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Successful second round of fusion experiments with Wendelstein 7-X

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Re: Successful second round of fusion experiments with Wendelstein 7-X

#211

Post by cygx »

skgoa wrote: post #186
phkahler wrote: post #46

Earlier quoted context omitted.

>> and W7-X basically only exists because German reunification happened, and the German government was looking for a big science project - any project - they could leverage to funnel money into East Germany That's the first time I've heard that. Brilliant!

It's wrong, though.

Well, it's wrong insofar that the federal government wasn't actively looking for projects to fund and then miraculously discovered W7-X in a drawer. Rather, W7-X people were looking for funding and shopping for locations, but failed to secure it until they stumbled onto this particular angle to push. It's no coincidence that a new branch of the Max Planck Institute was established in Greifswald, whereas all previous work was done in Garchingen.

At least, that's the story I've been told by one of the current top W7-X people over a glass of beer, though the main topic at the time was that the movers and shakers behind such big projects might not see them to completion due to retirement or even death.

Re: Successful second round of fusion experiments with Wendelstein 7-X

#212

Post by rficcaglia »

sonnyblarney wrote: post #176
philwelch wrote: post #127

Earlier quoted context omitted.

> Personally, I think one of the answers to "tech seems to have stalled" is that it's easy to underestimate how important cheap computational power is, even without "AI", to moving forward. For another example, as fantastic as the 1960s space projects may have been, I think they just weren't economically sustainable, so it isn't that amazing that they didn't become a self-sustaining industry right away. I think it's…

Excellent Post! You should do a Netflix series, Phil! Plus: GPS, Combustion Engine, The Web / Networking, Plastics/Chem revolution, and maybe soon AI?

There was an old BBC series called Connections that followed seemingly unrelated chains of inventions to their modern day endpoints. Worth finding on YouTube.

Edit: found Wikipedia link: https://en.wikipedia.org/wiki/Connections_(TV_series)

Re: Successful second round of fusion experiments with Wendelstein 7-X

#213

Post by axilmar »

lifeformed wrote: post #27
ttul wrote: post #3

Experiments like Wendelstein remind me that the only thing holding back fusion power is money for research like this. Every year, we spend billions on fossil fuel exploration because the return on investment is quick - just think about all the wells going in to extract shale oil. What if we collectively had the will to invest this much into fusion?

A company like Apple has a quarter trillion in cash laying around, they could jump start fusion and control near-limitless energy in several decades. I wish there was more of a visionary drive among institutions for intellectual curiosity and pushing the boundaries of humankind. And yes, I know why they don't... shareholders business plans risk blah blah blah. Reality is just so BORING. Maybe one day we'll find a way…

Why not print the money required for this kind of research? why does it have to be tax payer money? or private money?

Re: Successful second round of fusion experiments with Wendelstein 7-X

#214

Post by Recurecur »

ttul wrote: post #3

Experiments like Wendelstein remind me that the only thing holding back fusion power is money for research like this. Every year, we spend billions on fossil fuel exploration because the return on investment is quick - just think about all the wells going in to extract shale oil. What if we collectively had the will to invest this much into fusion?

> What if we collectively had the will to invest this much into fusion?

We should invest much more heavily into fission, and keep deuterium/tritium fission investment at around the current levels.

Why? Because deuterium/tritium fission like the stellerators and tokomaks use produces a lot of (energetic) neutrons, along with heating the plasma. That is very bad for two reasons. First, essentially unrecoverable energy is wasted by the neutrons. Second, the neutron exposure causes the reactor to become radioactive. So, the promise of "clean" fusion energy with no radioactive waste is not realized.

Aneutronic fusion is possible, but requires higher energy and different fuel. This is not yet being widely researched, but some interesting work is being done at LPP Fusion: https://lppfusion.com/

That is an effort I'd like to see funded much more fully.

At any rate, next-generation fission reactors are just as safe as deuterium/tritium fusion, are well understood, and many designs produce less and shorter-lived waste than the dinosaur PWR designs. It is beyond silly to not fully leverage clean, cheap fuel with a million times the energy density of fossil fuel while we work out the kinks with fusion. There is a necessity for reliable grid power alongside unreliable "renewables", and fission is the only viable CO2 free approach for the foreseeable future.

Re: Successful second round of fusion experiments with Wendelstein 7-X

#215

Post by lambdadmitry »

londons_explore wrote: post #194
michaelmachine wrote: post #72

Earlier quoted context omitted.

There is a video available here as well: https://www.youtube.com/watch?v=Gtf-1JibORg

Those videos show surprising 'hotspot' lines - I would expect the plasma to be far more evenly distributed.

Because really hot plasma doesn't emit in visible range, it's all x-ray, so what you are seeing is it's (relatively) cool edge. It might have colder regions, but that doesn't necessarily mean that the main volume is unstable.

Re: Successful second round of fusion experiments with Wendelstein 7-X

#216

Post by lambdadmitry »

pfdietz wrote: post #196
alexgmcm wrote: post #10

Earlier quoted context omitted.

From my classes some years ago IIRC the main benefit of the Stellarator was the lack of a plasma current which is no longer needed for plasma heating due to advances in neutral beam injection technologies. The plasma current seems to create some instabilities so we may be able to achieve better confinement with a device that doesn't have one. I would also agree with the other comments that we can't afford to put all…

The big advantage of stellarators vs. tokamaks is their lack of disruptions. Tokamak disruptions are a very serious problem that, if not well-solved, promise to put tokamaks into the technology garbage can. A disruption can, in the worst case, generate runaway relativistic electron beams that can melt holes through the first wall. The first and primary goal of ITER is to show that the disruption problem can be and ha…

Are talking about ELMs? Isn't it a basically solved problem then? I was under impression that between KSTAR's active field disruption coils and pellet injection they are more or less controlled (and we'll have confirmation from MAST Upgrade quite soon). Or am I wrong?

Re: Successful second round of fusion experiments with Wendelstein 7-X

#217

Post by pfdietz »

lambdadmitry wrote: post #216
pfdietz wrote: post #196

Earlier quoted context omitted.

The big advantage of stellarators vs. tokamaks is their lack of disruptions. Tokamak disruptions are a very serious problem that, if not well-solved, promise to put tokamaks into the technology garbage can. A disruption can, in the worst case, generate runaway relativistic electron beams that can melt holes through the first wall. The first and primary goal of ITER is to show that the disruption problem can be and ha…

Are talking about ELMs? Isn't it a basically solved problem then? I was under impression that between KSTAR's active field disruption coils and pellet injection they are more or less controlled (and we'll have confirmation from MAST Upgrade quite soon). Or am I wrong?

No, disruptions are catastrophic events where confinement is lost very rapidly. As the plasma cools an electric field builds up from the decaying current, and this field can accelerate runaway electrons in narrow beams to relativistic energies. Worst case >70% of the stored magnetic energy from the current in the plasma gets dumped into these electrons. If they hit the wall they can explode a hole in it.

https://en.m.wikipedia.org/wiki/Tokamak#Plasma_disruptions

Re: Successful second round of fusion experiments with Wendelstein 7-X

#218

Post by lambdadmitry »

pfdietz wrote: post #217
lambdadmitry wrote: post #216

Earlier quoted context omitted.

Are talking about ELMs? Isn't it a basically solved problem then? I was under impression that between KSTAR's active field disruption coils and pellet injection they are more or less controlled (and we'll have confirmation from MAST Upgrade quite soon). Or am I wrong?

No, disruptions are catastrophic events where confinement is lost very rapidly. As the plasma cools an electric field builds up from the decaying current, and this field can accelerate runaway electrons in narrow beams to relativistic energies. Worst case >70% of the stored magnetic energy from the current in the plasma gets dumped into these electrons. If they hit the wall they can explode a hole in it. https://en.m…

Ah, I see. It looks they did something about it though https://www.iter.org/newsline/-/3183 are you skeptical that that can work?

Re: Successful second round of fusion experiments with Wendelstein 7-X

#219

Post by pfdietz »

lambdadmitry wrote: post #218
pfdietz wrote: post #217

Earlier quoted context omitted.

No, disruptions are catastrophic events where confinement is lost very rapidly. As the plasma cools an electric field builds up from the decaying current, and this field can accelerate runaway electrons in narrow beams to relativistic energies. Worst case >70% of the stored magnetic energy from the current in the plasma gets dumped into these electrons. If they hit the wall they can explode a hole in it. https://en.m…

Ah, I see. It looks they did something about it though https://www.iter.org/newsline/-/3183 are you skeptical that that can work?

Some disruptions occur almost instantly. The system will have very little time to react. And how are they going to train or test it? A single unmitigated disruption will damage the reactor.

https://wsx.lanl.gov/Disruptions/Disruption-Risk-poster-Wurd...

https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lar...

Re: Successful second round of fusion experiments with Wendelstein 7-X

#220

Post by pfdietz »

zamalek wrote: post #163
ttul wrote: post #3

Experiments like Wendelstein remind me that the only thing holding back fusion power is money for research like this. Every year, we spend billions on fossil fuel exploration because the return on investment is quick - just think about all the wells going in to extract shale oil. What if we collectively had the will to invest this much into fusion?

> What if we collectively had the will to invest this much into fusion? The big problem is that fusion has reached its end-game in military applications: we have the h-bomb. Sure, there's the hypothetical fusion submarines and carriers, but what do those really provide beyond their fission equivalent? If we could find some novel thing that fusion power solves for the military, then fusion would be solved.

Fusion in ships is a ridiculous idea. Fission has much better power density, and volume in ships is limited.
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