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"That’s because they had to use 500 MJ of energy into the lasers to deliver 1.8 MJ to the target – so even though they got 2.5 MJ out, it’s still far less than the energy they needed for the lasers in the first place. In other words, the energy output (largely heat energy) was still only 0.5% of the input."

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Partly that's because they use laser tech from the 1990s, with less than 1% efficiency. Now we have NIF-class lasers with over 20% efficiency.

https://physicstoday.scitation.org/do/10.1063/pt.6.2.2021102...

They'd still be getting only ~1/4 of power input with a 20% efficiency laser.

Yes, but the overall we get "more power out of the building then we put in" isn't the goal. They are trying to drive the Q factor of the reaction itself up. If they get that to > 5x what the laser strike hits (a very real probability) it's likely trying to make a building that has a net positive Q makes sense.

That building would use modern lasers, modern supercapactiors, etc. to significantly change the "other" parts of the equation.

This is like making a program work on your laptop, but realizing that scaling up to production with 1000 laptops would be too costly, so you use actual servers. But you are in no rush to code directly on a server machine.

Converting the heat energy to electricity loses an additional 50-70%.

I don't see that scaling anytime soon, still more than two orders of magnitude away. But never say never.

The exact numbers depend on the form of fusion in question, but fusion does have some several places where it has quite substantial x^n growth possibilities, where "n" is definitely greater than one and can be greater than two at times, sometimes even substantially so. This means that there is some real, concrete hope for improvement in a way that, say, solar could never improve more than 4-5x where it is now because the absolutely best it could ever hope for is 100% efficiency. At the core, this is because as you get the plasma hotter and more confined, the rate of fusion goes up very quickly, much much beyond linear increases.

This is laser based fusion, which is super cool, but it might be a stretch to expect 200x more efficient lasers. Still maybe there's other things you could do, like make a bigger fusion reaction. Hydrogen bombs do it, so maybe.

The lasers they use today are 20x less efficient than state of the art. The capacitors are also massively less efficient. So they only "need" to drive the Q factor of the reaction up by ~5x to be positioned to build something with a net energy gain.

Because of the physics of fusion (or ICF) returns on power are non linear. It's very much possible research here results in a path to a "net gain facility".

I wasn't aware actually. I was under the mistaken impression that their progress has only been possible because they were using state of the art lasers. This could actually be possible then, and far sooner than magnetic containment fusion.

If they replaced the lasers in this building from the 90's with a modern light source it would immediately do two orders of magnitude. Research like this needs to focus on solving, and experimenting with one problem (in this case the physics of inertial confinement fusion). They are not _trying_ to build something which gets "net power out of the building". So don't assume you're net in, net out ratios are representative of what a plant targeted doing that would be.

It's quite easy to see that replacing the lasers, the capacitors, etc. with more modern technology would have an immediate effect. But it doesn't matter until doing the reaction at all makes sense. That's what they are focusing on.

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