Princeton SATELLITE SYSTEMS | PPPL PRINCETON PLASMA PHYSICS LABORATORY Direct Fusion Drive provide game-changing power and propulsion in space Stephanie Thomas, PSS Michael Paluszek, PSS Dr. Samuel Cohen, PPPL JPL Advanced Space Propulsion Workshop, 2014 Talk Outline - PFRC Reactor Design and Experiments - Variable Thrust and Specific Impulse via Augmentation - Missions - Alpha Centauri - L2 Space Telescope - Asteroid Deflection - Mars Mission - Conclusions Summary - DFD produces power AND thrust - FRC fusion reactor exhausts fusion products plus additional deuterium to produce thrust - Heating method naturally limits size: 1-10 MW and size of minivan - Low neutron radiation using 3He as fuel - 3He is in limited supply, enough for approx. 100 MW/year - Perfect for space applications PRFC Reactor Design UNIQUE PRFC DESIGN Princeton Field Reversed Configuration (PFRC) - Field Reversed Configuration (FRC) - Simple geometry with fewer coils - RF heating with odd-parity rotating magnetic fields naturally limits reactor size - Plasma radius in range 20-40 cm - Size of 1-10 MW which is ideal for space - Confinement with high temperature superconducting coils - Burns aneutronic D and 3He with beta greater than 0.8 - Linear configuration allows for configuration as a rocket engine - Magnetic Nozzle - Add H or D+ to augment thrust - Variable exhaust velocity - 50 to 20,000 km/s - P = 0.5 T u_E / η, with η ~0.5 Diagram components labeled: Gas Box, Propellant, SOL Heating Section, Box Coil, Closed Field Region, Fueling, RMF_o Antenna, Field Shaping Coils, Separatrix, D-He3 Fusion, Nozzle Coil, Shielding, Exhaust Plume. PFRC Experiments at PPPL - Princeton Plasma Physics Laboratory performing experiments with DOE funding - Concluded PFRC-1 a, b, c in 2011 - PFRC-2 operating now; goal is to demonstrate keV plasmas with pulse lengths to 0.3 s - MNX experiment on plasma detachment in nozzle - Princeton Satellite Systems performing mission and trajectory design, space balance of plant studies under IR&D - Four joint PPPL/PSS patents Table of Machines: - PFRC-1: Objectives: Electron Heating; Goals/Achievements: 3 ms pulse*, 0.15 kG field*, e-temp = 0.3 keV*; Plasma Radius: 4 cm; Time Frame: 2008-2011; Total Cost: $2M - PFRC-2: Objectives: Ion Heating; Goals/Achievements: 0.1 s pulse*, 1.2 kG field, i-temp = 1 keV; Plasma Radius: 8 cm; Time Frame: 2011-2015; Total Cost: $6M - PFRC-3: Objectives: Heating above 5 keV; Goals/Achievements: 10 s pulse, 10 kG field, i-temp = 5 keV; Plasma Radius: 16 cm; Time Frame: 2015-2019; Total Cost: $20M - PFRC-4: Objectives: D-He3 Fusion; Goals/Achievements: 1000 s pulse, 60 kG field, i-temp = 50 keV; Plasma Radius: 25 cm; Time Frame: 2019-2023; Total Cost: $50M Rotating Magnetic Fields (RMF) - Parity refers to the symmetry of the magnetic field mirrored across the z=0 midplane - Frequency is a fraction of the ion cyclotron frequency for the helium-3 - Would be 0.3 to 2 MHz - Provides all the startup power and a fraction of the heating power during operation - RF antennas shown to the right (PFRC-2 Design and RMF_o Antennas diagrams) Variable Thrust and Isp THRUST AUGMENTATION WITH D+ DFD Thrust and Isp Envelope - The DFD design envelope fits between traditional chemical, electric and nuclear propulsion methods. - Fusion products of the deuterium-helium-3 (D/He3) reaction have a very high exhaust velocity: 25,000 km/s - We can convert some of their kinetic energy into thrust by transfering energy from the fusion products. Equations: P = (1/2) * (T * u_E / η); ṁ = T / u_E Chart highlights: LOx/Kerosene, Nuclear Lightbulb (GCNR), Nuclear Thermal (NERVA), LOx/LH2, Asteroid Deflection Design, Earth-Mars Roundtrip Design, 1 MW to 100 MW (ten 10MW modules) DFD, MPD, Hall Thrusters, Ion Thrusters, DS4G, Fusion (D/He-3). Thrust Augmentation - H or D is used as a propellant- it flows along the magnetic field lines outside of the separatrix; scrape-off layer (SOL) e- are heated by the fusion products that are ejected into the SOL; e- energy transferred to ions in plume expansion - This reduces the exhaust velocity of the fusion products from 25,000 km/s to ~50 km/s and increases thrust to >20 N - Thrust/Isp is adjustable based on rate that gas is injected into the gas box - The exhaust plume is directed by a magnetic nozzle, consisting of a throat coil and nozzle coils to accelerate the flow. Diagram labels: Axial field coils, Gas box, Box coil, Propellant, OFR, SOL heating section, Closed field region, Field shaping coils, Separatrix, OFR, Nozzle coil (Ei = 0.1-1 keV), Potential-drop ion-acceleration region, Exhaust plume. Magnetic nozzle: 3D simulations in LSP - Modeling provides evidence for detachment - Expanding plasma plume at 2.18 μs - Inside nozzle: - n_e = 10^11 cm^-3 - T_i = 1 eV - T_e = 100 eV - At z = 100 cm: - KE (H+) ~ 2 keV Plots: (v_z/v)/(B_z/B), KE_i, n_i vs R and Z coordinates (by M. Khodak). Space Plant Components Schematic flow chart illustrating interconnections among: - 3He Injector, D Injector, Gas Box - Plasma, RF, RF Generator, Coil Refrigerator, Radiator, Space - Magnetic Nozzle, HTS Coil Blanket - Bremss, Synch, Helium Coolant, Generator, Heat Engine, Radiator (Power Recycling) - Neutron shielding, 3He and D tanks, Auxiliary Power Unit, Electrolysis (D2O / O2), Restart, Spacecraft Power Bus. Mars Mission Energy Balance Energy flow diagram: - Fusion: 11.5 MW - 1 MW -> Gas Box -> 1 MW - Bremsstrahlung: 2.05 MW - Synchrotron - Neutron - Thrust: 4.2 MW - RMF_o: 0.6 MW (0.5 MW from auxiliary/recycling, 1.1 MW total loop power) - Heat Engine (60% Efficiency): receives 7.8 MW thermal input -> generates 3.58 MW / 0.18 MW / 4.57 MW to subsystems, rejects 3.12 MW to Radiators. Alpha Centauri Starship VISIT THE STARS! DARPA 100 YEAR STARSHIP SYMPOSIUM 2011 Synopsis: Alpha Centauri - Stable orbits possible around stars A and B - Deliver 500 kg payload - Nine 10 MW engines - 14 N thrust - u_E 12,000 km/s - 500 year transit - Achieve 0.15 c - Two 10 MW engines - 7.5 N thrust - u_E 3200 km/s - 700 year transit - 3He 564.7 kg Includes mission trajectory and vehicle 3D plan plots. Final Orbit Insertion - Go into 1 AU orbit around star A or B - Then transfer into polar orbit around (potential) planet Diagrams show Alpha-Centauri Orbital Plane, thrust normal to orbital plane, and orbit lowering maneuvers to final 1 AU orbit. L2 Space Telescope INTERPLANETARY SPACE TUG IAC 2012 Mission: Telescope to Sun-Earth L2 - 1 MW engine - Electrical power 1.25 MW - Propulsion power 1.13 MW - Transit ~40 days from GPS - Payload mass 6200 kg - ΔV 3.1 km/s - 40 N thrust - u_E 56.5 km/s - 3He 50 g - D 353 kg Accompanied by 3D vehicle layout illustration. Deploying the James Webb Telescope - Circular restricted three-body simulation - Trajectory shows spiral from GPS (12.7 days), insertion burn at 28.5 days (for 16 hrs), total 37.5 days to L2. - Delta-V = 3.1 km/s (Initial Alt. = 20232 km from GPS; From LEO: Add 3.6 km/s, 15.9 days). Asteroid Deflection SAVE THE WORLD! IEPC 2013 Synopsis: Asteroid Deflection - Must reach an asteroid and apply ΔV to it to avoid orbital keyhole - ΔV to Apophis 10-30 km/s in 175-270 days - ΔV to asteroid 0.3 m/s - 10 MW engine - Thrust: 500 N - Burn time: 23 days - Mass flow 0.02 kg/s - 41000 kg propellant Asteroid Deflection Maneuvers Illustration of b-Plane geometry, unperturbed vs actual/Earth-perturbed closest point of approach, example keyhole, incoming asymptote, outgoing asymptote, relative velocity V_infinity. Deflection Capability Analysis - Use Apophis 2029 encounter with Earth - Consider an asteroid half the size of Apophis - Maximize separation at time of impact - Maximize distance - Vary delta-v - Vary thrust level - Investigate tradeoff of deflection distance vs. fuel mass - "Knee" at 500 N Plot shows Distance (Earth Diameters) vs Fuel Mass (1,000 kg) for various delta-v values (0.1 to 1.0 m/s) and thrust levels up to 2 kN. Example Deflection Geometry - Consider two maneuvers: - Along-Track (vertical) - Cross-Track (horizontal) - Goal is to move ellipse away from keyhole and Earth focus - Along-track deflection is always much easier Diagram illustrates 2D Encounter in B-Plane: Move 1.5 Earth Radii Along-Track - 0.15 m/s vs Move 2 Earth Radii Cross-Track - 3.0 m/s. Example Deflection Maneuver - Maximizing deflection distance (with ΔV limit) - Apply 23 day along-track burn at perigee to optimally change SMA and create drift Graphs showing Hills-Frame Position (Earth Radii) and Thrust History (kN) over time (days). Mars Mission HUMAN EXPLORATION IAC 2014 Synopsis: Mars Roundtrip - Humans to Mars, orbit for several weeks and return to LEO - Total ΔV of 50 km/s - Trip time 310 days - 30 MW engines - Thrust ~ 300-400 N - Total mass of 124 MT fits within SLS envelope Includes Mars transfer vehicle structural and habitat concept rendering. Mars Trajectory and SLS - Modified Lambert trajectory - 30 days in Mars orbit - 50 km/s and 310 days roundtrip - 130 MT max for SLS Extended launch Trajectory Comparison Table: - Low Thrust Spiral: Roundtrip ΔV = 11.2 km/s, Total Trip Time = 12 years - High Thrust Hohmann Transfer: Roundtrip ΔV = 10.8 km/s, Total Trip Time = 975 days - Continuous Thrust: Roundtrip ΔV = 106.7 km/s, Total Trip Time = 277.5 days - Lambert Solution (Ideal, not attainable): Roundtrip ΔV = 47.8 km/s, Total Trip Time = 210 days - Modified Fixed Burn Lambert: Roundtrip ΔV = 49.10 km/s, Total Trip Time = 310 days Conclusions Conclusions - DFD has the potential to enable many missions - Human Mars exploration with shorter flight durations, lower mass and abort capability - Game-changing power and capability for outer planet missions including asteroid deflection - Military applications for high-power Earth orbit missions - Demonstration of a burning plasma possible in 10-12 years with enough funding, ~$50M - Flight by 2032 possible - Fusion may be closer than you think! See you on Mars! Boarding pass graphics showing flight MTV-1 departing Earth 14APR2032 (Flight Duration: 135 days) and departing Mars 26SEP2032 (Flight Duration: 144 days). For More Information Stephanie Thomas: [email protected] Dr. Samuel Cohen: [email protected] Princeton Satellite Systems 6 Market St. Suite 926 Plainsboro, NJ 08536 (609) 275-9606 http://www.psatellite.com References Papers/Conferences: - Y. Razin et al., A direct fusion drive for rocket propulsion, Acta Astronautica, Vol. 105, Issue 1, December 2014, pp. 145-155 - M. Paluszek et al, Direct Fusion Drive for a Human Mars Orbital Mission, 65th INTERNATIONAL ASTRONAUTICAL CONGRESS, Sept. 29-Oct. 3, 2014 - Joseph B. Mueller et al, Direct Fusion Drive Rocket for Asteroid Deflection, 33rd International Electric Propulsion Conference, October 6–10, 2013 - G. Pajer, Y. Razin, M. Paluszek, A. H. Glasser, S. Cohn, Modular Aneutronic Fusion Engine, Space Propulsion 2012, May 2012 - Modular Aneutronic Fusion Engine for an Alpha Centauri Mission, M. Paluszek, S, Hurley, G. Pajer, S. Thomas, J. Mueller, S. Cohen, D. Welch, DARPA 100 Year Starship Conference, September 2011. Patents: - M. Buttolph, D. Stotler and S. Cohen, “Fueling Method for Small, Steady-State, Aneutronic FRC Fusion Reactors,” 61/873,651, filed September 4, 2013. - M. Paluszek, E. Ham, S. Cohen and Y. Razin, “In Space Startup Method for Nuclear Fusion Rocket Engines,” 61/868,629, filed August 22, 2013. - S. Cohen, G. Pajer, M. Paluszek and Y. Razin, “Method to Produce High Specific Impulse and Moderate Thrust From a Fusion-Powered Rocket Engine,” PCT/US2013/40520, filed May 10, 2013. - S. Cohen, G. Pajer, M. Paluszek and Y. Razin, “Method to Reduce Neutron Production in Small Clean Fusion Reactors,” PCT/US13/33767, filed March 25, 2013. Challenges of Direct Fusion Drive - Need to demonstrate a burning plasma (PFRC-4) - Need to get Helium-3 - Not that much needed, terrestrial sources have enough to support Mars exploration - Moon and gas giants are future sources - Must minimize engine mass - Need high power per unit mass - Need ways to startup the reactor in space - Recent provisional patent using a chemical rocket engine: Paluszek, Cohen, Ham - Long duration cryogenic fuel storage in space - NASA has R&D in this area - Need all the supporting hardware to be low mass and have high reliability - Ideally last for multiple missions - Radiation shielding - Neutrons (but not too many) - Bremsstrahlung – x-rays - Synchrotron DFD-Based Space Transportation Network - DFD-powered space station - 3He mined on Moon, transported to station by DFD powered electromagnetic launchers - Supports robotic missions, such as asteroid deflection and outer planet exploration - Human missions to Mars, Asteroid Belt, and the Inner Planets Diagram shows network including Mars Mission, DFD Transfer Vehicle, DFD Space Station, NASA Space Launch System, Asteroid Deflection, and Robotic Missions.