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Major nuclear fusion milestone reached as ‘ignition’ triggered in a lab

524 points by elorant 5y ago

mastrsushi 5y ago
Test
dfdz 5y ago
This more carefully worded Nature article [1] explains that the experiment did not meet the technical definition of ignition. That is why they wrote 'ignition' in quotes in the article title. [1] https://www.nature.com/articles/d41586-021-02338-4 https://www.nature.com/articles/d41586-021-02338-4
bjowen 5y ago
Oh come on, this story again? This is great news for physics PhDs and the NIF machine is cool as hell, but it’s research to keep the US’s doomsday devices up to date. This does very little to stave off the other doomsday threat before us and nothing to justify the breathless reportage that it’s getting.
Parnee 5y ago
Fusion berries powering cell phones for weeks. I'll take two.
kragen 5y ago
Does this mean you can now build a hydrogen bomb without uranium or plutonium? If not, why not?
- coolspot 5y ago
  Man-made nuclear fusion is not self-sustaining, requires massive infrastructure to ignite very little of material. Nuclear fission of unstable isotopes is self-sustaining chain reaction that converts a lot of matter into energy without much of hardware - just put some sub-critical mass of Plutonium into a sphere lined with conventional explosives. See also: https://en.wikipedia.org/wiki/Pure_fusion_weapon https://en.wikipedia.org/wiki/Pure_fusion_weapon
  - kragen 5y ago
    Well, of course that's always been true in the past, but isn't "ignition" precisely the point at which it becomes self-sustaining? Isn't that the distinction between "ignition" and not "ignition"? I mean, you're not the right person to ask (you apparently think plutonium is a brand name), but maybe somebody reading this understands the issues. You don't even need explosives to get a self-sustaining nuclear fission chain reaction if you don't want a bomb; Harry Daghlian did it accidentally, Fermi did it underneath Stagg Field in Chicago in 01942, we do it routinely to generate electricity, and 16 fossil natural nuclear fission reactors have been discovered in Oklo. The explosives are only there to keep a rapid chain reaction from driving the pieces apart before you get enough yield for a weapon. It's true that the NIF would not make a very useful bomb, being difficult to deliver to enemy territory even by ship, and probably inflicting more damage on the funding agency than the destroyed enemy city. But a significant part of that is non-recurring engineering costs, and it's probably possible to miniaturize it to a significant degree. I read Freeman Dyson's autobiography recently, and he claims (contrary to the report of continuing DOE research in the Wikipedia article) one of the things they stopped working on in the 01960s due to the arms treaties was specifically hydrogen bombs that didn't require fission igniters.
    - tsimionescu 5y ago
      Ignition in the case of ICF means that, for the brief time while the shockwave from the initial laser burst is still keeping the plasma together, you get to fuse all of the D+T in your pellet. Once the initial velocity is lost, the high-temperature He dissipates away. Not ahcieving ignition means that the plasma cools too rapidly and the fusion reaction stops even before the brief microseconds of inertial confinement are lost. Perhaps if you could deliver enough energy to a large enough pellet, you could use this to build a bomb, but today it is far too small for that, and the reaction wouldn't work with a larger fuel pellet (the geometry that allows the extreme pressures needed for fusion would not be easily achieved with a larger pellet, since even the wave-length of the laser is relevant at this level).
      - kragen 5y ago
- tsimionescu 5y ago
  Because to achieve 1MW of energy from fusion, you put 200MW of power into the lasers. And, you have to fire these lasers with unfathomable precision at a tiny piece of gold, in order to heat up an even tinier pellet of hydrogen, which then heats up enormously for a few milliseconds before fizzing out. ICF is a good way of studying what happens inside a hydrogen bomb, but it is in no way imaginable how you could use it as a weapon in itself. At this point, you'd be much, much better off just firing the lasers at your target (though even that wouldn't achieve much, unless you target is kind enough to step in front of a highly sensitive, gigantic laser). Edit: corrected a typo graciously pointed out by GP.
  - kragen 5y ago
    What stops you from using the "even tinier piece pellet of hydrogen"[sic] from initiating fusion in a slightly less tiny pellet of hydrogen that it's sitting on top of, which initiates fusion in a slightly less tiny pellet of hydrogen, and so on? Aside from concern for your own survival, of course. Maybe if you can't fathom the precision required to irradiate the NIF hohlraum sufficiently isotropically to achieve ignition in the first place, you shouldn't be trying to answer this question.
    - tsimionescu 5y ago
      > What stops you from using the "even tinier piece pellet of hydrogen"[sic] from initiating fusion in a slightly less tiny pellet of hydrogen that it's sitting on top of, which initiates fusion in a slightly less tiny pellet of hydrogen, and so on? Aside from concern for your own survival, of course. The same thing that stops you from igniting the initial pellet with the hohlraum - you don't have anything creating the kind of confinement necessary to keep the plasma together. The only thing allowing the plasma to get hot enough for fusion is the initial velocity of the inward-spreading shockwave from the initial explosion of the outer shell of the pellet. As the velocity of this shockwave inevitably decreases, confinement is inevitably lost and the plasma dissipates and cools down. Probably in principle you could use the energy of the first pellet's plasma to cause similar shockwaves in a second, larger pellet and so on, but that requires an entirely different geometry, its not just a matter of putting the second pellet close to the first one.
- 00N8 5y ago
  No, the ignition here is small - on the order of a stick of dynamite. There's no reasonable way to scale it up to the size of a hydrogen bomb. Even if the lasers could just be scaled up larger & still work, which they can't b/c the lasers would make too dense of plasma & block their own beams, the number you'd need & the geometry of trying to use it on a full scale bomb would be totally impractical even for a single test. Also, a city sized laser ignition source w/ a bomb at the middle wouldn't be a useful weapon even if it were possible
tehbeard 5y ago
I don't know what has happened more, nuclear fusion "breakthroughs", or Voyager "leaving the solar system"...
- boringg 5y ago
  Agree. I will add in the mix new Energy Storage breakthroughs. The cynic in me suspects its a research money grab or a validation on money spent with no real forward trajectory. At least the voyager is clearly plodding along towards the Oort Cloud and eventually out of the solar system. Sadly I will be long dead and hopefully these comments will still live on (300 year estimate for Oort Cloud at its current speed of 1M miles a day).
- cyberpsybin 5y ago
  because nuclear fusion is an endgame; it going to take centuries
- hinkley 5y ago
  Fusion breakthroughs for sure, but I hear you about Voyager.
- _justinfunk 5y ago
  Or "water discovered on Mars"
- carabiner 5y ago
  New dental treatment will eliminate cavities.
Animats 5y ago
Oh, this is just laser fusion. One pulse of power. That's not a power source, even potentially. It's a lab-sized H-bomb experiment. This isn't one of the magnetic containment systems achieving ignition and sustaining the reaction. Now that would be an achievement.
- Robotbeat 5y ago
  Internal combustion piston engines also do intermittent combustion. If you were to make a power plant based off of this, you would need dozens of these per second (and much more efficient lasers and a tritium breeding liquid lithium metal jacket and… a lot of other stuff).
  - ClumsyPilot 5y ago
    The capsules are tiny and do not generate usefull amount of energy. ITER is planned to generate 500,000,000W. Thats actually usefull
    - harles 5y ago
      500MW of heat from 620MW of electricity seems far from useful. Interesting, but not useful.
    - smaddox 5y ago
      1 MJ is enough to vaporize roughly half a liter of water that started at room temperature. That's nothing to sneaze at. Obviously you would need to do with a high rate (e.g. once per second) in order for it to be viable for power production. No reason the lasers couldn't do that. The challenge is making the pellets cost effective at scale. Currently, they cost something like $10k each.
      - tsimionescu 5y ago
        The bigger problem is the precision-machined hohlraum the pellets sit in for ignition. That costs millions of dollars, is crucial for actually achieving anything, and is destroyed in the process.
tantony 5y ago
Is this "plasma breakeven" or overall break-even?
- akeck 5y ago
  Probably just "plasma breakeven" Sabine talks about the issue. [1] https://backreaction.blogspot.com/2021/10/how-close-is-nuclear-fusion-power.html https://backreaction.blogspot.com/2021/10/how-close-is-nucle...
  - mlindner 5y ago
    Sabine actually is completely misleading and misconstrues a bunch of facts. None of these plants are even attempting to have real energy breakeven and spend a ton of energy supplying experiments and unrelated support equipment. They don't even have a method of capturing energy as that's not the point as it would make it harder to test the physics. Additionally these plants have high amounts of "startup energy consumption" that is also factored in to the energy usage but would be amortized out over a long run. Trying to use the absolute power consumption of the experiment as if that's where the state of the art is at for true energy break even is completely wrong. Plasma breakeven is all anyone is really working on. Once you have plasma breakeven you have a self-sustaining heater basically, which then can be used to create energy. The point of an "ignited plasma" is that it's self-sustaining and just pumps out heat, even if most of the energy is used to keep the reaction going.
    - tootie 5y ago
      I think her meaning is pretty clear and correct. As much as plasma breakeven may be the entire goal of ITER it's absolutely setting them up for a badly missed public expectation. The day they declare net positive output, the world will ask when we can start building infrastructure and the answer will be "30 more years" and then they'll get their funding yanked forever.
      - mlindner 5y ago
        ITER isn't even possible to create an economic nuclear reactor out of because it's too big. The sheer size of a ITER-sized reactor doesn't get us to economical reactors. ITER is a science experiment, not a commercial reactor design. High-field strength high temperature superconductor based allows much smaller sizes than ITER, but ITER was designed with the technology that was available in the late 1990s.
OJFord 5y ago
Previously passim: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=major%20fusion&sort=byDate&type=story https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que... (Edit: along with other, I now realise different, news from MIT.) (Including my submission of this same link, not discussed: https://news.ycombinator.com/item?id=28219462 https://news.ycombinator.com/item?id=28219462, but the others are the same news.) Discussed mostly in: ~~https://news.ycombinator.com/item?id=28462151 https://news.ycombinator.com/item?id=28462151 and:~~(edit, per above) https://news.ycombinator.com/item?id=28219337 https://news.ycombinator.com/item?id=28219337
- ortusdux 5y ago
  SPARC ≠ NIF
  - OJFord 5y ago
    Ok, I hadn't realised the MIT one I said 'mostly discussed in' was different, but the others are this.
amarant 5y ago
I thought ignition had been achieved a long time ago. Is the article saying this is the first time for this particular lab to achieve ignition, or have I confused my fusion hype-terminology? I genuinely can't tell, as the article is written in Hype rather than English...
- wffurr 5y ago
  First time for an internal confinement system using lasers instead of a tokamak using magnetic confinement.
  - jacquesm 5y ago
    Inertial confinement. https://en.wikipedia.org/wiki/Inertial_confinement_fusion https://en.wikipedia.org/wiki/Inertial_confinement_fusion
- leephillips 5y ago
  The Univ. of CA lab that operates NIF has an entire public relations department, paid for by US taxpayers, whose purpose is to generate this hype in order to influence Congress (they are the ultimate audience for all of this) to keep spending more US taxpayer money on NIF. NIF's real purpose is stockpile stewardship, so the funding is not really in jeopardy; but they always want more.
option 5y ago
fusion sound fantastic in principle. But in the meantime we can and should addressed most of our energy needs with fission.
- aerostable_slug 5y ago
  Not sure why this is downvoted. Fission works, and it works well. The waste problem is massively overstated and also, aside from NIMBY politics, solved.
  - cronix 5y ago
    There are also things like tidal waves, earthquakes and other unforeseen things that do pop up from time to time and cause big issues. We can say it's rare, statistically very unlikely, etc., but no one wants to be a Fukushima and that image is still pretty fresh and hard to combat logically. That said, one thing that I think would really help is to have smaller reactors, more of them, and using a standardized and approved design. I remember hearing an interview with an Oregon State University professor some 15+ years ago who was working on a project that did just that. IIRC, he said one major contributing factor to the cost of building a reactor, besides waste, is that basically each one is designed and engineered from scratch. He envisioned more of an assembly line. Universal design, universal parts, etc. I believe they went on to form a company called NuScale and a quick DDG search led to this: > "Portland company's innovative nuclear reactor OK'd by feds (September 26 2020)" ... The modules — each capable of producing 60 megawatts of energy, which is enough to power 45,000 homes — also allow a plant to scale up as needed, with a maximum capacity of 12 modules for a total of 720 megawatts. https://pamplinmedia.com/pt/9-news/482166-388954-portland-companys-innovative-nuclear-reactor-okd-by-feds https://pamplinmedia.com/pt/9-news/482166-388954-portland-co...
greenail 5y ago
Sweet, nucluear fusion now must only be 20 years away!
- Iv 5y ago
  20 years ago we were joking about it being 40 year away. So yes, it is timely progress. I am still bitter that we don't invest more on this research which has the potential to solve the climate crisis "unexpectedly".
  - iammisc 5y ago
    > I am still bitter that we don't invest more on this research which has the potential to solve the climate crisis "unexpectedly". Unfortunately, solving the climate crisis would put many a pundit out of a job.
    - junon 5y ago
      Something tells me the alternative is going to do much more than putting people out of jobs.
      - iammisc 5y ago
        I agree, but the bureaucrats in charge are more responsive to their own immediate needs than to the long-term outcomes. That is to say, it is in their best interests to prevent an exciting new technology to come out and eradicate the problem as then they would no longer have their jobs.
  - nnamtr 5y ago
    I'm somehow afraid of a world in which huge amounts of energy can be wasted without having a bad conscience. Probably it would lead to some new problems.
    - bogwog 5y ago
      Just think of all the personal data you could collect!
ttul 5y ago
August 2021
- aero-glide2 5y ago
  elorant is posting from oort cloud, be easy on him.
  - ttul 5y ago
    Oh good. I wasn't aware they had relocated quite that far oort.
xixixao 5y ago
> Fusion ignition is the point at which a nuclear fusion reaction becomes self-sustaining. This occurs when the energy being given off by the fusion reactions heats the fuel mass more rapidly than various loss mechanisms cool it. https://en.m.wikipedia.org/wiki/Fusion_ignition https://en.m.wikipedia.org/wiki/Fusion_ignition
- gremIin 5y ago
  How is this any different than the term 'breakeven' [0]? > Breakeven describes the moment when plasmas in a fusion device release at least as much energy as is required to heat them [0] https://www.iter.org/sci/BeyondITER https://www.iter.org/sci/BeyondITER Is this just a case of multiple terms for the same phenomenon, and do plasma physicists have a preference?
  - detaro 5y ago
    The wikipedia article linked answers that.
  - deleted 5y ago
    [deleted]
  - falcrist 5y ago
    That question is answered in the wikipedia link above. > Ignition should not be confused with breakeven, a similar concept that compares the total energy being given off to the energy being used to heat the fuel. The key difference is that breakeven ignores losses to the surroundings, which do not contribute to heating the fuel, and thus are not able to make the reaction self-sustaining. Breakeven is an important goal in the fusion energy field, but ignition is required for a practical energy producing design.
- AutumnCurtain 5y ago
  >Early reports estimated that 250 kilo-joules of energy was deposited on the target (roughly 2/3 of the energy from the beams), which resulted in a 1.3 Megajoule output from the fusing plasma. Incredible progress over where they were just a couple years ago.
stevespang 5y ago
rehashing old news that no 3rd party independent facility can verify since NIF is the only site in the world with such a device . . . .
vfclists 5y ago
Funny how this story gets posted after soon after Dr Sabine Hossenfelder's debunking and deflate the fusion power hype - https://www.youtube.com/watch?v=LJ4W1g-6JiY https://www.youtube.com/watch?v=LJ4W1g-6JiY with a genuine Hans Gruber accent :)
- seoaeu 5y ago
  Do you have any context on who Dr. Hossenfelder is or why their "debunking" is meaningful?
  - mrtranscendence 5y ago
    She's a German physicist who has made a name for herself, I think, arguing that mathematical beauty should not be a factor when constructing solutions to problems in theoretical physics. I think construing her video as a "debunking" does it a disservice, for what it's worth. It's a call for journalists and laypeople to be cautious when interpreting lab results. She doesn't "dunk on" fusion power or say that it's not worth investigating.
    - willis936 5y ago
      For a physicist she claims to know strikingly little about fusion energy research while still offering up opinions. Why did the good doctor fail to mention triple product? Why did the good doctor conflate ICF machines and MCF machines? Why did the good doctor imply that research progress is tied to Q (which is a metric that only progresses in times of large funding/when nuclear machines are being built)? It seems the good doctor has smoke to blow, rather than truth to spread.
      - mrtranscendence 5y ago
        For one, her channel is firmly oriented towards a lay audience; she explains topics in physics in relatively simple terminology. That limits the level of discourse. Second, she's not a fusion researcher, she's a theoretical physicist. It's possible that she made an error (though I can't speak to whether that's actually the case, as I know next to nothing about physics generally). Third, I don't think she really implied that research progress is entirely tied to Q. But YMMV.
deleted 5y ago
[deleted]
ph4 5y ago
So is the goal just to fuel our current patterns of consumption and development with fusion, or nuclear, or whatever?
- _jal 5y ago
  If cheap commercial fusion became a reality, no. We would use far more energy.
- HPsquared 5y ago
  Would more cheap (in all ways) energy be a bad thing? I don't think so, people pay money for that sort of thing.
  - hinkley 5y ago
    Heat pollution. Green house gasses are not the only way to cook ourselves. Though there are some people working on beaming heat into space, I suspect they haven’t fully accounted for heat absorption by atmospheric dust.
    - woah 5y ago
      I'm guessing any possible energy generated by manmade fusion plants would be miniscule compared to that hitting the earth from the sun every day.
      - hinkley 5y ago
        That's not how homeostasis works.
    - HPsquared 5y ago
      It'd be interesting to ponder whether such a "heat ray" would work, in terms of thermodynamics. Some kind of heat pump, the hot side of which is hot enough to radiate into space? I can't imagine that having a net cooling effect when considering the Carnot efficiency of a refrigeration cycle. Maybe a giant ice machine in space? (Then again, any ice would probably create more heating than cooling as it enters our gravity well or deorbits). Anyone have any ideas?
rfrey 5y ago
Meta-question about fusion energy -something I don't understand about the movement. I spent a few years as CTO of a company providing heat-to-electricity plants. We financed and built them off high-heat plants like natural gas turbines. The "fuel" was heat going up the stack - so it was essentially free. We still couldn't compete with conventional electricity plants, even with a $30/tonne price on carbon in Canada. Geothermal energy is the same: sustainable, long-life electricity with no "fuel" costs, but it costs 2-3x as much to build a geothermal plant (in most areas, depends on geology) as e.g. a natural gas turbine powered plant, so the overall cost of electricity is much higher and you can't get financing. How is fusion different? The fuel will be free and unlimited, but the "levelized cost of electricity", dominated by the capital cost of the plant, will still be much higher than other sources of electricity. I don't think there's a world -- even one where the onerous regulations go away and a market price on carbon is available -- where the LCOE of fusion power is less than that from natural gas, or even close.
- mchusma 5y ago
  Id answer this in 2 ways: First. Let's say we have a trillion people in space stations/multiple planets. Fusion is a energy source that can plausibly power them. Second. fission works close to other sources, but is so hampered by regulation that it hasn't gotten to be affordable. This may be fixed in the future. micro-reactors solve the biggest economy of scale issues and a renewed bipartisan interest in nuclear could help it be politically viable. If fission works in theory, fusion definitely works in theory (as the energy output is much higher).
- asdff 5y ago
  That just tells me that we haven't priced the externalities of carbon based energy appropriately, if the green solution is still more costly. Increase the carbon tax and things will pencil out fast.
- orangepurple 5y ago
  You can't put a price on energy independence in a free market economy. Energy independence is a military objective and a matter of national security. The costs are difficult to put in perspective.
wolf550e 5y ago
@dang This was reported and discussed 12 days ago: https://news.ycombinator.com/item?id=28704298 https://news.ycombinator.com/item?id=28704298 The important thing to know is that the NIF is about nuclear weapons design (verification of modeling software used for nuclear weapons design), not about developing fusion power plants.
- floatingatoll 5y ago
  Note that @dang doesn't actually notify dang, unless he happens to open this article and see it out of the corner of his eye or something. If you want to report a frontpage dupe, emailing the mods using the footer Contact link is an efficient method (or you can just flag it as I did, which has relatively the same effect if enough people do).
- snek_case 5y ago
  Kind of crazy that we're still spending money on this. Do we really need better H-bombs?
  - blake1 5y ago
    The fear is that the nuclear weapons sitting in storage are assumed to be functional, but might turn out not to be. This could have dangerous geopolitical consequences. We can study how the materials age, but have to use simulation to understand the effects on the detonation given the test ban. This research helps calibrate the simulations. The civilian applications of the facility are secondary, as others have pointed out.
  - chemeng 5y ago
    The US military probably thinks so, but I believe a major goal of NIF is the ability to model whether the ones the US already built will still work without setting one off.
not2b 5y ago
We're still a very long way off. Sabine Hossenfelder has a good explanation of what's wrong with most reporting on progress toward fusion: http://backreaction.blogspot.com/2021/10/how-close-is-nuclear-fusion-power.html http://backreaction.blogspot.com/2021/10/how-close-is-nuclea... edit: not sure why this was downvoted, it's directly relevant and the video and transcript discuss this experiment. It quotes Arthur Turrell: "This phenomenal breakthrough brings us tantalisingly close to a demonstration of 'net energy gain’ from fusion reactions – just when the planet needs it." But this comes close to getting Qplasma to be 1, which is about a factor of 50-70 lower than getting Q to be 1 (total power into the reactor vs usable power out of the reactor).
- willis936 5y ago
  >not sure why this was downvoted Perhaps because spreading the agenda-oriented opinion about fusion of someone who knows exactly as much about fusion as a high-schooler maybe isn't the best? https://news.ycombinator.com/item?id=28781178 https://news.ycombinator.com/item?id=28781178
  - not2b 5y ago
    Wow. A respected PhD theoretical physicist knows exactly as much about fusion as a high schooler? See her Wikipedia page for her resume: https://en.m.wikipedia.org/wiki/Sabine_Hossenfelder https://en.m.wikipedia.org/wiki/Sabine_Hossenfelder
    - willis936 5y ago
      If she knows more then she knowingly deceived the public in her video to forward an agenda. Which explanation is worse to you?
ohcomments 5y ago
Next step.... Implement this in a spaceship and GTFO'a here...
pmdulaney 5y ago
Three cheers to the special relationship -- specifically as it extends to nuclear fusion!
deleted 5y ago
[deleted]
mbgerring 5y ago
Pretty interesting how this huge rash of articles about the same 2 or 3 fusion experiments have appeared just as the Federal government is considering where to spend resources in energy infrastructure for the next ten years. Who’s the publicist?
- p1mrx 5y ago
  I don't think it's a huge rash of articles; it's the same old news from August resurfacing every couple weeks.
tediousdemise 5y ago
What are the odds of runaway fusion occurring? Is there any consideration that a violent reaction could engulf the planet and end life as we know it?
- regularfry 5y ago
  Zero.
  - tediousdemise 5y ago
    Is this because the chain reaction is limited by the fuel source?
    - regularfry 5y ago
      The fusion reaction needs containment, the right fuel, and massive amounts of energy in just the right place. It's phenomenally difficult to marshal the containment necessary to make the energy from a fusion reaction go into more fusion and not, say, warming up the test chamber a fraction. Yes, the fact that there's not much fuel is important, but not as important as the finickiness of making the plasma do what you want in the first place. One of the major problems (arguably the problem) with tokamak or similar fusion reactors is that if the plasma ever touches the edge of the vessel, it immediately cools down and stops being plasma. It can't fuse with itself any more, much less trigger anything else to start. Heavier atoms need more energy to fuse, that's why you see hydrogen, helium, lithium bandied about in these discussions. The amount of energy needed to fuse the atoms in the walls of a fusion reactor is literally supernova-scale. We're not talking "there's an engineering tolerance built in for safety", rather "as a civilisation it's not immediately conceivable how we might generate amounts of energy that large". Given that the majority of the earth is made out of elements that are inconveniently heavy, runaway fusion is absolutely, definitely, totally, completely not a problem.
thehappypm 5y ago
I'm struggling to understand what exactly happens. The deuterium and tritium mixture is hydrogen -- so it is a gas? So is it in some sort of gas-containing container, that also lets laser light through -- probably some kind of glass container? What kind of glass container can survive having this much energy pumped through it, and such a hot gas inside it? https://en.wikipedia.org/wiki/Fusion_ignition https://en.wikipedia.org/wiki/Fusion_ignition
- Robotbeat 5y ago
  It’s actually frozen deuterium tritium. Inside a small pellet blasted by X-rays which compress the pellet until it’s hot and dense enough for the fusion energy produced to continue burning and heating the deuterium/tritium until much more energy is produced than the energy of the X-rays. It all happens in an instant. The pellet’s structure doesn’t survive. But it happens fast enough that just the inertia of the pellet (turning to a gas and then a plasma) keeps things confined for long to fuse a significant amount of the deuterium/tritium.
  - thehappypm 5y ago
    How do you freeze hydrogen?
    - pfdietz 5y ago
      You make it very cold.
bob229 5y ago
i guess it's just 20 years away then hahaha
DreamFlasher 5y ago
Old?
ashton314 5y ago
If I'm not mistaken, part of Star Trek: Into Darkness was filmed at a fusion research center. They used it as the backdrop for engineering/warp core. Just slap on a few starfleet decals and you're good to go!
omgJustTest 5y ago
PhD nuclear engineer here: The National Ignition Facility (NIF) is a fusion facility that seeks to study fusion (ie, meet the Lawson[1] criteria) through compression of a tiny spec of tritium or deuterium-tritium ice inside of a cylindrical tube called a Hohlraum[2]. Achieving fusion in this case can be assessed by a simple energy balance, canonically referred to as the "Q" factor[3]. Q=1 implies the fusion process released the same amount of energy the input-laser put in to the reactor. Q=2 is largely accepted as the minimum viable criteria for a fusion-power reactor (one unit of Q to return to the reactor, one unit of Q to be exported to the grid, power conversion unit etc for actual use). 1.3MJ is the claimed number by the article, while impressive for inertial confinement fusion (ICF), it lacks the context that the laser-input-power is ~2-4MJ (ie a Q~0.5). A bit more context: the best-of-the-best shots at NIF produce an idealistic energy balance that cannot sustain a reaction. There are a lot of other practical considerations such as how you would provide continuous power from the NIF Holhraums, what materials would stand up-to 100 DPA [4] damage from radiation bombardments, and a host of others. An open secret is that NIF's purpose is not exclusively fusion. Additionally JET appears to have a Q~0.67 according to wikipedia [3]. [1] https://en.wikipedia.org/wiki/Lawson_criterion https://en.wikipedia.org/wiki/Lawson_criterion [2] https://en.wikipedia.org/wiki/Hohlraum https://en.wikipedia.org/wiki/Hohlraum [3] https://en.wikipedia.org/wiki/Fusion_energy_gain_factor https://en.wikipedia.org/wiki/Fusion_energy_gain_factor [4] https://gcep.stanford.edu/pdfs/UVaodfDrAb3BdgeRCpoy-w/10-Zin https://gcep.stanford.edu/pdfs/UVaodfDrAb3BdgeRCpoy-w/10-Zin... slide 11.
ourmandave 5y ago
Fusion is the fuel of the future - and it always will be.
- pfdietz 5y ago
  Unlikely. At some point, the meme will just sputter out. Fusion will be as much the energy source of the future as dirigibles will be the aircraft of the future.

524 points by elorant 5y ago

Test

dfdz 5y ago

This more carefully worded Nature article [1] explains that the experiment did not meet the technical definition of ignition. That is why they wrote 'ignition' in quotes in the article title. [1] https://www.nature.com/articles/d41586-021-02338-4 https://www.nature.com/articles/d41586-021-02338-4

bjowen 5y ago

Oh come on, this story again? This is great news for physics PhDs and the NIF machine is cool as hell, but it’s research to keep the US’s doomsday devices up to date. This does very little to stave off the other doomsday threat before us and nothing to justify the breathless reportage that it’s getting.

Parnee 5y ago

Fusion berries powering cell phones for weeks. I'll take two.

kragen 5y ago

Does this mean you can now build a hydrogen bomb without uranium or plutonium? If not, why not?

coolspot 5y ago
Man-made nuclear fusion is not self-sustaining, requires massive infrastructure to ignite very little of material. Nuclear fission of unstable isotopes is self-sustaining chain reaction that converts a lot of matter into energy without much of hardware - just put some sub-critical mass of Plutonium into a sphere lined with conventional explosives. See also: https://en.wikipedia.org/wiki/Pure_fusion_weapon https://en.wikipedia.org/wiki/Pure_fusion_weapon
- kragen 5y ago
  Well, of course that's always been true in the past, but isn't "ignition" precisely the point at which it becomes self-sustaining? Isn't that the distinction between "ignition" and not "ignition"? I mean, you're not the right person to ask (you apparently think plutonium is a brand name), but maybe somebody reading this understands the issues. You don't even need explosives to get a self-sustaining nuclear fission chain reaction if you don't want a bomb; Harry Daghlian did it accidentally, Fermi did it underneath Stagg Field in Chicago in 01942, we do it routinely to generate electricity, and 16 fossil natural nuclear fission reactors have been discovered in Oklo. The explosives are only there to keep a rapid chain reaction from driving the pieces apart before you get enough yield for a weapon. It's true that the NIF would not make a very useful bomb, being difficult to deliver to enemy territory even by ship, and probably inflicting more damage on the funding agency than the destroyed enemy city. But a significant part of that is non-recurring engineering costs, and it's probably possible to miniaturize it to a significant degree. I read Freeman Dyson's autobiography recently, and he claims (contrary to the report of continuing DOE research in the Wikipedia article) one of the things they stopped working on in the 01960s due to the arms treaties was specifically hydrogen bombs that didn't require fission igniters.
  - tsimionescu 5y ago
    Ignition in the case of ICF means that, for the brief time while the shockwave from the initial laser burst is still keeping the plasma together, you get to fuse all of the D+T in your pellet. Once the initial velocity is lost, the high-temperature He dissipates away. Not ahcieving ignition means that the plasma cools too rapidly and the fusion reaction stops even before the brief microseconds of inertial confinement are lost. Perhaps if you could deliver enough energy to a large enough pellet, you could use this to build a bomb, but today it is far too small for that, and the reaction wouldn't work with a larger fuel pellet (the geometry that allows the extreme pressures needed for fusion would not be easily achieved with a larger pellet, since even the wave-length of the laser is relevant at this level).
    - kragen 5y ago
tsimionescu 5y ago
Because to achieve 1MW of energy from fusion, you put 200MW of power into the lasers. And, you have to fire these lasers with unfathomable precision at a tiny piece of gold, in order to heat up an even tinier pellet of hydrogen, which then heats up enormously for a few milliseconds before fizzing out. ICF is a good way of studying what happens inside a hydrogen bomb, but it is in no way imaginable how you could use it as a weapon in itself. At this point, you'd be much, much better off just firing the lasers at your target (though even that wouldn't achieve much, unless you target is kind enough to step in front of a highly sensitive, gigantic laser). Edit: corrected a typo graciously pointed out by GP.
- kragen 5y ago
  What stops you from using the "even tinier piece pellet of hydrogen"[sic] from initiating fusion in a slightly less tiny pellet of hydrogen that it's sitting on top of, which initiates fusion in a slightly less tiny pellet of hydrogen, and so on? Aside from concern for your own survival, of course. Maybe if you can't fathom the precision required to irradiate the NIF hohlraum sufficiently isotropically to achieve ignition in the first place, you shouldn't be trying to answer this question.
  - tsimionescu 5y ago
    > What stops you from using the "even tinier piece pellet of hydrogen"[sic] from initiating fusion in a slightly less tiny pellet of hydrogen that it's sitting on top of, which initiates fusion in a slightly less tiny pellet of hydrogen, and so on? Aside from concern for your own survival, of course. The same thing that stops you from igniting the initial pellet with the hohlraum - you don't have anything creating the kind of confinement necessary to keep the plasma together. The only thing allowing the plasma to get hot enough for fusion is the initial velocity of the inward-spreading shockwave from the initial explosion of the outer shell of the pellet. As the velocity of this shockwave inevitably decreases, confinement is inevitably lost and the plasma dissipates and cools down. Probably in principle you could use the energy of the first pellet's plasma to cause similar shockwaves in a second, larger pellet and so on, but that requires an entirely different geometry, its not just a matter of putting the second pellet close to the first one.
00N8 5y ago
No, the ignition here is small - on the order of a stick of dynamite. There's no reasonable way to scale it up to the size of a hydrogen bomb. Even if the lasers could just be scaled up larger & still work, which they can't b/c the lasers would make too dense of plasma & block their own beams, the number you'd need & the geometry of trying to use it on a full scale bomb would be totally impractical even for a single test. Also, a city sized laser ignition source w/ a bomb at the middle wouldn't be a useful weapon even if it were possible

tehbeard 5y ago

I don't know what has happened more, nuclear fusion "breakthroughs", or Voyager "leaving the solar system"...

boringg 5y ago
Agree. I will add in the mix new Energy Storage breakthroughs. The cynic in me suspects its a research money grab or a validation on money spent with no real forward trajectory. At least the voyager is clearly plodding along towards the Oort Cloud and eventually out of the solar system. Sadly I will be long dead and hopefully these comments will still live on (300 year estimate for Oort Cloud at its current speed of 1M miles a day).
cyberpsybin 5y ago
because nuclear fusion is an endgame; it going to take centuries
hinkley 5y ago
Fusion breakthroughs for sure, but I hear you about Voyager.
_justinfunk 5y ago
Or "water discovered on Mars"
carabiner 5y ago
New dental treatment will eliminate cavities.

Animats 5y ago

Oh, this is just laser fusion. One pulse of power. That's not a power source, even potentially. It's a lab-sized H-bomb experiment. This isn't one of the magnetic containment systems achieving ignition and sustaining the reaction. Now that would be an achievement.

Robotbeat 5y ago
Internal combustion piston engines also do intermittent combustion. If you were to make a power plant based off of this, you would need dozens of these per second (and much more efficient lasers and a tritium breeding liquid lithium metal jacket and… a lot of other stuff).
- ClumsyPilot 5y ago
  The capsules are tiny and do not generate usefull amount of energy. ITER is planned to generate 500,000,000W. Thats actually usefull
  - harles 5y ago
    500MW of heat from 620MW of electricity seems far from useful. Interesting, but not useful.
  - smaddox 5y ago
    1 MJ is enough to vaporize roughly half a liter of water that started at room temperature. That's nothing to sneaze at. Obviously you would need to do with a high rate (e.g. once per second) in order for it to be viable for power production. No reason the lasers couldn't do that. The challenge is making the pellets cost effective at scale. Currently, they cost something like $10k each.
    - tsimionescu 5y ago
      The bigger problem is the precision-machined hohlraum the pellets sit in for ignition. That costs millions of dollars, is crucial for actually achieving anything, and is destroyed in the process.

tantony 5y ago

Is this "plasma breakeven" or overall break-even?

akeck 5y ago
Probably just "plasma breakeven" Sabine talks about the issue. [1] https://backreaction.blogspot.com/2021/10/how-close-is-nuclear-fusion-power.html https://backreaction.blogspot.com/2021/10/how-close-is-nucle...
- mlindner 5y ago
  Sabine actually is completely misleading and misconstrues a bunch of facts. None of these plants are even attempting to have real energy breakeven and spend a ton of energy supplying experiments and unrelated support equipment. They don't even have a method of capturing energy as that's not the point as it would make it harder to test the physics. Additionally these plants have high amounts of "startup energy consumption" that is also factored in to the energy usage but would be amortized out over a long run. Trying to use the absolute power consumption of the experiment as if that's where the state of the art is at for true energy break even is completely wrong. Plasma breakeven is all anyone is really working on. Once you have plasma breakeven you have a self-sustaining heater basically, which then can be used to create energy. The point of an "ignited plasma" is that it's self-sustaining and just pumps out heat, even if most of the energy is used to keep the reaction going.
  - tootie 5y ago
    I think her meaning is pretty clear and correct. As much as plasma breakeven may be the entire goal of ITER it's absolutely setting them up for a badly missed public expectation. The day they declare net positive output, the world will ask when we can start building infrastructure and the answer will be "30 more years" and then they'll get their funding yanked forever.
    - mlindner 5y ago
      ITER isn't even possible to create an economic nuclear reactor out of because it's too big. The sheer size of a ITER-sized reactor doesn't get us to economical reactors. ITER is a science experiment, not a commercial reactor design. High-field strength high temperature superconductor based allows much smaller sizes than ITER, but ITER was designed with the technology that was available in the late 1990s.

OJFord 5y ago

Previously passim: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&query=major%20fusion&sort=byDate&type=story https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que... (Edit: along with other, I now realise different, news from MIT.) (Including my submission of this same link, not discussed: https://news.ycombinator.com/item?id=28219462 https://news.ycombinator.com/item?id=28219462, but the others are the same news.) Discussed mostly in: ~~https://news.ycombinator.com/item?id=28462151 https://news.ycombinator.com/item?id=28462151 and:~~(edit, per above) https://news.ycombinator.com/item?id=28219337 https://news.ycombinator.com/item?id=28219337

ortusdux 5y ago
SPARC ≠ NIF
- OJFord 5y ago
  Ok, I hadn't realised the MIT one I said 'mostly discussed in' was different, but the others are this.

amarant 5y ago

I thought ignition had been achieved a long time ago. Is the article saying this is the first time for this particular lab to achieve ignition, or have I confused my fusion hype-terminology? I genuinely can't tell, as the article is written in Hype rather than English...

wffurr 5y ago
First time for an internal confinement system using lasers instead of a tokamak using magnetic confinement.
- jacquesm 5y ago
  Inertial confinement. https://en.wikipedia.org/wiki/Inertial_confinement_fusion https://en.wikipedia.org/wiki/Inertial_confinement_fusion
leephillips 5y ago
The Univ. of CA lab that operates NIF has an entire public relations department, paid for by US taxpayers, whose purpose is to generate this hype in order to influence Congress (they are the ultimate audience for all of this) to keep spending more US taxpayer money on NIF. NIF's real purpose is stockpile stewardship, so the funding is not really in jeopardy; but they always want more.

option 5y ago

fusion sound fantastic in principle. But in the meantime we can and should addressed most of our energy needs with fission.

aerostable_slug 5y ago
Not sure why this is downvoted. Fission works, and it works well. The waste problem is massively overstated and also, aside from NIMBY politics, solved.
- cronix 5y ago
  There are also things like tidal waves, earthquakes and other unforeseen things that do pop up from time to time and cause big issues. We can say it's rare, statistically very unlikely, etc., but no one wants to be a Fukushima and that image is still pretty fresh and hard to combat logically. That said, one thing that I think would really help is to have smaller reactors, more of them, and using a standardized and approved design. I remember hearing an interview with an Oregon State University professor some 15+ years ago who was working on a project that did just that. IIRC, he said one major contributing factor to the cost of building a reactor, besides waste, is that basically each one is designed and engineered from scratch. He envisioned more of an assembly line. Universal design, universal parts, etc. I believe they went on to form a company called NuScale and a quick DDG search led to this: > "Portland company's innovative nuclear reactor OK'd by feds (September 26 2020)" ... The modules — each capable of producing 60 megawatts of energy, which is enough to power 45,000 homes — also allow a plant to scale up as needed, with a maximum capacity of 12 modules for a total of 720 megawatts. https://pamplinmedia.com/pt/9-news/482166-388954-portland-companys-innovative-nuclear-reactor-okd-by-feds https://pamplinmedia.com/pt/9-news/482166-388954-portland-co...

greenail 5y ago

Sweet, nucluear fusion now must only be 20 years away!

Iv 5y ago
20 years ago we were joking about it being 40 year away. So yes, it is timely progress. I am still bitter that we don't invest more on this research which has the potential to solve the climate crisis "unexpectedly".
- iammisc 5y ago
  > I am still bitter that we don't invest more on this research which has the potential to solve the climate crisis "unexpectedly". Unfortunately, solving the climate crisis would put many a pundit out of a job.
  - junon 5y ago
    Something tells me the alternative is going to do much more than putting people out of jobs.
    - iammisc 5y ago
      I agree, but the bureaucrats in charge are more responsive to their own immediate needs than to the long-term outcomes. That is to say, it is in their best interests to prevent an exciting new technology to come out and eradicate the problem as then they would no longer have their jobs.
- nnamtr 5y ago
  I'm somehow afraid of a world in which huge amounts of energy can be wasted without having a bad conscience. Probably it would lead to some new problems.
  - bogwog 5y ago
    Just think of all the personal data you could collect!

ttul 5y ago

August 2021

aero-glide2 5y ago
elorant is posting from oort cloud, be easy on him.
- ttul 5y ago
  Oh good. I wasn't aware they had relocated quite that far oort.

xixixao 5y ago

> Fusion ignition is the point at which a nuclear fusion reaction becomes self-sustaining. This occurs when the energy being given off by the fusion reactions heats the fuel mass more rapidly than various loss mechanisms cool it. https://en.m.wikipedia.org/wiki/Fusion_ignition https://en.m.wikipedia.org/wiki/Fusion_ignition

gremIin 5y ago
How is this any different than the term 'breakeven' [0]? > Breakeven describes the moment when plasmas in a fusion device release at least as much energy as is required to heat them [0] https://www.iter.org/sci/BeyondITER https://www.iter.org/sci/BeyondITER Is this just a case of multiple terms for the same phenomenon, and do plasma physicists have a preference?
- detaro 5y ago
  The wikipedia article linked answers that.
- deleted 5y ago
  [deleted]
- falcrist 5y ago
  That question is answered in the wikipedia link above. > Ignition should not be confused with breakeven, a similar concept that compares the total energy being given off to the energy being used to heat the fuel. The key difference is that breakeven ignores losses to the surroundings, which do not contribute to heating the fuel, and thus are not able to make the reaction self-sustaining. Breakeven is an important goal in the fusion energy field, but ignition is required for a practical energy producing design.
AutumnCurtain 5y ago
>Early reports estimated that 250 kilo-joules of energy was deposited on the target (roughly 2/3 of the energy from the beams), which resulted in a 1.3 Megajoule output from the fusing plasma. Incredible progress over where they were just a couple years ago.

stevespang 5y ago

rehashing old news that no 3rd party independent facility can verify since NIF is the only site in the world with such a device . . . .

vfclists 5y ago

Funny how this story gets posted after soon after Dr Sabine Hossenfelder's debunking and deflate the fusion power hype - https://www.youtube.com/watch?v=LJ4W1g-6JiY https://www.youtube.com/watch?v=LJ4W1g-6JiY with a genuine Hans Gruber accent :)

seoaeu 5y ago
Do you have any context on who Dr. Hossenfelder is or why their "debunking" is meaningful?
- mrtranscendence 5y ago
  She's a German physicist who has made a name for herself, I think, arguing that mathematical beauty should not be a factor when constructing solutions to problems in theoretical physics. I think construing her video as a "debunking" does it a disservice, for what it's worth. It's a call for journalists and laypeople to be cautious when interpreting lab results. She doesn't "dunk on" fusion power or say that it's not worth investigating.
  - willis936 5y ago
    For a physicist she claims to know strikingly little about fusion energy research while still offering up opinions. Why did the good doctor fail to mention triple product? Why did the good doctor conflate ICF machines and MCF machines? Why did the good doctor imply that research progress is tied to Q (which is a metric that only progresses in times of large funding/when nuclear machines are being built)? It seems the good doctor has smoke to blow, rather than truth to spread.
    - mrtranscendence 5y ago
      For one, her channel is firmly oriented towards a lay audience; she explains topics in physics in relatively simple terminology. That limits the level of discourse. Second, she's not a fusion researcher, she's a theoretical physicist. It's possible that she made an error (though I can't speak to whether that's actually the case, as I know next to nothing about physics generally). Third, I don't think she really implied that research progress is entirely tied to Q. But YMMV.

deleted 5y ago

[deleted]

ph4 5y ago

So is the goal just to fuel our current patterns of consumption and development with fusion, or nuclear, or whatever?

_jal 5y ago
If cheap commercial fusion became a reality, no. We would use far more energy.
HPsquared 5y ago
Would more cheap (in all ways) energy be a bad thing? I don't think so, people pay money for that sort of thing.
- hinkley 5y ago
  Heat pollution. Green house gasses are not the only way to cook ourselves. Though there are some people working on beaming heat into space, I suspect they haven’t fully accounted for heat absorption by atmospheric dust.
  - woah 5y ago
    I'm guessing any possible energy generated by manmade fusion plants would be miniscule compared to that hitting the earth from the sun every day.
    - hinkley 5y ago
      That's not how homeostasis works.
  - HPsquared 5y ago
    It'd be interesting to ponder whether such a "heat ray" would work, in terms of thermodynamics. Some kind of heat pump, the hot side of which is hot enough to radiate into space? I can't imagine that having a net cooling effect when considering the Carnot efficiency of a refrigeration cycle. Maybe a giant ice machine in space? (Then again, any ice would probably create more heating than cooling as it enters our gravity well or deorbits). Anyone have any ideas?

rfrey 5y ago

Meta-question about fusion energy -something I don't understand about the movement. I spent a few years as CTO of a company providing heat-to-electricity plants. We financed and built them off high-heat plants like natural gas turbines. The "fuel" was heat going up the stack - so it was essentially free. We still couldn't compete with conventional electricity plants, even with a $30/tonne price on carbon in Canada. Geothermal energy is the same: sustainable, long-life electricity with no "fuel" costs, but it costs 2-3x as much to build a geothermal plant (in most areas, depends on geology) as e.g. a natural gas turbine powered plant, so the overall cost of electricity is much higher and you can't get financing. How is fusion different? The fuel will be free and unlimited, but the "levelized cost of electricity", dominated by the capital cost of the plant, will still be much higher than other sources of electricity. I don't think there's a world -- even one where the onerous regulations go away and a market price on carbon is available -- where the LCOE of fusion power is less than that from natural gas, or even close.

mchusma 5y ago
Id answer this in 2 ways: First. Let's say we have a trillion people in space stations/multiple planets. Fusion is a energy source that can plausibly power them. Second. fission works close to other sources, but is so hampered by regulation that it hasn't gotten to be affordable. This may be fixed in the future. micro-reactors solve the biggest economy of scale issues and a renewed bipartisan interest in nuclear could help it be politically viable. If fission works in theory, fusion definitely works in theory (as the energy output is much higher).
asdff 5y ago
That just tells me that we haven't priced the externalities of carbon based energy appropriately, if the green solution is still more costly. Increase the carbon tax and things will pencil out fast.
orangepurple 5y ago
You can't put a price on energy independence in a free market economy. Energy independence is a military objective and a matter of national security. The costs are difficult to put in perspective.

wolf550e 5y ago

@dang This was reported and discussed 12 days ago: https://news.ycombinator.com/item?id=28704298 https://news.ycombinator.com/item?id=28704298 The important thing to know is that the NIF is about nuclear weapons design (verification of modeling software used for nuclear weapons design), not about developing fusion power plants.

floatingatoll 5y ago
Note that @dang doesn't actually notify dang, unless he happens to open this article and see it out of the corner of his eye or something. If you want to report a frontpage dupe, emailing the mods using the footer Contact link is an efficient method (or you can just flag it as I did, which has relatively the same effect if enough people do).
snek_case 5y ago
Kind of crazy that we're still spending money on this. Do we really need better H-bombs?
- blake1 5y ago
  The fear is that the nuclear weapons sitting in storage are assumed to be functional, but might turn out not to be. This could have dangerous geopolitical consequences. We can study how the materials age, but have to use simulation to understand the effects on the detonation given the test ban. This research helps calibrate the simulations. The civilian applications of the facility are secondary, as others have pointed out.
- chemeng 5y ago
  The US military probably thinks so, but I believe a major goal of NIF is the ability to model whether the ones the US already built will still work without setting one off.

not2b 5y ago

We're still a very long way off. Sabine Hossenfelder has a good explanation of what's wrong with most reporting on progress toward fusion: http://backreaction.blogspot.com/2021/10/how-close-is-nuclear-fusion-power.html http://backreaction.blogspot.com/2021/10/how-close-is-nuclea... edit: not sure why this was downvoted, it's directly relevant and the video and transcript discuss this experiment. It quotes Arthur Turrell: "This phenomenal breakthrough brings us tantalisingly close to a demonstration of 'net energy gain’ from fusion reactions – just when the planet needs it." But this comes close to getting Qplasma to be 1, which is about a factor of 50-70 lower than getting Q to be 1 (total power into the reactor vs usable power out of the reactor).

willis936 5y ago
>not sure why this was downvoted Perhaps because spreading the agenda-oriented opinion about fusion of someone who knows exactly as much about fusion as a high-schooler maybe isn't the best? https://news.ycombinator.com/item?id=28781178 https://news.ycombinator.com/item?id=28781178
- not2b 5y ago
  Wow. A respected PhD theoretical physicist knows exactly as much about fusion as a high schooler? See her Wikipedia page for her resume: https://en.m.wikipedia.org/wiki/Sabine_Hossenfelder https://en.m.wikipedia.org/wiki/Sabine_Hossenfelder
  - willis936 5y ago
    If she knows more then she knowingly deceived the public in her video to forward an agenda. Which explanation is worse to you?

ohcomments 5y ago

Next step.... Implement this in a spaceship and GTFO'a here...

pmdulaney 5y ago

Three cheers to the special relationship -- specifically as it extends to nuclear fusion!

deleted 5y ago

[deleted]

mbgerring 5y ago

Pretty interesting how this huge rash of articles about the same 2 or 3 fusion experiments have appeared just as the Federal government is considering where to spend resources in energy infrastructure for the next ten years. Who’s the publicist?

p1mrx 5y ago
I don't think it's a huge rash of articles; it's the same old news from August resurfacing every couple weeks.

tediousdemise 5y ago

What are the odds of runaway fusion occurring? Is there any consideration that a violent reaction could engulf the planet and end life as we know it?

regularfry 5y ago
Zero.
- tediousdemise 5y ago
  Is this because the chain reaction is limited by the fuel source?
  - regularfry 5y ago
    The fusion reaction needs containment, the right fuel, and massive amounts of energy in just the right place. It's phenomenally difficult to marshal the containment necessary to make the energy from a fusion reaction go into more fusion and not, say, warming up the test chamber a fraction. Yes, the fact that there's not much fuel is important, but not as important as the finickiness of making the plasma do what you want in the first place. One of the major problems (arguably the problem) with tokamak or similar fusion reactors is that if the plasma ever touches the edge of the vessel, it immediately cools down and stops being plasma. It can't fuse with itself any more, much less trigger anything else to start. Heavier atoms need more energy to fuse, that's why you see hydrogen, helium, lithium bandied about in these discussions. The amount of energy needed to fuse the atoms in the walls of a fusion reactor is literally supernova-scale. We're not talking "there's an engineering tolerance built in for safety", rather "as a civilisation it's not immediately conceivable how we might generate amounts of energy that large". Given that the majority of the earth is made out of elements that are inconveniently heavy, runaway fusion is absolutely, definitely, totally, completely not a problem.

thehappypm 5y ago

I'm struggling to understand what exactly happens. The deuterium and tritium mixture is hydrogen -- so it is a gas? So is it in some sort of gas-containing container, that also lets laser light through -- probably some kind of glass container? What kind of glass container can survive having this much energy pumped through it, and such a hot gas inside it? https://en.wikipedia.org/wiki/Fusion_ignition https://en.wikipedia.org/wiki/Fusion_ignition

Robotbeat 5y ago
It’s actually frozen deuterium tritium. Inside a small pellet blasted by X-rays which compress the pellet until it’s hot and dense enough for the fusion energy produced to continue burning and heating the deuterium/tritium until much more energy is produced than the energy of the X-rays. It all happens in an instant. The pellet’s structure doesn’t survive. But it happens fast enough that just the inertia of the pellet (turning to a gas and then a plasma) keeps things confined for long to fuse a significant amount of the deuterium/tritium.
- thehappypm 5y ago
  How do you freeze hydrogen?
  - pfdietz 5y ago
    You make it very cold.

bob229 5y ago

i guess it's just 20 years away then hahaha

DreamFlasher 5y ago

Old?

ashton314 5y ago

If I'm not mistaken, part of Star Trek: Into Darkness was filmed at a fusion research center. They used it as the backdrop for engineering/warp core. Just slap on a few starfleet decals and you're good to go!

omgJustTest 5y ago

PhD nuclear engineer here: The National Ignition Facility (NIF) is a fusion facility that seeks to study fusion (ie, meet the Lawson[1] criteria) through compression of a tiny spec of tritium or deuterium-tritium ice inside of a cylindrical tube called a Hohlraum[2]. Achieving fusion in this case can be assessed by a simple energy balance, canonically referred to as the "Q" factor[3]. Q=1 implies the fusion process released the same amount of energy the input-laser put in to the reactor. Q=2 is largely accepted as the minimum viable criteria for a fusion-power reactor (one unit of Q to return to the reactor, one unit of Q to be exported to the grid, power conversion unit etc for actual use). 1.3MJ is the claimed number by the article, while impressive for inertial confinement fusion (ICF), it lacks the context that the laser-input-power is ~2-4MJ (ie a Q~0.5). A bit more context: the best-of-the-best shots at NIF produce an idealistic energy balance that cannot sustain a reaction. There are a lot of other practical considerations such as how you would provide continuous power from the NIF Holhraums, what materials would stand up-to 100 DPA [4] damage from radiation bombardments, and a host of others. An open secret is that NIF's purpose is not exclusively fusion. Additionally JET appears to have a Q~0.67 according to wikipedia [3]. [1] https://en.wikipedia.org/wiki/Lawson_criterion https://en.wikipedia.org/wiki/Lawson_criterion [2] https://en.wikipedia.org/wiki/Hohlraum https://en.wikipedia.org/wiki/Hohlraum [3] https://en.wikipedia.org/wiki/Fusion_energy_gain_factor https://en.wikipedia.org/wiki/Fusion_energy_gain_factor [4] https://gcep.stanford.edu/pdfs/UVaodfDrAb3BdgeRCpoy-w/10-Zin https://gcep.stanford.edu/pdfs/UVaodfDrAb3BdgeRCpoy-w/10-Zin... slide 11.

ourmandave 5y ago

Fusion is the fuel of the future - and it always will be.

pfdietz 5y ago
Unlikely. At some point, the meme will just sputter out. Fusion will be as much the energy source of the future as dirigibles will be the aircraft of the future.