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Comment by web007 | Hacker News Reader

> The results from the experiment on 8 August indicate an energy output of over one mega-joule, which marks the threshold agreed for the onset of 'ignition' and is six times the previous highest energy achieved.

They got 1Mj output from > 500TW input - this is a "major milestone" but only a small step on the path to fusion.

NIF is fascinating, and has been promising for the past decade. The idea of kick-starting fusion with lasers sounds awesome, and then more awesome when you realize just how much energy you need for fusion. They're shooting terawatts of laser at a target the size of a hollow grain of rice, and they're not there yet!

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Why are you comparing energy and power numbers directly? Without a time component I can’t tell whether those numbers are ridiculous or impressive.

If your 500TW laser only fires for 1 nanosecond then you’re only putting in 500kJ so you’re getting 200% yield. If you’re firing your 500TW laser for an hour, well that obviously isn’t as impressive.

NIF, remember, is funded by the DoD. It's not a civilian reactor research program: it's a device for testing fusion reactions in the lab now that the Comprehensive Test Ban Treaty means that they're not allowed to test H-bombs out in Nevada.

This is not to say that it isn't fascinating and there won't be spin-off findings of use to the development of civil fusion reactors, but actual reactor research (e.g. JET, ITER, Wendelstein-7X) is all about magnetic containment for protracted periods (tens to thousands of seconds). And ITER, running on tritium and deuterium, is supposed to use 50 MW of heating power to create a plasma of 500 MW (thermal) for periods of 400 to 600 seconds. No need for a 500TW peak power input (actually much, much lower when you look at it in terms of megajoules delivered in a few nanoseconds).

>NIF, remember, is funded by the DoD. It's not a civilian reactor research program: it's a device for testing fusion reactions in the lab now that the Comprehensive Test Ban Treaty means that they're not allowed to test H-bombs out in Nevada.

*DOE’. There is a quasi-separation of powers, where DOE ‘owns’ the weapons and the DOD ‘uses’ them.

‘See for example the NNSA.

The DOE is a fascinating organization btw…anyone who is so nonchalant about public oversight and security practices that the DOD gets angry at them has to be fun at parties.

Story time?

https://en.wikipedia.org/wiki/Megan_Rice

The 500TW are meaningless, the actual input is around 1.5MJ, meaning they got almost 80% of their input as energy back.

Where did you get this number? It’s a couple of orders of magnitude too low.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.12...

This article mentions they used 1.5MJ of energy for the fusion process, it seems to be related to this news, on wikipedia you can find a cited NYTimes article stating 80% of the energy input was released.

And I don't get where you get "couple order of magnitude too low" from, 500TW means nothing, it's a workload, not the total work the laser performed. Over a few nanoseconds, that checks out.

(1) That’s from 2018. (2) It does not say what you say it says. It does not state how much energy was “used”. The laser is about 1% efficient. (3) That 80%, which is the number that goes with this recent news, has nothing to do with the “energy input”. It is 80% of the energy that their models say was absorbed by the hohlraum. These are part of where my couple of orders of magnitude remark comes from.

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