rickair7777

https://www.npr.org/2022/12/13/11422...climate-change

This is getting a lot of media attention, but I feel compelled to point out that it's much less of a breakthrough and more of a milestone.

We have been close to or right at break-even energy production in a fusion core for some time, now we're a little further along, clearly on the right side of the Q (fusion energy gain) scale. Looks they got Q = 1.4 ish (Q =1.0 is breakeven).

But to produce viable commercial power output you'd need a Q value well above break even, maybe 20-40? The ITER project is shooting for Q =10, but their goal is fusion core science not actual energy production.

There are also ideas which would capture fusion energy via the magnetic fields used to contain it, basically extract electrical power directly out of the core which would dispense with the conventional heat capture=>boil water=>spin turbine model. This might work commercially with a lower Q. Specifically Helion corporation's concept.

JamesNoBrakes

It's a sham. They are using Qlaser/plasma figures instead of Qtotal. So they are saying x amount of laser energy yielded y amount of fusion energy...but they are not telling you how much it takes to power said laser to get to that energy...and lasers, especially of this magnitude, are far from "efficient". So the total power in is way way more than what they are claiming, what was produced was only a fraction of that.

More on this here, although she was referencing the latest round at the time of her video, I've gone back and looked carefully at this latest breakthrough and they appear to be referencing the power of the laser, just like she is talking about, not the total power.
https://www.youtube.com/watch?v=LJ4W1g-6JiY

rickair7777

Yes the lasers are about 1% efficient so you can just add a couple zeros to the actual input energy.

I suspect lasers are an evolutionary dead-end as far as fusion goes. Super-conducting electromagnetic compression/containment looks a lot better to me given advances in cryogenics and magnets.

This experiment was a step in the right direction, but only a step. Not sure why DOE blew it out of proportion. Maybe to distract from their non-binary luggage theft problems?

Government fusion research is slow and plodding. Sabine's commentary on that is entirely rational. She pointed out sort of correctly that you're only going to convert ballpark 50% of heat to electricity... reality is that conventional power plants have dramatically increased their efficiency in recent years, and all of that would apply to fusion as well since heat is heat once you generate it. I suspect ballpark 70% might be achievable. Plus you have the opportunity to use low-grade waste heat for industrial processes or even campus HVAC.

And the Helion concept, or anything similar, would dispense with heat conversion entirely... my gut says that's the way to go since the nature of magentic containment is that it works both ways. Exactly like we have starter/generators on some airplanes... if you need a motor anyway, why not use it as a generator too?

We also now see private money entering the process... much of that will of course be doomed to failure but the potential does exist for a SpaceX style disruption from the private sector. One can hope.

Round Luggage

Yes the private companies have really made this interesting.

JamesNoBrakes

Hypothesized in the video: funding.

It's not that there is no progress, this IS progress...it's just not the kind of progress that would make fusion practical in a few years and THAT is why we keep getting burned by it, because this kind of stuff makes some people think "it's just round the corner" then a few years go by and they are thinking "well, what happened?". It's not a few year around the corner. Tritium supply is a huge problem. There is the twisted-contorted field reactor that doesn't have some of the issues as the traditional plasma-magnet reactor, but the biggest issue these days is that while they can make the reaction break even as far as the amount of plasma or laser energy...the energy to create that plasma field or laser beam is far in excess of the plasma or laser energy...so it's a long long ways from producing a viable/practical reaction.

rickair7777

Good video about Helion.

https://www.youtube.com/watch?v=_bDXXWQxK38


Worth noting, they use Deuterium-He3 fusion to avoid the high energy overhead of generating Tritium as in Tokamak concepts. Their process generates the He3 on the fly for immediate consumption in the core, and also produces Tritium which will be stored ad decay over a period of years into more He3.

JamesNoBrakes

The Stellerator reactor is another concept that appears to have much more potential utility as a reactor design, able to breed tritium. Also worth a look and pretty fascinating.