PFRC Paper Accepted to Physics of Plasmas

Our colleague Eugene Evans of PPPL has had his paper, “Particle-in-cell studies of fast-ion slowing-down rates in cool tenuous magnetized plasma,” accepted for publication in Physics of Plasmas. The article is tentatively scheduled for the April 2018 issue. A quote from the reviewer:

The paper … is an interesting, well-written paper that uses PIC to build upon earlier direct numerical simulation methods based on molecular dynamics. The authors present a clearly written discussion of the scaling properties of slowing down theory to support their numerical studies. The authors do a very good job describing the simulation approach they take… Of particular note in the paper is the good agreement between their numerical data and the sub-thermal model even when the effective computational log(lambda) was on the order of 1…  the authors did not stop with their results but instead applied their conclusions to the FRC reactor, predicting that the neutron production rate is 100 times lower than a conventional DT Tokamak.

This paper is key to the low radiation levels claimed for our PFRC design, and hence the Direct Fusion Drive. The fast ion slowing-down is what causes the tritium and other fusion ash to exit the machine. You can view a preprint on arXiv.

We will post again once the paper is published and available from Physics of Plasmas.

Fusion Power Associates Meeting

I attended the 2017 Fusion Power Associates meeting in Washington, D.C. on December 6 and 7. Fusion Power Associates is a non-profit, tax-exempt research and educational foundation, providing timely information on the status of fusion development and other applications of plasma science and fusion research.

The annual meeting brought together experts in all areas of nuclear fusion research including scientists and engineers from ITER, the Princeton Plasma Physics LaboratoryTAE TechnologiesGeneral Atomic and many others! The meeting gave a great overview of the state of nuclear fusion power generation. We learned that ITER is 50% complete and on its way to first plasma in 2025. Planning has begun on Demo, the follow-on to ITER.

The Joint European Torus plans a D-T campaign in 2019 and hopes to set new fusion benchmarks. We learned about Korea Superconducting Tokamak Advanced Research  (KStar). It has achieved longer than 70 second pulses in H-mode and has suppressed ELM for more than 34 seconds. KStar has in-vessel control coils.

There were several speakers from the University of Rochester along with colleagues from the national laboratories talking about advances in laser compression of fuel pellets. This work is for nuclear weapons research but could be applied to inertial confinement fusion.

I gave the last talk of the meeting on Princeton Satellite Systems and PPPL’s work on DFD, nuclear fusion propulsion for spacecraft.

Second DFD Patent Awarded

We are pleased to report that an additional patent has been awarded for DFD! US Patent 9,822,769, “Method and Apparatus to Produce High Specific Impulse and Moderate Thrust from a Fusion-Powered Rocket Engine”, was published on Nov. 21, 2017. It’s now available from the US patent office website!

Here is a link to the patent from the Department of Energy’s Energy Innovation Portal! The inventor on the patent are Dr. Cohen, of PPPL, and three PSS engineers: Gary Pajer, Michael Paluszek, and Yosef Razin.

Fusion Rocket Engine

Rendezvous with 1I/’Oumuamua

An interstellar asteroid, 1I/’Oumuamua, was discovered on a highly hyperbolic orbit by Robert Weryk on October 19, 2017 moving with a speed of  26.32 km/s. It appears to come from the direction of the star Vega in the constellation Lyra. It would be really great to send a mission to rendezvous and fly in formation with 1I/’Oumuamua to study the asteroid. The high velocity makes it hard to do with current technology.

Direct Fusion Drive (DFD) might provide a answer. We designed a spacecraft with a 1 MW DFD power plant and assumed a launch on March 16, 2030. The following plots show the trajectory and the force, mass and power of the spacecraft during the 23 year mission. As you can see we don’t have to use the full 1 MW for propulsion so we have plenty of power for data transmission and the science payload.


The code for this analysis will be available in Release 2018.1 of the Princeton Satellite Systems  Spacecraft Control Toolbox for MATLAB.

Asteroid Day

June 30 is Asteroid Day. Asteroid Day is a reminder that we need to protect the Earth from asteroids. We need both an early warning system and a means for deflecting asteroids. The B612 Foundation is working on an early warning system. Direct Fusion Drive, a nuclear fusion rocket engine technology under development jointly by Princeton Satellite Systems and the Princeton Plasma Physics Laboratory could provide the means to deflect asteroids that are on a course to collide with the earth. We published a paper in October 2013 on how this might be done

Direct Fusion Drive Rocket for Asteroid Deflection [PDF], J. Mueller, Y. Razin, S. Cohen, A. Glasser, et al, 33rd International Electric Propulsion Conference.

Samuel Cohen, inventor of the Princeton Field Reversed Configuration reactor that is the core of our engine, co-authored a paper on comet deflection.

We are currently supported by a DOE grant, two NASA STTRs and a NASA Phase II NIAC grant! For more information go to our nuclear fusion page.

Foundations of Interstellar Studies Workshop

Dr. Sam Cohen and I had a good time at the Foundations of Interstellar Studies Workshop this week in NY! While we were only able to stay for the first day on “Energetic Reaction Engines”, there were many thoughtful discussions on applying fusion technology to interstellar travel. Here I am in the group photo from the welcome event Monday night, held at the Harvard Club with an interesting and wide-ranging display of interstellar art! (I’m in the first row on the far right).

Group photo

Group photo from Foundations of Interstellar Studies workshop

The workshop was almost a mini-NIAC reunion, as NIAC fellows Phil Lubin and Ray Sedwick were there, and Heidi Fern was due to present her Mach Effect thruster on Thursday. Also NIAC External Council member Lou Friedman of the Planetary Society was in attendance (very back of the photo).

Our presentation for this conference focused on how the PFRC addresses the key parameters needed for a “net positive” fusion reactor: energy confinement, current drive, plasma heating, and plasma stability. We are often asked “why fusion will work this time”, and this paper does a good job of explaining why the PFRC is different enough from other approaches to work! The workshop is going to submit all of the papers to the Journal of the British Interplanetary Society, which is the oldest astronautical journal in the world (1934).

We also discussed the parameters the propulsion system will need to achieve to reach Alpha Centauri in various time scales, as well as a more near-term mission deliver a gravitational lens telescope to 550 AU. Reaching Alpha Centauri in anything close to a human lifetime remains a significant challenge, but PFRC could be part of an architecture to reach the star in 300 to 500 years, and slow down enough to go into orbit around the potentially Earth-like planets there! The 550 AU telescope mission, however, could be achieved in as little as 12 years with just one small PFRC and is an exciting new mission possibility.

Our next interstellar appearance will be at the Tennessee Valley Interstellar Workshop in October in Huntsville, AL!

DFD paper accepted for Workshop of Interstellar Flight

Our paper “Direct Fusion Drive for Interstellar Exploration” has been accepted for the Workshop of Interstellar Flight that will be held at CUNY City Tech, 13-15 June 2017! The workshop is organized by the Institute for Interstellar Studies and City Tech’s Physics Department and Center for Theoretical Physics.

We will present the latest results from our NASA NIAC work on DFD design as well as applications to interstellar missions, including:

  • A mission to 550 AU to perform gravitational lensing imaging of exoplanets;
  • Flyby missions to the nearest star;
  • A mission to go into orbit about a planet orbiting either Alpha-Centauri A or Alpha-Centauri B.

NASA NIAC Phase II selected!

We received notice today, March 31, 2017, that our NASA NIAC Phase II proposal was selected for award! We will be able to continue working on the Direct Fusion Drive with PPPL for two more years. Hooray! Dr. Joseph Minervini of MIT will be joining our team to help advance our understanding of the trade space for the superconducting coils, using the very latest data from high-temp superconductor manufacturers. It’s going to be exciting research!

Here’s a link to NASA’s official project summary.