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Nuclear physicist explains why fusion ignition is hailed as a major breakthrough

285 points by nkurz 4y ago

_joel 4y ago
Anton Petrov did a great video on it https://www.youtube.com/watch?v=1g_A5tEApa0 https://www.youtube.com/watch?v=1g_A5tEApa0
a3w 4y ago
Fusion bombs soon with a laser primer instead of fission for heat generation? Not yet I guess. Clean power? Perhaps never.
- the_third_wave 4y ago
  I think you're overestimating the amount of energy released in a single fusion event and underestimating the machinery needed to generate and focus the laser pulses on the hohlraum. Remember there is no fusion chain reaction, the thing would need to keep on pumping pellets into the "primer" while firing laser pulses to keep the energy flowing. Compared to a 'simple' fission primer with a neutron reflector I don't really see the gain in a laser-primed fusion weapon, at least not one in the line of current fusion bombs.
- fallingknife 4y ago
  Actually, the tech that you are hinting at would guarantee clean fusion power. If you could generate clean fusion explosions, detonate underground and use the heat to generate power. Nuclear bombs are currently the only net energy positive fusion devices we have.
  - arethuza 4y ago
    Most bomb designs are fission-fusion-fission - most of the energy comes from the fission of the casing of the secondary by neutrons from the fusion process in the secondary. Edit: Mind you - there were tests like the huge Tsar Bomba that de-rated at 100+ Mt design to 50Mt be leaving out the final fission stage - the output being mostly from fusion. https://en.wikipedia.org/wiki/Tsar_Bomba https://en.wikipedia.org/wiki/Tsar_Bomba
    - denton-scratch 4y ago
      My understanding is that what you're referring to as a "fusion" stage is really a fusion-enhanced fission stage. All the stages of normal "H-bombs" are fission stages, using a small fusion core to generate a flood of neutrons, which results in the fission fuel combusting more completely. Pure fission bombs tend to disintegrate long before enough neutrons have been generated to achieve complete combustion. The inclusion of a small core of lithium deuteride results in a much more efficient fission bomb. I suppose these NIF tests are tiny pure fusion explosions; but I'm not aware of any practical weapon that generated energy mainly from fusion.
      - arethuza 4y ago
        "fusion-enhanced fission stage" The primary is fusion boosted fission, the core ("spark-plug") of the secondary is also fusion boosted fission surrounded by dry fusion fuel (lithium deuteride) and then a fissionable tamper. My understanding is that X rays from the primary compress the entire secondary package - which ignites the spark-plug and then the fusion fuel is caught between the incoming tamper and the exploding spark-plug at its core and ignited. So there does appear to be a real "fusion" stage - with a lot of other steps involving fission and fusion. https://en.wikipedia.org/wiki/Thermonuclear_weapon https://en.wikipedia.org/wiki/Thermonuclear_weapon
        denton-scratch 4y ago
        The cited article says: "Fast fission of the tamper and radiation case is the main contribution to the total yield and is the dominant process that produces radioactive fission product fallout." The way I read that, even in a large H-bomb, little of the yield is the direct result of fusion reactions. Rather, the neutrons produced by the fusion reaction dramatically increase the efficiency of the fission reactions, which on their own would not produce enough neutrons to fission more than a small part of the fissile material before the device disintegrates.
        arethuza 4y ago
  - rgmerk 4y ago
    It might guarantee clean fusion power, but there's no guarantee it would be in any way economic. Edward Teller proposed something along these lines with conventional two-stage nuclear explosives back in the 1970s, but it was rapidly abandoned as horribly inefficient and costly: https://en.wikipedia.org/wiki/Project_PACER https://en.wikipedia.org/wiki/Project_PACER I know this stuff is fun to speculate about but the boring and unsexy option of more solar panels, wind turbines, and transmission lines is likely to be both cheaper and more politically saleable.
    - denton-scratch 4y ago
      > clean fusion power From what I understand, practical routes to fusion all produce a lot of fast neutrons, and tritium. The neutrons make the surrounding equipment radioactive, and create toxic elements. The tritium is itself toxic, and is hard to contain. And the high neutron flux means that such a machine could easily be used to create weapons-grade plutonium, by irradiating uranium. And come decommissioning time, the reactor itself is a pile of toxic waste that will need long-term storage. I don't believe that fusion is inherently dirty; just that none of the technologies currently being investigated can be described as "clean". And they all run the risk of nuclear proliferation. IANAP.
      - DennisP 4y ago
        These issues apply to D-T fuel, whose output energy is 80% high-energy neutrons. Helion is using D-D/D-He3, whose output would be only 6% neutrons, at lower energy. If you do the D-D reactions in specialized fuel production facilities, you could sell the He3 to anyone with an He3 power plant and they'll have zero neutron radiation to deal with or misuse. Even with D-T, the reactor waste would stop being dangerously radioactive in a few decades.
      - LarryMullins 4y ago
        All of what you say is true. But on the plus side, you don't have the transuranic waste. Transuranic waste is the worst waste, the most dangerous and the most expensive and vital to store properly.
      - 4y ago
anonymousDan 4y ago
The conversation has some good stuff.
graderjs 4y ago
- d4mi3n 4y ago
  Cheap power enables a lot of things, like synthesis of fertilizers or the ability to cheaply desalinate water. It won’t fix these crisis directly, but it would reduce or remove a lot of the contributing factors.
  - graderjs 4y ago
    Sure, it's complex interaction. But where should our focus priorities be, what task should we do first...what should we publish most about??? Maybe my priorities are wrong...what are you saying?
    - _joel 4y ago
      It's possible to do 2 things at once.
      - graderjs 4y ago
        Of course, more focus on food security tho. Using the rising tide of promotion of fusion to draw attention to this more important goal is a good.
- TeMPOraL 4y ago
  > produce enough food to feed everyone? The soil crisis and the phosphorus crisis.... Are all ultimately problems of energy being too scarce (and therefore too expensive).
  - graderjs 4y ago
    I don't think so. You can be doing the wrong (unsustainable thing), even if you could afford to do the right thing.
LatteLazy 4y ago
The title doesn't match the contents. There is no actual justification of why this is a breakthrough. IMHO it's a milestone, not a breakthrough. This is because it is only a marginal improvement on previous results and it is very unlikely to significantly change the state of either the science or industrial products without further work.
- subradios 4y ago
  This specific marker is a breakthrough. We did not know until three weeks ago if laser ignited fusion reactions could be created that released more energy than was transmitted into the fuel. Now we know it is possible, it has been done. The next question is, can we create enough industrial efficiency to create a working motor generator set. A hard problem to be sure, but proving that it is a problem that we have is itself a breakthrough.
  - russdill 4y ago
    I'm confused why it matters. If I heat something with 2J of energy and it released 1J of energy, it's like the matter has been heated with 3J of energy. If I can extract heat energy with 80% efficiency, I can extract 2.4J, more energy than was put in.
  - LatteLazy 4y ago
    That is very small though, for a "breakthrough". That's my issue. We already knew that laser ignited fusion worked (that it triggers fusion). And we still don't know it can produce more energy than it consumes overall (one of the big questions for this sort of fusion). Really, we have gone from being 0.5% efficient to 1% efficient (I believe). One way to describe that is doubling the output. And that is technically true. But it's quite misleading as it will have no actual impact in the real world. Add to that that this was quite predictable. And that we will need at least 3 very big breakthroughs before this is viable (much more efficient lasers, a continuous method and either replacement of the fuel or a very easy supply of deuterium). I just don't see this as a big deal. That's why I called it a milestone. It's progress. But it isn't huge, unexpected, change-in-the-real-world progress.
garyclarke27 4y ago
Most interesting fact from the article. At the system level it took 300 million Joules to produce 3 Million a 1% return - so still a very long way to go! With this kind of approach I can’t see how fusion can ever be cheap, the capital costs are enormous. Better to focus on standardised production lines for small fission reactors.
- Jensson 4y ago
  Engineered lasers are over 10x more efficient at emitting light than what they got, and it is very possible they could improve the fusion ignition process to generate more per laser needed, so I wouldn't rule this out yet.
- tmikaeld 4y ago
  For one, it's theoretically impossible to make lasers 102 times more efficient, especially if you consider the current industrial efficiency of up to 20% (30% under special conditions). For example, the maximum efficiency of a laser is limited by the quantum efficiency of the laser material, which is the ratio of the number of photons emitted by the laser to the number of charge carriers (electrons and holes) injected into the laser material. The quantum efficiency of most laser materials is less than 100%, which means that there is a limit to the efficiency that can be achieved. In addition, the efficiency of a laser is also limited by the thermodynamic laws of thermodynamics, which state that it is not possible to convert heat or any other form of energy into work with 100% efficiency. This means that there is always some amount of waste heat generated when a laser is operated, which limits its efficiency. In other words, fusion is unlikely to be using lasers for the ignitions. UPDATE: People here seem to believe in self-sustained fusion, but this has never been tried or proven to be possible - no one know how much energy is needed for repeated ignition. The current plan is to re-ignite new pellets fed into the containment.
  - danbruc 4y ago
    For one, it's theoretically impossible to make lasers 102 times more efficient, especially if you consider the current industrial efficiency of up to 20% (30% under special conditions). That is not true. You can of course not make a 10 % efficient laser more than 10 times more efficient, but there is no limit to how much more efficient you can make a laser in general, you just have to start with an inefficient enough one. And the NIF lasers are quite inefficient, according to Wikipedia - which might have slightly outdated numbers as someone pointed out to me - they turn 422 MJ stored in capacitors into 1.8 MJ UV laser light, that is an efficiency of 0.43 %. Bringing this up to the 20 % you mentioned would already almost be a factor of 50. Also not all of the gain has to come from more efficient lasers, the fusion process could also be made more efficient. But you are of course correct that there is some general limit to laser efficiency, therefore the question is if the fusion gain can compensate this and all additional losses during the conversion into electricity further down the line.
dncornholio 4y ago
People don't believe the hype anymore so the solution is to not make 1 news article, but dozens of news articles. Maybe the people will start believing again! I've seen as many articles that says it's not as major of a breakthrough. It's marginal at best.
albertopv 4y ago
Real Engineering published a video about Helion Energy company. I don't have the tools to filter out commercial BS, still it seems to me to be most promising effort. The idea to get electricity directly from magnetic fields instead of boiling water is very intriguing.
- moffkalast 4y ago
  I've also been quite surprised watching that one, it's completely novel approach to fusion and it may be the best way to mass adoption. If they can make it work that is. What most surprised me about NIF's ignition announcement was that this was even news. I'd assumed for years that most if not all tokamaks and stellerators could already achieve at least some brief fusion, just not to a useful degree. Turns out they're all just elaborate plasma heaters...
  - albertopv 4y ago
    I'm very skeptical about those great announcements, even more when there's an announcement of the announcement. 300MJ in, 3MJ out, I wouldn't call it a breakthrough, maybe a milestone, nothing more.
    - moffkalast 4y ago
      I mean yeah it doesn't really change much in terms of usability, but it is the point from where onwards you can actually say you're doing fusion and not just heating stuff to high temps.
    - Cthulhu_ 4y ago
      And yet, they need to keep making announcements, else their funding will be cut. They knew all along that fusion energy would take decades to develop, and every year they need billions in funding to keep pushing for advancements. They can't just go radio silent until they're like "we've done it", they need to regularly publish papers and make big media announcements etc. Come to think of it, the LHC has been silent for a good while. Edit: It had a 3 year hiatus, started up again April this year.
bawolff 4y ago
Everything i have heard about this makes it sound more like a milestone than a breakthrough. I.e. its great it happened and an important step, but its not shocking that we eventually did it. When i hear breakthrough i think of something more unexpected. I.e. figuring out how to solve a problem we had no idea how to solve.
- vesinisa 4y ago
  Exactly.. The article fails to answer the question posed by its very title. What I've gathered, this was a very much expected result and NOT a "breakthrough". And with regards to making fusion a viable source for commercial, large-scale energy production .. this is only tangential at best to that effort. The problem with celebrating "fake victories" (and being scolded for calling them out) is that when there really is a breakthrough (i.e. something so big it fundamentally changes our perception of the problem), people are going to think you are making just another over-hyped publicity stunt. I am definitely of the opinion that such media attention focused advertising of (otherwise perfectly valid) fundamental research is doing no one favors (not the researches nor the public.)
  - tpmx 4y ago
    Another danger: I've seen quite a few people arguing in (a European context) that we shouldn't build out nuclear in the "short term", "since we can just get fusion without any of the downsides of fission".
    - jokteur 4y ago
      I've seen also people arguing that we should never ever build nuclear fission again because it is "bad". What I want to say is that bad faith arguments will always exist, and calling this a breakthrough won't significantly increase the number of people using bad faith arguments, because they would just find another excuse instead of the fusion one.
  - zmgsabst 4y ago
    Their chart seems to indicate that this is a qualitative improvement where the kind of fusion produced substantially changed. I share your skepticism towards commercial impact — but this is certainly a breakthrough in their technology. Just look at the chart. https://en.m.wikipedia.org/wiki/National_Ignition_Facility#/media/File%3ANIF_output_over_10_years.png https://en.m.wikipedia.org/wiki/National_Ignition_Facility#/...
muglug 4y ago
I love the reference to a hairdryer. Science communication at its best that helped me put this all in context.
rob74 4y ago
Still unconvinced why this is such a major breakthrough - it may be the first net-positive controlled fusion, but the distinction between controlled and uncontrolled fusion is a bit academic in this case. In uncontrolled fusion (https://en.wikipedia.org/wiki/Thermonuclear_weapon https://en.wikipedia.org/wiki/Thermonuclear_weapon), you are using a nuclear fission primary stage to generate enough energy to start the fusion reaction in the secondary stage. In the NIF, you are using lasers (that have to be aligned to trillionths of a meter and damage their own guiding optics everytime they fire) to start the fusion reaction in a smaller pellet (that costs hundreds of thousands of dollars). So the only real difference between the first and the second case is that the H-bomb is smaller, much more expensive per amount of energy released, and explodes inside a chamber. And it's obvious to pretty much everyone who is paying attention that transforming this setup into a working and cost-effective fusion power plant is a very tall order. Also, what somehow always gets left out of these articles is that the NIF is a military facility financed from the "(Nuclear) Stockpile Stewardship" budget. So its primary objective is studying fusion in a controlled way, but for building better bombs (and retaining the expertise necessary to build them), not for energy production.
- Systemic33 4y ago
  With regards to NIF being a military facility, I'd very much think that energy production (cheap, safe, limitless?) is very much a military needs as much as a civilian need. Even if said energy goes further to power laser weapons or other exotic power hungry systems; energy is energy, and something has to produce it.
  - oblio 4y ago
    The internet was a military need from what I remember. The military said something like: "Telephone routing is point to point and inflexible, if the enemy cuts out 1-2 lines of communication, an entire section is completely cut off. We need something better." That something better turned out to be packed switching where you just throw stuff along a network and the network ensures that the packet reaches the destination, but you could theoretically have two packets going from Bucharest to Johannesburg, one through India and the second one through Canada.
sudhirj 4y ago
It’s practical proof that in a single pulse we can get more energy out than we put in. We do spend a shit ton of energy setting up the pulse, and we haven’t figure out how to get that energy out and make electrons move, but it’s been proven possible. The “breakthrough” is the proof that it’s possible. Everything else is now optimisation and engineering, and needs mostly time, sweat and money.
- maegul 4y ago
  Yea, and I wonder how much our need, at a cultural level, for progress will factor into this. If we feel like we need to progress and can't go "backward" with our energy technology, there may just be an irrational impetus to make it happen. Solar and wind etc may just feel too "primitive" and nuclear too old and toxic and Chernobyl. Fusion though, once there's enough buy in and enough of a sense of it being doable, would fit our expectation of technological progress.
  - pmontra 4y ago
    Culture bends to circumstances. When or where people can't cook or stay warm using the power sources they are accustomed to they go back in an instant to old ones. Logging and campfires, stoves, etc.
  - ehnto 4y ago
    The practical reality is that solar and wind are still getting deployed en masse, people who want electricity don't really care what how science feels about progress etc. They just want their lights to turn on and for cheap. Since renewables are currently cheap, that's what we're deploying a decent amount of (depending on geography of course).
- Retric 4y ago
  Sort of. This milestone is liberating more fusion energy than photons used to start the reaction, but the energy source for the machine was electricity and it produced zero electricity. If you tried to convert the heat back to electricity you would be talking less than 0.1% of the electricity used being recovered at the other end.
nottorp 4y ago
No one's commenting on the self sustaining part. Would it have kept going without external energy input if they had more fuel? I don't think the 1% system wide would matter if it just went on after the first few seconds.
- sandworm101 4y ago
  No. This was inertial confinement fusion, like in a bomb. The reaction could not have continued under any circumstance. The only hope would be to run this test repeatedly, like ten times a second, and somehow pull put power. But this machine has no hope of even attempting that.
- rurban 4y ago
  They are not talking about a few seconds, they are talking about a few nanoseconds. Which is NOT stable at all. A few seconds would be a major breakthrough indeed.
wumms 4y ago
> more than 5 million degrees Fahrenheit (3 million Celsius) – about 100 times hotter than the surface of the Sun As my fear of Crichton's Gell-Mann Amnesia sets in, I'm being pedantic: either its about 545 times hotter than the surface of the sun (5.500°C) or they've reached "only" 0.55 million degrees Celsius. Also: its only 519 times hotter than the surface of the sun when using absolute temperature (5.778 K).
Whitespace 4y ago
I find it interesting that people talk in absolutes ("fusion will never be economical!") when the devices they're using were "impossible" only a few decades ago. Also the difference between a 4:00:00 marathon and a 3:59:59 is less than a 0.007% improvement but it's a huge victory nonetheless. Once someone proves an arbitrary numerical barrier can be overcome humans tend to make a lot of progress shortly thereafter.
jackmott42 4y ago
I can tell you that regular people took the announcements as a sign that nuclear fusion as a real useful thing is imminent, and couldn't be convinced otherwise! But then if your announcements are completely rational you don't get as much funding. A lot of us nerds on HN don't like it when people do propaganda, but I assume we also like to win, right?
- koppe 4y ago
  They literally said it would take decades for this to become "useful", I don't think they made it seem closer than it is at all
- danuker 4y ago
  > But then if your announcements are completely rational you don't get as much funding. If your goal is to gain funding, the rational announcement IS to sensationalize.
- hinkley 4y ago
  When people have been doing the propaganda for longer than I have been alive, I become an old, salty fucker.
  - 8bitsrule 4y ago
    I recall reading an old 60s issue of 'Physics Today'; someone prophesized fusion ws 20 years away. None of that in the (look, it's still around) recent article. Insightful details are present. And some honesty ... e.g. "The agency toned down the ignition objective, emphasizing NIF’s ongoing experiments to investigate materials’ behavior under extreme densities and pressures in support of nuclear stockpile maintenance." [https://physicstoday.scitation.org/do/10.1063/PT.6.2.20221213a/full/ https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121...]
    - hinkley 4y ago
      > in support of nuclear stockpile maintenance I may not speak for everyone but I certainly don’t find that comforting and know at least a few people who would agree.
tonmoy 4y ago
This type of nuclear fusion uses tritium, and since we can’t extract it from nature the only way to obtain it is very energy extensive. For this type of fusion to make sense producing tritium+lasers have to require less energy than the output, right?
- acidburnNSA 4y ago
  The power plant version of this produces enough tritium as it captures the heat in a breeding blanket of lithium outside the core.
  - world-set-free 4y ago
    Lithium-6 is not as cheap as coal per energy delivered after all is said and done.
masoudd 4y ago
We already have a stable fusion going. It's 8 light minutes away. All you have to do is to point a solar panel at it to harvest the energy.
- hrgiger 4y ago
  Korean reactor reached 7 times hotter than sun, when I was reading it made me laugh that humans said fuck the dyson sphere and skipped a step on Kardashev scale yet still I find it ironic that this one built with military support. https://www.sciencealert.com/koreas-fusion-reactor-ran-7-times-hotter-than-the-sun-for-almost-30-seconds https://www.sciencealert.com/koreas-fusion-reactor-ran-7-tim...
- deleted 4y ago
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- jeffbee 4y ago
  Gravity confinement fusion with optical coupling. Really much, much more practical than the fanciful notion that NIF will miraculously lead to a commercial energy source that ingests diamond-coated nanopellets and has a duty cycle of 1:1e15.
  - dumbotron 4y ago
    NIF is probably a dead end for fusion power, but this is still an important milestone.
torpfactory 4y ago
Being able to do “ignition” reliably means you can do experiments in a regime where the energy from fusion starts to become a large part of the reaction. Dynamics in this regime are non-linear, so being able to actually test there is fairly important. Updating models and simulation inputs based on these results should make some further progress possible. This device is significantly different than a power reactor, but other efforts might see a benefit from a better understanding of reaction physics during “ignition”.
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graycat 4y ago
Ah, maybe there is a point so far not mentioned: For a hint, the work was at the NIF, National Ignition Facility. Even to start a wood fire, need an ignition facility. Then the fire continues on its own putting out much more energy than was used with the matches or whatever during the ignition. Then the energy from the fire ignites the wood that is not yet burning. As we now know, once the nuclear reaction is ignited, the reaction generates more energy than was used with the lasers for the ignition. Then, sure, we can expect that the energy of the reaction should, without more energy from lasers, have the reaction continue. Right, I'm ignoring a long list of what are sometimes called engineering details, e.g., that this is inertial confinement fusion! Ah, at one time I worked for KMS, that is the company of Kip M. Siegel, as at Google and Wikipedia: "KMS Fusion was the first and only private sector company to pursue controlled thermonuclear fusion research through use of laser technology." https://en.wikipedia.org/wiki/Kip_Siegel https://en.wikipedia.org/wiki/Kip_Siegel The report at the time was that KMS had achieved fusion neutrons. Hmm .... I didn't work on fusion but was hired because I knew quite a lot about the fast Fourier transform (FFT).
photochemsyn 4y ago
This article is obviously a PR piece, not an objective review, and the interviewee receives funding from the program. Looking around a bit, here's a discussion from 2018 that's a bit more revealing: https://physicstoday.scitation.org/do/10.1063/pt.6.2.20180615b/full/ https://physicstoday.scitation.org/do/10.1063/pt.6.2.2018061... > "In the latest round of experiments, the capsule shells consisted of diamond doped with a thin layer of tungsten, and the hohlraums were made of depleted uranium. Earlier experiments had used plastic shells and gold hohlraums. Sebastien Le Pape, lead author of the paper, says the uranium hohlraum boosted the peak energy deposited on the capsule by 25 terawatts, for a total of about 450 TW." Clearly the cost of these fuel capsules is prohibitive when it comes to any practical power production system, plus there's nothing like an energy capture-and-conversion-to-electricity system being developed. It certainly looks more like nuclear weapons research than power production research. The real goal is just preserving the budgetary outlay: > "The new results were achieved before the Trump administration proposed cutting funding for NIF by $57 million, to $287 million in fiscal year 2019. That would have forced a 30% reduction in the number of experimental shots of the 192-beam laser. Lawmakers instead added to NIF’s funding next year: The final appropriation will likely end up between the $330 million included in a House-passed bill and $344 million included in a Senate measure." Notably, DOE budgets for solar PV development remain entirely minuscule in comparison, which is one reason why it's China, not the USA, that has mastered efficient production of high-efficiency, high-durability monocrystalline silicon PV panels at scale. These of course compete directly with natural gas for power production, and the US wants to be the biggest natural gas exporter in the world. Not hard to understand what's really going on at the DOE/NNSA, whose original name was the Manhattan Project, then the AEC: https://en.wikipedia.org/wiki/United_States_Atomic_Energy_Commission https://en.wikipedia.org/wiki/United_States_Atomic_Energy_Co...
UltraViolence 4y ago
Long story short: it has never been done before and that's why it's a breakthrough. Never mind that it's totally impractical and far from something we could use to solve our energy problems TODAY. We need to focus on building hundreds if not thousands of nuclear fission reactors and to reduce the population growth through birth control outside the Western world.
college_physics 4y ago
well, we have a serious energy addiction problem as large parts of the population got used to unsustainably high per-capital energy lifestyles (basically burning fossil fuel repositories like there is no tomorrow). so any paths to clean energy production are worth pursuing - provided they don't create an illusory sense of comfort and unsubstantiated hope that some fancy tech will solve everything. fundamentally though, one would think that trying to create artificially solar interior conditions on Earth while the planet is literarily drenched in sunlight is not the shortest path to energy salvation. Life has invented already several ways to harness that energy and we have invented a few more in the meantime. I think the odds are that we will have more (as in: sufficiently) efficient harnessing of solar energy long before we create locally little suns to play with.
floxy 4y ago
Does anyone know what the conversion mechanism from the laser to x-rays is? Is that just because the lasers heat up the inside of the hohlraum, and the x-rays are just the black-body radiation from that?
nforgerit 4y ago
I'm just an interested layman on the sideline watching from "old Europe" but can't help but ask: Is everything okay with your science-media sector over there in the US? Lately, I've been asked to believe this weird wormhole story[0] and now this "major breakthrough" in fusion ignition? This all smells like too much marketing BS to me. [0] https://www.quantamagazine.org/physicists-create-a-wormhole-using-a-quantum-computer-20221130/ https://www.quantamagazine.org/physicists-create-a-wormhole-...
- salawat 4y ago
  You are not alone in pondering that, even from someone living on this side of the pond.
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patientplatypus 4y ago
HarHarVeryFunny 4y ago
I'm far more excited by the innovative Helion fusion design, which unlike the NIF is intended for commercial use, and is in an advanced stage of development. NIF seems more like a way to conduct military related nuclear physiscs research rather than intended/suitable to ever be used for power generation. https://www.youtube.com/watch?v=_bDXXWQxK38 https://www.youtube.com/watch?v=_bDXXWQxK38 Helion seems far more practical than the Tomahawk designs such as ITER, which seem they'll be too expensive to compete with solar/wind.
world-set-free 4y ago
They are lacking more than 100x https://lasers.llnl.gov/about/how-nif-works/power-conditioning https://lasers.llnl.gov/about/how-nif-works/power-conditioni...

285 points by nkurz 4y ago

Anton Petrov did a great video on it https://www.youtube.com/watch?v=1g_A5tEApa0 https://www.youtube.com/watch?v=1g_A5tEApa0

a3w 4y ago

Fusion bombs soon with a laser primer instead of fission for heat generation? Not yet I guess. Clean power? Perhaps never.

the_third_wave 4y ago
I think you're overestimating the amount of energy released in a single fusion event and underestimating the machinery needed to generate and focus the laser pulses on the hohlraum. Remember there is no fusion chain reaction, the thing would need to keep on pumping pellets into the "primer" while firing laser pulses to keep the energy flowing. Compared to a 'simple' fission primer with a neutron reflector I don't really see the gain in a laser-primed fusion weapon, at least not one in the line of current fusion bombs.
fallingknife 4y ago
Actually, the tech that you are hinting at would guarantee clean fusion power. If you could generate clean fusion explosions, detonate underground and use the heat to generate power. Nuclear bombs are currently the only net energy positive fusion devices we have.
- arethuza 4y ago
  Most bomb designs are fission-fusion-fission - most of the energy comes from the fission of the casing of the secondary by neutrons from the fusion process in the secondary. Edit: Mind you - there were tests like the huge Tsar Bomba that de-rated at 100+ Mt design to 50Mt be leaving out the final fission stage - the output being mostly from fusion. https://en.wikipedia.org/wiki/Tsar_Bomba https://en.wikipedia.org/wiki/Tsar_Bomba
  - denton-scratch 4y ago
    My understanding is that what you're referring to as a "fusion" stage is really a fusion-enhanced fission stage. All the stages of normal "H-bombs" are fission stages, using a small fusion core to generate a flood of neutrons, which results in the fission fuel combusting more completely. Pure fission bombs tend to disintegrate long before enough neutrons have been generated to achieve complete combustion. The inclusion of a small core of lithium deuteride results in a much more efficient fission bomb. I suppose these NIF tests are tiny pure fusion explosions; but I'm not aware of any practical weapon that generated energy mainly from fusion.
    - arethuza 4y ago
      "fusion-enhanced fission stage" The primary is fusion boosted fission, the core ("spark-plug") of the secondary is also fusion boosted fission surrounded by dry fusion fuel (lithium deuteride) and then a fissionable tamper. My understanding is that X rays from the primary compress the entire secondary package - which ignites the spark-plug and then the fusion fuel is caught between the incoming tamper and the exploding spark-plug at its core and ignited. So there does appear to be a real "fusion" stage - with a lot of other steps involving fission and fusion. https://en.wikipedia.org/wiki/Thermonuclear_weapon https://en.wikipedia.org/wiki/Thermonuclear_weapon
      - denton-scratch 4y ago
        The cited article says: "Fast fission of the tamper and radiation case is the main contribution to the total yield and is the dominant process that produces radioactive fission product fallout." The way I read that, even in a large H-bomb, little of the yield is the direct result of fusion reactions. Rather, the neutrons produced by the fusion reaction dramatically increase the efficiency of the fission reactions, which on their own would not produce enough neutrons to fission more than a small part of the fissile material before the device disintegrates.
        arethuza 4y ago
- rgmerk 4y ago
  It might guarantee clean fusion power, but there's no guarantee it would be in any way economic. Edward Teller proposed something along these lines with conventional two-stage nuclear explosives back in the 1970s, but it was rapidly abandoned as horribly inefficient and costly: https://en.wikipedia.org/wiki/Project_PACER https://en.wikipedia.org/wiki/Project_PACER I know this stuff is fun to speculate about but the boring and unsexy option of more solar panels, wind turbines, and transmission lines is likely to be both cheaper and more politically saleable.
  - denton-scratch 4y ago
    > clean fusion power From what I understand, practical routes to fusion all produce a lot of fast neutrons, and tritium. The neutrons make the surrounding equipment radioactive, and create toxic elements. The tritium is itself toxic, and is hard to contain. And the high neutron flux means that such a machine could easily be used to create weapons-grade plutonium, by irradiating uranium. And come decommissioning time, the reactor itself is a pile of toxic waste that will need long-term storage. I don't believe that fusion is inherently dirty; just that none of the technologies currently being investigated can be described as "clean". And they all run the risk of nuclear proliferation. IANAP.
    - DennisP 4y ago
      These issues apply to D-T fuel, whose output energy is 80% high-energy neutrons. Helion is using D-D/D-He3, whose output would be only 6% neutrons, at lower energy. If you do the D-D reactions in specialized fuel production facilities, you could sell the He3 to anyone with an He3 power plant and they'll have zero neutron radiation to deal with or misuse. Even with D-T, the reactor waste would stop being dangerously radioactive in a few decades.
    - LarryMullins 4y ago
      All of what you say is true. But on the plus side, you don't have the transuranic waste. Transuranic waste is the worst waste, the most dangerous and the most expensive and vital to store properly.
    - 4y ago

anonymousDan 4y ago

The conversation has some good stuff.

graderjs 4y ago

d4mi3n 4y ago
Cheap power enables a lot of things, like synthesis of fertilizers or the ability to cheaply desalinate water. It won’t fix these crisis directly, but it would reduce or remove a lot of the contributing factors.
- graderjs 4y ago
  Sure, it's complex interaction. But where should our focus priorities be, what task should we do first...what should we publish most about??? Maybe my priorities are wrong...what are you saying?
  - _joel 4y ago
    It's possible to do 2 things at once.
    - graderjs 4y ago
      Of course, more focus on food security tho. Using the rising tide of promotion of fusion to draw attention to this more important goal is a good.
TeMPOraL 4y ago
> produce enough food to feed everyone? The soil crisis and the phosphorus crisis.... Are all ultimately problems of energy being too scarce (and therefore too expensive).
- graderjs 4y ago
  I don't think so. You can be doing the wrong (unsustainable thing), even if you could afford to do the right thing.

LatteLazy 4y ago

The title doesn't match the contents. There is no actual justification of why this is a breakthrough. IMHO it's a milestone, not a breakthrough. This is because it is only a marginal improvement on previous results and it is very unlikely to significantly change the state of either the science or industrial products without further work.

subradios 4y ago
This specific marker is a breakthrough. We did not know until three weeks ago if laser ignited fusion reactions could be created that released more energy than was transmitted into the fuel. Now we know it is possible, it has been done. The next question is, can we create enough industrial efficiency to create a working motor generator set. A hard problem to be sure, but proving that it is a problem that we have is itself a breakthrough.
- russdill 4y ago
  I'm confused why it matters. If I heat something with 2J of energy and it released 1J of energy, it's like the matter has been heated with 3J of energy. If I can extract heat energy with 80% efficiency, I can extract 2.4J, more energy than was put in.
- LatteLazy 4y ago
  That is very small though, for a "breakthrough". That's my issue. We already knew that laser ignited fusion worked (that it triggers fusion). And we still don't know it can produce more energy than it consumes overall (one of the big questions for this sort of fusion). Really, we have gone from being 0.5% efficient to 1% efficient (I believe). One way to describe that is doubling the output. And that is technically true. But it's quite misleading as it will have no actual impact in the real world. Add to that that this was quite predictable. And that we will need at least 3 very big breakthroughs before this is viable (much more efficient lasers, a continuous method and either replacement of the fuel or a very easy supply of deuterium). I just don't see this as a big deal. That's why I called it a milestone. It's progress. But it isn't huge, unexpected, change-in-the-real-world progress.

garyclarke27 4y ago

Most interesting fact from the article. At the system level it took 300 million Joules to produce 3 Million a 1% return - so still a very long way to go! With this kind of approach I can’t see how fusion can ever be cheap, the capital costs are enormous. Better to focus on standardised production lines for small fission reactors.

Jensson 4y ago
Engineered lasers are over 10x more efficient at emitting light than what they got, and it is very possible they could improve the fusion ignition process to generate more per laser needed, so I wouldn't rule this out yet.
tmikaeld 4y ago
For one, it's theoretically impossible to make lasers 102 times more efficient, especially if you consider the current industrial efficiency of up to 20% (30% under special conditions). For example, the maximum efficiency of a laser is limited by the quantum efficiency of the laser material, which is the ratio of the number of photons emitted by the laser to the number of charge carriers (electrons and holes) injected into the laser material. The quantum efficiency of most laser materials is less than 100%, which means that there is a limit to the efficiency that can be achieved. In addition, the efficiency of a laser is also limited by the thermodynamic laws of thermodynamics, which state that it is not possible to convert heat or any other form of energy into work with 100% efficiency. This means that there is always some amount of waste heat generated when a laser is operated, which limits its efficiency. In other words, fusion is unlikely to be using lasers for the ignitions. UPDATE: People here seem to believe in self-sustained fusion, but this has never been tried or proven to be possible - no one know how much energy is needed for repeated ignition. The current plan is to re-ignite new pellets fed into the containment.
- danbruc 4y ago
  For one, it's theoretically impossible to make lasers 102 times more efficient, especially if you consider the current industrial efficiency of up to 20% (30% under special conditions). That is not true. You can of course not make a 10 % efficient laser more than 10 times more efficient, but there is no limit to how much more efficient you can make a laser in general, you just have to start with an inefficient enough one. And the NIF lasers are quite inefficient, according to Wikipedia - which might have slightly outdated numbers as someone pointed out to me - they turn 422 MJ stored in capacitors into 1.8 MJ UV laser light, that is an efficiency of 0.43 %. Bringing this up to the 20 % you mentioned would already almost be a factor of 50. Also not all of the gain has to come from more efficient lasers, the fusion process could also be made more efficient. But you are of course correct that there is some general limit to laser efficiency, therefore the question is if the fusion gain can compensate this and all additional losses during the conversion into electricity further down the line.

dncornholio 4y ago

People don't believe the hype anymore so the solution is to not make 1 news article, but dozens of news articles. Maybe the people will start believing again! I've seen as many articles that says it's not as major of a breakthrough. It's marginal at best.

albertopv 4y ago

Real Engineering published a video about Helion Energy company. I don't have the tools to filter out commercial BS, still it seems to me to be most promising effort. The idea to get electricity directly from magnetic fields instead of boiling water is very intriguing.

moffkalast 4y ago
I've also been quite surprised watching that one, it's completely novel approach to fusion and it may be the best way to mass adoption. If they can make it work that is. What most surprised me about NIF's ignition announcement was that this was even news. I'd assumed for years that most if not all tokamaks and stellerators could already achieve at least some brief fusion, just not to a useful degree. Turns out they're all just elaborate plasma heaters...
- albertopv 4y ago
  I'm very skeptical about those great announcements, even more when there's an announcement of the announcement. 300MJ in, 3MJ out, I wouldn't call it a breakthrough, maybe a milestone, nothing more.
  - moffkalast 4y ago
    I mean yeah it doesn't really change much in terms of usability, but it is the point from where onwards you can actually say you're doing fusion and not just heating stuff to high temps.
  - Cthulhu_ 4y ago
    And yet, they need to keep making announcements, else their funding will be cut. They knew all along that fusion energy would take decades to develop, and every year they need billions in funding to keep pushing for advancements. They can't just go radio silent until they're like "we've done it", they need to regularly publish papers and make big media announcements etc. Come to think of it, the LHC has been silent for a good while. Edit: It had a 3 year hiatus, started up again April this year.

bawolff 4y ago

Everything i have heard about this makes it sound more like a milestone than a breakthrough. I.e. its great it happened and an important step, but its not shocking that we eventually did it. When i hear breakthrough i think of something more unexpected. I.e. figuring out how to solve a problem we had no idea how to solve.

vesinisa 4y ago
Exactly.. The article fails to answer the question posed by its very title. What I've gathered, this was a very much expected result and NOT a "breakthrough". And with regards to making fusion a viable source for commercial, large-scale energy production .. this is only tangential at best to that effort. The problem with celebrating "fake victories" (and being scolded for calling them out) is that when there really is a breakthrough (i.e. something so big it fundamentally changes our perception of the problem), people are going to think you are making just another over-hyped publicity stunt. I am definitely of the opinion that such media attention focused advertising of (otherwise perfectly valid) fundamental research is doing no one favors (not the researches nor the public.)
- tpmx 4y ago
  Another danger: I've seen quite a few people arguing in (a European context) that we shouldn't build out nuclear in the "short term", "since we can just get fusion without any of the downsides of fission".
  - jokteur 4y ago
    I've seen also people arguing that we should never ever build nuclear fission again because it is "bad". What I want to say is that bad faith arguments will always exist, and calling this a breakthrough won't significantly increase the number of people using bad faith arguments, because they would just find another excuse instead of the fusion one.
- zmgsabst 4y ago
  Their chart seems to indicate that this is a qualitative improvement where the kind of fusion produced substantially changed. I share your skepticism towards commercial impact — but this is certainly a breakthrough in their technology. Just look at the chart. https://en.m.wikipedia.org/wiki/National_Ignition_Facility#/media/File%3ANIF_output_over_10_years.png https://en.m.wikipedia.org/wiki/National_Ignition_Facility#/...

muglug 4y ago

I love the reference to a hairdryer. Science communication at its best that helped me put this all in context.

rob74 4y ago

Still unconvinced why this is such a major breakthrough - it may be the first net-positive controlled fusion, but the distinction between controlled and uncontrolled fusion is a bit academic in this case. In uncontrolled fusion (https://en.wikipedia.org/wiki/Thermonuclear_weapon https://en.wikipedia.org/wiki/Thermonuclear_weapon), you are using a nuclear fission primary stage to generate enough energy to start the fusion reaction in the secondary stage. In the NIF, you are using lasers (that have to be aligned to trillionths of a meter and damage their own guiding optics everytime they fire) to start the fusion reaction in a smaller pellet (that costs hundreds of thousands of dollars). So the only real difference between the first and the second case is that the H-bomb is smaller, much more expensive per amount of energy released, and explodes inside a chamber. And it's obvious to pretty much everyone who is paying attention that transforming this setup into a working and cost-effective fusion power plant is a very tall order. Also, what somehow always gets left out of these articles is that the NIF is a military facility financed from the "(Nuclear) Stockpile Stewardship" budget. So its primary objective is studying fusion in a controlled way, but for building better bombs (and retaining the expertise necessary to build them), not for energy production.

Systemic33 4y ago
With regards to NIF being a military facility, I'd very much think that energy production (cheap, safe, limitless?) is very much a military needs as much as a civilian need. Even if said energy goes further to power laser weapons or other exotic power hungry systems; energy is energy, and something has to produce it.
- oblio 4y ago
  The internet was a military need from what I remember. The military said something like: "Telephone routing is point to point and inflexible, if the enemy cuts out 1-2 lines of communication, an entire section is completely cut off. We need something better." That something better turned out to be packed switching where you just throw stuff along a network and the network ensures that the packet reaches the destination, but you could theoretically have two packets going from Bucharest to Johannesburg, one through India and the second one through Canada.

sudhirj 4y ago

It’s practical proof that in a single pulse we can get more energy out than we put in. We do spend a shit ton of energy setting up the pulse, and we haven’t figure out how to get that energy out and make electrons move, but it’s been proven possible. The “breakthrough” is the proof that it’s possible. Everything else is now optimisation and engineering, and needs mostly time, sweat and money.

maegul 4y ago
Yea, and I wonder how much our need, at a cultural level, for progress will factor into this. If we feel like we need to progress and can't go "backward" with our energy technology, there may just be an irrational impetus to make it happen. Solar and wind etc may just feel too "primitive" and nuclear too old and toxic and Chernobyl. Fusion though, once there's enough buy in and enough of a sense of it being doable, would fit our expectation of technological progress.
- pmontra 4y ago
  Culture bends to circumstances. When or where people can't cook or stay warm using the power sources they are accustomed to they go back in an instant to old ones. Logging and campfires, stoves, etc.
- ehnto 4y ago
  The practical reality is that solar and wind are still getting deployed en masse, people who want electricity don't really care what how science feels about progress etc. They just want their lights to turn on and for cheap. Since renewables are currently cheap, that's what we're deploying a decent amount of (depending on geography of course).
Retric 4y ago
Sort of. This milestone is liberating more fusion energy than photons used to start the reaction, but the energy source for the machine was electricity and it produced zero electricity. If you tried to convert the heat back to electricity you would be talking less than 0.1% of the electricity used being recovered at the other end.

nottorp 4y ago

No one's commenting on the self sustaining part. Would it have kept going without external energy input if they had more fuel? I don't think the 1% system wide would matter if it just went on after the first few seconds.

sandworm101 4y ago
No. This was inertial confinement fusion, like in a bomb. The reaction could not have continued under any circumstance. The only hope would be to run this test repeatedly, like ten times a second, and somehow pull put power. But this machine has no hope of even attempting that.
rurban 4y ago
They are not talking about a few seconds, they are talking about a few nanoseconds. Which is NOT stable at all. A few seconds would be a major breakthrough indeed.

wumms 4y ago

> more than 5 million degrees Fahrenheit (3 million Celsius) – about 100 times hotter than the surface of the Sun As my fear of Crichton's Gell-Mann Amnesia sets in, I'm being pedantic: either its about 545 times hotter than the surface of the sun (5.500°C) or they've reached "only" 0.55 million degrees Celsius. Also: its only 519 times hotter than the surface of the sun when using absolute temperature (5.778 K).

Whitespace 4y ago

I find it interesting that people talk in absolutes ("fusion will never be economical!") when the devices they're using were "impossible" only a few decades ago. Also the difference between a 4:00:00 marathon and a 3:59:59 is less than a 0.007% improvement but it's a huge victory nonetheless. Once someone proves an arbitrary numerical barrier can be overcome humans tend to make a lot of progress shortly thereafter.

jackmott42 4y ago

I can tell you that regular people took the announcements as a sign that nuclear fusion as a real useful thing is imminent, and couldn't be convinced otherwise! But then if your announcements are completely rational you don't get as much funding. A lot of us nerds on HN don't like it when people do propaganda, but I assume we also like to win, right?

koppe 4y ago
They literally said it would take decades for this to become "useful", I don't think they made it seem closer than it is at all
danuker 4y ago
> But then if your announcements are completely rational you don't get as much funding. If your goal is to gain funding, the rational announcement IS to sensationalize.
hinkley 4y ago
When people have been doing the propaganda for longer than I have been alive, I become an old, salty fucker.
- 8bitsrule 4y ago
  I recall reading an old 60s issue of 'Physics Today'; someone prophesized fusion ws 20 years away. None of that in the (look, it's still around) recent article. Insightful details are present. And some honesty ... e.g. "The agency toned down the ignition objective, emphasizing NIF’s ongoing experiments to investigate materials’ behavior under extreme densities and pressures in support of nuclear stockpile maintenance." [https://physicstoday.scitation.org/do/10.1063/PT.6.2.20221213a/full/ https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121...]
  - hinkley 4y ago
    > in support of nuclear stockpile maintenance I may not speak for everyone but I certainly don’t find that comforting and know at least a few people who would agree.

tonmoy 4y ago

This type of nuclear fusion uses tritium, and since we can’t extract it from nature the only way to obtain it is very energy extensive. For this type of fusion to make sense producing tritium+lasers have to require less energy than the output, right?

acidburnNSA 4y ago
The power plant version of this produces enough tritium as it captures the heat in a breeding blanket of lithium outside the core.
- world-set-free 4y ago
  Lithium-6 is not as cheap as coal per energy delivered after all is said and done.

masoudd 4y ago

We already have a stable fusion going. It's 8 light minutes away. All you have to do is to point a solar panel at it to harvest the energy.

hrgiger 4y ago
Korean reactor reached 7 times hotter than sun, when I was reading it made me laugh that humans said fuck the dyson sphere and skipped a step on Kardashev scale yet still I find it ironic that this one built with military support. https://www.sciencealert.com/koreas-fusion-reactor-ran-7-times-hotter-than-the-sun-for-almost-30-seconds https://www.sciencealert.com/koreas-fusion-reactor-ran-7-tim...
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jeffbee 4y ago
Gravity confinement fusion with optical coupling. Really much, much more practical than the fanciful notion that NIF will miraculously lead to a commercial energy source that ingests diamond-coated nanopellets and has a duty cycle of 1:1e15.
- dumbotron 4y ago
  NIF is probably a dead end for fusion power, but this is still an important milestone.

torpfactory 4y ago

Being able to do “ignition” reliably means you can do experiments in a regime where the energy from fusion starts to become a large part of the reaction. Dynamics in this regime are non-linear, so being able to actually test there is fairly important. Updating models and simulation inputs based on these results should make some further progress possible. This device is significantly different than a power reactor, but other efforts might see a benefit from a better understanding of reaction physics during “ignition”.

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graycat 4y ago

Ah, maybe there is a point so far not mentioned: For a hint, the work was at the NIF, National Ignition Facility. Even to start a wood fire, need an ignition facility. Then the fire continues on its own putting out much more energy than was used with the matches or whatever during the ignition. Then the energy from the fire ignites the wood that is not yet burning. As we now know, once the nuclear reaction is ignited, the reaction generates more energy than was used with the lasers for the ignition. Then, sure, we can expect that the energy of the reaction should, without more energy from lasers, have the reaction continue. Right, I'm ignoring a long list of what are sometimes called engineering details, e.g., that this is inertial confinement fusion! Ah, at one time I worked for KMS, that is the company of Kip M. Siegel, as at Google and Wikipedia: "KMS Fusion was the first and only private sector company to pursue controlled thermonuclear fusion research through use of laser technology." https://en.wikipedia.org/wiki/Kip_Siegel https://en.wikipedia.org/wiki/Kip_Siegel The report at the time was that KMS had achieved fusion neutrons. Hmm .... I didn't work on fusion but was hired because I knew quite a lot about the fast Fourier transform (FFT).

photochemsyn 4y ago

This article is obviously a PR piece, not an objective review, and the interviewee receives funding from the program. Looking around a bit, here's a discussion from 2018 that's a bit more revealing: https://physicstoday.scitation.org/do/10.1063/pt.6.2.20180615b/full/ https://physicstoday.scitation.org/do/10.1063/pt.6.2.2018061... > "In the latest round of experiments, the capsule shells consisted of diamond doped with a thin layer of tungsten, and the hohlraums were made of depleted uranium. Earlier experiments had used plastic shells and gold hohlraums. Sebastien Le Pape, lead author of the paper, says the uranium hohlraum boosted the peak energy deposited on the capsule by 25 terawatts, for a total of about 450 TW." Clearly the cost of these fuel capsules is prohibitive when it comes to any practical power production system, plus there's nothing like an energy capture-and-conversion-to-electricity system being developed. It certainly looks more like nuclear weapons research than power production research. The real goal is just preserving the budgetary outlay: > "The new results were achieved before the Trump administration proposed cutting funding for NIF by $57 million, to $287 million in fiscal year 2019. That would have forced a 30% reduction in the number of experimental shots of the 192-beam laser. Lawmakers instead added to NIF’s funding next year: The final appropriation will likely end up between the $330 million included in a House-passed bill and $344 million included in a Senate measure." Notably, DOE budgets for solar PV development remain entirely minuscule in comparison, which is one reason why it's China, not the USA, that has mastered efficient production of high-efficiency, high-durability monocrystalline silicon PV panels at scale. These of course compete directly with natural gas for power production, and the US wants to be the biggest natural gas exporter in the world. Not hard to understand what's really going on at the DOE/NNSA, whose original name was the Manhattan Project, then the AEC: https://en.wikipedia.org/wiki/United_States_Atomic_Energy_Commission https://en.wikipedia.org/wiki/United_States_Atomic_Energy_Co...

UltraViolence 4y ago

Long story short: it has never been done before and that's why it's a breakthrough. Never mind that it's totally impractical and far from something we could use to solve our energy problems TODAY. We need to focus on building hundreds if not thousands of nuclear fission reactors and to reduce the population growth through birth control outside the Western world.

college_physics 4y ago

well, we have a serious energy addiction problem as large parts of the population got used to unsustainably high per-capital energy lifestyles (basically burning fossil fuel repositories like there is no tomorrow). so any paths to clean energy production are worth pursuing - provided they don't create an illusory sense of comfort and unsubstantiated hope that some fancy tech will solve everything. fundamentally though, one would think that trying to create artificially solar interior conditions on Earth while the planet is literarily drenched in sunlight is not the shortest path to energy salvation. Life has invented already several ways to harness that energy and we have invented a few more in the meantime. I think the odds are that we will have more (as in: sufficiently) efficient harnessing of solar energy long before we create locally little suns to play with.

floxy 4y ago

Does anyone know what the conversion mechanism from the laser to x-rays is? Is that just because the lasers heat up the inside of the hohlraum, and the x-rays are just the black-body radiation from that?

nforgerit 4y ago

I'm just an interested layman on the sideline watching from "old Europe" but can't help but ask: Is everything okay with your science-media sector over there in the US? Lately, I've been asked to believe this weird wormhole story[0] and now this "major breakthrough" in fusion ignition? This all smells like too much marketing BS to me. [0] https://www.quantamagazine.org/physicists-create-a-wormhole-using-a-quantum-computer-20221130/ https://www.quantamagazine.org/physicists-create-a-wormhole-...

salawat 4y ago
You are not alone in pondering that, even from someone living on this side of the pond.

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patientplatypus 4y ago

HarHarVeryFunny 4y ago

I'm far more excited by the innovative Helion fusion design, which unlike the NIF is intended for commercial use, and is in an advanced stage of development. NIF seems more like a way to conduct military related nuclear physiscs research rather than intended/suitable to ever be used for power generation. https://www.youtube.com/watch?v=_bDXXWQxK38 https://www.youtube.com/watch?v=_bDXXWQxK38 Helion seems far more practical than the Tomahawk designs such as ITER, which seem they'll be too expensive to compete with solar/wind.

world-set-free 4y ago

They are lacking more than 100x https://lasers.llnl.gov/about/how-nif-works/power-conditioning https://lasers.llnl.gov/about/how-nif-works/power-conditioni...