SPARC Fusion Reactor on Track for 2035

The SPARC Fusion reactor team have made good theoretical progress to the goal of a commercial nuclear fusion reactor. SPARC is a compact, high-field, DT burning tokamak, from the Massachusetts Institute of Technology and Commonwealth Fusion Systems.

The SPARC design with a 12.2 tesla magnetic field and 8.7 megaamps and Ion Cyclotron Range of Frequency Heating (ICRF) power up to 25 MW targets a minimum fusion gain over double the input power with output power. SPARC should get over ten times the input power (Q > 10) and 140 MW of fusion. This would mean SPARC will be burning plasma at those performance levels.

The SPARC project was launched in early 2018. they have been working on the superconducting magnets that are key to making the fusion system much smaller.

There are now seven new peer-reviewed papers that detail the underlying physics basis for the SPARC machine.

CFS and MIT’s PSFC are building the advanced magnets that will allow CFS to build significantly smaller and lower-cost fusion power plants. They are on track to build a successful 20 Tesla, large-bore magnet in 2021. The magnets will then be used in SPARC, which is on track to begin construction in 2021 and demonstrate net energy gain from fusion for the first time in history by 2025. SPARC will pave the way for the first commercially viable fusion power plant called ARC.

Journal of Plasma Physics -Overview of the SPARC tokamak

Journal of Plasma Physics – Projections of H-mode access and edge pedestal in the SPARC tokamak

Journal of Plasma Physics- Divertor heat flux challenge and mitigation in SPARC

Journal of Plasma Physics-Physics basis for the ICRF system of the SPARC tokamak

Ion cyclotron range of frequencies (ICRF) heating will be the sole auxiliary heating method on SPARC.

Journal of Plasma Physics – MHD stability and disruptions in the SPARC tokamak

Journal of Plasma Physics – Fast-ion physics in SPARC

SOURCES – Cambridge, Commonwealth Fusion Systems, Journal of Plasma Physics
Written by Brian Wang,

47 thoughts on “SPARC Fusion Reactor on Track for 2035”

  1. Still better than ITERs pace of 50 years to build a single research reactor, trim it in an start doing interesting experiments.

  2. DEMO is sold as a commercial prototype fusion reactor built on ITER-technology (AKA obsolete technology), necessitating it to be 15% larger than ITER(50% greater volume). If you build DEMO and it succeeds spectacularly with all its stated goals (Q>25, P > 2 GWth etc) it will still be a giant neon sign proclaiming to the world that fusion power will never be commercially viable. A successful DEMO reactor is worse than nothing.

  3. Helium-3 is useless. It's much harder than D-T fusion. It is about as hard as D-D fusion. It produces less radiation, but that doesn't matter; we are talking about something like 2 meters of shield instead of 4 meters. Concrete, water and steel are cheap, so who on Earth cares? In space, yeah, maybe, but the weight increase of having a D-He3 reactor instead of a D-T reactor is probably on the same order as the weight of a shield (in space it only has to shield in one direction; there's nothing for neutrons to bounce on once they are thrown off into space in the wrong direction. On the Moon or on Mars, dirt is cheap and abundant; it is much better to bring less materials with you, which favours D-T. The only remaining advantage of D-D or D-He3 in those situations is not having to have a breeding blanket for tritium; you just bring the fuel, burn it once, don't care if you toss away some fuel without burning it.

  4. Yes, cannot get too picky over wording in a comment. We are on the same team. That is for editors and poof weeders. But I still have my cost doubts about baseload fusion power plants, given the advantages of power beaming to Earth, from Space, over other distribution systems. Sun = free fusion reactor up and running, doing the big scale distribution already. But that is for easy even tho big stuff, power grid. Sure hope this NASA *cold fusion* works!

  5. #Not all space enthusiasts

    Indeed I would count myself as a space enthusiast, but not a He3 mining enthusiasts.

    I mean, the people who go on about mining He3 on the moon are a group of space enthusiasts (but not the only one).

    Anyway, this is all moot.

    Next day's news is that NASA has solved fusion and we should all short coal and gas as hard as we can.

    Yes, stodgy old NASA, whom many were saying should be abandoned and broken up as clinging to last century space tech, might just have kicked us into the future we have all assumed wasn't going to ever arrive.

  6. Adam Smith really had this one nailed. The price of free fusion reactors is competing with Space Solar, child of another free, currently existing fusion reactor. The Sun has a pretty good distribution system going for itself, lots everywhere close that is not blocked by matter. By close, that depends on need, but ten times out further than Neptune is doable. Asteroid belt inwards, no big prob. In any direction, BTW. Collect this light into current/voltage, or boil water? Power beam from Space to Earth, or what, conducting wires (aka *transmission* lines) ? Now, about that free SPARC fusion reactor. I was kidding!

  7. "transferring them back to Earth would be easy enough." Yes, but even better is understanding O'Neill, and using them IN Space, as Oldjar07 indicated, 3rd para, even tho he is taking Euro-centric (corresponds to Earth-centric) viewpoint. He is basically describing moving into Space, but questioning the quick mining profit. I agree with his viewpoint, except think of Space Solar as quick "gold". Valuable enuf to get going towards the other things, even helping those who stay. Certainly helping those hoping to expand, leaving Earth as a Nature Preserve.

  8. "The He3 enthusiasts are not talking about ISRU", "space enthusiasts still cling to it (He3) as being one of the only space mining prospects that could provide space mission levels of money". This is what I am trying to fix, the notion that "space enthusiasts""cling" to it. NO. We clearly cling to ISRU!!

  9. Yeah, but Dan you are the one talking about ISRU. The He3 enthusiasts are not talking about ISRU, they are talking about mining stuff from the moon and returning it to Earth.

    So, to justify the dream of space mining (not for ISRU, but as a resource for Earth) you want to start with something that is concentrated enough in value that returning a couple of tonnes is a valid payload. Then you can work up to hundreds of tonnes, then thousands, then millions…

    Just as the European exploitation of the Americas started with looting Gold. Moved on to mining silver. And then started to build up farms producing sugar, cotton, tobacco etc.

    An earlier European attempt (the Vikings) tried to get started with furs, ivory, timber etc, but the value per tonne didn't justify the high shipping prices in those days*.

    Now, you can solve the problem another way, by adopting ISRU. Extracting space resources to support existing space missions. But that's not what the He3 fans are on about.

    * Interesting to wonder how history would have developed if the Vikings had found a native civilization in Eastern Canada who had gold and silver to loot.

  10. Yes, but that asteroid is clearly not what ISRU is, rather something beyond, needing ISRU to happen, but still part of the plan. I did start the quote a little late, leaving off the "one of the", but still the focus of your comment is on returning more or less stuff to Earth, *mining*, not the ISM/ISRU that is needed first, no matter what happens later. ISM/ISRU is the primary current focus of *mining*, which is why your comment surprised me. And, for me, the ISM/ISRU stuff is older than either the current names or the thought that there even might be water on the Moon. "space mission levels of money" needed now! I'll "cling to it".

  11. Just on this forum, many space-mining enthusiasts start on about
    ice -> water -> fuel

    but soon end up at

    billion tonne asteroids made of nickel that would supply the Earth market for centuries.

  12. I saw an analysis of exactly that. The value Europe got from their colonisation of the Americas.

    The analysis was published in the 1770s, so not biased by the view of the wealth of the Americas that we have today.

    The conclusion was that the vast majority of the value was in the form of new crops. Potatoes, Maize, all sorts of beans that sort of thing. Which were then grown in the old world.

    If we do find things like that in space: wonderful new chemistry, fantastic new biology. Buxom alien spacegirls… ahem, then transferring them back to Earth would be easy enough.

  13. That was the target back in the 70s too. Not to be a naysayer, but when it comes to fusion one really shouldn't put give too much credence to "date targets".

  14. Umm, that's kind of what guys were saying back in the 70s. I would offer you a bet that we won't see either in the next 25 years, but who's gonna remember that in 25 years….

  15. Well, when I read the article in the mag I think was 10. So no, I didn't contribute. That said, I think you're missing my point – which is "don't believe any predictions that anyone makes about the timelines of new technology".

  16. There has been no construction yet for SPARC — it isn't to start construction until 2021. Assuming the quote shown by Kenny Hill is accurate, the SPARC folks plan to use 20 tesla magnets.

  17. To get a little more specific to your example, not to disagree with it in general, but to perhaps find special cases. "gold mine" for example. The first thing Europe wanted/got from Americas was gold, already mined and collected. Gold is information, not really useful in itself at the time, just a *measure* of money, how much wealth you have, or a trading token. Also, very light for its value, actually "worth its weight in . . .". So it is more like info we get thru comm sats, a very valuable and long existing Space *resource*, that has no mass, and is easily delivered to Earth. Easier than American (the hemisphere) gold, actually. Space efficiently provides the solar energy to these sats, they provide value just by using another property of Space, line of sight to large areas of Earth. Already there, already big returns. Space Solar is just the same thing, with bigger stuff, so energy itself is caught, not just enuf to carry a signal. Also, the Space Solar equipment is so much bigger than comm sats that it has to be made from ISM/ISRU, not launched. But still, no actual mass brought back yet. And, global heating solved! Space opened! Get rich!!!

  18. I am glad that there are fusion system research alternatives to major infrastructure/ engineering super-projects requiring superconducting magnets and crazy-power lasers – even NASA and small-ish labs are promising first plasma within 5 – 10 years – lattice confinement and DPF, respectively. As someone who believes in an overwhelmingly centralized energy system with mass distribution and local supporting renewables rather than the other way around — beefing up hub power 'nodes' with something to supplement/ augment/ replace nuclear and current fossil is the way. Especially with transit and localized travel stagnating and EV/ distance commuting likely to expand – even if it is less daily miles and more single-trip miles.

  19. Except Space Solar, as Doctorpat mentioned, which is not mining in the traditional sense. A *small* relatively amount of mining is needed to build the collectors and transmitters, but that is done >90% (Criswell sez 98%) in Space (Moon or NEO/TCO) and used in Space (Moon or SPS), so the Earth's resources, including very poor Earth solar in this case, do not count, they would have to be launched, the initial problem O'Neill saw in 1969-76 and on. The basic radar tech for Space Solar was adequate in the '60s, certainly is now. Solar cell tech same. Rockets getting better, altho ISM/ISRU is to avoid rockets mostly, but they are needed to get started and cheap ones certainly help. We should have started in 1977, when I first started recommending it, or earlier. Improved Criswell plan came out in 1984, but it is a good benchmark, easy to visualize and hugely scalable to global heating cure size. Now, there is a "positive return". The task is so large, it will kick start all other Space activities, while making a profit!!!! This will continue the process you describe, much more quickly. See ppg 12-13 for the very first steps that pay profit.

  20. Taking a Euro-centric view of the world, it wasn't until well into the 1800's that Europe actually saw positive returns in their initial investment in the American colonies. Ironically it wasn't until most of the territories and colonies had been lost before Europe saw positive returns from them.

    This is no different than space. Anything in space past LEO isn't going to lead to positive returns for us anytime soon, though I do expect it to be quicker than the American colony example. I don't expect resource imports from space are going to be profitable without significant subsidies. Earth already has plentiful resources and anything you can find in space, you could probably find on Earth for much cheaper if you look hard enough.

    What space does provide though, is the opportunity to expand. Space exploration can expand our knowledge and technology potential in a way we couldn't likely get staying on Earth. Space is like a giant research lab we can test exotic new energy technologies and entirely different ways of building things and living that we can't really experience on Earth. It's not resource extraction, but space IP or intellectual property that is going to be the true gold mine of space.

  21. No, actually "GreenLeaf" is correct. The output scales as B^3, and the B is twice as high for SPARC compared to ITER, which gives them 8 times the fusion output per volume. Which is about 10x for the same volume of plasma…

  22. You do not have to mine the moon for He3 if you have a fusion reactor that can use it, then you can also produce He3 from fusing D+D. That is a lot more economic than mining the moon where He3 is not actually _that_ common. Best place to mine for it would be Jupiter, IIRC, but again it is unnecessary.

  23. "only space mining prospects that could provide space mission levels of
    money without needing billions of tonnes of material being returned" I'm actually quite surprised by this statement! I don't recall much talk about bringing lunar material back to Earth, not anytime soon. The lunar mining was to avoid having to launch stuff. Sure, eventually the Space material would get cheap enuf to compete with Earth supplies, on Earth!, but for quite a while, the very processing plants to do that have to be built, from lunar materials. Way too expensive to launch. That ISM/ISRU project is the exact thing we need "space mission levels of money" for, 40 years ago.

  24. I studied Physics w/ the dinos, and certainly think we should learn how to do this, but energy is actually pretty easy to get for baseload grid needs, and price will be a huge factor, for that market. But there are many places where concentrated energy is needed, and certainly anything interstellar, crewed or robotic, will benefit. Now, if they can get MIGMA sort of thing, current w/o boiling water, cool!

  25. SPARK is not working on a He3 technology. They are going for D-T.

    The He3_from_the_moon thing appears to be a claim that might have made sense for a few years many decades ago, but the actual Fusion researchers have long abandoned the concept, while space enthusiasts still cling to it as being one of the only space mining prospects that could provide space mission levels of money without needing billions of tonnes of material being returned.

    (Other options being antimatter gathered from the Solar wind, and yes, I'll concede, solar energy being beamed back)

  26. Back in the 1970s when I was a young lad, I remember reading a science magazine article about fusion power. It predicted we would have it in 15-25 years. Of course, that same mag had also predicted we would have flying cars in the same timeline. Not to sound harsh, but where's my flying car and where's my fusion power?

  27. SPARC probably has a greater likelihood of success as a smaller project can make changes faster and cheaper.

    After all both of them are only test reactors, if anything SPARC will probably refine the science for the DEMO reactor that succeeds ITER.

    It would be nice if they could finally crack commercial fusion before my inevitable MI shuffles me off this mortal coil – hopefully once the science is fully proven at scale it will only be a case of investment to get them popping up everywhere and displacing all but renewable power generation and nuclear.

  28. I love this direction of fusion physics and I love the minutia of the technical solutions that the scientists/engineers/students at MIT is finding. So cool with the "onion"-like magnet constuction that allows for easy access and repairs.

    Note that the ITER-track demands so large fusion reactors that it would probably never make commercial sense, even if all technical challenges were solverd. SPARC, however, makes perfect commercial sense.

  29. I'd love to see this work. There's very likely no stopping fusion from becoming the main component of the world energy grid, no matter how much money is thrown at it by people who don't want that change. And, once we can start brining back Helium 3 from the moon (which is quite a long way off, I know), I understand fusion reactors could be made much more efficient.

    2035 isn't so far off. ~15 years to a commercial reactor isn't much of a wait, if they can pull it off.

  30. They have a similar possibility of ultimate success as ITER. They're using REBCO magnets and the same well-established tokamak physics basis for ITER.
    If they fail, it will most likely be due to the vicissitudes of commerce rather than any inability to resolve any technical issue.

  31. And SPARC plans first plasma 2025, power on the grid 2035.

    Reactors that size of SPARC have been built in four years and gotten fairly close to breakeven, so this schedule doesn't seem outlandish. SPARCs more powerful magnetic field gives them about 10X the output for the same size reactor.


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