Wendelstein 7-X: Gigajoule energy turnover generated for eight minutes • Hacker News Board

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

#171

Post by KyleBerezin » Sat, Aug 12, 2023, 1:01 AM UTC

colordrops wrote: post #131

KyleBerezin wrote: post #114

Earlier quoted context omitted.

Yea they are kinda confusing, especially when you get into the 3D ones like klien bottles and roman surfaces. I also recently learned that if you make a mobius shaped transmission line (like a ladder line) and you send a pulse down it, that pulse will continue looping until it dissipates (or forever if it is a superconductor). https://www.microwavejournal.com/articles/21001-printed-reso... I have no idea if there are…

Are real life superconductors ideal, i.e. they truly would store a charge forever (at least until the material disintegrated)? Or is there some sort of loss, albeit much less than typical resistance?

So long as you do not exceed a certain current, they have zero resistance. There are other forms of parasitics though that can effect it.

Those crazy electromagnets they use on these stellarator are simple superconducting loops that they 'charge' by inducing a current. That current is maintained so long as the superconductor stays below a certain temp. There is even something called a SMES (superconducting magnetic energy storage) that stores power this way, as I understand it they have a 0% self discharge rate.

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

#172

Post by KyleBerezin » Sat, Aug 12, 2023, 1:09 AM UTC

NovaDudely wrote: post #159

KyleBerezin wrote: post #90

Earlier quoted context omitted.

These 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 fo…

First thing that comes to mind is like twisted pairing on cables. Distributes the external/internal forces more equally. Is it anything like this?

No, 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.

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

#173

Post by klodolph » Sat, Aug 12, 2023, 1:20 AM UTC

KyleBerezin wrote: post #163

klodolph wrote: post #148

Earlier quoted context omitted.

1. Something “in a superconducting state” has zero resistance, but the transition to superconducting states is not sudden, and there are various things which disrupt that state like magnetic fields. 2. Alternating currents will dissipate even with zero resistance, because the circuit will emit EM waves.

Ladder lines are balanced transmission lines, so they do not emit EM radiation.

Wouldn’t that require kind of an idealized transmission line, not just a superconducting one?

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

#174

Post by less_less » Sat, Aug 12, 2023, 1:31 AM UTC

waterheater wrote: post #80

white_dragon88 wrote: post #10

Earlier quoted context omitted.

You know enough to say more. Say more!

I'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…

> 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).

It doesn't completely annihilate to produce pure energy. It produces helium-4 and two protons. Or you can react helium-3 + deuterium to produce helium-4 and one proton. The point is that helium-4 and protons are easier to shield against than neutrons, don't turn your reactor radioactive, and at least in theory their energy can be extracted directly (eg through induction) instead of through heat.

Edited to add: except helium-3 + deuterium still produces neutrons, because sometimes the deuterium will react with itself to produce helium-3 and a neutron.

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

#175

Post by KyleBerezin » Sat, Aug 12, 2023, 1:32 AM UTC

klodolph wrote: post #173

KyleBerezin wrote: post #163

Earlier quoted context omitted.

Ladder lines are balanced transmission lines, so they do not emit EM radiation.

Wouldn’t that require kind of an idealized transmission line, not just a superconducting one?

Yes. I don't think super conduncting ressonators of any design are perfect.

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

#176

Post by pschuegr » Sat, Aug 12, 2023, 1:57 AM UTC

waterheater wrote: post #80

white_dragon88 wrote: post #10

Earlier quoted context omitted.

You know enough to say more. Say more!

I'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…

great comment, thanks - this is why I read HN

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

#177

Post by mastersummoner » Sat, Aug 12, 2023, 1:58 AM UTC

dylan604 wrote: post #164

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…

Even 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

I've listened to that song hundreds of times yet somehow never realized it was Worf.

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

#178

Post by gregfjohnson » Sat, Aug 12, 2023, 2:02 AM UTC

Question for this knowledgeable group of people: Which fusion start-ups look promising? How does inertial confinement look? Any thoughts on the newly funded start-up Blue Laser Fusion? Any thoughts on one of the older players, TAE? How about Commonwealth? Helion? Others?

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

#179

Post by dylan604 » Sat, Aug 12, 2023, 2:12 AM UTC

mastersummoner wrote: post #177

dylan604 wrote: post #164

Earlier quoted context omitted.

Even 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

I've listened to that song hundreds of times yet somehow never realized it was Worf.

I 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.

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

#180

Post by greesil » Sat, Aug 12, 2023, 2:13 AM UTC

gregfjohnson wrote: post #178

Question for this knowledgeable group of people: Which fusion start-ups look promising? How does inertial confinement look? Any thoughts on the newly funded start-up Blue Laser Fusion? Any thoughts on one of the older players, TAE? How about Commonwealth? Helion? Others?

Zap Energy. They're at least thinking about co-opting existing infrastructure.

https://www.neimagazine.com/news/newszap-energy-considers-re...

Also their concept is just so weird, I love it. Worst case it works in space as a nuclear fusion drive :)

My guess is that they're all going to tank without government money, unless by some miracle they have truly found some special low-cost of operation on the first try that beats the current heavily optimized solutions for power generation.