[bnjemian]

I'd be very interested to see the breakdown of input energy costs. Most notable is the raw energy cost required to power the lasers and control machinery in the experiment. But then there are other costs, all of which must be amortized over time for any real-world use case to exist. I say this because the journalists in this piece imply that net gain is simply based off of the amount of energy pumped into the experiment while it operated, but the total input energy would clearly be more than that.

On the extreme end, there's the energy cost of building the machine and engineering its components. For the vast majority of these, we can probably all agree that were a fusion power plant to be built, the net gain would fully eclipse these initial inputs fairly quickly. This may sound silly, but remember that the economic context where fusion so often sits is one that centers on renewable energy and sustainability. These costs do have to be accounted for.

On the other end, there's the energy cost consumables. For example, the deuterium and tritium fuel input into the device, which need to be purified (deuterium from water, possibly tritium from the atmosphere) or otherwise isolated (from what I understand, tritium is a byproduct from fission reactors and they serve as its primary source in scientific applications). It may well be that the energy cost of acquiring these consumables is fractions to fractions of a fraction of the energy cost of running the device, effectively constituting a rounding error. But I think when we're talking about net gain, a clear definition and accounting of the input energy required to run the experiment would be useful to communicate to the public.

I hope we see disclosure of these details with all the expected caveats when the peer-reviewed article goes to print and journalists have another feeding frenzy.

[teilo]

Early reports are are not good. For every joule delivered to the chamber, it takes 100 joules of electrical power. Heat to electricity is 50% efficient at best. Reports are that with 2.1mj of input, they generated 2.5 mj of output. Taking inputs and electrical production into account, this means 0.6% is all they are getting out vs. what they put in.

These over-unity reports are meaningless, because every damn one of them only measures Q-plasma, not Q-total.

[leephillips]

NIF people like to call this the “target gain”, but someone there has been whispering “net gain” to the journalists, in their ongoing campaign of deliberately deceptive hype. But “target gain” isn’t even (pellet output)/(laser output). The denominator is laser energy deposited in the hohlraum; the rest of it doesn’t count. And this deposited laser energy is estimated based on a model of laser deposition—it’s not measured. (At least, this is the way it was the last time I bothered reading a paper from NIF. I got bored with it a while ago.) The modeling codes are classified; no one without a need to know gets to examine them, and they are not well benchmarked. So the actual target gain is likely < 1 in any case.

[dmix]

> The modeling codes are classified

What is the justification for keeping it classified?

[zardo]

NIFs purpose is to validate simulations of thermonuclear weapon detonations. The default is going to be classified, it's making something public that would have to be justified.

[Schroedingersat]

Because it's a weapons program that is entirely unrelated to power generation.