[baldfat]

It's a big deal but its decades away. To do this they need to repeatably do it every few seconds. Right now they can do it once per week.

BIG CAVIET: The energy to power the laser is greater than the return. The return in energy is just greater than the energy the laser put in. So net loss. We need more efficient lasers and be able to make this repeatable and reliable. We are not closer except theory is being proven.

[johnbellone]

I have been reading these comments like yours for days. I am not picking on you. But the research program isn't being funded to build more efficient lasers. Those already exist. The lasers at the NIF are decades old and haven't been updated because it isn't the point of the research.

[d23]

I'm baffled by the comments on this topic in particular. Do people just spout off in the comments now despite no background in the field? I don't really recall a time in the past where this was so prevalent on HN. I used to be able to trust that some industry expert would be in the comments section fact checking headlines and adding nuance, but now I see far too many contradictions, strange takes, and obvious red flags (see: "BIG CAVIET").

[krastanov]

This always happens when physics is discussed on Hacker News (it is the only topic on which I consider myself an expert). In particular, there are some really weird takes on Quantum Information, in both directions.

[baldfat]

I was a research librarian in an academic setting. So, I can do research and have an informed opinion. Now if I was to dispute the information then sure I need to have a masters or PhD in the field to have reasons why the vast majority is wrong. I cannot find a single article from an academic background stating that current laser technology will work. Nor do I see anyone that doesn't say decades away.

[Robotbeat]

We are definitely closer. Achieving ignition and scientific break even is a necessary step before we decide to build a demonstration power plant facility.

Lawrence Livermore national lab was working on this problem (under the LIFE project, including developing much more efficient solid state lasers, etc) but was correctly chastised for it being a waste of money because they had not yet achieved ignition or break even. The engineering challenges to make a commercial power plant can distract from the task of actually achieving break even and ignition. (And they still need to increase the gain to about 25-50 to get enough energy out to make useful electricity without heroic efficiency efforts… although since they have achieved ignition in a repeatable way, this should be doable.)

There’s so much lazy criticism about NIF that could be addressed just by perusing the Wikipedia article on the topic and the proposed successor: https://en.wikipedia.org/wiki/Laser_Inertial_Fusion_Energy#M...

[ambicapter]

> under the LIFE project, including developing much more efficient solid state lasers, etc) but was correctly chastised for it being a waste of money

How is this a waste of money? Surely there are other applications which can use more efficient lasers?

[noobermin]

You have to understand. I got a PhD in this field. For years, scientists in droves stopped applying for grants saying they were actually doing fusion because funding sources just lost faith in the effort. ICF requires a lot more investment in capital to run than MCF generally, it seems. These scientists moved on to study things like novel radiation and ion beam sources (which similar laser-plasma interactions provide) but they stopped going for fusion specifically because the government just lost faith in the effort. Now, the pendulum will swing.

The answer is yes, we can use more efficient lasers. If you ever are lucky enough to get a tour of NIF, they have a cute little exhibit where they show you if they redesigned NIF with modern technology, they could fit the three football field machine into something the size of a table. That display itself is likely 10 years old by now, and laser science has advanced even beyond it. Now that NIF has proven it's possible, I imagine there will finally be money in fusion again (ICF specifically, if I were in MCF I'd be worried sick now) and someone somewhere will make the newer NIF that won't be just taking 300MJ in and 2MJ out.

[DennisP]

Other people are already developing the lasers. We have NIF-class lasers now with over 20% efficiency, compared to the <1% efficiency of NIF's lasers. We also have petawatt lasers that can fire once per second.

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

[ambicapter]

Why isn't NIF using these lasers? Wouldn't bringing down the power requirements of their lasers have helped them get to "break-even" faster?

[Robotbeat]

Because they have limited money.

[DennisP]

And it's easy enough to figure out the overall ratio if they'd used newer lasers.

[Robotbeat]

Not these exact ones. And one of the important things required is scale: can you think of anything that requires tens of megawatts of average pulsed laser energy which ISN’T military? (And the military has very different requirements for wavelength, etc.) And those other efforts can also seek their own funding (there’s not a lot of money in fusion research).

If you’re in a budget constrained environment and you’re not already 100% certain this approach is the right one for future power plants, you focus on achieving the energy gain needed for such a power plant first, and the first step of that is ignition (ie where the heat of the reaction sustains some more of the reaction, not just external heat) and scientific breakeven. Once you’ve shown scientific breakeven and ignition, that’s when it makes sense to start investing a bit in the other balance of plant items.

But the bulk of the effort should still be in increasing the energy gain by leveraging ignition, IMHO.

[RajT88]

> We are not closer except theory is being proven.

I think by most definitions that means, "closer". Proof of concept is a huge deal.

POC doesn't mean it will be viable, even once they manage to make it net-positive. Let's say they get the lasers to be more efficient - there are other inefficiencies in the system further upstream you have to account for.

So, yes, there is a long way to go still, and there's no way to be sure it will be economically viable at the end of it. As an example - look at algae biofuel. That was a working example, not just proof of concept but working at scale - but it couldn't compete on price with petroleum when it was below 4-5 dollars or so.

We won't know until we get there. But the promise it holds (easily obtainable fuel, which won't blight the land if the plant fails) is worth the investment.