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Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

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Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#61

Post by b3orn »

hedora wrote: post #38
Eji1700 wrote: post #6

Earlier quoted context omitted.

Mostly, they don't? There should be more funding in this area, but at some point you've got to build it, and that takes a ton of time. Regulations/bureaucracy could be better but at the end of the day you're not going to cut off a ton of time safely. Once you have a working model iteration gets much much faster, but we've simply been hitting walls for decades.

Is there a minimum viable size for a fusion reactor? If it scaled down ennough, they could just launch prototypes into space, and see if they explode.

I'm no expert on this, but a minimum viable size exists and it's much larger than what you could just launch into space. I watched a video on this years ago, I don't recall the exact relation to size but if I'm not remembering this completely wrong there's a minimum size you need for a fusion reactor to "ignite", ITER is huge for a reason.

Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#62

Post by slashdev »

aquafox wrote: post #56

Interesting fact: Nuclear fusion, even if we'll make it work, won't stop global warming, because the heat it creates heats up the earth enough to bring us outside the Paris agreement: https://twitter.com/rahmstorf/status/1605967891928596481

Assuming I trust the math, that’s plotting exponential growth in energy usage out for 80 years, and assuming a fully nuclear grid. Neither of those is likely. Lastly the Paris accord is a pipe dream that will never happen. A target to aim for, and miss. Nothing more.

Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#63

Post by themagician »

KyleBerezin wrote: post #3

Ahh, Wendelstein is that stellerator reactor. The stellerator is really cool, and an alternative to a tokamak reactor. Tokamak is the doughnut shaped reactor, and it has a problem where the plasma near the outer circumference has less magnetic confinement. The stellerator is similar, but confines the plasma to a ribbon and folds it over on itself in a mobius-like arrangement. I used to be really interested in this, b…

I find the geometry of things like this fascinating. We typically think in such simple shapes. I feel like my brain can do triangle, rectangle and maybe hexagons and that's about it. I remember when I finally understood radians enough to really understand circles and waveforms—I felt so enlightened. Like I actually remember the moment when it clicked. For years I was just "doing the work" without actually understanding what I was doing, but once I was able to understand it… it's like something changed in my brain.

I want to be able to think in mobius, but my brain is currently like, "No thanks."

Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#64

Post by dale_glass »

tboughen wrote: post #50
tootie wrote: post #33

Earlier quoted context omitted.

If a Hollywood screenwriter were naming a crazy science device, they would come up with something like Wendelstien 7-X

My favourite fact about it comes from https://phys.org/news/2016-02-plasma-physicist-discusses-wen... “…the supporting structure can only withstand the forces if the interfaces between the ten individual segments of the central rings, which weighs several tonnes, are built with a level of precision of less than 100 millionths of a metre…” - and they found a small family business in the north of Italy capable of doing…

Odd units.

1 meter = 100 cm = 1000mm.

So 1 millionth of a meter = 1/1000th of 1mm.

thus, 100 millionths of a meter = 0.1mm, or ~4 thou in American units. Easily achievable by hobbyists, let alone by serious, professional equipment.

Sure, that is a pretty exacting specification for what I suppose is a big machine, but I'm pretty sure very normal things like say, car engines get made to far tighter tolerances.

Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#65

Post by aeyes »

sp332 wrote: post #55
jahnu wrote: post #31

Earlier quoted context omitted.

That seems amazingly cheap! Are we really down to that low level of cost?

Grid-scale solar is $33/MWh (+) https://emp.lbl.gov/publications/utility-scale-solar-2022-ed... and the Netherlands uses 1,000,000,000 MWh/year https://ourworldindata.org/energy/country/netherlands so it's only off by a factor of ~2. (+) These numbers are for the USA. I found a mention of a cheaper project in Chile https://about.bnef.com/blog/cost-of-new-renewables-temporari... but I don't know what the situation is…

Chile is an outlier, the plants are in remote locations in the Atacama desert where you have two compelling reasons to build solar plants: There is a lot of space where nobody lives and the sun is always shining. There are mountains but there are also lots of places which are flat for as far as the eye can see, an example would be the Cerro Dominador plant which probably didn't require any ground preparation.

On http://generadoras.cl/tipos-energia/energia-solar scroll down to "Capacidad por región", Antofagasta and Atacama are the desert regions in the with over 90% of installed capacity.

In Germany or the Netherlands it is a bit harder to find space for large solar plants.

Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#66

Post by munchler »

anonuser123456 wrote: post #22

I don’t get it; who cares? We know the equations to burn plasma; that’s the easy part. The hard part is building a machine that can burn plasma and breed tritium at appreciable rates. Why even bother with these machines that can never be built economically?

Maintaining a controlled fusion reaction for eight freaking minutes seems like a pretty worthwhile accomplishment in and of itself. The only other place this is known to occur is in the center of a star. Doing it here on Earth is pretty mind-blowing IMHO.

Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#67

Post by mjfl »

The Stellarator is theoretically a superior design over the Tokamak, designed to neutralize the JxB force, where J is the current through the plasma and B is the magnetic field guiding the plasma around the device. By twisting the plasma into a shape where the curl of B (proportional to J) is parallel to B, i.e. a helix, the cross product is 0, and thus there are no net magnetohydrodynamic forces on the plasma.

Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#68

Post by sdwr »

themagician wrote: post #63
KyleBerezin wrote: post #3

Ahh, Wendelstein is that stellerator reactor. The stellerator is really cool, and an alternative to a tokamak reactor. Tokamak is the doughnut shaped reactor, and it has a problem where the plasma near the outer circumference has less magnetic confinement. The stellerator is similar, but confines the plasma to a ribbon and folds it over on itself in a mobius-like arrangement. I used to be really interested in this, b…

I find the geometry of things like this fascinating. We typically think in such simple shapes. I feel like my brain can do triangle, rectangle and maybe hexagons and that's about it. I remember when I finally understood radians enough to really understand circles and waveforms—I felt so enlightened. Like I actually remember the moment when it clicked. For years I was just "doing the work" without actually understandi…

I'll argue that "thinking in mobius" is simpler than thinking in circles, and more true to life than thinking in basic shapes.

The core concepts in mobius-land are local curvature and global cumulative field.

Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#69

Post by Retric »

dale_glass wrote: post #64
tboughen wrote: post #50

Earlier quoted context omitted.

My favourite fact about it comes from https://phys.org/news/2016-02-plasma-physicist-discusses-wen... “…the supporting structure can only withstand the forces if the interfaces between the ten individual segments of the central rings, which weighs several tonnes, are built with a level of precision of less than 100 millionths of a metre…” - and they found a small family business in the north of Italy capable of doing…

Odd units. 1 meter = 100 cm = 1000mm. So 1 millionth of a meter = 1/1000th of 1mm. thus, 100 millionths of a meter = 0.1mm, or ~4 thou in American units. Easily achievable by hobbyists, let alone by serious, professional equipment. Sure, that is a pretty exacting specification for what I suppose is a big machine, but I'm pretty sure very normal things like say, car engines get made to far tighter tolerances.

You messed up at your last step 1 millionth = 1mm, 10 millionth = 0.1mm, 100 millionth = 0.01mm

0.01mm is very difficult when you’re talking large custom objects with complex shapes.

Re: Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes

#70

Post by midasuni »

idiotsecant wrote: post #45
karmajunkie wrote: post #30

This is perhaps an obvious question to some, but I'll ask it anyway: How is the power generated here converted into usable electricity? I know for conventional fission reactors the heat of fission is basically used to run a steam turbine. Given the extreme heat of the plasma, and that it must be magnetically suspended so that it doesn't even touch the sides of the containment, how is that heat transferred to some oth…

Yes, the boring and actually feasible answer is steam. But it sure is fun to dream! https://en.wikipedia.org/wiki/Direct_energy_conversion

Isn’t one of the problems with nuclear that it increases water temperature in rivers
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