15 ms·

Here's the paper. http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13008.html http://www.nature.com/nature/journal/vaop/ncurrent/full/natu... The

Here's the paper. http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13008.html http://www.nature.com/nature/journal/vaop/ncurrent/full/natu... They would like to charge you $32 to look at it, nature-ally. The fusion yield is (?) 14 kilojoules (inferring this from physicist Mark Herrman's "5 million billion fusions" [WaPo], at 18 MeV per fusion), which is a moderate improvement over the 8 kilojoule achivement from last fall: https://news.ycombinator.com/item?id=6459289 https://news.ycombinator.com/item?id=6459289 [WaPo] http://www.washingtonpost.com/national/health-science/fusion-energy-milestone-reported-by-california-scientists/2014/02/12/f511ed18-936b-11e3-84e1-27626c5ef5fb_story.html http://www.washingtonpost.com/national/health-science/fusion... The "1%" energy efficiency figure [a] is misleading: 14 kJ is about 1% of 1.5 MJ of ultraviolet light hitting the fuel capsule. But creating that UV pulse consumed 3 MJ of infrared light, which in turn took 400 MJ from the flash bulbs driving the IR laser. So the system efficiency is more like 0.003% (and throwing in hypothetical turbines to generate electricity, 0.001%). https://en.wikipedia.org/wiki/National_Ignition_Facility#NIF_and_ICF https://en.wikipedia.org/wiki/National_Ignition_Facility#NIF... [a] I'm referring to this: "while more energy came from fusion than went into the hydrogen fuel, only about 1 percent of the laser's energy ever reached the fuel." (update: from yosyp's link, the fusion figures were 14.4 kJ, and 17.3 kJ, on two different runs: https://news.ycombinator.com/item?id=7227950 https://news.ycombinator.com/item?id=7227950

cLeEOGPw 13y ago
As I understand, they are hoping to achieve fusion ignition, where no additional external energy will be required to generate power. So current efficiency calculations are irrelevant in that case.
- throwaway_yy2Di 13y ago
  Yes, but in the article they also say this isn't possible with their current techniques. Anyone have a figure that represents how far off they are?
  - sliverstorm 13y ago
    they also say this isn't possible with their current techniques. That's fine by me, it was not very long ago that we were unable to get more out of the fuel than we put into the fuel. That's step one to fusion ignition, and was done for the very first time last fall, so as far as I'm concerned they are still fleshing out step one.
    - bcoates 13y ago
      Doesn't every H-bomb have substantial positive fuel yield?
      - deleted 13y ago
        [deleted]
      - cenhyperion 13y ago
        It makes it all at once, and that's the issue.
throwaway_yy2Di 13y ago
Quick summary of the numbers from wikipedia: 422 MJ capacitors ←────────────┐ ↓ │ (?) xenon flash lamps │ ↓ │ 3 MJ IR laser pulse │ ↓ │ 1.5 MJ UV pulse │ ↓ │ 150 kJ X-ray pulse │ ↓ │ * 14-17 kJ Fusion yield (this story) │ ↓ │ 7-9 kJ Potential electricity →────────┘ system breakeven https://en.wikipedia.org/wiki/National_Ignition_Facility#NIF_and_ICF https://en.wikipedia.org/wiki/National_Ignition_Facility#NIF...
- VladRussian2 13y ago
  wrt. 422MJ->3MJ, xenon flash lamp pumping As it was already mentioned in the threads like this before, the NIF was built using the technology that was available in those years of the past when NIF was planned and started. Flash lamp pumped lasers are bigger, more expensive and much less efficient, i.e. mere few percents efficiency at best vs. tens of percent efficiency of modern laser diode pumped IR lasers. (Even with such improvement though, i still think laser driven fusion is inferior to many other forms of inertial confinement and much less probable to result in system-level break-even. My personal favorite, Sandia Z-machine is on the scale of 15% efficiency of generating X-ray pulse, and schemes like deep plasma focus or polywell by-pass the energy to radiation conversion stage all together and thus avoid related losses.)
Finster 13y ago
I'm on campus right now and can download the PDF. I'd upload it, but I don't want to pull an Aaron Swartz. <_< EDIT: Okay here, but I have limited bandwidth so get it while you can: https://mega.co.nz/#!CNgVhZra!JcsLGB5y0FGUffI4rdyNr-BBl82YJDNH1ah3_4kSPcU https://mega.co.nz/#!CNgVhZra!JcsLGB5y0FGUffI4rdyNr-BBl82YJD...
- TeMPOraL 13y ago
  They won't get after you because of one paper. Please, do it for the betterment of mankind :).
  - unepipe 13y ago
    It's not worth it. The terrorists won.
    - oscargrouch 13y ago
      By terrorists you mean those illusionary guys that the politicians use as the boogie man, to beat down the rationality of ordinary people by provoking fear, so they are legally allowed to do virtually anything without nobody to stop them?
      - mildtrepidation 13y ago
        I want to downvote this. I really do. And I think when I feel justified in doing so that things will have improved.
        lotsofmangos 13y ago
        It would be cool if there were a globally inclusive political movement that continuously stood for election in multiple countries simultaneously. It could then be called the Terraists and possibly solve the whole issue through discordant namespace collision.
      - TeMPOraL 13y ago
yosyp 13y ago
cheers https://dl.dropboxusercontent.com/u/26434203/nature13008.pdf https://dl.dropboxusercontent.com/u/26434203/nature13008.pdf
- leobelle 13y ago
  No offense to anyone, but this link should be deleted. You may not like the system, but HN isn't the place to protest IP laws with civil disobedience. A lot of YC companies have their own IP they'd like to protect I'm sure.
  - sillysaurus2 13y ago
    Why not let the mods say what should or shouldn't be on HN? No need to speak for them.
  - Retric 13y ago
    Not all IP laws are equivalent. Also, civil disobedience has been known to work in the past.
    - leobelle 13y ago
      Your first sentence is a subjective value statement (that I probably don't agree with). Both your first and second sentence are irrelevant to my argument.
      - Retric 13y ago
        How is saying Drug Patents lasting 20 years vs copy write on a tweet lasting the lifetime of the author plus what 80 years a subjective statement? IMO, IP is a loaded term that distorts the wide range of issues. IM for Intellectual Monopoly is much closer to the truth. To be clear I have no problem with the idea of copyright or a well run power company being run as a local monopoly, but there outside of the normal business. And the goals should be finding rules that best serve society not the owners of said monopoly.
  - 13y ago
TrainedMonkey 13y ago
I talked to a friend who works there, this is more of a PR move. Back at the lab it is business as usual.
- beloch 13y ago
  The PR guys often work on a different schedule than the actual science, but those times do usually correlate well with the funding deadlines for some strange reason... It's probably work as usual at the NIF because everyone is working on a big, long, grinding project that's slowly making progress rather than bashing out stunning Eureka moments complete with Dom Perignon showers like you see in a Hollywood flick.
  - TrainedMonkey 13y ago
    They are working towards ignition as measured by total neutron output. As soon as they detect significant enough jump to warrant ignition claim there will be Eureka moment with Dom Perignon. Right now they are 3 orders of magnitude off (10^15 they get, 10^18 or better 10^19 they want).
beefman 13y ago
17.3 kJ for the latest shot, according to the paper. But only some 8 kJ of that came from fusion (the balance came from the laser input). D-T fusions are about 17.6 MeV, but 80% of that is in neutrons, which escape unless captured in a special blanket. The 8 kJ reported was all alphas. So 8 kJ / 3.5 MeV = 1.4e16 fusions, vs. 5e15 in the quote. He was probably talking about a previous shot. For comparison, a typical AA battery stores 16 kJ.
- throwaway_yy2Di 13y ago
  You're misreading. E_{DT} is not the D+T fusion yield; it is the heat absorbed by the D+T fuel target (sum of external heating and self-heating from fusion alphas). E_{fusion} is the fusion yield. E_{fusion} is the calculated neutron yield Y_{total}=6.1e15 times 17.6 MeV: 17.2 kJ + rounding. Check out page 3, right column.
  - beefman 13y ago
    Quite right, there were 6.1e15 fusions.

cLeEOGPw 13y ago

As I understand, they are hoping to achieve fusion ignition, where no additional external energy will be required to generate power. So current efficiency calculations are irrelevant in that case.

throwaway_yy2Di 13y ago
Yes, but in the article they also say this isn't possible with their current techniques. Anyone have a figure that represents how far off they are?
- sliverstorm 13y ago
  they also say this isn't possible with their current techniques. That's fine by me, it was not very long ago that we were unable to get more out of the fuel than we put into the fuel. That's step one to fusion ignition, and was done for the very first time last fall, so as far as I'm concerned they are still fleshing out step one.
  - bcoates 13y ago
    Doesn't every H-bomb have substantial positive fuel yield?
    - deleted 13y ago
      [deleted]
    - cenhyperion 13y ago
      It makes it all at once, and that's the issue.

throwaway_yy2Di 13y ago

Quick summary of the numbers from wikipedia: 422 MJ capacitors ←────────────┐ ↓ │ (?) xenon flash lamps │ ↓ │ 3 MJ IR laser pulse │ ↓ │ 1.5 MJ UV pulse │ ↓ │ 150 kJ X-ray pulse │ ↓ │ * 14-17 kJ Fusion yield (this story) │ ↓ │ 7-9 kJ Potential electricity →────────┘ system breakeven https://en.wikipedia.org/wiki/National_Ignition_Facility#NIF_and_ICF https://en.wikipedia.org/wiki/National_Ignition_Facility#NIF...

VladRussian2 13y ago
wrt. 422MJ->3MJ, xenon flash lamp pumping As it was already mentioned in the threads like this before, the NIF was built using the technology that was available in those years of the past when NIF was planned and started. Flash lamp pumped lasers are bigger, more expensive and much less efficient, i.e. mere few percents efficiency at best vs. tens of percent efficiency of modern laser diode pumped IR lasers. (Even with such improvement though, i still think laser driven fusion is inferior to many other forms of inertial confinement and much less probable to result in system-level break-even. My personal favorite, Sandia Z-machine is on the scale of 15% efficiency of generating X-ray pulse, and schemes like deep plasma focus or polywell by-pass the energy to radiation conversion stage all together and thus avoid related losses.)

Finster 13y ago

I'm on campus right now and can download the PDF. I'd upload it, but I don't want to pull an Aaron Swartz. <_< EDIT: Okay here, but I have limited bandwidth so get it while you can: https://mega.co.nz/#!CNgVhZra!JcsLGB5y0FGUffI4rdyNr-BBl82YJDNH1ah3_4kSPcU https://mega.co.nz/#!CNgVhZra!JcsLGB5y0FGUffI4rdyNr-BBl82YJD...

TeMPOraL 13y ago
They won't get after you because of one paper. Please, do it for the betterment of mankind :).
- unepipe 13y ago
  It's not worth it. The terrorists won.
  - oscargrouch 13y ago
    By terrorists you mean those illusionary guys that the politicians use as the boogie man, to beat down the rationality of ordinary people by provoking fear, so they are legally allowed to do virtually anything without nobody to stop them?
    - mildtrepidation 13y ago
      I want to downvote this. I really do. And I think when I feel justified in doing so that things will have improved.
      - lotsofmangos 13y ago
        It would be cool if there were a globally inclusive political movement that continuously stood for election in multiple countries simultaneously. It could then be called the Terraists and possibly solve the whole issue through discordant namespace collision.
    - TeMPOraL 13y ago

yosyp 13y ago

cheers https://dl.dropboxusercontent.com/u/26434203/nature13008.pdf https://dl.dropboxusercontent.com/u/26434203/nature13008.pdf

leobelle 13y ago
No offense to anyone, but this link should be deleted. You may not like the system, but HN isn't the place to protest IP laws with civil disobedience. A lot of YC companies have their own IP they'd like to protect I'm sure.
- sillysaurus2 13y ago
  Why not let the mods say what should or shouldn't be on HN? No need to speak for them.
- Retric 13y ago
  Not all IP laws are equivalent. Also, civil disobedience has been known to work in the past.
  - leobelle 13y ago
    Your first sentence is a subjective value statement (that I probably don't agree with). Both your first and second sentence are irrelevant to my argument.
    - Retric 13y ago
      How is saying Drug Patents lasting 20 years vs copy write on a tweet lasting the lifetime of the author plus what 80 years a subjective statement? IMO, IP is a loaded term that distorts the wide range of issues. IM for Intellectual Monopoly is much closer to the truth. To be clear I have no problem with the idea of copyright or a well run power company being run as a local monopoly, but there outside of the normal business. And the goals should be finding rules that best serve society not the owners of said monopoly.
- 13y ago

TrainedMonkey 13y ago

I talked to a friend who works there, this is more of a PR move. Back at the lab it is business as usual.

beloch 13y ago
The PR guys often work on a different schedule than the actual science, but those times do usually correlate well with the funding deadlines for some strange reason... It's probably work as usual at the NIF because everyone is working on a big, long, grinding project that's slowly making progress rather than bashing out stunning Eureka moments complete with Dom Perignon showers like you see in a Hollywood flick.
- TrainedMonkey 13y ago
  They are working towards ignition as measured by total neutron output. As soon as they detect significant enough jump to warrant ignition claim there will be Eureka moment with Dom Perignon. Right now they are 3 orders of magnitude off (10^15 they get, 10^18 or better 10^19 they want).

beefman 13y ago

17.3 kJ for the latest shot, according to the paper. But only some 8 kJ of that came from fusion (the balance came from the laser input). D-T fusions are about 17.6 MeV, but 80% of that is in neutrons, which escape unless captured in a special blanket. The 8 kJ reported was all alphas. So 8 kJ / 3.5 MeV = 1.4e16 fusions, vs. 5e15 in the quote. He was probably talking about a previous shot. For comparison, a typical AA battery stores 16 kJ.

throwaway_yy2Di 13y ago
You're misreading. E_{DT} is not the D+T fusion yield; it is the heat absorbed by the D+T fuel target (sum of external heating and self-heating from fusion alphas). E_{fusion} is the fusion yield. E_{fusion} is the calculated neutron yield Y_{total}=6.1e15 times 17.6 MeV: 17.2 kJ + rounding. Check out page 3, right column.
- beefman 13y ago
  Quite right, there were 6.1e15 fusions.