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Comment by tanzam75 | Hacker News Reader

> total energy dumped into the entire system: 1.7 megajoules. In comparison, the fusion power produced was a paltry 8 kilojoules

In other words, the National Ignition Facility hasn't achieved ignition yet.

If you can actually achieve ignition, then nobody will care about the megajoules needed to get it ignited. Because once you've got ignition, you can get an arbitrary amount of energy out.

But if you can't get ignition, well, then, that pesky 0.3% heating efficiency will still leave you a couple of orders of magnitude away from engineering breakeven.

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> get an arbitrary amount of energy out.

Not really. You have to build larger, or more, power plants. So you have to make enough extra energy to sell to pay for plants.

While they have had problems in the recent past: https://www.sciencenews.org/article/ignition-failed

~~ They've since had ignition: http://www.independentnews.com/news/article_792110c0-2c5b-11... ~~

[I'm positive that the ICF's predecessors also achieved ~~ignition~~ fusion on smaller scales.]

The real trick is that [0] you need to get out more than you put in (exceed break-even) [1] you need to be able to harness the energy produced by the ignition and [2] be able to do it over and over again, producing reliable power.

> They've since had ignition

No. Notice how it is worded.

> "More importantly, Moses said, the mechanism that generated the powerful energy burst appeared to be the self-sustaining thermonuclear fusion process that defines ignition."

In other words, they did not achieve ignition. They achieved something that is necessary to get ignition. Specifically, alpha heating.

This is another important step on the road to ignition. It is not, however, ignition itself.

Why do you think the title of the article says "Marks Progress Toward Ignition," rather than "Finally Achieves Ignition?"

And this seems to hand out a wealth of information as to why they haven't gotten there yet: http://www.reddit.com/r/technology/comments/1nxtyb/nuclear_f...

You're right. In my head "ignition"=fusion, so I was auto-translating as I was skimming. They're looking for something slightly different, and probably using energy output (among other things) as indications of self-sustained fusion, which we've certainly obtained in bombs (fission explosion sets off fusion reaction ☞ big bada boom).

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