5 ms·

So, they generated 3.15 MJ energy from the target, at a cost of an input of 2.05 MJ laser light. Pretty exciting. However those lasers aren't very efficient, g

So, they generated 3.15 MJ energy from the target, at a cost of an input of 2.05 MJ laser light. Pretty exciting. However those lasers aren't very efficient, generating the 2.05 MJ required more than 300 MJ of electricity. What is the path forward... Can anyone elaborate? Do we make the lasers 100x more efficient? Will hitting a target with a 100x mass yield 315 MJ? Edit: thanks everyone for the clarification. Really helps me putting the numbers in context.

teach 4y ago
Apparently the semiconductor industry already has lasers that are 20x more efficient than what was used in this experiment.
- isoprophlex 4y ago
  Interesting, thanks! So the low laser efficiency isn't really important in interpreting the importance of this news.
- adrian_b 4y ago
  The semiconductor lasers cannot produce pulses short enough for such applications. They can be used only as the pumping sources for the solid-state lasers or fiber lasers that can produce the short pulses. So the efficiencies of two lasers must be multiplied. I doubt that there is any chance to obtain an electrical to light conversion efficiency above 10%. So the energy generated by the fusion reaction should be much greater than 10 times the light energy, to be able to produce excess energy, even with lasers 10 times more efficient than now.
- dark-star 4y ago
  Even if semiconductor lasers could put out the power required (they can't...), a 20x improvement would still mean the efficiency is only around 20%, so you'd still be putting in 10 MJ to get out 2 MJ... Yes, it's better, but the argument still holds
lordnacho 4y ago
I don't get it. Wouldn't that mean it required 302.05MJ to get 3.15MJ?
- teach 4y ago
  Yes. In nuclear fusion, "ignition" means that you get more energy out than the lasers impart. This is the first time anyone has pulled that off in decades of trying, which is a big deal. But practical nuclear fusion would of course require that you get out more energy _from the entire system_ than you put in, and getting there will require even more problems to be solved. But now at least one obstacle has been overcome!
  - JumpCrisscross 4y ago
    > "ignition" means that you get more energy out than the lasers impart. This is the first time anyone has pulled that off in decades of trying, which is a big deal. The term is refreshingly intuitive. For decades we've been striking stone and flint. Sparks. We just got a bit of kindling going. It's no bonfire. But it's a big step forward.
  - WithinReason 4y ago
    >This is the first time anyone has pulled that off in decades of trying, which is a big deal. Are you sure of that? This is from 2014: https://arstechnica.com/science/2014/02/giant-leap-for-nuclear-fusion-as-scientists-get-more-energy-out-than-fuel-put-in/?itm_source=parsely-api https://arstechnica.com/science/2014/02/giant-leap-for-nucle...
    - falcor84 4y ago
      Quoting from the article you linked to: Hurricane’s current output, although more than the hydrogen fuel put into the reaction, hasn’t yet reached the stated goal to achieve “ignition," where nuclear fusion generates as much energy as the lasers supply. At that point it might be possible to make a sustainable power plant based on the technology.
    - 4y ago
deleted 4y ago
[deleted]
femto113 4y ago
Scaling the NIF's approach (laser inertial confinement) isn't about more reaction mass per pulse, it's about more frequent pulses, and is probably not going to be practical or cost effective in the foreseeable future. The fuel pellets are tiny (~2mm), their container is only about 1cm and must be nearly perfectly spherical. A continuous power plant would consume about half a million of them per day (6 per second), all of which need to be shot with perfect timing, precision, and reliability to the exact center of the laser sphere. My guess is magnetic systems are much more likely to ever be used in power generation.
- laweijfmvo 4y ago
  This feels important. We already know that fusion "works" (proof: look up). But it's not possible to recreate the conditions of a star on Earth. So if this method is also impractical, why would I care that it "works"?
  - femto113 4y ago
    Scientifically it's potentially very interesting: close up observation of what's going on in the center of a star and all that. I'd ignore all "the future of free clean energy is upon us at last!" hype. That's the lab and the government officials trying to drum up publicity that can then be milked for financial/political capital (it costs many billions to build and run a facility like this), coupled with lazy news outlets trying to milk sensationalist headlines for eyeballs.
    - TheOtherHobbes 4y ago
      This seems far more credible than the "This means fusion in ten years!" hot takes, which are - frankly - completely implausible, whether they're coming from physicists or journalists. Weapons research might be a motivator too. I would be astounded if this can be commercialised. Not because I'm cynical for the sake of it, but because I cannot in good faith see a credible engineering path which might make that possible without spectacular breakthroughs in a number of disciplines. MCF seems more likely to get somewhere. But my best guess is that advances in renewables will have made fusion redundant within ten years. There is far more scope for incremental and affordable improvements in collection, distribution, and storage than there is for the Big Science breakthroughs required to build one commercially viable ICF plant.
iamgopal 4y ago
Let’s say there are 20 different system used to make this ( laser powering, energy collections, target energy density etc etc ) , we only need to make 10 of those system 200 percent efficient to increase overall efficiency to 1000 times , within range of usefulness, I think we will be achieve this.

teach 4y ago

Apparently the semiconductor industry already has lasers that are 20x more efficient than what was used in this experiment.

isoprophlex 4y ago
Interesting, thanks! So the low laser efficiency isn't really important in interpreting the importance of this news.
adrian_b 4y ago
The semiconductor lasers cannot produce pulses short enough for such applications. They can be used only as the pumping sources for the solid-state lasers or fiber lasers that can produce the short pulses. So the efficiencies of two lasers must be multiplied. I doubt that there is any chance to obtain an electrical to light conversion efficiency above 10%. So the energy generated by the fusion reaction should be much greater than 10 times the light energy, to be able to produce excess energy, even with lasers 10 times more efficient than now.
dark-star 4y ago
Even if semiconductor lasers could put out the power required (they can't...), a 20x improvement would still mean the efficiency is only around 20%, so you'd still be putting in 10 MJ to get out 2 MJ... Yes, it's better, but the argument still holds

lordnacho 4y ago

I don't get it. Wouldn't that mean it required 302.05MJ to get 3.15MJ?

teach 4y ago
Yes. In nuclear fusion, "ignition" means that you get more energy out than the lasers impart. This is the first time anyone has pulled that off in decades of trying, which is a big deal. But practical nuclear fusion would of course require that you get out more energy _from the entire system_ than you put in, and getting there will require even more problems to be solved. But now at least one obstacle has been overcome!
- JumpCrisscross 4y ago
  > "ignition" means that you get more energy out than the lasers impart. This is the first time anyone has pulled that off in decades of trying, which is a big deal. The term is refreshingly intuitive. For decades we've been striking stone and flint. Sparks. We just got a bit of kindling going. It's no bonfire. But it's a big step forward.
- WithinReason 4y ago
  >This is the first time anyone has pulled that off in decades of trying, which is a big deal. Are you sure of that? This is from 2014: https://arstechnica.com/science/2014/02/giant-leap-for-nuclear-fusion-as-scientists-get-more-energy-out-than-fuel-put-in/?itm_source=parsely-api https://arstechnica.com/science/2014/02/giant-leap-for-nucle...
  - falcor84 4y ago
    Quoting from the article you linked to: Hurricane’s current output, although more than the hydrogen fuel put into the reaction, hasn’t yet reached the stated goal to achieve “ignition," where nuclear fusion generates as much energy as the lasers supply. At that point it might be possible to make a sustainable power plant based on the technology.
  - 4y ago

deleted 4y ago

[deleted]

femto113 4y ago

Scaling the NIF's approach (laser inertial confinement) isn't about more reaction mass per pulse, it's about more frequent pulses, and is probably not going to be practical or cost effective in the foreseeable future. The fuel pellets are tiny (~2mm), their container is only about 1cm and must be nearly perfectly spherical. A continuous power plant would consume about half a million of them per day (6 per second), all of which need to be shot with perfect timing, precision, and reliability to the exact center of the laser sphere. My guess is magnetic systems are much more likely to ever be used in power generation.

laweijfmvo 4y ago
This feels important. We already know that fusion "works" (proof: look up). But it's not possible to recreate the conditions of a star on Earth. So if this method is also impractical, why would I care that it "works"?
- femto113 4y ago
  Scientifically it's potentially very interesting: close up observation of what's going on in the center of a star and all that. I'd ignore all "the future of free clean energy is upon us at last!" hype. That's the lab and the government officials trying to drum up publicity that can then be milked for financial/political capital (it costs many billions to build and run a facility like this), coupled with lazy news outlets trying to milk sensationalist headlines for eyeballs.
  - TheOtherHobbes 4y ago
    This seems far more credible than the "This means fusion in ten years!" hot takes, which are - frankly - completely implausible, whether they're coming from physicists or journalists. Weapons research might be a motivator too. I would be astounded if this can be commercialised. Not because I'm cynical for the sake of it, but because I cannot in good faith see a credible engineering path which might make that possible without spectacular breakthroughs in a number of disciplines. MCF seems more likely to get somewhere. But my best guess is that advances in renewables will have made fusion redundant within ten years. There is far more scope for incremental and affordable improvements in collection, distribution, and storage than there is for the Big Science breakthroughs required to build one commercially viable ICF plant.

iamgopal 4y ago

Let’s say there are 20 different system used to make this ( laser powering, energy collections, target energy density etc etc ) , we only need to make 10 of those system 200 percent efficient to increase overall efficiency to 1000 times , within range of usefulness, I think we will be achieve this.