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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

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 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 ago
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.
- tw061023 3y ago
  I understand the theory. I just hope I will live long enough to see a winner in this race. To be honest, I've been interested in the domain for quite a time and I still want to build a fusor or a polywell at some point just to see it glow. Probably won't happen though.
  - waterheater 3y ago
    The most difficult parts to obtain will be the power supply and vacuum chamber. Still, there's nothing like garage fusion!
jcheng 3y ago
> The very _complexity_ of it somehow feels subtly wrong, like doubling down in the wrong direction. This made me think of modern jet fighters being designed to be aerodynamically unstable, making them all but impossible for human pilots to operate without flight computers. Apparently the maneuverability benefits make the added complexity more than worth it. https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon#Relaxed_stability_and_fly-by-wire https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting...
avar 3y ago
> The very _complexity_ of it > somehow feels subtly wrong. Why is in complex? Because it's not all square corners or a donut shape? I understand that it was hard to build, but isn't that just because it's a one-off? Any one part of the inside of it looks no more oddly shaped than the outside of any modern car, and we've managed to scale that.
_0w8t 3y ago
The big plus of stellarator design is inherent absence of plasma instabilities affecting tokamaks. Notice that future upgrade of Wendelstein may allow to hold plasma for a hour compared with minutes at best with tokamaks. Many physicists for that reason believes stellarator is the only way to archive practical fusion.

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 ago

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.

tw061023 3y ago
I understand the theory. I just hope I will live long enough to see a winner in this race. To be honest, I've been interested in the domain for quite a time and I still want to build a fusor or a polywell at some point just to see it glow. Probably won't happen though.
- waterheater 3y ago
  The most difficult parts to obtain will be the power supply and vacuum chamber. Still, there's nothing like garage fusion!

jcheng 3y ago

> The very _complexity_ of it somehow feels subtly wrong, like doubling down in the wrong direction. This made me think of modern jet fighters being designed to be aerodynamically unstable, making them all but impossible for human pilots to operate without flight computers. Apparently the maneuverability benefits make the added complexity more than worth it. https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting_Falcon#Relaxed_stability_and_fly-by-wire https://en.wikipedia.org/wiki/General_Dynamics_F-16_Fighting...

avar 3y ago

> The very _complexity_ of it > somehow feels subtly wrong. Why is in complex? Because it's not all square corners or a donut shape? I understand that it was hard to build, but isn't that just because it's a one-off? Any one part of the inside of it looks no more oddly shaped than the outside of any modern car, and we've managed to scale that.

_0w8t 3y ago

The big plus of stellarator design is inherent absence of plasma instabilities affecting tokamaks. Notice that future upgrade of Wendelstein may allow to hold plasma for a hour compared with minutes at best with tokamaks. Many physicists for that reason believes stellarator is the only way to archive practical fusion.