DOW-UAP-D146, AAWSAP DIRD, Aneutronic Fusion Propulsion II, November 2010

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(U) Aneutronic Fusion Propulsion The Defense Intelligence Reference Document provides nonsubstantive but authoritative reference information related to intelli ence to ics or methodolo ies. Prepared by: Technology Warning Division (DW0-4) Defense Warning Office Directorate for Analysis Defense Intelligence Agency AAP Person 85, AAP Person 88, AAP Person 89 COPYRIGHT WARNING: Further dissemination of the photographs in this publication is not authorized. This product is one of a series of advanced technology reports produced in FY 2010 under the Defense Intelligence Agency, Defense Warning Office's Advanced Aerospace Weapons System Applications CMWSA} program Comments or questions pertaining to this document should be addressed to !AAP Person 1 }\AwsA Program Manager, Defense Intelligence Agency, ATTN: JUIAF -

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Figure 1. Fusion Reaction Cross Sections vs. Temperature..................................... 4 Figure 5. IEC Fusor and Polywell Confinement Configurations ............................... 8 Figure 6. Magnetized Target Fusion Experiment at LANL...................................... 10 Figure 7. Dense Plasma Focus (Lawrenceville Plasma Physics)............................ 10 Figure 8. Specific Power as a Function of Plasma Temperature of Fusion Rocket. 11 Figure 9. Colliding Beam Fusion Reactor .............................................................. 12 Figure 10. DPF Thruster System With Direct Conversion ...................................... 12 Figure 11. Magnetized Target Fusion Reactor ...................................................... 13 Figure 12. MHD Air-Breathing and Fusion Rocket Aerospace Plane ...................... 13 Figure 13. Design of an IEC Jet Thruster - Experimental Device........................... 18 Figure 14. Comparison of Fusion, Nuclear-Thermal, and Chemical Propulsion for Same Payload....................................................................................................... 19 Figure 15. Thrust-to-Weight Ratio and Exhaust Velocity Regimes for Various Long- Range Space Propulsion Options.......................................................................... 19 Figure 16. Bussard Ram let.................................................................................. 20 Figure 17. Progress in Tokamak Magnetic Confinement Fusion ............................ 22 Figure 18. ITER Design Concept With BWR Size and Blanket Segment ................. 23 Figure 19. Experiments To Prove a Plasma Fusion Propulsion Concept ................ 28 Figure 20. Roadmap to Aneutronic Fusion Propulsion Development..................... 29 Table 1: Principal Fusion Reactions...........................................................................3 Table 2: Fusion Peak Interaction Temperatures and Fusion Energy to X-rays.........4 Table 3: Fusion Ignition Temperatures.....................................................................5 Table 4: Advanced Fusion Concept Reactor Companies..........................................24

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Aneutronic Fusion Propulsion Controlled fusion energy production has been under development for 60 years. The primary objective has been gaining the ability to create terrestrial power plants using deuterium and tritium as fuel. Unfortunately, this objective has been eluded for both technical and economic reasons. However, the threshold for achieving success in applying fusion to propulsion is considerably relaxed, especially if fuels are used that do not use tritium. Tritium has to be continuously bred; these reactions yield fast neutrons, which require shielding and cause structural materials to be periodically replaced. Such "aneutronic" fusion fuels, such as hydrogen fusing with Boron-11, have been studied extensively for space propulsion applications since the 1980s. This report reviews the basic fusion plasma physics, design concepts that apply aneutronic fusion for propulsion, and the requirements for transitioning to space. The predominant concepts studied include magnetic field reversed configuration, dense plasma focus and inertial electrostatic confinement. All of these concepts have venture capital funded programs for terrestrial fusion power. When applied to space or near-space propulsion, they can exceed the performance of any conventional electric thruster. The future technology development of aneutronic fusion propulsion will initially be motivated by the very large GEO satellites that will be developed in the next 20 years for commercial and military broadband communication. Further development of very-high-power propulsion systems(> 100 kW) to Mars and beyond will require major developments in all technology areas for confinement pulsed power and ion fuel beam accelerators.

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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 initial 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: 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,