DOW-UAP-D146: Aneutronic Fusion Propulsion, Part II - Confinement Schemes, Satellite Thrusters and a Roadmap to 2060

Source file: DOW-UAP-D146_AAWSAP-DIRD-Aneutronic-Fusion-Propulsion-II-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-08-1011-004 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 released copy; (U) markings on the inner title and one paragraph; made public in 2026) Page count: 36 VIRIN: 260918-D-D0360-1135 PURSUE Release: 6

Summary

This is the second of two DIRDs in Release 6 with an identical title, "Aneutronic Fusion Propulsion." Both are dated 1 November 2010, both share the same information cutoff date of 20 July 2010, and their control numbers are consecutive: DIA-08-1011-003 for Part I (DOW-UAP-D145) and DIA-08-1011-004 for this one. But they are separate works. Part I was written by a single author, AAP Person 83; Part II by three authors, AAP Person 85, AAP Person 88 and AAP Person 89, and neither paper refers to the other.

The difference shows in the structure. Part I is a textbook that starts with the rocket equation and ends with a worksheet for a trip to Proxima Centauri. Part II is a systems study, with a one-page "Summary" up front, seven chapters and endnotes: a concept overview (Chapter 1), fusion plasma physics and four confinement methods (Chapter 2), reactors and thrusters for propulsion (Chapter 3), applications by range, from near space to the stars (Chapter 4), existing U.S., international and privately funded programs (Chapter 5), a three-phase development outlook to 2050 (Chapter 6) and conclusions (Chapter 7). It has 20 figures and five tables, and 20 endnotes, most of them to professional journals and conferences.

Its central conclusion runs against popular imagination: the first use of aneutronic fusion will not be an interstellar ship but a thruster for a large communications satellite. The paper does not mention UFOs or UAP.

Research Article

A lower bar than a power plant

The summary page opens with an admission: controlled fusion energy has been under development for 60 years, and the goal, power plants running on deuterium-tritium, "has been eluded for both technical and economic reasons." But, the authors argue, "the threshold for achieving success in applying fusion to propulsion is considerably relaxed," especially without tritium, which must be continuously bred and whose reactions produce fast neutrons. Chapter 1 adds the history: when Lyman Spitzer invented the stellarator in 1951, only five years were expected to be needed; in 1983 Robert Bussard "rediscovered" the Fusor that Robert Hirsch had described in his 1966 doctoral thesis, together with the inventor Philo Farnsworth.

Chapter 1 also announces three conclusions the paper will support: aneutronic propulsion may have near-term uses replacing satellite ion thrusters, extending to interplanetary flight; it will require extensive technology development for air and near-space use; and it "will not be practical beyond the solar system" without breakthrough propulsion physics. The authors also complain that the space science community has given the problem too little attention, and that launch, in-space assembly and materials need to enter the design early.

Plasma physics and four ways to confine it

Chapter 2 sets out the data in three tables. Table 1 lists fusion reactions: D-T releases 17.59 MeV, and among the "advanced fusion fuels" D-He3 releases 18.35 MeV and p-B11 8.68 MeV in three helium nuclei. Table 2 compares fusion power with bremsstrahlung (x-ray) losses at the peak reaction temperature: 140 for D-T, 5.3 for D-He3, but only 0.57 for p-B11 and 0.21 for p-Li6, meaning that in the last two the plasma radiates away more than fusion produces. Table 3 gives ignition temperatures: 13.6 keV for D-T, 58 for D-He3, 66 for p-Li6 and 123 for p-B11. The conclusion is stated precisely: "While the ignition temperature is up to a factor of 10 higher for the aneutronic fusion reactions, the confinement power required for ignition will be one to two orders of magnitude greater." The authors also define the gain factor Q: breakeven is Q = 1, practical use requires Q above 5, and a power plant Q above 30.

There follows a survey of four confinement families. Magnetic confinement: magnetic mirrors (Figure 2 illustrates the idea with Jupiter's magnetic field), tokamaks and stellarators, at pressures around one bar and confinement times of seconds to minutes, but at the scale of a plasma 6 meters in major radius and 6 meters high merely to demonstrate ignition. The field-reversed configuration (FRC), a plasma ellipsoid that generates its own confining field, is far smaller but prone to a "tilting" instability in which the plasma ring flips over and flies apart. Inertial confinement: pellets of about 10 milligrams, and at the NIF, 192 laser beams; the practical hurdle for a reactor is making and compressing ten pellets a second. Electrostatic confinement (IEC), the Farnsworth-Hirsch Fusor: the authors fairly note the critique that in the simple configuration net energy is not viable for anything but D-T, and present gridless alternatives such as the Polywell and the POPS trap developed at Los Alamos. And magneto-inertial confinement, including the magnetized target fusion experiment at Los Alamos (LANL) and the dense plasma focus (DPF), which the authors call "by far the simplest and least elaborate magnetic confinement concept to achieve aneutronic fusion ignition."

From reactor to thruster: tons and megawatts

Chapter 3 explains why every propulsion study since the early 1990s abandoned D-T: heavy shielding for 14-MeV neutrons, the launch safety of tritium, and the complexity of breeding it. That left D-He3 and p-B11. The chapter cites figures from published designs. A "seminal" 1993 study estimated a 968-megawatt D-He3 reactor at 112 tons, against 999 tons for an equivalent D-T system. Optimization with a colliding-beam FRC cut this to 33 tons producing 100 megawatts, in a chamber 7 meters long and 0.84 meters across, with half the fusion products sent to a direct converter for electricity and half expelled as thrust (Figure 9). A proton-boron DPF reactor, the lightest of all, is estimated at 16 tons, 800 megawatts and about 1,000 kilonewtons of thrust at a specific impulse of about 1,300 seconds, pulsing at 10 hertz or more (Figure 10). And magnetized target fusion with colliding plasmoids might reach 20 tons and 300 megawatts.

Inside the atmosphere the numbers collapse. Converting the DPF reactor's 800 megawatts to thrust through a gas turbine would give 15 newtons per megawatt, only 1,224 kilograms of thrust for a 16,000-kilogram vehicle. Thrust per kilogram of reactor would have to rise by a factor of 50 to 100. The alternative studied is a combined "aerospace plane" (Figure 12): chemical and air-breathing engines up to Mach 7, air-breathing propulsion with MHD power generation from Mach 7 to 14, and fusion propulsion from Mach 14 to orbit, in the "2025 time period" according to the figure. The rest of the chapter reviews the electric propulsion families fusion might enhance: gridded ion thrusters, Hall thrusters (about 1,500 seconds, up to about 3 newtons), magnetoplasmadynamic thrusters, the European Space Agency's helicon double-layer thruster and VASIMR, whose VX-200 engine, 200 kilowatts and about 300 kilograms, was due to be tested on the space station.

Applications by range: from satellite to star

Chapter 4 is what makes this a systems paper, and it is also the only part with an explicit military framing. In near space, the thrusters could not lift a vehicle off the ground, but a craft in orbit could "dip down and maneuver in the atmosphere and return to orbit," as long as it does not slow below Mach 14. The authors list three possible missions: antisatellite threat avoidance, unpredictable reconnaissance of Earth or space targets, and unpredictable "neutralization" of such targets, adding that "the details of such applications will be the subject of separate studies."

The nearest application is in Earth orbit. NASA's Hall thrusters run at 6.4 to 72.5 kilowatts and produce 0.3 to 2.5 newtons; a 4.5-kilowatt system from Aerojet and Lockheed Martin, which demonstrated 244 millinewtons at a specific impulse of 1,981 seconds, flew in 2010 on military communication and surveillance satellites. Future satellites with 20 to 50 kilowatts of broadcast power will need more thrust per kilowatt, and that is the motivation for development. The candidate is a spherical "IEC jet thruster" (Figure 13), estimated at 35 millinewtons for 750 watts, a specific impulse of 3,000 seconds and 45 millinewtons per kilowatt; adding a 150-kilowatt ion beam to heat a proton-boron plasma close to ignition (Q of about 1) should raise the specific impulse above 5,000 seconds.

Interplanetary flight requires a specific power of at least 1 kilowatt per kilogram at exhaust velocities of 100,000 to 1,000,000 meters per second, and Figure 14 compares an Earth-Mars mission using chemical, nuclear-thermal and fusion propulsion. As for the stars: moving a space-shuttle-sized vehicle (100 tons) to Alpha Centauri would, by the authors' estimate, take energy equivalent to a million kilograms of mass. Bussard's 1960 "ramjet," which would scoop interstellar hydrogen with magnetic fields (Figure 16), is judged "unlikely to be realized."

Money, programs and the roadmap

Chapter 5 gives a numerical snapshot as of 2010. The U.S. Department of Energy's fusion budget for fiscal 2010 was $421 million, over half of it for tokamaks, and only about $20 million for advanced concepts and high-energy-density plasma physics; $135 million went to ITER. ITER's operating date, the paper says, slipped from 2002 to 2020 at a cost of $20 billion, and after downscaling to 2025 at $25 billion, and it needs 36 kilograms of tritium for its initial fueling. The authors compare this with GE's ESBWR fission reactor, about $3 billion for 1.2 gigawatts of electricity, and conclude: "It is clear that a tokamak power plant could not compete with the fission plant at current market energy prices." Table 4 lists five private companies and their funding: Lawrenceville Plasma Physics (DPF, proton-boron, $4 million), Electron Power Systems ($6 million), General Fusion ($10 million), EMC2 with the Polywell ($11 million, with $100 million needed) and TriAlpha (beam-heated FRC, $50 million, with $100 million needed). According to the authors, Lawrenceville and TriAlpha have been shown conceptually to support low-mass aneutronic propulsion systems.

Chapter 6 divides the future into three phases: 2010 to 2020, leveraging private DPF, FRC and IEC work and the IEC thruster as a near-term replacement for Hall thrusters; 2020 to 2030, engineering design and ground testing, including high-temperature superconductors to replace Nb3SnCu and NbTi; and 2030 to 2050, integration into platforms and prototype flight tests. Table 5 lists nine supporting technologies, from high-temperature plasma containers to fuel storage. The roadmap in Figure 20 runs in sequence from physics demonstration, technology development, ground demonstration and flight demonstration to a "Manned Mission" at the edge of the axis, around 2060, provided "success criteria" such as plasma beta above 1, ignition, sustained ignition and power balance are met.

Significance

Among AAWSAP's twelve technical areas, the paper mainly serves propulsion and power generation, through direct conversion of particle energy into electricity. Because of Chapter 4 it is also one of the papers in the series that speaks directly to a "weapon system" context: evading antisatellite weapons, reconnaissance and neutralization of targets, and thrusters already flying on military satellites.

Reading it alongside Part I is useful. D145 is a single-author textbook, drawing partly on online sources, that ends with a worksheet for Proxima Centauri and ultimately prefers antimatter. D146 draws on the professional literature, concentrates on confinement methods and on reactor masses and powers, and puts the satellite first. They also differ on one technical point: D145 gives "Lawson criteria" values by which proton-boron would look easier to ignite than D-T, while Table 3 here shows the conventional picture, 123 keV for p-B11 against 13.6 for D-T. On Bussard, both papers mention EMC2, but D146 dismisses his ramjet and highlights Lawrenceville and TriAlpha instead.

The paper does not mention UFOs, UAP or any sighting. Its closing sentence sets the tone: "The future needs to be focused more on science and engineering and less on science fiction."

Key People

Locations

Key Concepts

Notable Quotes

"However, the threshold for achieving success in applying fusion to propulsion is considerably relaxed, especially if fuels are used that do not use tritium." -- page 5

"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." -- page 6

"While the ignition temperature is up to a factor of 10 higher for the aneutronic fusion reactions, the confinement power required for ignition will be one to two orders of magnitude greater." -- page 9

"In fact, any vehicle in orbit could benefit from such a propulsion device to dip down and maneuver in the atmosphere and return to orbit with the aid of fusion propulsion as long as it does not slow below Mach 14." -- page 22

"It is clear that a tokamak power plant could not compete with the fission plant at current market energy prices." -- page 27

"Pulsed-powered DPF or IEC aneutronic fusion thrusters may have near-term applications to replace current satellite ion thrusters." -- page 35

"Aneutronic fusion propulsion will not be practical beyond the solar system unless breakthrough propulsion physics is developed that can assist the flight to the next stellar system where fusion thrusters can then be used." -- page 35

"The future needs to be focused more on science and engineering and less on science fiction." -- page 35