3 ms·

We can debate the importance, but it’s clear that they’ve made a qualitative leap in their technology the past few years — a “breakthrough”. https://en.wikiped

We can debate the importance, but it’s clear that they’ve made a qualitative leap in their technology the past few years — a “breakthrough”. https://en.wikipedia.org/wiki/National_Ignition_Facility#/media/File%3ANIF_output_over_10_years.png https://en.wikipedia.org/wiki/National_Ignition_Facility#/me...

HPsquared 4y ago
That's quite the leap, clearly some big progress when it's presented like that.
rz2k 4y ago
And that graph does not include the 2022 experiment with 3.15, which also happened to be the first one with net positive output.
- Robotbeat 4y ago
  Yup, here’s the one: https://physicstoday.scitation.org/do/10.1063/PT.6.2.20221213a/full/media/sizes/full/figure2-3.jpg https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121... Credit: Mark Herrmann/LLNL From this article: https://physicstoday.scitation.org/do/10.1063/PT.6.2.20221213a/full/ https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121... Clear qualitative difference. Additionally, this is laser energy, but the lasers aren’t used directly. They produce X-rays which are the ones that actually drive the ablative implosion of the fuel pellet. If you used X-rays directly, the gain value would be MUCH higher… I think by that measure, they would’ve achieved Q=1 back in 2013? Note that hey COULD use the lasers directly to drive implosion but haven’t yet. The Hohlraum/X-ray/indirect method I think produces more consistent lighting on the target, and is more analogous to the operation of an H-bomb, which is partly what this entire process is intended to replicate. They may do future experiments to try direct drive, in preparation for actually using this as a power production method and improving the efficiency dramatically… in combination with far higher efficiency modern lasers, this could enable Q high enough for net electricity production.
  - pfdietz 4y ago
    It should be noted that even if the lasers were 100% efficient, this result is not sufficient to achieve a practical fusion power plant. That target could produce maybe $0.02 worth of electrical energy. That's nowhere close to paying for the plant, even totally ignoring operating costs. A real plant would need target yields 100 to 1000 times larger, with all the engineering issues that would entail.
    - Robotbeat 4y ago
      Of course, because you learn to spark fire before you build a power plant. NIF is nothing like a power plant. It was designed for stockpile stewardship and for fusion ignition demonstration, and they intentionally cancelled efforts to solve the engineering challenges of making this into a power plant, because doing so was premature without the ignition breakthrough. https://en.wikipedia.org/wiki/Laser_Inertial_Fusion_Energy https://en.wikipedia.org/wiki/Laser_Inertial_Fusion_Energy
serioussecurity 4y ago
Not to diminish the achievement, but not making that graph log scale was deeply dishonest.
- maria2 4y ago
  How is it dishonest?
  - monetus 4y ago
    A log curve, rather than linear, would make the bars in the center taller and not give the same appearance of a massive change in the measurement. Not for me to say, but I'm guessing that, as is, it doesn't represent the work put into the effort as well as possible.
    - maria2 4y ago
      Yes, that's what a log scale does to a graph. But why do you feel a log scale is appropriate in this situation? To me, a linear scale is a much better choice. The underlying data isn't necessarily exponential, so there isn't a compelling reason to use a log scale.

HPsquared 4y ago

That's quite the leap, clearly some big progress when it's presented like that.

rz2k 4y ago

And that graph does not include the 2022 experiment with 3.15, which also happened to be the first one with net positive output.

Robotbeat 4y ago
Yup, here’s the one: https://physicstoday.scitation.org/do/10.1063/PT.6.2.20221213a/full/media/sizes/full/figure2-3.jpg https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121... Credit: Mark Herrmann/LLNL From this article: https://physicstoday.scitation.org/do/10.1063/PT.6.2.20221213a/full/ https://physicstoday.scitation.org/do/10.1063/PT.6.2.2022121... Clear qualitative difference. Additionally, this is laser energy, but the lasers aren’t used directly. They produce X-rays which are the ones that actually drive the ablative implosion of the fuel pellet. If you used X-rays directly, the gain value would be MUCH higher… I think by that measure, they would’ve achieved Q=1 back in 2013? Note that hey COULD use the lasers directly to drive implosion but haven’t yet. The Hohlraum/X-ray/indirect method I think produces more consistent lighting on the target, and is more analogous to the operation of an H-bomb, which is partly what this entire process is intended to replicate. They may do future experiments to try direct drive, in preparation for actually using this as a power production method and improving the efficiency dramatically… in combination with far higher efficiency modern lasers, this could enable Q high enough for net electricity production.
- pfdietz 4y ago
  It should be noted that even if the lasers were 100% efficient, this result is not sufficient to achieve a practical fusion power plant. That target could produce maybe $0.02 worth of electrical energy. That's nowhere close to paying for the plant, even totally ignoring operating costs. A real plant would need target yields 100 to 1000 times larger, with all the engineering issues that would entail.
  - Robotbeat 4y ago
    Of course, because you learn to spark fire before you build a power plant. NIF is nothing like a power plant. It was designed for stockpile stewardship and for fusion ignition demonstration, and they intentionally cancelled efforts to solve the engineering challenges of making this into a power plant, because doing so was premature without the ignition breakthrough. https://en.wikipedia.org/wiki/Laser_Inertial_Fusion_Energy https://en.wikipedia.org/wiki/Laser_Inertial_Fusion_Energy

serioussecurity 4y ago

Not to diminish the achievement, but not making that graph log scale was deeply dishonest.

maria2 4y ago
How is it dishonest?
- monetus 4y ago
  A log curve, rather than linear, would make the bars in the center taller and not give the same appearance of a massive change in the measurement. Not for me to say, but I'm guessing that, as is, it doesn't represent the work put into the effort as well as possible.
  - maria2 4y ago
    Yes, that's what a log scale does to a graph. But why do you feel a log scale is appropriate in this situation? To me, a linear scale is a much better choice. The underlying data isn't necessarily exponential, so there isn't a compelling reason to use a log scale.