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Comment by trilobyte | Hacker News Reader

Am I reading it correctly that they achieved a ~53% output of energy over input?

>>:Am I reading it correctly that they achieved a ~53% output of energy over input?

Let's add some words. The output energy is electromagnetic radiation and heat. When they do make a conversion to usable energy (electricity) there will be conversion losses.

On the input side, they are measuring laser energy. The lasers are not very efficient so this overlooks a bunch of losses on the input side as well.

They are probably 100x away from real energy gain, and the facility isn't even designed to be used that way.

Never the less, it is a milestone along the way.

2.05 MJ in, 3.15 MJ out.

That's amazing.

Minus the laser power supply, is it correct?

Press release states: "meaning it produced more energy from fusion than the laser energy used to drive it."

The 2.05 MJ put into the reaction includes the laser power supply then, it would seem, unless they are bad at press releases. But 2.05 MJ is not a lot of power.

2.05 MJ is what made it into the system from the laser. It took a lot more to power the laser.

That's what I was trying to figure out. So is it still a net-negative overall?

Yea very curious as well would need to dig a little deeper. If it's the beam energy it means we need more efficient lasers or to scale larger to overcome the energy losses from making a laser beam.

Still even if it's just the beam we are at an energy positive which is still great news because it mean the fundamentals are working.

Still other issues though, the biggest in my opinion are an effective way to produce Tritium and energy extraction.

Looks like the Nature article (https://www.nature.com/articles/d41586-022-04440-7) is more clear about it still being a net loss. Still an important step forward, but it's important to contextualize it.

It's a net negative with a factor of 400 or so. This breakthrough is not really a breakthrough, it's just marketed as such because NIF needs to justify their funding. Compressing pellets of fusion fuel using lasers has no chance of ever forming the basis of a nuclear reactor.

It's scientifically interesting because a self-sustaining reaction (until the fuel was consumed that is) was achieved in a lab setting (as opposed to in a hydrogen bomb). There might be fusion plasma data in there that are of importance to more serious attempts at actually building fusion reactors.

If it was net-positive today they'd already be plugging it into the grid.

If I remember from the article/discussion from yesterday, "laser energy" is the energy in the laser beam, but creating that 2 MJ laser beam required 200 MJ.

> creating that 2 MJ laser beam required 200 MJ

NIF uses notoriously inefficient lasers. They lase fine. Just not efficiently. From what I've seen, that 200 MJ would be closer to 20 MJ with modern equipment.

Still a gap! And there is still making the fuel, making and replacing the reactor as well as collection losses. But we're within two orders of magnitude of system break even, which is closer than we've ever been.

Yes. The lasers are supplied with 400 megajoules, but it's a start.

What would it take to store/feedback the gained (converted) energy to power the lasers? Sort of like a bootstrap with a very inefficient source of power, and over time transition to the produced clean energy?

Armchair scientisting aside, this news seems like the most exciting news over the past few years - a great way to end this year (/pandemic). We are far out from a production-ready thingy, but if it took decades for brilliant scientists to conjure up this initial clunky toy thingy, I am sure an army of scientists/companies would work at building the real thing much, much faster: we had only a freaking 8086 not 30 years ago!!

We have the basic blueprint from government funded research no less.

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