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Ahh, Wendelstein is that stellerator reactor. The stellerator is really cool, and an alternative to a tokamak reactor. Tokamak is the doughnut shaped reactor, a
by KyleBerezin 3y ago
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, but forgot it existed over the years. Glad to see it works!
https://en.wikipedia.org/wiki/Stellarator https://en.wikipedia.org/wiki/Stellarator
- white_dragon88 3y agoYou know enough to say more. Say more!
- gabereiser 3y agoSeconded. This is fascinating stuff and reminds me of some crazy rant some guy was telling me about anti-gravity and how electromagnetic “ribbons” could propel you. Obviously the guy was nuts, right? How would one go about learning more about electromagnetic plasma containment folding?
- KyleBerezin 3y agoHaha, no I am just some random guy who reads too many Wikipedia articles. "Electromagnetic plasma containment folding" does sound like something a crazy person at a bus station would rant about. My explanation was definitely over simplified, but I'm not knowledgable enough to go into detail on the topic. I can't even point you towards something to read on the topic since everything I read about it is like 15 years old at this point.
- tootie 3y agoIf a Hollywood screenwriter were naming a crazy science device, they would come up with something like Wendelstien 7-X
- tboughen 3y agoMy favourite fact about it comes from https://phys.org/news/2016-02-plasma-physicist-discusses-wendelstein-x.amp 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 this!
- dale_glass 3y agoOdd 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.
- Retric 3y agoYou 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.
- dale_glass 3y agoOh, English fail on my part then. I had assumed that 100 millionths of a metre == 100 * 1/1000000.
- eis 3y agoThe german site of the source speaks of 0.1mm so you were correct > bei Toleranzen von teilweise nur 0,1 Millimeter https://www.ipp.mpg.de/de/aktuelles/presse/pi/2020/01_20 https://www.ipp.mpg.de/de/aktuelles/presse/pi/2020/01_20
- dylan604 3y ago>"Electromagnetic plasma containment folding" does sound like something a crazy person at a bus station would rant about. Or the very person that someone with a show like Art Bell would have as a guest.
- StackOverlord 3y ago> Dr. Ning Li of Huntsville, AL passed peacefully away on July 27, 2021. She was 79 years old. One of the world's leading scientists in super-conductivity anti-gravity. Dr. Li had constructed first 12" HTSD of the world in late 90s. https://www.berryhillfh.com/obituary/ning-li?lud=4CF765EE88E7526FCBA619C30101F7E6 https://www.berryhillfh.com/obituary/ning-li?lud=4CF765EE88E...
- gabereiser 3y agoI just read a bunch of stuff about her from her son. About how he took care of her in her advanced years and her alzheimer's disease. Sad but also peculiar about her DoD work and how she "never talked about it". I wonder what it was? trying to get an alien craft working again? developing anti-gravity weapon? a ship? a hoverboard? please say it was a hoverboard. Her claim that "You can take a bowling ball and place it and it will stay." is fascinating. I would love to see footage/video of this. Small electro marbles and globes are one thing, a bowling ball or other large non-magnetic object!? man oh man!
- waterheater 3y agoI'm not that guy, but I can speak to what you're asking. I've followed Wendelstein 7-X for almost a decade. Nuclear fusion occurs at extremely-high temperatures. As you heat your fusion fuel to sufficiently-high temperatures to allow fusion, the matter transitions into a plasma, which is great: plasmas react to electromagnetic fields. As such, a major challenge with achieving viable nuclear fusion is making a vessel capable of holding the fusion reaction. Because we can't create on-demand gravity wells, the next best option for confinement is using electromagnetic fields to hold the plasma in the air. So, you now have an "electromagnetic bottle" capable of suspending a fusion reaction above the reactor's walls. Now, you have another issue: how do you ensure the fuel will sufficiently mix to sustain a fusion reaction? One approach is to move the plasma in a loop. The topologically-simplest method to accomplish this loop is the torus. Such a plasma-confinement device is called a tokamak. A tokamak uses two magnetic fields, torodial and polodial, to accomplish its task. The torodial field is driven through the plasma to push it forward, while the polodial field pulls the plasma in toward the center. Proper balance of these fields will allow the plasma to circuit the vessel following a helical path, achieving confinement. However, driving two separate magnetic fields is energy-intensive, and a successful fusion reactor will want to minimize its own power consumption to maximize the amount available for external usage. Enter the stellarator. The stellarator also drives the plasma around in a circle, it but uses a single magnetic field. How? It "tricks" the plasma into "thinking" there's only one magnetic field by using computer-optimized magnets with highly-complex geometries. This provides stellarators with a major engineering advantage over tokamaks and is a primary reason Wendelstein 7-X would have chosen it. With the confinement vessel topology largely identified, the next main step is to figure out how to build a vessel able to contain a sustained fusion reaction. For context, fusion experiments traditionally only operate on timescales of milliseconds to maybe a second. The reason? Fusion occurs at millions of degrees, and keeping the reaction vessel cool, ensuring a continuous supply of fuel, and dealing with reaction "exhaust" (e.g., alpha particles) and stray high-energy neutrons from the common deuterium-tritium reaction (which irradiate your reactor walls because neutrons don't react with electomagnetic fields) is a major, major engineering challenge. Any operational, net-positive fusion reactor must be able to operate for days, weeks, and months on end. What Wendelstein 7-X has been attempting to do for years is demonstrate that building such a vessel is even possible. Their overall goal is to sustain a fusion reaction for about 30 minutes. Such a timescale will show a proof-of-concept system which enables sustained fusion reactions to occur. Currently, the preferred fuel is deuterium-tritium because the fuel is generally available and has an attainable fusion temperature. The stray neutron issue can be mitigated by lining reactor walls with lithium to breed tritium fuel. Even better is to use the helium3-helium3 reaction, which completely annihilate to produce pure energy as the output (welcome to e=mc^2, enjoy your stay). The main holdups are: (1) the reaction occurs at much higher temperatures than deuterium-tritium, and (2) he(lium)3 is quite scarce on Earth. Once Wendelstein 7-X shows how to engineer a proper confinement vessel at a "lower" temperature, you can then work on the higher temperature levels required for he3-he3. Also, he3 is plentiful on the surface of the moon, so mining the surface of the moon will be performed to obtain the required fuel, which is the fundamental premise of the movie "Moon". Someone asked for information on electromagnetic plasma containment folding. I recommend reading up on magnetohydrodynamics (MHD). It's the mathematical and physical foundation of your interest.
- lostlogin 3y agoAre you able to say more about what you do? Judging by your comments, you have some idea what you are talking about.
- themagician 3y agoI 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."
- sdwr 3y agoI'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.
- stjohnswarts 3y agoSorry those just aren't the way the average joe on the street thinks about things.
- willis936 3y agoThey're actually quite simple geometries in the right (unintuitive and warped) coordinate system.
- eternityforest 3y agoDoing 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 there are probably people out there who can see that entire design in their head. To me it's like unicycling on a tightrope or skateboarding or realistic oil painting or playing piano well. I have no real concept or reference point for what that experience must be like.
- Simon_O_Rourke 3y agoJust curious as to why a Mobius strip type arrangement is better than a toroid? Is it anything to do with the turbulence in the plasma flow being easier to control?
- KyleBerezin 3y agoThese are great questions for someone more knowledgable, but as I understand it, If you follow a single point on the surface all the way around the loop, it will spend as much time in high confinement as it does in low confinement. That explains why folding is important, as for the mobius, I oversimplified a bit. The Wendelstein has 5 folds, making it a mobius, but I think I read about one in Spain that had only 4 folds. That would mean the mobius isn't imperitive, but I'm sure there is a good reason for it. Really a stellerator doesn't need 'folding' at all, they can be as simple as a twisted torroid. I didn't want to go into excruciating detail though, the more in detail I go the more likely I am to say something that is wrong lol. Edit: I looked it up, the one in spain is called "TJ-II"
- NovaDudely 3y agoFirst thing that comes to mind is like twisted pairing on cables. Distributes the external/internal forces more equally. Is it anything like this?
- KyleBerezin 3y agoNo, twisted pair wires are really cool but different. When you push current down one wire you pull current down the other. The signal is passed through the differential of those 2 wires. If the wire is hit with EM interference, that change will be seen as a 'common mode voltage', that is, both wires will be 'pushed' or 'pulled' the same amount, and you won't see a differential. That effect works both ways too, where a single wire with a digital signal will spew out radio waves, 2 wires with opposing signal cancel each other out and emit no em waves. The effect with the stellarator is more like stirring a pot.
- 3y ago
- tw061023 3y agoWhat'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 electrical engineering and having access to proper civilan equipment can build one with ease - seems to be invented _after_ both stellarator and tokamak. That said, I never particularly liked stellarator design. The very _complexity_ of it somehow feels subtly wrong, like doubling down in the wrong direction. However, this is one of the cases where I would absolutely love to be proven wrong. We are far past due big breakthroughs in the field.
- rkangel 3y ago> The very _complexity_ of it somehow feels subtly wrong, like doubling down in the wrong direction I read an article a while ago which sold me on the stellarator that said something like: "The tokamak has magnets in a configuration that gives simple engineering but hard physics, whereas the stellarator has hard engineering to make a complex magnet but that results in simple physics". The engineering is a much more understood beast. It was still fairly novel as they had to have a computer do the design of the magnets, but that is now a solved problem. But then if that allows us to simplify the (very difficult and novel) physics it feels like the "obviously" correct decision. The other thing that makes me a stellarator fan is that the JET/ITER work is later and more expensive that predicted at every stage. The W7-X provided a plan for the runs they wanted to do and upgrades to the reactor and they have basically run entirely to schedule.
- waterheater 3y agoCompared 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.
- dylan604 3y agoEven just reading "mobius" and I cannot not hear the line from Warf "There is this theory of the mobious. It twists in the fabric of space where time becomes a loop. Time becomes a loop. Time becomes a loop." Of course, I'm referencing the Orbital track
- mastersummoner 3y agoI've listened to that song hundreds of times yet somehow never realized it was Worf.
- dylan604 3y agoI didn't either, since I spelled it Warf! I never watched Star Trek (probably get my HN privileges revoked for that), but I did know that much. And then the Reading Rainbow guy's "whatever happened will happen again". I know the character's name is Geordie or whatever, but he didn't have the right accent for him to be a Geordie, so he will forever be Reading Rainbow guy instead.
- downvotetruth 3y agoKunta Kinte is closer to his roots.
- noduerme 3y agoWow. A triple play.
- hinkley 3y agoHe could have been the Jeopardy guy too.
- dylan604 3y agoBut I didn't grow up watching him on Jeopardy, so no, he would never be that guy either.
- imtringued 3y agoIt not only works. It beats tokamak reactors by orders of magnitude to the point that it and ITER are the only fusion reactors that even matter, so saying that you forgot about one of the most important fusion reactors in history is highly condescending.
- rolandog 3y ago> The stellerator is really cool, and an alternative to a tokamak reactor. They should've gone with a catchier name like "forbidden cruller".