars trip in four weeks instead of 12 months; the British Interplanetary Society's Project Daedalus (1973 to 1978), a probe to Barnard's Star, 5.9 light-years away, in 50 years at up to 12% of light speed; Medusa, with a "sail" ahead of the payload; Project Longshot by the U.S. Navy and NASA, which would have reached Alpha Centauri in about 100 years; the NASA Glenn Research Center's Discovery II vehicle, to Jupiter and Saturn in 4 to 6 months; and a joint JPL, Rocketdyne and Rockwell design with a 6,000-ton launch mass that would take a crew to Mars in 100 days.

The commercial section focuses on EMC2, Robert Bussard's company in Santa Fe, New Mexico, whose work the paper says was funded by DARPA, NASA and the U.S. Navy. Its QED engine (Figure 11) is based on the Farnsworth-Hirsch fusor, an inertial electrostatic confinement device patented in 1968: ions of deuterium and helium-3, or of boron-11, are injected into the center of a spherical chamber, and the fusion heat is used to heat hydrogen expelled through a Laval nozzle. The paper also mentions the European Space Agency's Advanced Concepts Team and the "Crossfire Fusor," which, according to the paper, would theoretically allow a trip to Alpha Centauri in three years.

The next thirty years and the fuel bill for the stars

Chapter 6 opens with a 1961 quotation from Arthur C. Clarke: "The short-lived Uranium Age will see the dawn of space flight; the succeeding era of fusion power will witness its fulfillment." It then analyzes four missions. Reaching low Earth orbit takes about 30 megajoules per kilogram, and fusion rules itself out for the same reason NERVA did: radioactive exhaust near populations. The author expects single-stage-to-orbit (SSTO) flight to be achieved within the next 30 years. For Mars: a Hall-effect drive with an Isp of 8,000 seconds produces only 2.5 newtons and needs 140 kilowatts, so a craft with the mass of the space station (370 tons) would take at least four years; a 30-day trip, desirable to limit radiation, would require 10,000 such drives and 1.36 gigawatts. For the moons of Jupiter and Saturn, nuclear thermal propulsion remains in the author's view the practical choice, with "no unresolved scientific hurdles," while pulsed fusion is a far-term option.

Appendix B and the worksheet in Appendix D turn all this into numbers. The author assumes the Bussard aneutronic propulsion system, weighing 14 tons, attached to a craft with the mass of the International Space Station, with an ideal specific impulse of Isp/c = 0.119. At a very gradual 0.001 g, accelerating half the way and decelerating the other half, the trip to Proxima Centauri, 4.22 light-years, takes about 127 years, the peak speed is about 6.5% of light speed, and "Even at this modest acceleration, 85% of the initial mass of the spacecraft will have to be fuel/propellant." If fuel is capped at half the craft's mass, top speed is 8% of light speed. For comparison, Appendix C calculates that an antimatter rocket at 0.05 g would get there in 18.5 years at 43% of light speed.

Here the most important caveat also appears. The Bussard engine itself is reported at a specific impulse of only 1,500 to 6,000 seconds, requiring 4.5 to 8 gigawatts, very far from the 3.6 million seconds of the "ideal fusion drive" in Table 3. The author lists three research challenges for the next 20 to 30 years: ignition (reliable p-B11 fusion, the paper says, has only been demonstrated in a laboratory, with a picosecond laser, in 2005 by V. S. Belyaev in Russia, and requires 300 keV, about 3.3 billion degrees), materials able to survive the heat and radiation, and 10-tesla electromagnets.

Contradictions and limits

The paper is a synthesis of open literature, leaning heavily on Bussard's papers and on online sources (two endnotes cite Wikipedia). A full reading turns up several internal inconsistencies worth flagging. VASIMR's specific impulse is given as 30,000 seconds in Table 1, 5,000 on page 14 and 6,000 in Table 3, and in Table 3 the Bussard drive row is identical to the VASIMR row. The Hall drive appears as 8,000 seconds in the text and 2,500 in the table. The D-T ignition energy appears as 5 to 10 keV, 50 keV and 66 keV in different places. On the Lawson criteria the paper says "lower values" indicate easier ignition, yet by its own numbers p-B11 would then be easier to ignite than D-T, contrary to the temperatures it gives and to its statement on page 43 that D-T is "the easiest fusion reaction to initiate." The worksheet says it assumes 1 g but actually computes with g/1000. And the section headed "Muon-Catalyzed Fusion" in fact describes loading deuterium into metal crystals by electrolysis and never explains the role of muons.

The last appendix strays from fusion into "Heim Quantum Theory" and "graviphotons" for propulsion without ejecting mass. The author presents this cautiously: there are few peer-reviewed articles, and "physicists disagree with the formulation of the theory and its results"; the recommendation is only to follow the work.

Significance

Among AAWSAP's twelve technical areas the paper mainly serves propulsion, and to a lesser extent power generation (direct conversion of particle energy into electricity with an MHD generator) and human effects (shielding the crew from radiation). There is no unusual or classified claim in it: it is an educational survey of known technology, and it concludes openly that ignition is the obstacle and that this hurdle "has thwarted the ability for fusion reactors to generate commercial electricity." Notably, at the end of a paper about fusion the author prefers antimatter, because the technique to harvest and store small amounts of antihydrogen, it says, already exists.

The difference from Part II, DOW-UAP-D146, is substantial: D145 is a single-author textbook with equations, history and an eye on interstellar missions; D146, by three other authors, is organized around plasma-confinement methods, propulsion architectures and applications by range, and sees the nearest use in high-power electric propulsion for satellites and spacecraft rather than interstellar flight. The paper does not mention UFOs, UAP or any sighting.

Key People

Locations

Key Concepts

Notable Quotes

"Aneutronic fusion promises to be an important mechanism for future space propulsion, although novel accelerator or laser systems must be researched and developed in order to initiate, sustain, and control the fusion reaction." -- page 8

"The point here is that for spaceflight to anywhere other than near destinations, our present rocket technology is insufficient." -- page 10

"While fusion reactors have the potential to produce incredible amounts of energy from relatively inexpensive fuel (deuterium, tritium, helium-3), the problems of initiating, controlling, and sustaining the fusion reaction remain unsolved." -- page 22

"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." -- page 24

"Even at this modest acceleration, 85% of the initial mass of the spacecraft will have to be fuel/propellant." -- page 42

"Among the various aneutronic fusion propulsion technologies developed, Robert Bussard and his colleagues appear to have the best developed proposals." -- page 37

"Antimatter engines are a more promising technology, since the technique to harvest and store small amounts of antihydrogen already exists." -- page 37

"There are few peer-reviewed articles on Heim Quantum Theory, and physicists disagree with the formulation of the theory and its results." -- page 45