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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

#91

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 can't really think in (visualize) 3d shapes, so I depend a lot on 3D geometry programs when I design things like for my microscope. A fair number of people I've talked to can visualize complex shapes in their head, rotate them around, do interference checking, etc.

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

#92
post #60
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

Why the down votes? What is factually wrong with that statement?

Didn’t downvote you, but having unlimited energy source is worth it and can allow us to remove heat from earth. Human-caused CO2 alone contributes 2.1W/sqm while all current human energy production is 0.04W/sqm . Removing extra CO2 alone would offset 50x energy production growth. Then you can do things like placing reflective satellites between earth and sun.

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

#93

Earlier quoted context omitted.

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…

Doing CAD design is really interesting. A lot of stuff is just 2.5D, extrusions of 2D sketches sitting on other 2D sketches. Then you accidentally make something truly 3D by intersecting things and realize you have no idea what you're looking at, couldn't imagine it if you closed your eyes, couldn't replicate it if you had a picture of the result and didn't know the 2D inputs that made it... and then you realize ther…

Just drawing a 3D slanted plane to match the front of my printer made my head hurt: https://www.printables.com/model/526981-ender-3-s1-quad-z-br...

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

#94
post #86

I am thinking why companies making so huge reactors, everything should be simple just for test to get energy

It's a been a long time, but in a talk at Google, I think Bussard said that power output scales with the 5th power of the radius of the device. There's really no point making a small one.

Bussard's last reactor concept, polywell, didn't work.

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

#95

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.

millionths of a meter are known as micron so most people would call this '100 micron' (or '100 micrometers') which is indeed close to 4 thou, as you calculated, and is the level of accuracy of my ~$500 3d printer.

1 thou was achievable in routine shops in the 1940s and a tenth of a thou (2.54 micron) is a common accuracy to target these days. Obviously it depends on the context and the size of the object, at some point you move away from cutting to using grinding and lapping to achieve your results, which is ultra-timeconsuming.

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

#97

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…

What's interesting is that stellarator actually is not just an alternative, but a wholly parallel branch of evolution - it's not like one was invented strictly after another, and the authors of both designs never knew about the other's work before they completed theirs. What's even more interesting is that the fusor - the simplest possible design for a thermonuclear reactor, so simple that anyone skilled in electrica…

Compared to a tokamak, the stellarator bring engineering efficiency while matching performance. Though ideas for the tokamak and the stellarator may have emerged together, the main reason tokamaks were built first is because they COULD be built. Without computer-assisted magnet design, stellarators simply couldn't be properly built; the magnetic geometries are just too complex.

In the long run, it's not known stellarators will be the eventual winner in the long race for a viable fusion reactor. The attributes in a winner will be net-positive operational efficiency and superior energy harvesting abilities. Perhaps multiple approaches will be viable.

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

#98
post #60
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

Why the down votes? What is factually wrong with that statement?

Because the argument involves unlimited future growth in energy use. Compared to the current energy use, fusion (assuming it could be made to work practically) would indeed solve global warming.

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

#99
I greet W7-X with a huge yawn. A reactor based on stellarators will still be very large and have very low volumetric power density. The beta is not good, so these would only work with DT, and suffer from the generic problems of all DT schemes.

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

#100
post #60
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

Why the down votes? What is factually wrong with that statement?

The burning of 1 kg of coal heats the earth in two ways:

A) the energy that is produced immediately (about 24MJ)

B) the excess energy absorbed from the Sun over many subsequent years, caused by CO2 emitted burning that coal.

The B is much larger than A. The fusion only produces A, but not B.

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