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Home , Direct Fusion Drive, Magnetic nozzle

: Enabling Rapid Deep Space Propulsion Presented by: Stephanie Thomas

DIRECT FUSION DRIVE

FISO Telecon 05-29-19

‹#› Team Members

Stephanie Thomas Michael Paluszek PrincetonFUSION Charles Swanson SYSTEMS Princeton Satellite Systems 6 Market St. Suite 926 Plainsboro, NJ 08536 http://www.psatellite.com

Dr. Samuel Cohen Princeton Physics Lab Plainsboro, NJ

This material is based upon work supported by NASA under award No. NNX16AK28G and 80NSSC18K0040

2 DFD vs. PFRC

Field Shaping RF Heating Field Shaping RF Heating Coils Fuel Antenna Coils Fuel Antenna Mirror Coil Coil

D-3He D-3HeD-3He Fusion FusionFusion Exhaust Plume Coolant Exhaust Propellant

Cool Plasma Energy Absorbed Heat and Ash Extraction Cool Energy Absorbed Ion Acceleration Plasma

PFRC: Princeton Field-Reversed DFD: Direct Fusion Drive Configuration • PFRC with an open end • Compact toroid configuration • SOL flow rate adjusted to produce • RF heating desired thrust and Isp • FRC “in a mirror” • “thrust augmentation” • SOL flow removes fusion exhaust • Power AND Propulsion in one device

3 Why Build a Small, Clean, Fusion Reactor?

PFRC will produce 1-10 MWe per mini-van size reactor, with almost no radiation. Civilian NASA and DoD Space DoD Terrestrial — Distributed and remote power — Deep space robotic missions — The electric battlefield ⁃ Villages in Alaska — Lunar/Mars settlements — Small Naval combatants — Mobile and emergency power — Asteroid/comet intervention — Forward power ⁃ Hurricane damage, — Space platform power — Fusion powered drones for ex. Puerto Rico — High power communications boost phase missile defense — Modular power satellites ⁃ Low capital cost power plants

4 PFRC Technology: Simple, Small, Clean

— FRC: Field-Reversed Configuration — Enabled by new magnetic plasma heating method ⁃ Steady-state operation — Simple linear array of PFRC-2 in operation at PPPL Field Shaping RF Heating magnetic coils Coils Fuel Antenna Nozzle Coil — Small size permits clean operation D-3He Fusion (ultra low radioactivity) Exhaust Plume — Easily direct flow for Propellant Cool engine mode Plasma Energy Absorbed Ion Acceleration Schematic of Rocket Configuration

5 5/27/19 PFRC Programmatic Support to Date

MNX PFRC-1 PFRC-2 DOE 1998-2015 DOE FES 2002-2009 DOE FES 2010-2016

NIAC STTRs ARPA-E OPEN NASA 2016-2019 NASA 2017-2020 2019-2020

6 NASA Has an Interest in Small Fusion

NASA Power & Propulsion Needs — Deep Space Gateway in cislunar space — Manned surface bases on High Power Interplanetary moon, Mars Communication missions — Orbital platforms Fusion Plant — Outer planet and moon missions ⁃ Landers and submarines to explore geology and search for 550 AU life Orbital Platforms observatory — Near interstellar telescopes, solar gravitational lens Surface Bases — Interstellar asteroid intercept — Communications

3He mining & transport

7 5/27/19 Why Fusion Propulsion: Deep Space Rapid Transit

What can you do with a 1-2 MW fusion engine and a 10,000 kg mission?

1 year 2 years 3 years 4 years 5 years

1 AU 5 AU 10 AU 20 AU 30 AU 40 AU 2 MW 1 MW 0.6 MW

8 Advanced Propulsion Big Picture

Theoretical Maximum Delta-V 300 DFD Isp: 10198 s Structural Fraction (F): 0.02 ∆ V = u log( (1+F)/F ) max e 250

200 Nuclear Electric VASIMR Isp: 4997 s V (km/s)

∆ 150 Lambert 100 Nuclear Electric Hall Isp: 2040 s

50 Nuclear Thermal Isp: 900 s Chemical Isp: 462 s

0 0 5 10 15 20 25 30 Pluto Transfer Time (yrs) Achievable delta-V is fundamentally limited by the structural fraction and exhaust velocity…

9 DFD Technical & Team Videos on Website

https://youtu.be/hggqvB5I95I

https://youtu.be/vS4o7W3UP4M

10 DFD: Propulsion and Power in One Compact Device

The engine uses RF heating

to create a Field Shaping RF Heating Coils Fuel Antenna CLOSED field lines, Nozzle Coil Field-Reversed Configuration (FRC) D-3He inside a Fusion 1-2 m magnetic mirror, producing power AND thrust Propulsion and Power in One Device

The fusing plasma acts as the heating source Field Shaping Coils Nozzle Coil for cool propellant flowing outside the confinement region. This D-3He process of Fusion Exhaust thrust augmentation Plume Propellant gives us substantial thrust Cool Energy Absorbed Ion Acceleration with high exhaust Plasma velocity!

Thrust: ~5-10 N/MWf Impulse: ~10,000-20,000 s

‹#› Power and Propulsion in One Device

Producing power: • Fusion deposits heat in Radiation the walls (x-rays and microwaves) • Brayton cycle engine converts heat to • Excess heat rejected to Heat space Brayton Engine ~60% Fraction of : Electricity

Radiation Exhaust Radiation 45% 55% Exhaust Radiator ~40%

13 NIAC: Pluto Explorer Mission with DFD

Single launch from Earth, fly directly to Pluto with constant thrust Engine 1100 kg Radiator Area 120 m2 Radiators 250 kg

Fuel (D2) 7250 kg Helium-3 0.5 kg

Liquid D2 tank 2.6 m radius

Gas 3He tank 0.95 m radius Fuel Tanks 400 kg Put a 1000 kg spacecraft in orbit around Pluto, Lander 200 kg beam power to a lander using optical transmission, Structure 300 kg return high-definition video – Orbiter 500 kg and get there in less than 5 years! payload Launch Mass 10000 kg

14 NIAC Pluto Explorer Vehicle Design

D, 3He Tanks under Sun Shield

Lander Solar Array

Optical DFD Engines Comm Radiator

15 STOP RIGHT THERE. How is a fusion drive suddenly achievable?

‹#› DFD is DIFFERENT from other fusion reactor concepts

1. Unique heating method 2. SIMPLE configuration 3. SMALL size 4. CLEAN operation – low radiation à FRC has 10x better confinement than tokamak à FRC has 20x higher ! à FRC can contain 5x higher density

These features make it uniquely suited for use in space! Unique Heating: RMF Current Drive

• Antenna currents creating rotating magnetic & • Current is driven • Very efficient drive at null • Closed field lines

“odd-parity” -- fields are in opposite directions on either side of machine midplane “even-parity” – single antenna loop; open field lines

(still from an animation) 18 Simple: Linear Array of Coils

Propellant Addition Heating Ion Acceleration

Axial Field Coils Box Coil Nozzle Gas Box Coil Exhaust Closed Field Region

Open Field Open Field Region Region Separatrix SOL heating section

Ash Coolant

The linear configuration means the reactor could be assembled in segments and simply pulled apart as needed.

19 Small: DFD is REALLY small

Typical tokamak reactor: • 1000-4000 MW • 60 m tall • Development in 30-50 years

PFRC reactor: • 1-10 MW • 2 m diameter • Development in 5-10 years • Small enough to fit on a single launch vehicle

ITER research reactor Person for scale

20 Clean: D-3He can burn Aneutronic fuels

Main Fusion Reaction Power ⁃ D + 3He ® 4He (3.6 MeV) + p (14.7 MeV) 98.4%

+ ® +

Side reactions ⁃ D + D ® T (1.01 MeV) + p (3.02 MeV) 0.88% ⁃ D + D ® 3He (0.82 MeV) + n (2.45 MeV) 0.72% ⁃ D + T ®4He (3.5 MeV) + n (14.1 MeV) <0.05% T ® cooled and exhausted before it can fuse 3He ® exhausted 4He ® exhausted p ® exhausted n ® deposit energy in walls as heat

21 Tritium Ash Removal

In actuality, hundreds of orbits occur before the tritium is captured on a SOL field line – time < 20 ms!

In the above graph, just a few orbits of each type are shown. An animation is included in our technical video.

22 CLEAN: Ultra low radiation

23 DFD is DIFFERENT than other fusion concepts

Simple Small Clean • Linear array of • Plasma radius • D-3He fuel ~25 cm • Exhaust tritium • Easily directed • Engine is 1-2 m before it can fuse plume diameter • <1% power in neutrons

24 Why now? Its Faster and Cheaper to Develop a Small Machine Size Radioactivity Available Fuel Complexity Small FRC < 10 MW Time Cost : <$100M : < 5 years : >$10B : > 20 years Cost Time

Tokamaks

> 200 MW Size Radioactivity T Breeding Complexity

25 Summary of Key Physics Points

Hamiltonian code (“RMF”) showed current drive and rapid ion and electron heating.

! PFRC-1 demonstrated rapid electron heating, stability 103 x better than predicted by MHD, and, indirectly, FRC formation

PFRC-2 thus far has demonstrated 100x improved particle confinement and stability 105x better than predicted by MHD

PIC model demonstrated current drive, field reversal by RMFo, and excellent agreement with full x-ray EEDF

26 Computational Tools Applied

Expanding plume; leading edge of the D+ plume is getting to 900 eV, Isp = 30,000 s Orbit of ion heated by RMF LSP: particle in cell; RMF: single particle; kinetic Hamiltonian

Model of plasma heating and flow in SOL UEDGE: multi-species fluid model 27 Experimental Apparatus

— Concluded PFRC-1 a, b, c in 2011; breakthrough achieved in FRC electron heating methods ⁃ Electron heating to > 200 eV — PFRC-2 operating now ⁃ Goal is to demonstrate keV plasmas with pulse lengths to 0.3 s § Electron heating to > 500 eV ⁃ Operated with up to 40 kW power ⁃ MNX computational studies on plasma detachment via (LSP) — Major upgrades taking place under new ARPA-E OPEN grant ⁃ Higher RF and magnet power ⁃ Lower frequency to heat ions

28 Cohen/Swanson, Compact Toroid & FIF, 2017 5/27/19 PFRC-2 Experiment

29 TWO NASA PROJECTS: 1. NASA NIAC STUDY 2. NASA PHASE II STTR

‹#›30 Questions to Answer

1. Can PFRC really produce (net power from) fusion? 2. Can DFD be made to operate for long durations in space? 3. Can DFD achieve the necessary specific power for the desired mission parameters?

Our NASA work is primarily addressing questions 2 and 3; continuing work at PPPL, and our new ARPA-E OPEN grant, address question 1.

31 NIAC: Systems Analysis of the DFD Engine

Electrolysis

D2O Auxiliary Power O2 Unit Startup RF Generator Coil Radiator Refrigerator Gas D Box Plasma HTS Coil Blanket Coil Cooling 3He Space Thermal Conversion neutrons Bremsstrahlung Generator Synchotron

Brayton Shielding Coolant Radiator Heat Engine

32 5/27/19 Typical Reactor Parameters

Parameter Value The fuel ratio sacrifices some power density Fuel D-3He for lower radiation (less D-D fusion). Fuel Ratio 1:3 Parameter Value rs 0.3 m n 3-5x1020/m3 Elongation, K 5-10 e Te 50 keV Baxial 5-7 T Ti - Deuterium 70 keV Bnozzle 20 T Ti – Helium-3 70-140 keV BRMF/Baxial ~0.1-0.5% S*/K 2.8 (kinetic) ! 0.85 " 0.02 Plasma current 10 MA LH RF frequency 0.2 MHz SOL temperature 20-120 eV

33 Power Flow and Specific Power – 1 MW

• RMF power is ~10% of the fusion power • Specific power is higher for larger engines, since the mirror magnets remain the same • Range, 0.5 – 1.5 kW/kg, based on assumptions for shielding and other subsystems

34 5/27/19 Engine and Spacecraft Design

Structure 9% Shielding 26%

Radiators 19%

Power Conversion Magnets 13% 24% RMF System Cooling 8% 1%

Example Mass Breakdown

35 Thrust and Velocity Model

UEDGE Velocity Model 6 120

5.5 Results indicate a feasible range of flow 115 rates for the SOL to absorb the energy 5 110 from the fusion products. 4.5 4 105

3.5 UEDGE Thrust Model 100 6 60 3

5.5 2.5 95 Input Power (MW) Exhaust Velocity (km/s) 5 50 2 90 4.5 1.5 40 85 4 1

3.5 0.5 80 30 0.1 0.2 0.3 0.4 0.5 0.6 3 Mass Flow (g/s) Thrust (N)

2.5 Input Power (MW) 20 2 This gives us a numerical model to trade 1.5 10 thrust and . 1

0.5 0 0.1 0.2 0.3 0.4 0.5 0.6 Mass Flow (g/s)

36 Magnet Design Tools

New, self-consistent Grad-Shafranov magnetic flux solutions with plasma

Individual magnet currents estimated

Latest design: PLASMA Flow LTS axial magnets Mirror AND 2-3 T axial magnets 20-30 T mirror HTS mirror magnets 5-7 T central field

Grad-Shafranov: equilibrium equation in ideal magnetohydrodynamics (MHD) for a two dimensional plasma

37 New Work: Magnet STTR Phase II

• T2.01 Advanced • New Phase II STTR • Create an LTS magnet 7 cm testbed • Use pulsed inner copper

coil to simulate FRC Warm Bore: Mandrel: ~30 cm plasma formation 24 cm

Insert: • Test impact on magnets 28 cm of plasma formation in close proximity • Design HTS magnets in detail

38 Closed-Loop Power Plant Design

Field Shaping RF Heating Coils Fuel Antenna Mirror Coil

D-3He Fusion

Coolant Exhaust

Cool Plasma Energy Absorbed Heat and Ash Extraction

39 NEXT STEPS AND ROADMAP TO FLIGHT

40 Path to Fusion in the PFRC

Field reversal Raise power and field High field operation Long pulse stability (200 kW and 0.1 T) Particle exhaust Electron heating Lower frequency Demonstrate fusion (100 eV bulk and 700 Heat ions eV tail with 20 kW) STTR: magnets Next Steps Confirmed In Progress ARPA-E: heating

Machine PFRC-1 PFRC-2 PFRC-3 PFRC-4 Objectives Electron Heating Ion Heating Heating above 5 keV D-He3 Fusion

Fuel H H H, D D-3He

Goals/ 0.3 s pulse* 3 ms pulse* 1000 s pulse Achievements* 1.2 kG field 10 s pulse 0.15 kG field* 60 kG field e-temp = 0.5 keV* 10 kG field e-temp = 0.3 keV* i-temp = 50 keV i-temp = 1 keV i-temp = 5 keV RF power = 10 kW RF power = 1 MW RF power = 30*/200 kW

Plasma Radius 4 cm 8 cm 16 cm 25 cm Time Frame 2008-2011 2011-2020 2020-2023 2023-2025

41 Key Enabling Innovations for Space

Heat PFRC Magnets Radiators Cryogenics Engine

High-temp Compact “dry” Ceramics Carbon- Lightweight cooling of carbon tanks LTS 1-10 MW Electric “mini" Transmission reactor

Woven fiber New 2nd gen HTS Carbon- Low fins coatings carbon radioactivity recuperator

42 8/1/18 Notional Roadmap to Flight

2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030

PFRC-3 Conversion Testbed Superconducting magnets Brayton cycle PFRC-4: Fusion Fields 1-2 T development DFD Flight Prototype Ions to 5 keV Non-fusion heat Demonstrate long source pulses of D-3He fusion No radioactivity! Steady state Flight Applicable to all Fields 5-7 T Full shielding nuclear power Achieve 50-100 keV Reactor systems Optimize mass 100 s pulses Fueling beams ISS test Startup system Cryogenics Thrust Carbon radiators Conversion Plume steering Payload!

43 Mission Concept: Titan Autogyro

44 Mission Concept: Solar Gravitational Lens

Deliver telescope in < 15 years

Flyby 600

400

200

Distance (AU) 0 0 2 4 6 8 10 12 14

Image: Aerospace Corp. 600

400

200

Velocity (km/s) 0 0 2 4 6 8 10 12 14

4000

2000

Mass Fuel (kg) 0 0 2 4 6 8 10 12 14 Time (years) Princeton Satellite Systems

45 Thank You

Stephanie Thomas [email protected]

Princeton Satellite Systems 6 Market St. Suite 926 Plainsboro, NJ 08536 http://www.psatellite.com (609) 275-9606

Dr. Samuel Cohen [email protected] Princeton Plasma Physics Lab Plainsboro, NJ

46 Your favorite mission is better with a fusion engine!

Solar gravitational lens Saturn Cislunar space gateway Mars base Uranus Pluto orbiter and lander

Lunar base Titan Asteroid defense

High-power Earth satellites Europa Neptune Interstellar precursor

47 Backup Slides

ADDITIONAL TECHNICAL INFORMATION

‹#› Fusion “Cross-Sections”

Reaction Rates −20 10

−22 x x 10 x • D-3He requires −24 10 D-T 10x higher −26 10 D-D temperature

/sec) −28 3 10 D-3He Reactor operating than D-T −30 10 temperatures • p-B11 requires −32 10 higher still

Mean Sigma V (m −34 10 p-11B

−36 10 D−D−n D−D−p −38 10 D−T D−He3 p−B11 −40 10 0 1 2 3 10 10 10 10 Temperature (KeV) Princeton Satellite Systems

49 Neutron Reduction Mechanisms in the PFRC

1.Tokamak -> FRC ⁃ Neutron load actually WORSE 2.Fuel – D-3He 3.Size – small radius FRC ⁃ First big reduction in overall load 4.Fast removal of tritium in scrape-off layer 5.Low D fuel ratio: ⁃ D/3He of 1:3 6.Non-equilibrium: 3 ⁃ D heating only ½ as much as He by wRMF ⁃ Beam-like distributions

50 UEDGE Ion Velocity Model

51 UEDGE Ion and Electron Temperatures

Ion Temperature (eV)

0.4 20 The ions cool off as they 0.35 accelerate down the 0.3 15 magnetic nozzle. r 0.25 10 0.2

0.15 5 The carry some 0.1 thermal energy with them. -4 -3 -2 -1 0 1 2 3 4 5 z

Electron Temperature (eV) (2 MW, 4.3 kA) 0.4 20 0.35

0.3 15

r 0.25 10 0.2

0.15 5 0.1

-4 -3 -2 -1 0 1 2 3 4 5 z

52