FusionFusion SpaceSpace Propulsion--Propulsion-- AA ShorterShorter TimeTime FrameFrame thanthan YouYou ThinkThink JohnJohn F.F. SantariusSantarius FusionFusion TechnologyTechnology InstituteInstitute UniversityUniversity ofof WisconsinWisconsin JANNAFJANNAF Monterey,Monterey, 5-85-8 DecemberDecember 20052005 D-3He and Pulsed-Power Fusion Approaches Would Shorten Development Times $$$ Fusion D-3HeD-3He FRC,FRC, dipole,dipole, Rocket spheromak,spheromak, ST;ST; Pulsed-powerPulsed-power MTF,MTF, PHD,PHD, fast-ignitorfast-ignitor JFS 2005 Fusion Technology Institute 2 D-3He Fusion Will Provide Capabilities Not Available from Other Propulsion Options 107 Fusion ) s 6 / 10 10 kW/kg m ( y 1 kW/kg t i c o l 5 0.1 kW/kg e 10 v t Nuclear us (fission) Ga s-core fission ha electric x 4 E 10 Nuclear thermal Chemical 103 10-5 10-4 10-3 10-2 10-1 1 10 Thrust-to-weight ratio JFS 2005 Fusion Technology Institute 3 Predicted Specific Power of D-3He Magnetic Fusion Rockets Is Attractive (>1 kW/kg) • Predictions based on reasonably detailed magnetic fusion rocket studies. Specific Power First Author Year Configuration (kW/kg) Borowski 1987 Spheromak 10.5 Borowski 1987 Spherical torus 5.8 Santarius 1988 Tandem mirror 1.2 Bussard 1990 Riggatron 3.9 Teller 1991 Dipole 1.0 Nakashima 1994 Field-reversed configuration 1.0 Emrich 2000 Gasdynamic mirror 130 Thio 2002 Magnetized-target fusion 50 Williams 2003 Spherical torus 8.7 Cheung 2004 Colliding-beam FRC 1.5 JFS 2005 Fusion Technology Institute 4 Fusion Propulsion Would Enable Fast and Efficient Solar-System Travel • Fusion propulsion would dramatically reduce trip times (shown below) or increase payload fractions. 1000 Chemical (Isp=450 s) 800 ) s Nuclear y thermal a 600 (Isp=900 s) (d Fusion e (1 kW/kg) m i 400 t Fusion ip r (10 kW/kg) T 200 0 Earth-Mars Earth-Jupiter (29% payload) (4% payload) JFS 1999 JFS 2005 Fusion Technology Institute 5 Key Fusion Fuels for Space Propulsion 1st generation fuels: 2nd generation fuel: D + T → n (14.07 MeV) + 4He (3.52 MeV) D + 3He → p (14.68 MeV) + 4He (3.67 MeV) D + D → n (2.45 MeV) + 3He (0.82 MeV) 3rd generation fuels: → p (3.02 MeV) + T (1.01 MeV) 3He + 3He → 2 p + 4He (12.86 MeV) {50% each channel} p + 11B → 3 4He (8.68 MeV) 10-21 L 1 - s 3 -22 m 10 D-3He H t a r D-T n p-11B o -23 i t 10 c 3 a He- e Re D-D 3He 10-24 1 5 10 50 100 500 Ion temperature keV JFS 2005 Fusion Technology Institute 6 H L D-3He Fuel Requires Continuation of the Remarkable Progress of Fusion Physics • Decades of plasma physics progress created sophisticated tools that will facilitate the development of innovative concepts: 10,000,000,000 1,000,000,000 Computer Chip Memory (Bytes) ITER 100,000,000 10,000,000 JET TF TR 1,000,000 JET TF TR ¾ Experimental 100,000 JET JET TF TR techniques 10,000 PDX JET 1,000 DIII-D Achieved (DHe3) ¾ DIII Achieved (DD) Diagnostics 100 PLT Achieved (DT) Pro jected (DT) ¾ Computational 10 Alcator C modeling 1 Fusion Power (Watts) 0.1 ¾ Theory ATC, Alcator A 0.01 1970 1975 1980 1985 1990 1995 2000 2005 2010 Year JFS 2005 Fusion Technology Institute 7 D-3He Fuel and High β Relax Engineering Constraints • Reduced neutron flux allows 1 D-T ¾ Smaller radiation shields, e s D-D a e ¾ Smaller magnets, m l s e r a l p ¾ Less activation, g r e n o 3 ¾ Easier maintenance, and r ed fa He:D -1 10 =1:2 o ¾ Potentially, proliferation- i n s o u r fy t proof fusion power plants. u e Tritium burn on nm n fraction = 50% 3 • Increased charged-particle s o He:D i as t c =1:1 a flux allows direct energy r 3He:D=3:1 Ff conversion to thrust or 10-2 1 10 100 electricity. Ion temperature keV ¾ Nonlinear gain in useful power / radiator mass H L Pthr/Mrad α η/(1-η) JFS 2005 Fusion Technology Institute 8 D-3He Fuel Could Make Good Use of the High Power Density Capability of Some Innovative Fusion Concepts • D-T fueled innovative concepts become limited by neutron wall loads or surface heat loads well before they reach β or B-field limits. • D-T fueled FRC’s (β~85%) optimize at B ≤ 3 T. • D-3He needs a factor of ~80 above D-T fusion power densities. ¾ Superconducting magnets can Power Density Relative to a D TFRC with 85%and B 3T reach at least 20 T. - b= = ¾ Fusion power density scales as 2 4 2000 β B . 1000 x ¾ Potential power-density 1000 100 x 10 x improvement by increasing 1 x 0 β and B-field appears at right. 1 20 0.75 15 0.5 10 b 0.25 5 B T 0 JFS 2005 Fusion Technology Institute H L 9 Plasma Power Flows in Linear Devices Give More Design Flexibility than Flows in Toroidal Devices • Power density can be very high due to β2B4 scaling, but first-wall heat fluxes would remain manageable. ¾ Charged-particle power transports from internal plasmoid to edge region and then out ends of fusion core. ¾ Magnetic flux tube can be “pinched” on one end by increasing the magnetic field on that side, giving primarily single-ended flow. • Pulsed concepts gain similar advantages by reflecting plasma from a magnetic nozzle. Expanded Not to scale FRC core region flux tube to reduce heat flux Neutrons Bremsstrahlung ThrustThrust Charged particles JFS 2005 Fusion Technology Institute 10 Low Radiation Damage in D-3He Reactors Allows Permanent First Walls and Shields to be Designed 120 C) 0 ° ( e UWMAK-III (Mo) ARIES-IV (SiC) ARIES-I (SiC) r u 100 t a r 0 e p UWMAK-II (AS) m 800 e T ARIES-RS (V) TITAN (V) l HSR (AS) WITAMIR-I (FS) a r ARIES-II (V) u t 600 ASRA-6C (AS) ARIES-ST (FS) c ARIES-III u Apollo-L3 MARS (FS) r t NUWMAK (Ti) MINIMARS (FS) S m 400 u STARFIRE (AS) m UWMAK-I (AS) i UWTOR-M (FS) x a Apollo-L M 200 “Permanent DT Fuel life regime D3He Fuel for steel 0 0 1000 2000 3000 Maximum dpa per 30 Full Power Years JFS 2005 Fusion Technology Institute 11 Radioactive Waste Disposal is Much Easier for D-3He Reactors than for D-T Reactors D-3He D-T 30 full-power years 5 full-power years Class A Low- activation Class C Tenelon HT-9 Low- steel activation Tenelon Deep Geologic Burial HT-9 steel JFS 2005 Fusion Technology Institute 12 Fusion Rockets Would Provide Electricity Production and Materials Processing Capabilities at Destination • Direct conversion to electricity • Plasmas provide many materials could take advantage of the processing capabilities. natural vacuum in space. B.J. Eastlund and W.C. Gough, “The Fusion Barr & Moir experiment, LLNL Torch--Closing the Cycle from Use to (Fusion Technology, 1973) Reuse,” WASH-1132 (US AEC, 1969). JFS 2005 Fusion Technology Institute 13 A Well Documented Lunar 3He Resource Exists • Lunar 3He concentration verified from Apollo 11, 12, 14, 15, 16, & 17 plus USSR Luna 16 & 20 samples. • Analysis indicates that ~109 kg of 3He exists on the lunar surface, or ~1000 y of world energy supply. • One-way Earth-Mars trip requires ~100 kg 3He. • 40 tonnes of 3He would supply the entire 2004 US electricity needs. • ~400 kg 3He (8 GW-y fusion energy) is accessible on Earth for R&D. L.J. Wittenberg, J.F. Santarius, and G.L. Kulcinski, “Lunar Source of 3He for Commercial Fusion Power,” Fusion Technology 10, 167 (1986). JFS 2004 Fusion Technology Institute, University of Wisconsin 14 Well-Developed Terrestrial Technology Gives Access to ~109 kg of Lunar 3He • Bucket-wheel excavators • Bulk heating • 33 kg 3He / year • Heat pipes • ~600 tonnes volatiles / year • Conveyor belt • 556 km2 / year • v = 23 m / h JFS 2005 Fusion Technology Institute 15 Lunar 3He Mining Produces Other Useful Volatiles JFS 2005 Fusion Technology Institute 16 D-3He Field-Reversed Configuration (FRC) Appears Attractive for Fusion Propulsion • FRCs possess key desired • Recent encouraging results: characteristics for D-3He fusion: ¾ Emerging understanding of why FRCs appear far more stable than ¾ Very high β≡Pplasma/PB-field ¾ Linear external B field MHD theory predicts. ¾ Cylindrical geometry ¾ Attractive current drive by rotating magnetic fields (RMF) demonstrated. From Univ. of Washington web page for the Star Thrust Experiment (STX): www.aa.washington.edu/AERP/RPPL/STX.html JFS 2005 Fusion Technology Institute 17 Spherical Torus Space Propulsion Would Benefit from the Substantial DOE ST Research Effort • Very low aspect-ratio version of the tokamak. • High β, implying high power density. • Critical issues: recirculating power and providing thrust. • Glenn Research Center design: C.H. Williams, et al., NASA TM 2005- 2 m 213559. Pegasus ST experiment, Univ. of Wisconsin 2 m JFS 2005 Fusion Technology Institute 18 The Dipole Configuration Offers a Relatively Simple Design That an MIT/Columbia Team Has Begun Testing Io plasma torus around Jupiter LDX experiment (MIT) 0.65 m Dipole space propulsion design: E. Teller, A.J. Glass, T.K. Fowler, A. Hasegawa, and J.F. Santarius, “Space Propulsion by Fusion in a Magnetic Dipole,” Fusion Technology 22, 82 (1992). JFS 2005 Fusion Technology Institute 19 Magnetized-Target Fusion (MTF) • Ionized material from the fusion micro-explosion would reflect from • Plasma jets a diverging would converge, magnetic nozzle to compress, and produce thrust.