NASA funds Direct Drive Fusion Propulsion

Tom Kalbfus · 2016-04-13 09:35:03

NASA funds Direct Drive Fusion Propulsion
The Direct Fusion Drive (DFD) concept provides game-changing propulsion and power capabilities that would revolutionize interplanetary travel. DFD is based on the Princeton Field-Reversed Configuration (PFRC) fusion reactor under development at the Princeton Plasma Physics Laboratory. The mission context we are proposing is delivery of a Pluto orbiter with a lander. The key objective of the proposal is to determine the feasibility of the proposed Pluto spacecraft using improved engine models. DFD provides high thrust to allow for reasonable transit times to Pluto while delivering substantial mass to orbit: 1000 kg delivered in 4 to 6 years. Since DFD provides power as well as propulsion in one integrated device, it will also provide as much as 2 MW of power to the payloads upon arrival. This enables high-bandwidth communication, powering of the lander from orbit, and radically expanded options for instrument design. The data acquired by New Horizons' recent Pluto flyby is just a tiny fraction of the scientific data that could be generated from an orbiter and lander. We have evaluated the Pluto mission concept using the Lambert algorithm for maneuvers with rough estimates of the engine thrust and power. The acceleration times are sufficiently short for the Lambert approximation, i.e. impulsive burns, to have some validity. We have used fusion scaling laws to estimate the total mission mass and show that it would fit within the envelope of a Delta IV Heavy launch vehicle. Estimates of the amount of Helium 3 required to fuel the reactor are within available terrestrial stores.

In this Phase I study, we propose to analyze the Pluto mission concept using new models of the engine. We will develop an optimal trajectory including limits on the thrust steering and range of throttle. The throttling of the thrust and specific impulse will affect the efficiency, which we have not yet attempted to model.

Direct Fusion Drive is a unique fusion engine concept with a physically feasible approach that would dramatically increase the capability of outer planet missions. The fusion-enabled Pluto mission proposed here is credible, exciting, and the benefits to this and all outer planet missions are difficult to overstate. The truly game-changing levels of thrust and power in a modestly sized package could integrate with our current launch infrastructure while radically expanding the science capability of these missions

There was a 2014 presentation on the Princeton Direct drive fusion concepts. and a work from 2013

• 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 transferring energy from the fusion products.

The work has been covered at Nextbigfuture back in 2014 and in 2013

This is different than the John Slough's direct fusion drive rocket design. John Slough also had NASA funding.

tahanson43206 · 2021-09-14 12:11:53

RobertDyck appears to have found an update to this original topic by Tom Kalbus ...

http://newmars.com/forums/viewtopic.php … 00#p185000

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RobertDyck · 2021-09-14 12:54:38

Ok, merging topics...

phys.org: Spacecraft design could get to Titan in only 2 years using a direct fusion drive

The concept fusion drive, called a direct fusion drive (or DFD), is in development at the Princeton Plasma Physics Laboratory (PPPL). Scientists and Engineers there, led by Dr. Samuel Cohen, are currently working on the second iteration of it, known as the Princeton field reversed configuration-2 (PFRC-2). Eventually, the system's developers hope to launch it into space to test, and eventually become the primary drive system of spacecraft traveling throughout the solar system.

Wikipedia: Direct Fusion Drive

Principle
In the DFD system, the plasma is confined in a torus-like magnetic field inside of a linear solenoidal coil and is heated by a rotating magnetic field to fusion temperatures. Bremsstrahlung and synchrotron radiation emitted from the plasma are captured and converted to electricity for communications, spacecraft station-keeping, and maintaining the plasma's temperature. This design uses a specially shaped radio frequency (RF) "antenna" to heat the plasma. The design also includes a rechargeable battery or a deuterium-oxygen auxiliary power unit to startup or restart DFD.
The captured radiated energy heats to 1,500 K (1,230 °C; 2,240 °F) a He-Xe fluid that flows outside the plasma in a boron-containing structure. That energy is put through a closed-loop Brayton cycle generator to transform it into electricity for use in energizing the coils, powering the RF heater, charging the battery, communications, and station-keeping functions.
Thrust generation
Adding propellant to the edge plasma flow results in a variable thrust and specific impulse when channeled and accelerated through a magnetic nozzle; this flow of momentum past the nozzle is predominantly carried by the ions as they expand through the magnetic nozzle and beyond, and thus, function as an ion thruster.
Projected performance
Analyses predict that the Direct Fusion Drive would produce between 5-10 Newtons thrust per each MW of generated fusion power, with a specific impulse (Isp) of about 10,000 seconds and 200 kW available as electrical power. Approximately 35% of the fusion power goes to thrust, 30% to electric power, 25% lost to heat, and 10% is recirculated for the RF heating.

Note: 10 Newtons thrust = 1.0197162129779 kg-force. Can this be scaled up for TMI for a Large Scale Colonization Ship?

tahanson43206 · 2021-10-03 12:45:52

For RobertDyck .... there will be a talk on fusion in the upcoming Mars Conference ...

Helicity Space Co-Founder to Address Mars Society Convention about Fusion Drive Concept
The Mars Society is pleased to announce that Dr. Setthivoine You, Co-Founder and Chief Scientist of Helicity Space, will discuss his company’s Helicity Drive, a novel fusion drive concept, during the 24th Annual International Mars Society Convention, set for October 14-17, 2021.
Helicity Space is developing an in-space fusion propulsion and power technology, critical to enabling humanity’s access to the solar system, with a Helicity Drive-powered flight to Mars expected to take two months, without planetary alignment.
Dr. You received his M.S. degree and Ph.D. in physics from the Imperial College London, and spent 18 years involved in experimental and theoretical research in plasma physics at the University of Washington, CalTech, and the University of Tokyo before entering the private sector.
This year’s virtual Mars Society convention will be free of charge (although donations are welcomed). For complete details, including online registration, a list of confirmed speakers, and sponsorship opportunities, please click here. Regular updates will be posted in the coming weeks on the Mars Society web site and its social media platforms.

The Mars Society
11111 West 8th Avenue, unit A
Lakewood, CO 80215 U.S.A.
www.marssociety.org
https://www.facebook.com/TheMarsSociety
@TheMarsSociety
Copyright (c) 2021 The Mars Society
All rights reserved.

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tahanson43206 · 2025-09-03 13:17:08

The last post in this topic was 2021.... today someone (or some*thing*) on the Internet decided to recycle this old news:

https://www.universetoday.com/articles/ … sion-drive

The content seems to be identical to the article from phys.org that RobertDyck showed us.

It is past time for an update on this work. My own assessment is that the idea of doing ** anything ** with deuterium in a small engine is unlikely this century.

The article itself points to ITER as a model for a huge fusion reactor.

This topic is available if anyone in NewMars runs across an update.

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kbd512 · 2025-09-04 14:39:41

There's a major difference between the difficulty of confining a plasma long enough to use it to generate baseload electricity vs the far lower relative difficulty of intentionally allowing said plasma to escape from its magnetic confinement chamber to generate thrust. The technological bar to clear for generating electricity using fusion, in a manner similar to a fission reactor, is monumentally high. The bar to clear for achieving thrust has already been cleared. There's no question that using fusion to achieve thrust actually works.

When MSNW LLC did the initial development work on the concept, they proved that all major components worked to the degree required, but then NASA immediately pivoted to something that looked better in theory, namely continuous thrust generation from continuous fusion power, but continuous fusion requires long term plasma confinement, similar to a conventional Tokamak. That's the part we cannot yet do in a practical manner- fusion that generates net positive electrical output to use as input for a self-sustaining reaction.

Why did they do that?

NASA is focused on science, not producing tangible usable things like a pulsed fusion drive as an enabler for their own exploration missions.

That's the best answer I can come up with.

Calliban · 2025-09-04 15:02:37

Maybe the US needs a new space agency. One that is run as a partnership between public and private interests. Unlike NASA, it should be devoted to human colonisation and financial profit from space, rather than just sucking the teat of taxpayer dollars for make work projects and nebulous science goals. Other nations could cooperate on joint missions. But to do so, they should accept equitable portions of upfront costs.

Lunar and asteroid mining, orbital manufacturing of power satellites, space habitats and interplanetary ships would be its bread and butter. Research will be goal oriented and will be driven by technological readiness and relevance to financial and long-term human colonisation goals. Things like food production without sunlight, fusion drives, compact fission reactors, etc. We need something that works more like the Dutch East India company than a government agency obsessed with abstract science goals. Scientific research certainly is important. But it needs to go hand in hand with other priorities.

Last edited by Calliban (2025-09-04 15:09:17)

kbd512 · 2025-09-04 23:20:31

I think pure greenfield science is a worthy goal unto itself. I agree with the notion that pursuit of knowledge, for its own sake, is a worthy and laudable goal. However, when our stated exploration goals require better / cheaper / faster propulsion systems, and we have what's required on-offer from a competent corporation that can deliver the goods, I think that is where science must be goal-oriented. A number of corporations have offered improved engines over many decades now. Apart from SpaceX and Blue Origin, NASA is still using engines that were the product of 1970s development efforts. NASA and DoD spent billions upon billions of dollars on new engine designs, but none of them ever replaced what they've either been developing or actively using over 50+ years. That's the extent of what we have to show for all the efforts made by our various aerospace primes. There's no world where that makes rational sense, except in a carefully constructed one that's long since been strangled by bureaucracy. The RS-25 could've been evolved into something 3D-printed components, uncooled RCC nozzles, improved turbopump designs and materials, etc. We spent good money and decades of development work on all of that, yet it's nowhere to be found in the engines NASA is using to send people back to the moon. It's little wonder that their rockets cost so much and have flown so infrequently, relative to what was promised. We can't keep running the same program while expecting different results.

There's a reasonably logical progression to in-space propulsion technology, the one mission critical technology where all of humanity is weakest. We began with solid rockets which were more suitable for weapons than space launch vehicles. We swiftly moved on to liquid fueled engines. We developed ion engines around the same time the Apollo Program was in full-swing. Around the same time development of ion engines began in earnest, we also developed nuclear thermal rockets using compact / high power density fission reactor cores. Neither were intended to replace chemical rockets for orbital launch vehicles, but both were necessary in-space propulsion solutions to problems that chemical rockets could not address in a practical way. Fusion rockets are the next logical progression of in-space propulsion options. While we work on fusion rockets, we should continue to pursue propellantless "impulse" engines and warp drives. Although teleportation and various other Star Trek level technologies will likely require another century or more of development work, if we put forth the effort now, when it matters most to near-term colonization efforts, then we'll have "real starships" by the time we work out the details of the more advanced bits of Star Trek tech. What we cannot do, presuming the goal is real exploration and colonization, is to continue to aimlessly throw money at every potentially interesting new propulsion technology without maturing "within reach" technologies to relentlessly advance our propulsion systems. Pulsed fusion using supersonic implosion of light alloy foils to generate thrust is well within reach. Continuous fusion using gases would be better still, but we're probably at least a couple of decades away from that being achievable.

Why wait another several decades for "better fusion rockets", when a fully functional pulsed fusion rocket would mean on-demand access (no waiting for orbits to align) to the solar system within the next decade? All the individual pieces work. We need to put them together into a fully functional high-thrust / 5,000s+ Isp in-space propulsion system. This is an engineering task, rather than a greenfield tech development task. NASA balked at spending more money on completing development of a pulsed fusion rocket engine the moment a continuous fusion rocket looked as though it was a possibility. It's as if they cannot maintain focus long enough to produce a fully functional product usable for their own purposes. In their own words, they did that "because a continuous fusion rocket engine could be even better". That sounds great, but nobody has created a fully functional stationary continuous fusion reactor, so creating a flight weight continuous fusion rocket engine seems more than a little premature, even though there are companies actively pursuing this. We have to start somewhere, so clearing the lowest set of technological hurdles to an operational fusion rocket engine seems like the best place for NASA and JPL to start. Argue over how the rocket could be made "even better" after you have a TRL9 pulsed fusion rocket engine. Improving the TRL of a continuous fusion rocket engine ought to be that much easier when you already have an in-service pulsed fusion engine.

We need people and corporations to expand the edges of the performance envelope with the express purpose of using the fruits of their labor as a goal-oriented enabler for our stated exploration and colonization objectives. NASA, the agency, stated quite clearly that human exploration of Mars was the prize, even as it continued to pursue a plethora of pure science projects. While useful in their own right, the "result" which emerged over the course of many decades was an unfocused and unimaginative collection of distantly related science projects with no clear tieback to stated exploration objectives. The problem, at least as I see it, is the lack of measurable progress towards the agency's stated human exploration objective. Nobody who is in charge seems the least bit interested in true exploration, likely because it's dangerous, unpredictable, expensive, and requires unwavering determination to succeed. We clearly had that during the Apollo Program, but lost it somehow because we changed technologies. We looked for reasons why we couldn't succeed, rather than accepting and using what was on offer. For example, Shuttle-C should've been pursued during the Space Shuttle era to maintain the capability to conduct exploration missions. SLS is about 30 years late. ISS should've been used as a prototype Interplanetary Transport Vehicle. The means has always been there, but the will has not.

It would be fair to say that private corporations are now driving technological development aimed at specific exploration and colonization objectives, because various billionaires see space exploration and colonization as one of the few remaining, truly worthwhile, "next steps" in human development. After you acquire tens of billions of dollars, space exploration and colonization is the only worthwhile investment commensurate with the level of investment involved. You can build more factories to turn out new tech trinkets, gold-plate your toilets, or build an enormous yacht that might get used once per year, but eventually all of those "status symbols" will be viewed as empty idle pursuits by someone who is driven to build an empire. Elon Musk famously lives in a studio apartment, drives an unremarkable "standard" Tesla his company built, and owns a handful of clothes, because there's no point to accumulating more "stuff" that he'll never see or use. This is a very peculiar state of affairs, because traditionally governments have been the driving force behind exploration efforts.

The men and women who are now leading these efforts have looked upon what their governments are doing and said to themselves, "You're no longer completing the job that the people you represent expect to be done, after you sold them on the idea and spent obscene amounts of money. We don't have many milestones we can point to whereby progress can be shown to the general public. We're taking over where you've failed us." That's the quiet part, not typically said out-loud, but it's present in the minds of people looking at what NASA is doing and asking pointed questions about the apparent lack of progress. Do or do not. There is no "try".

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#1 2016-04-13 09:35:03

NASA funds Direct Drive Fusion Propulsion

#2 2021-09-14 12:11:53

Re: NASA funds Direct Drive Fusion Propulsion

#3 2021-09-14 12:54:38

Re: NASA funds Direct Drive Fusion Propulsion

#4 2021-10-03 12:45:52

Re: NASA funds Direct Drive Fusion Propulsion

#5 2025-09-03 13:17:08

Re: NASA funds Direct Drive Fusion Propulsion

#6 2025-09-04 14:39:41

Re: NASA funds Direct Drive Fusion Propulsion

#7 2025-09-04 15:02:37

Re: NASA funds Direct Drive Fusion Propulsion

#8 2025-09-04 23:20:31

Re: NASA funds Direct Drive Fusion Propulsion

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