10 ms·

You greatly underestimate the order of magnitude difference of produced energy in these two examples. You can't contain a bomb's hydrogen fusion reaction in a c

You greatly underestimate the order of magnitude difference of produced energy in these two examples. You can't contain a bomb's hydrogen fusion reaction in a chamber for the simple reason that you need a nuclear fission warhead just to ignite it. So if you want to produce useful, controlled energy outside of killing things, the lasers are your only shot for inertial confinement fusion. Yes they still get damaged, but lasers have seen ridiculous advancements in precision and instantaneous power over the past few decades. This news shows that practical fusion is now only an engineering problem, not a fundamental physics one - like it still is for Tokamaks and Stellarotors. For them noone knows if it is even possible to e.g. control turbulence long enough to achieve net positive energy gain.

randallsquared 4y ago
> You can't contain a bomb's hydrogen fusion reaction in a chamber You certainly can, if you use a large enough chamber. Pacer was exactly this. You just have to accept high proliferation risk.
- raverbashing 4y ago
  True. My crazy idea would be to use the heat and the pressure of these to pump water uphill. It is of course a crazy idea and you'd have to figure out a way to manage the pressure peak But it would be very interesting
  - mikepurvis 4y ago
    Pumped hydro has been a concept for a while now for grid storage of power; one of the limitations of it is just the rather unique geography required. Most places with adjacent reservoirs and enough vertical separation between them also have cottages, roads, and other infra that make it hard to be constantly draining and filling.
    - GuB-42 4y ago
      It is not just a concept, it represent the vast majority of grid energy storage today, we are talking about gigawatts. Hydro is the best, so good in fact that most of the good spots are already taken, because as you said, it requires a very specific geography.
    - lazide 4y ago
      It’s less that (IMO) - cottages and roads are usually not as dense on steep hillsides and the like, though of course they can’t be ignored entirely. The pipes involved are usually not the big issue, and the pumping ops are usually not the big issue either. The business model for pumped hydro requires relatively low cost to be economic and if it requires building a giant concrete water retention systems on top of large flat topped hills/mesas, near large drops in elevation, with water retention at the bottom of the large drop that is also really really expensive to build and requires specific geology to be economic. And if something gets messed up, it’s a huge liability [https://en.m.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_Station https://en.m.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Powe...], as it can cause very damaging flooding and be expensive to repair/replace. Worth doing when there is cheap power that can be stored and sold at higher rates later, but construction costs are really a huge part of it.
      - eitland 4y ago
        Or you can use multiple ordinary hydro power dams (i.e. ordinary lakes where one or more outlets are blocked). I'm fairly certain we have these multi level semi natural systems here in Norway, but I am not sure if we use them for pumped hydro. (Og course, if one doesn't care about ecology, one of those levels can be the sea.)
        lazide 4y ago
        Of course, and they are. They are even more limited in quantity, geologically.
        eitland 4y ago
  - psychlops 4y ago
    > My crazy idea would be to use the heat and the pressure of these to pump water uphill. This is a great idea, not crazy. It ignores the steampunk future that awaits us all!
- galangalalgol 4y ago
  Thank you for pointing me to Pacer, that was a fascinating read. They were apparently also considering digging a new panama canal with fusion bombs... In 1972 they decided it wasn't economical based on fuel price compared to yellowcake, but fissile fuel isn't the primary cost of fission power and the engineering costs of pacer would seem to be much lower.
  - yamtaddle 4y ago
    There's some old Asimov "Big Book of Science" sort of book I've got hanging around somewhere (dude definitely had aides/ghost-writers on some of that non-fic, right? Surely? At least researching and first-drafting for him to come through and punch up? Especially the more generic ones like that? I don't see how he'd have had the time to physically write that many words, otherwise, let alone also think about the words, considering his total output) that features the idea of nukes-as-tools pretty heavily, especially for canal digging and excavation generally.
    - mbg721 4y ago
      He cranked out a ton of books. I'd believe it was just him, especially with his plain-English style.
- AlanSE 4y ago
  Pacer took thinking about nuclear fuels in a lot of new and interesting directions. For the use case of interest, they really wanted to maximize the fusion yield fraction, minimize the radioactive products, and minimize the total yield. Had it ever been allowed to proceed to a commercial scale, these would have been very tight, very challenging, technical constraints. If you relax one of those requirements, then it becomes instantly clear that limitless cheap energy is possible. For a somewhat absurd example, imagine that we build Pacer plants in space instead of on Earth. There's no longer any size constraint on the blast chamber. You can go to triple-stage (like Tzar Bomba) or more designs, at which point the fusion fraction gets extremely close to 100%, and the cost per unit energy becomes somewhat hard to fathom. But on Earth, it still would have been expensive.
  - TheDudeMan 4y ago
    We can also trigger fusion bombs with nice clean anti-matter instead of dirty fission. But we'd have to get better at making anti-matter.
noobermin 4y ago
This is the real key. A LOT of people (and digging through their comment history, many of them) are MCF people who somehow poo-poo this result but then go on to extol how MCF schemes or companies are still a safer bet...even when none of them have even achieved any level of Q, heck they didn't even beat NIF's old result. If this result is "useless" and "shouldn't be news," then the whole field of MCF and all the start-ups are even more "useless" and should be even less as news, because a small non-zero number is still larger than zero.
- toomanyrichies 4y ago
  For those who were wondering what "MCF" is (like I was), the above author is likely referring to "magnetic confinement fusion"[1]. Contrast MCF with "inertial confinement fusion"[2] (ICF), a different (and apparently competing) approach taken by the National Ignition Facility in this latest announcement. 1. https://en.wikipedia.org/wiki/Magnetic_confinement_fusion https://en.wikipedia.org/wiki/Magnetic_confinement_fusion 2. https://en.wikipedia.org/wiki/Inertial_confinement_fusion https://en.wikipedia.org/wiki/Inertial_confinement_fusion
headsoup 4y ago
But isn't the 'net positive', itself only a factor in the very last stage of all of the input energy required for ignition? So they need to factor in all other components before looking at these orders of magnitude being useful?
- tadfisher 4y ago
  Yes, but that is still a breakthrough.
  - throwawaymaths 4y ago
    No, it's not. If you get to arbitrarily define at what point you count "energy in" (as the NIF people are), you could also define a clever spot for MCF to be net positive.
    - donquixote25 4y ago
      NIF's definition of Q was defined by the National Academy of Sciences and is analogous to the Q that MCF uses.
      - deleted 4y ago
        [deleted]
HPsquared 4y ago
Parent was basically saying it has not been a physics problem for decades, it's already an engineering problem and there is no change there. The physics are known to work and have been demonstrated decades ago in a different engineering context (i.e. weapons).
- jliptzin 4y ago
  Didn’t we already know it’s just an engineering problem by virtue of the sun existing?
  - woeirua 4y ago
    No. Just because the sun exists, does not mean that it is necessarily physically possible to emulate controlled nuclear fusion without an _immense_ gravity well. Ignition in this context is a validation of our understanding of the physics. _Now_ it is just an engineering problem.
  - mlyle 4y ago
    Ordinary hydrogen-hydrogen fusion in the sun only works because the sun is so freakin' huge. It's so unlikely even under the sun's massive gravitational and heat that the power output is about 270W/cubic meter-- compare to human metabolism or an energetic compost pile, which is over 1000W/cubic meter. We actually have to do a whole lot better than the sun, under far less favorable conditions-- to have practical fusion for energy generation on Earth. Inertial confinement fusion ignition (and to a lesser extent, thermonuclear weapons) strongly suggest this is possible.
    - jliptzin 4y ago
      Interesting, didn’t know that!
  - idiotsecant 4y ago
    Boy, the HN pedantry is potent this morning. The fact that black holes exist does not mean that we can spin one up to harvest it's hawking radiation for power. It's not just an engineering problem. That's not what that phrase means.
phkahler 4y ago
>> This news shows that practical fusion is now only an engineering problem, not a fundamental physics one - like it still is for Tokamaks and Stellarotors. Hahaha! That is the funniest BS I've heard about it yet! Fusion has always been "only an engineering problem" since the first H-bomb and this approach might actually be the farthest from useful even with is.
hilbert42 4y ago
"This news shows that practical fusion is now only an engineering problem, not a fundamental physics one..." Yes, I'd agree with that statement that it's only an engineering problem, but with a laser energy of 2 million joules and a fusion yield of only 3 million joules and an overall input of nearly 300 million joules to produce the lasers then I've no expectation of ever seeing a total net positive output in my lifetime let alone fully established working fusion plants providing power to ordinary customers. Moreover, compare the overall 'negative' efficiency of this experiment with the actual positive efficiencies of existing generation systems: solar: 20+%, combustion: 20%-40%, mechanical/electrical turbine: >97% and so on and we see there's three or so orders of magnitude to catch up upon. The task may not be impossible but don't hold your breath.
- mikeyouse 4y ago
  The 300 million joules to produce 2 million joules was almost entirely due to <1% efficient lasers.. even using “old” off the shelf solid state lasers with 15% efficiencies you’re already down to ~15 million joules. We’re much closer that the “300->2->3” implies. Some labs are already working with 20% efficient lasers, so hypothetically, Fusion is closer to “10->2->3” which is just amazing.
  - corille 4y ago
    There are different kinds of lasers. Last time I checked in 2018, Nd:glass lasers were the only choice for producing short, ultra-high power laser pulses with regular beam profile. Beam profile is very important for tight focusing. They may be 80's technology but these were produced in 2005. Efficient fiber optic lasers were already available but they are not suitable for the task. https://lasers.llnl.gov/about/how-nif-works/seven-wonders/laser-glass https://lasers.llnl.gov/about/how-nif-works/seven-wonders/la...
    - mikeyouse 4y ago
      So the NIF spec'ed out a replacement using a diode-pumped Yb:SFAP laser that they estimated to be 10% efficient in ~2009: https://en.wikipedia.org/wiki/Mercury_laser https://en.wikipedia.org/wiki/Mercury_laser https://www.laserfocusworld.com/test-measurement/research/article/16551380/highpower-solidstate-lasers-the-mercury-laser-moves-toward-practical-laser-fusion https://www.laserfocusworld.com/test-measurement/research/ar... The second link has more details, but they show a 0.7% efficient NIF vs. a 7% efficient Mercury laser in the tiny little chart graphic -- which would reduce the energy for this experiment from 285MJ to 28MJ. This is way outside my area of expertise, but from what I understand, the same general tech that LLNL used to generate the HAPLS for Europe's laser research could be applied to the Mercury-like lasers and increase efficiency even further. https://www.techbriefs.com/component/content/article/tb/insiders/pit/stories/45252 https://www.techbriefs.com/component/content/article/tb/insi...
simonh 4y ago
"This news shows that practical fusion is now only an engineering problem, not a fundamental physics one..." We've been able to reliably trigger stable fusion in controlled experimental facilities since before I was born in 1966. People have literally been claiming fusion power is just an engineering problem longer than my entire lifetime, and I'm no spring chicken. Ring me when they reach engineering breakeven, although optimistically the chances are it'll be my grandkids that take the call.
Animats 4y ago
> This news shows that practical fusion is now only an engineering problem, not a fundamental physics one - like it still is for Tokamaks and Stellarotors. For them no one knows if it is even possible to e.g. control turbulence long enough to achieve net positive energy gain. Well, sort of. This is "theoretical breakeven" - the reaction generated more energy than they put in. "Technical breakeven", where you generate enough power to run the thing, is 2-3 orders of magnitude away. It's not at all clear that pulsed fusion like this is a viable power source even if it reaches technical breakeven. The magnetic containment people are still struggling, but making progress. For a long time, everybody was looking for some clever magnet geometry that would yield stable plasmas, with limited success. Maybe active control will work. There are now people throwing machine learning at the problem.[1] [1] https://news.mit.edu/2022/fusion-machine-learning-turbulence-1101 https://news.mit.edu/2022/fusion-machine-learning-turbulence...
m4rtink 4y ago
Well, you can at least power space ships with it via the Orion drive. :)

randallsquared 4y ago

> You can't contain a bomb's hydrogen fusion reaction in a chamber You certainly can, if you use a large enough chamber. Pacer was exactly this. You just have to accept high proliferation risk.

raverbashing 4y ago
True. My crazy idea would be to use the heat and the pressure of these to pump water uphill. It is of course a crazy idea and you'd have to figure out a way to manage the pressure peak But it would be very interesting
- mikepurvis 4y ago
  Pumped hydro has been a concept for a while now for grid storage of power; one of the limitations of it is just the rather unique geography required. Most places with adjacent reservoirs and enough vertical separation between them also have cottages, roads, and other infra that make it hard to be constantly draining and filling.
  - GuB-42 4y ago
    It is not just a concept, it represent the vast majority of grid energy storage today, we are talking about gigawatts. Hydro is the best, so good in fact that most of the good spots are already taken, because as you said, it requires a very specific geography.
  - lazide 4y ago
    It’s less that (IMO) - cottages and roads are usually not as dense on steep hillsides and the like, though of course they can’t be ignored entirely. The pipes involved are usually not the big issue, and the pumping ops are usually not the big issue either. The business model for pumped hydro requires relatively low cost to be economic and if it requires building a giant concrete water retention systems on top of large flat topped hills/mesas, near large drops in elevation, with water retention at the bottom of the large drop that is also really really expensive to build and requires specific geology to be economic. And if something gets messed up, it’s a huge liability [https://en.m.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_Station https://en.m.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Powe...], as it can cause very damaging flooding and be expensive to repair/replace. Worth doing when there is cheap power that can be stored and sold at higher rates later, but construction costs are really a huge part of it.
    - eitland 4y ago
      Or you can use multiple ordinary hydro power dams (i.e. ordinary lakes where one or more outlets are blocked). I'm fairly certain we have these multi level semi natural systems here in Norway, but I am not sure if we use them for pumped hydro. (Og course, if one doesn't care about ecology, one of those levels can be the sea.)
      - lazide 4y ago
        Of course, and they are. They are even more limited in quantity, geologically.
        eitland 4y ago
- psychlops 4y ago
  > My crazy idea would be to use the heat and the pressure of these to pump water uphill. This is a great idea, not crazy. It ignores the steampunk future that awaits us all!
galangalalgol 4y ago
Thank you for pointing me to Pacer, that was a fascinating read. They were apparently also considering digging a new panama canal with fusion bombs... In 1972 they decided it wasn't economical based on fuel price compared to yellowcake, but fissile fuel isn't the primary cost of fission power and the engineering costs of pacer would seem to be much lower.
- yamtaddle 4y ago
  There's some old Asimov "Big Book of Science" sort of book I've got hanging around somewhere (dude definitely had aides/ghost-writers on some of that non-fic, right? Surely? At least researching and first-drafting for him to come through and punch up? Especially the more generic ones like that? I don't see how he'd have had the time to physically write that many words, otherwise, let alone also think about the words, considering his total output) that features the idea of nukes-as-tools pretty heavily, especially for canal digging and excavation generally.
  - mbg721 4y ago
    He cranked out a ton of books. I'd believe it was just him, especially with his plain-English style.
AlanSE 4y ago
Pacer took thinking about nuclear fuels in a lot of new and interesting directions. For the use case of interest, they really wanted to maximize the fusion yield fraction, minimize the radioactive products, and minimize the total yield. Had it ever been allowed to proceed to a commercial scale, these would have been very tight, very challenging, technical constraints. If you relax one of those requirements, then it becomes instantly clear that limitless cheap energy is possible. For a somewhat absurd example, imagine that we build Pacer plants in space instead of on Earth. There's no longer any size constraint on the blast chamber. You can go to triple-stage (like Tzar Bomba) or more designs, at which point the fusion fraction gets extremely close to 100%, and the cost per unit energy becomes somewhat hard to fathom. But on Earth, it still would have been expensive.
- TheDudeMan 4y ago
  We can also trigger fusion bombs with nice clean anti-matter instead of dirty fission. But we'd have to get better at making anti-matter.

noobermin 4y ago

This is the real key. A LOT of people (and digging through their comment history, many of them) are MCF people who somehow poo-poo this result but then go on to extol how MCF schemes or companies are still a safer bet...even when none of them have even achieved any level of Q, heck they didn't even beat NIF's old result. If this result is "useless" and "shouldn't be news," then the whole field of MCF and all the start-ups are even more "useless" and should be even less as news, because a small non-zero number is still larger than zero.

toomanyrichies 4y ago
For those who were wondering what "MCF" is (like I was), the above author is likely referring to "magnetic confinement fusion"[1]. Contrast MCF with "inertial confinement fusion"[2] (ICF), a different (and apparently competing) approach taken by the National Ignition Facility in this latest announcement. 1. https://en.wikipedia.org/wiki/Magnetic_confinement_fusion https://en.wikipedia.org/wiki/Magnetic_confinement_fusion 2. https://en.wikipedia.org/wiki/Inertial_confinement_fusion https://en.wikipedia.org/wiki/Inertial_confinement_fusion

headsoup 4y ago

But isn't the 'net positive', itself only a factor in the very last stage of all of the input energy required for ignition? So they need to factor in all other components before looking at these orders of magnitude being useful?

tadfisher 4y ago
Yes, but that is still a breakthrough.
- throwawaymaths 4y ago
  No, it's not. If you get to arbitrarily define at what point you count "energy in" (as the NIF people are), you could also define a clever spot for MCF to be net positive.
  - donquixote25 4y ago
    NIF's definition of Q was defined by the National Academy of Sciences and is analogous to the Q that MCF uses.
    - deleted 4y ago
      [deleted]

HPsquared 4y ago

Parent was basically saying it has not been a physics problem for decades, it's already an engineering problem and there is no change there. The physics are known to work and have been demonstrated decades ago in a different engineering context (i.e. weapons).

jliptzin 4y ago
Didn’t we already know it’s just an engineering problem by virtue of the sun existing?
- woeirua 4y ago
  No. Just because the sun exists, does not mean that it is necessarily physically possible to emulate controlled nuclear fusion without an _immense_ gravity well. Ignition in this context is a validation of our understanding of the physics. _Now_ it is just an engineering problem.
- mlyle 4y ago
  Ordinary hydrogen-hydrogen fusion in the sun only works because the sun is so freakin' huge. It's so unlikely even under the sun's massive gravitational and heat that the power output is about 270W/cubic meter-- compare to human metabolism or an energetic compost pile, which is over 1000W/cubic meter. We actually have to do a whole lot better than the sun, under far less favorable conditions-- to have practical fusion for energy generation on Earth. Inertial confinement fusion ignition (and to a lesser extent, thermonuclear weapons) strongly suggest this is possible.
  - jliptzin 4y ago
    Interesting, didn’t know that!
- idiotsecant 4y ago
  Boy, the HN pedantry is potent this morning. The fact that black holes exist does not mean that we can spin one up to harvest it's hawking radiation for power. It's not just an engineering problem. That's not what that phrase means.

phkahler 4y ago

>> This news shows that practical fusion is now only an engineering problem, not a fundamental physics one - like it still is for Tokamaks and Stellarotors. Hahaha! That is the funniest BS I've heard about it yet! Fusion has always been "only an engineering problem" since the first H-bomb and this approach might actually be the farthest from useful even with is.

hilbert42 4y ago

"This news shows that practical fusion is now only an engineering problem, not a fundamental physics one..." Yes, I'd agree with that statement that it's only an engineering problem, but with a laser energy of 2 million joules and a fusion yield of only 3 million joules and an overall input of nearly 300 million joules to produce the lasers then I've no expectation of ever seeing a total net positive output in my lifetime let alone fully established working fusion plants providing power to ordinary customers. Moreover, compare the overall 'negative' efficiency of this experiment with the actual positive efficiencies of existing generation systems: solar: 20+%, combustion: 20%-40%, mechanical/electrical turbine: >97% and so on and we see there's three or so orders of magnitude to catch up upon. The task may not be impossible but don't hold your breath.

mikeyouse 4y ago
The 300 million joules to produce 2 million joules was almost entirely due to <1% efficient lasers.. even using “old” off the shelf solid state lasers with 15% efficiencies you’re already down to ~15 million joules. We’re much closer that the “300->2->3” implies. Some labs are already working with 20% efficient lasers, so hypothetically, Fusion is closer to “10->2->3” which is just amazing.
- corille 4y ago
  There are different kinds of lasers. Last time I checked in 2018, Nd:glass lasers were the only choice for producing short, ultra-high power laser pulses with regular beam profile. Beam profile is very important for tight focusing. They may be 80's technology but these were produced in 2005. Efficient fiber optic lasers were already available but they are not suitable for the task. https://lasers.llnl.gov/about/how-nif-works/seven-wonders/laser-glass https://lasers.llnl.gov/about/how-nif-works/seven-wonders/la...
  - mikeyouse 4y ago
    So the NIF spec'ed out a replacement using a diode-pumped Yb:SFAP laser that they estimated to be 10% efficient in ~2009: https://en.wikipedia.org/wiki/Mercury_laser https://en.wikipedia.org/wiki/Mercury_laser https://www.laserfocusworld.com/test-measurement/research/article/16551380/highpower-solidstate-lasers-the-mercury-laser-moves-toward-practical-laser-fusion https://www.laserfocusworld.com/test-measurement/research/ar... The second link has more details, but they show a 0.7% efficient NIF vs. a 7% efficient Mercury laser in the tiny little chart graphic -- which would reduce the energy for this experiment from 285MJ to 28MJ. This is way outside my area of expertise, but from what I understand, the same general tech that LLNL used to generate the HAPLS for Europe's laser research could be applied to the Mercury-like lasers and increase efficiency even further. https://www.techbriefs.com/component/content/article/tb/insiders/pit/stories/45252 https://www.techbriefs.com/component/content/article/tb/insi...

simonh 4y ago

"This news shows that practical fusion is now only an engineering problem, not a fundamental physics one..." We've been able to reliably trigger stable fusion in controlled experimental facilities since before I was born in 1966. People have literally been claiming fusion power is just an engineering problem longer than my entire lifetime, and I'm no spring chicken. Ring me when they reach engineering breakeven, although optimistically the chances are it'll be my grandkids that take the call.

Animats 4y ago

> This news shows that practical fusion is now only an engineering problem, not a fundamental physics one - like it still is for Tokamaks and Stellarotors. For them no one knows if it is even possible to e.g. control turbulence long enough to achieve net positive energy gain. Well, sort of. This is "theoretical breakeven" - the reaction generated more energy than they put in. "Technical breakeven", where you generate enough power to run the thing, is 2-3 orders of magnitude away. It's not at all clear that pulsed fusion like this is a viable power source even if it reaches technical breakeven. The magnetic containment people are still struggling, but making progress. For a long time, everybody was looking for some clever magnet geometry that would yield stable plasmas, with limited success. Maybe active control will work. There are now people throwing machine learning at the problem.[1] [1] https://news.mit.edu/2022/fusion-machine-learning-turbulence-1101 https://news.mit.edu/2022/fusion-machine-learning-turbulence...

m4rtink 4y ago

Well, you can at least power space ships with it via the Orion drive. :)