PSS and the Princeton Plasma Physics Lab (PPPL) are collaborating on a new fusion technology. Direct Fusion Drive is a revolutionary direct-drive, fusion-powered rocket engine concept. Compact and clean-burning, each 1-10 MW Direct Fusion Drive (DFD) engine would produce both power and thrust with high specific power (low mass). Producing propulsion directly in the fusion engine is highly efficient, shortening trip times and increasing capability for a wide variety of space missions: robotic missions to the outer planets, human missions to the moon or Mars, missions to near interstellar space. Here on Earth, portable fusion microreactors will enable modular power plants and integrate seamlessly with the future distributed power grid.

DFD is based on the Princeton Field-Reversed Configuration (PFRC) reactor, a technology developed by Dr. Sam Cohen of PPPL. The reactor employs a unique “odd-parity” RF heating method, producing a steady-state, closed-field configuration with a highly efficient current drive. The PFRC-2 experimental machine is currently in operation at PPPL, a plasma pulse is shown below. Read more on the PFRC technical papers page!

PFRC-2 has been supported by the Department of Energy, ARPA-E, NASA Innovative Advanced Concepts and two NASA STTRs. Our NIAC context mission was a Pluto orbiter and lander that are delivered in just 4 years, and can send back the equivalent of HD video!

We have analyzed DFD for many missions and applications:

• Human Mars orbital mission
• Deploying the James Webb Telescope to a Lagrange point
• Asteroid deflection
• Jupiter Icy Moons Mission
• Pluto orbiter and lander
• Alpha Centauri
• 600+ AU gravity lens telescope
• Mobile and modular terrestrial power

In all cases, DFD reduces trip times and increases payload capability and science return! For the latest updates on our research, check out our DFD blog posts.

Publications and News:

• Nuclear fusion powered Titan aircraft, M. Paluszek, A. Price et al, Acta Astronautica, April 2023

• A Fusion-Propelled Transportation System to Produce Terrestrial Power Using Helium-3 From Uranus, S. J. Thomas and M. A. Paluszek, AIAA SciTech Forum, January 2023
• Lunar Cargo Tug Using Direct Fusion Drive, C. Swanson et al, AIAA SciTech Forum, January 2021
• Fast Human Missions to Mars Using Direct Fusion Drive with a Nuclear Thermal Stage, S. Thomas et al, AIAA ASCEND, November, 2020
• Direct Fusion Drive for Interstellar Exploration, S. Cohen et al, JBIS, February, 2019.
• Direct Fusion Drive for Rapid Deep Space Propulsion, Future In-Space Operations (FISO) Telecon, S. Thomas, May, 2019.
• Thrust Modeling and Power papers at the 2018 AIAA Propulsion and Energy Forum
• TheFusionPodcast interview with Stephanie Thomas
• Fusion-Enabled Pluto Orbiter and Lander, S. J. Thomas, M. Paluszek, S. Cohen, N. McGreivy, and E. Evans, AIAA Space Forum, September 2017.
• Scientific American and Space.com: Could Tiny Fusion Rockets Revolutionize Spaceflight? June 12, 2017
• NASA NIAC grant, Fusion-Enabled Pluto Orbiter and Lander
  • 2017 Phase II summary
  • Phase I final report (March, 2017)
  • 2016 Phase I summary and video of symposium talk (17:30 in)
• WHYY radio bit on DFD, April 14, 2017
• NASA 360 video on DFD, Feb 11, 2017
• Princetoninfo.com (US 1): At PPPL: Fusion for Energy, Eggs, and More. December 16, 2015.
• A direct fusion drive for rocket propulsion, Y. S Razin, G. Pajer, M. Breton, E. Ham, J. Mueller, M. Paluszek, A. H Glasser and S. A Cohen, Acta Astronautica, Number 1, pp 145–155, December, 2014, also from IAC 2012.
• Direct Fusion Drive [PDF], slides presented at the 20th Advanced Space Propulsion Workshop, S. Thomas, M. Paluszek, and S. Cohen, November, 2014.
• Direct Fusion Drive for a Human Mars Orbital Mission, M. Paluszek, G. Pajer, Y. Razin, J. Slonaker, S. Cohen, R. Feder, K. Griffin and M. Walsh, International Astronautical Congress, October, 2014.
• Time.com: Going to Mars via Fusion Power? Could Be. September, 2013.
• Direct Fusion Drive Rocket for Asteroid Deflection [PDF], J. Mueller, Y. Razin, S. Cohen, A. Glasser, et al, 33rd International Electric Propulsion Conference, October, 2013
• Aneutronic Fusion Engine for an Alpha Centauri Mission [PDF], slides presented at DARPA 100 Year Starship Conference, M. Paluszek, S, Hurley, G. Pajer, S. Thomas, J. Mueller, S. Cohen, D. Welch, September 2011.

PSS has licensed five patents from PPPL for commercializing the PFRC:

• “System and method for small, clean, steady-state fusion reactors”, S. Cohen and M. Chu Cheong, US 11,322,265 issued 5/3/2022
• “System and method for reducing heat loss from FRC bulk plasma,” US 11,164,681 issued
  11/02/2021
• “Fueling Method for Small, Steady-State, Aneutronic FRC Fusion Reactors,” US 10,811,159  issued 10/20/2020
• “Method To Produce High Specific Impulse and Moderate Thrust From a Fusion-Powered Rocket Engine,” S. Cohen, G. Pajer, M. Paluszek, Y. Razin, US Patent Number 9,822,769 issued 11/11/2017.
• “Method To Reduce Neutron Production in Small Clean Fusion Reactors,” S. Cohen, US Patent Number 9,767,925 issued 9/19/2017.

In addition we have patents specific to PFRC operation in space:

• “In Space Startup Method for Nuclear Fusion Rocket Engines,” Paluszek, M., Ham, E., Cohen, S., and Razin, Y. US Patent 10,811,143 issued 10/20/2020
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Princeton Satellite Systems has a doing-business-as name for terrestrial fusion applications: Princeton Fusion Systems. Visit our sister site for more information on PFRC!