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Comment by cwillu | Hacker News Reader

“Activities are about one thing and one thing only” is a fallacy.

It's good to remind people about weapons research interests. It's less good to completely dismiss the interests concerning energy production, or basic scientific research. They don't go away just “omgz military funding!”

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There are no true interests concerning energy production related to inertial confinement fusion. It is completely impossible for ICF to ever have a cost/watt that would make it even remotely economical. A coal power plant burning diamond instead of coal would almost certainly have better economic fundamentals than ICF can hope to achieve.

So this is weapons research and basic physics research caked in the language of power generation.

You're basically right about laser-driven fusion. But ultrafast mode-locking lasers do have other uses, such as X-ray generation [1]. And MagLIF is a derivative technology that should have a significantly better energy in/out ratio [2]. The big problem with all existing ICF concepts is their tendency to damage the facility (boom!), though.

1: source: a seminar I attended last year

2: http://en.wikipedia.org/wiki/MagLIF

As far as I understand from the wiki page, the Z-machine still requires a hohlraum, which I assume also requires the kind of precise machining that the NIH laboratory does as well. As such, it is essentially burning an extremely expensive fuel, obtaining small bursts of energy from it - requiring vast amounts of such targets every hour in constant operation, which basically makes it a complete no-go from any kind of economic standpoint.

Note that I'm not saying that it isn't an interesting or useful scientific experiment - it's just not a promising power source.

We spend vast sums characterizing materials before they become cheap plentiful and profitable, this certainly could be an important step towards power generation without making a step in that direction directly. I imagine characterizing the likes of fusion it would be some comfort that it's inefficient. Question how do you avoid the great filter? Answer very carefully.

That’s assuming they ever even make it to net positive energy output. The article carefully avoids mentioning that the lasers they use are wildly inefficient. It is very hard to break even when you lose 90% of your input power right at the start

But the relevant question is, how efficient are equivalent modern lasers? NIF was built in the early 2000s and laser technology has advanced quite a bit in the past couple decades.

The lasers they use are extremely specialized, since they have to deliver outrageous amounts of power for a very short period of time. Advancements in normal lasers may not be of much use here

Edit: Wow, looks like they have improved considerably

Yes, and lasers that do exactly that have advanced very quickly. We're up to multi-petawatt picosecond lasers now. We're getting high repetition rates instead of the once or twice per day of NIF, by using laser diodes in place of flashlamps. There are dozens of extreme laser facilities operating or under construction all over the world. And if I'm not misinterpreting this, efficiency is as high as 60%:

https://www.laserfocusworld.com/lasers-sources/article/14186...

where in the world have you seen anyone that is planning to try to use inertial confinement fusion for energy production?

In the present tense, maybe not, but in the past this was a real thing (or, at least, people were pretending it was).

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

> LIFE, short for Laser Inertial Fusion Energy, was a fusion energy effort run at Lawrence Livermore National Laboratory between 2008 and 2013.

ie an American nuclear weapons laboratory was doing it

The game played with inertial fusion is that when the energy people are skeptical, say it's about weapons, and when the weapons people are skeptical, say it's about energy.

You're not completely wrong, but there's a history of viable technologies being eschewed in favour of those with military applications.

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