8 ms·

and not a gigantic amount of fusion that you have in thermonuclear weapons, Ironically, this experiment was designed primarily to simulate the fusion you have

• dmix 4y ago
  From what I can tell this is mostly a useful cover story as a fallback for the moon-shot type energy potential. But are there serious downsides to having this be the case? Does it significantly distract away from the pursuit of energy? Or somehow fundamentally constrain the projects scope?
  • moloch-hai 4y ago
    Exactly the opposite: their task, assigned by Congress, is weapons work. Period. But pretending to work on "carbon-free energy" is good for funding, just now. Four years ago, being all about weapons opened the tap. Make no mistake, there is no story here. There will be no "unlimited free energy" from this, or any other fusion project. The fusion startups are spending down investors' money with zero possibility of payback (Helion conceivably excepted), because if they did get Q>1, they have no workable way to harness it. ITER will not even try to produce one watt-second of electricity. Its follow-on demo reactor won't start building until 2050, if not further delayed. We know the way to get unlimited free energy: solar. Build more, get more. It doesn't have bomb scientists making inflated claims; it just works, and better every year.
    • jboy55 4y ago
      At least ITER has a plausible, in a sci-fi story sense, way of creating a sustainable fusion reaction to which more fuel could be given. The fact the neutrons produced, if it did reach the high Q ratios, would irradiate and break down everything involved, is probably 2070's scientists and engineers problems to solve.
      • moloch-hai 4y ago
        In that paradise of abundant cheap solar and wind power, only weapons people will be interested in fusion. They will probably be trying to come up with zero-fallout things they can use tactically.
        • zbobet2012 4y ago
          Solar and wind power are not sufficient for spacecraft, and many other applications. Fusion power still has very interesting applications.
          • moloch-hai 4y ago
            Most likely, spacecraft will rely on power delivered via laser. If anybody succeeds in working out D-3He fusion, that could work in a spacecraft. (D-T, no.) We could probably scare up enough 3He to use for that, if there weren't too many.
            • PaulHoule 4y ago
              If anybody in the universe is doing interstellar travel I think they would have developed D-D fusion which is somewhat more difficult than D-³He or D-T fusion but probably possible with the a scaled up version of the same machine. Outside the frost line there is a lot of water and a higher percentage of D relative to H so it seems possible to "live off the land" between the stars without being dependent on starshine. A D-D reactor would produce ³He and T, a lot of those products would burn up in the reactor because the reaction rates are high but it would probably be possible to separate some of those out and use it as a breeder reactor that makes fuel for D-³He and D-T reactors elsewhere. I could picture the big D-D reactor running on a large comet or dwarf planet like Pluto producing D-³He for smaller reactors on spacecraft. (D-T not only produces a lot of neutrons but the T has a half life of 12 or so years and won't last for long journies.) My guess is that interstellar travelers would develop a lifestyle that works around the frost line, where generic bodies above a certain size have liquid water inside. If they were grabby they might consume Ceres or Pluto but might not really care about dry, idiosyncratic worlds like the Earth and Mars.
    • xbmcuser 4y ago
      If they can get a continuous fusion reaction going converting the heat energy from that to electricity won't be a problem. Getting a contained fusion reaction that gives out more energy than input is the problem how to convert that into electricity is not going to be a problem.
      • jacquesm 4y ago
        > If they can get a continuous fusion reaction going converting the heat energy from that to electricity won't be a problem. Even accepting the qualification that's not just a mere matter of engineering, capturing that heat from a source that hot is not without trouble. A bit like how there is plenty of energy in a single lightning strike and yet we can't easily catch it even though in principle 'just build a large enough capacitor and connect it to a lightning rod' is a workable recipe. > Getting a contained fusion reaction that gives out more energy than input is the problem Not in the least because the container itself is a very hard problem to solve. > how to convert that into electricity is not going to be a problem. It is also a problem, albeit a lesser one. The better way to look at all of these fusion projects is a way to do an end run around arms control limitations with as a very unlikely by-product the possible future generation of energy. But I would not hold my breath for that. Meanwhile, I'm all for capturing more of the energy output by that other fusion reactor that we all have access to, and learning how to store it over longer periods. Preferably to start with a couple of days with something that doesn't degrade (think very high density super capacitor rather than a battery), but I'll take advanced battery technology if it can be done cheap enough per storage cycle. We're getting there.
        • dd36 4y ago
          There’s not plenty of energy in a lightning strike. https://engineering.mit.edu/engage/ask-an-engineer/is-there-a-way-to-harness-electricity-from-lightning/ https://engineering.mit.edu/engage/ask-an-engineer/is-there-...
          • HPsquared 4y ago
            Funnily enough it's about the same order of magnitude as the fusion event discussed in this TFA: about 1 MJ. Energy from one hohlraum ≈ energy from two lightning strikes
    • elihu 4y ago
      > The fusion startups are spending down investors' money with zero possibility of payback (Helion conceivably excepted), because if they did get Q>1, they have no workable way to harness it. ITER will not even try to produce one watt-second of electricity. Its follow-on demo reactor won't start building until 2050, if not further delayed. You seem to be awfully certain of that. I'm not an expert in this area, but my understanding is that the MIT Arc reactor is planned to use FLiBe as a liquid coolant that absorbs heat/neutrons/etc from the fusion reaction and is pumped into heat exchangers to boil water to run turbines. I mean, maybe there's some details not worked out and maybe I'm misunderstanding how it works, but it seems like a plan to generate electricity to me. There's no plan to hook ITER up to a thermal plant because it's a research reactor not a power plant, but there's no conceptual reason they couldn't do it. (Not that ITER is a great example; the design is already antiquated before it's even finished.)
      • moloch-hai 4y ago
        "Some details"... Have you ever built anything? Driving steam turbines, even with other costs at zero, leaves you uncompetitive with renewables. But other costs would be very, very far from zero. Extracting the grams of tritium at PPB concentration dissolved in 1000 tons of FLiBe every day so you have fuel for tomorrow is an expensive job all by itself. Making a whole new reactor every year or two because it destroyed itself with neutron bombardment is another.
        • Dylan16807 4y ago
          > Driving steam turbines, even with other costs at zero, leaves you uncompetitive with renewables. Everything gets beaten by renewables when they're at high output. But renewables plus reliable storage costs a lot more, and there's no way it's cheaper than steam turbines attached to a bottomless source.
          • moloch-hai 4y ago
            You seem to forget that storage also has no operating expense. The cost of operating a steam turbine far exceeds the cost of the coal or uranium driving it. But the steam turbine would not be the only operating expense for fusion. We don't know exactly what it would cost to sieve a thousand tons of molten FLiBe every day to get out the tritium produced that day, because no one even knows any way to achieve it at all. But it would certainly be a huge daily expense, if achieved.
• _cs2017_ 4y ago
  How would it help build better weapons? I thought the existing thermonuclear bombs do the job perfectly fine. Sure, the military might want to make them a bit smaller or a bit cheaper, but is it really such a big deal as to warrant a major announcement?
  • jacquesm 4y ago
    Given the limitations on nuclear research for weapons purposes any information that can be gleaned from these experiments that is 'dual use' is more than welcome with the parties that are currently stymied by various arms control agreements. This is also why you will see a lot of supercomputer capacity near such research, it allows simulation of experiments with high fidelity rather than the experiments themselves. These are all exploitation of loopholes. The biggest value is probably in being able to confirm that the various computer models accurately predict the experimental outcomes. This when confirmed at scale will allow for the computer models to be used for different applications (ie: weapons research) with a higher level of confidence.
    • _cs2017_ 4y ago
      Presumably these computer models are mostly useful for creating new designs (since the old designs were proven by real tests). Would such new designs be convincing enough to the adversary to fulfill its role as a strategic deterrence? When (in XX years?) almost all US nukes are only simulated on computers and not actually tested, the Russians may start wondering if the US aresnal actually works, no? That would be a horrible outcome, since it means the Russians would be taking somewhat greater risks in their decision-making. Wouldn't far outweigh any opertaional or financial benefits the newer designs offer? I suppose one could argue that if the loss of confidence in strategic weapons matched the actual loss in reliability, it might be a "no op" (although even this is arguable). But if the Russians think the US simulations suck, while the US is actually building really good simulations, the loss of confidence would be greater than the actual loss in reliability. In the extreme case, the nukes work great, but everyone thinks they are scrap metal. Of course, the same happens in reverse: if the Russians are upgrading their weapons to untested designs, the US may start underestimating the risk.