3 ms·

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

by rz2k 4y ago

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

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

by 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