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Successful second round of fusion experiments with Wendelstein 7-X

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Re: Successful second round of fusion experiments with Wendelstein 7-X

#61

Post by pfdietz »

gmueckl wrote: post #54
pastullo wrote: post #31

Earlier quoted context omitted.

The idea of having many small fusion reactors is quite interesting. I never thought about it and i would normally dismiss it since building a big one is cheaper than building many little ones. However, SpaceX and their 9-engine Falcon rocket teach us a different story. Sometimes building smaller yet complicated power plants is cheaper than building fewer ones but bigger. Would be great to know more about the economic…

The real issue is surface to volune ratio of the contained plasma. This needs to be as small as possible for the containment to be effective (reduced energy losses through the surface area). So you want your reactors to be as big as possible.

From an engineering point of view, though, you want the reactor to be as small as possible. That's because output is limited by the power/area that the first wall can withstand. So, the volumetric power density will be inversely proportional to the linear dimensions of the reactor.

Re: Successful second round of fusion experiments with Wendelstein 7-X

#62

Post by twic »

cygx wrote: post #21
hyperbovine wrote: post #11

Earlier quoted context omitted.

Err no, money is not "the only thing" keeping us from having fusion power. I can think of one other thing which is that it's damn hard to create stellar-core conditions inside of a small containment vessel on Earth. It's not obvious that throwing more money at the problem is going to change this. After all, fusion research has been funded in some form or another since the 1950s. I'll bet if you added up all the resea…

Just for the record, you don't re-create stellar-core conditions with earth-bound fusion devices: We don't have the means, and the yield would suck. Now, it is true that there's still fundamental research to be done until energy production via nuclear fusion becomes a reality, but we're reasonably confident that we could make the conventional approaches work. However, that research is Big Science, and there's no poli…

> However, that research is Big Science

Some of the progress in recent years is from the development of ideas that can be tried at much smaller scales, like the ST40:

https://www.youtube.com/watch?v=Cjzok6h2-xA

This is something that spherical tokamak research has been hammering away at for years:

https://en.wikipedia.org/wiki/Spherical_tokamak

Re: Successful second round of fusion experiments with Wendelstein 7-X

#63

Post by sandworm101 »

cygx wrote: post #29
sandworm101 wrote: post #25

Earlier quoted context omitted.

>>> However, that research is Big Science, Not all of it. The big science approach is a function of "pure" fusion research done from the assumption that containment/ignition only comes from magnetic fields and particle collisions. Some are approaching it from different directions, even using physical forces to trigger ignition (ie slamming the hydrogen with a big hammer). This isn't crazy stuff, just a more practical…

Hence my qualifier 'conventional approaches'. I wish those working on alternative approaches the best of luck, and some of the experiments look like a lot of fun (they get to blow things up - I've seen videos where plastering was raining from the ceiling of the control room ;)).

I'd say that the "conventional" approach for triggering fusion is physical. We've been triggering fusion in nuclear weapons for many years and the physicalities of it are very well understood. What general fusion is doing is essentially a non-destructive nuclear secondary. Triggering fusion with magnets, without moving parts, is imho the unconventional way of getting to fusion. It is only conventional in comparison to fusion research. The practical users of fusion (the armed forces) don't use magnets.

Re: Successful second round of fusion experiments with Wendelstein 7-X

#64

Post by ChuckMcM »

lifeformed wrote: post #27
ttul wrote: post #3

Experiments like Wendelstein remind me that the only thing holding back fusion power is money for research like this. Every year, we spend billions on fossil fuel exploration because the return on investment is quick - just think about all the wells going in to extract shale oil. What if we collectively had the will to invest this much into fusion?

A company like Apple has a quarter trillion in cash laying around, they could jump start fusion and control near-limitless energy in several decades. I wish there was more of a visionary drive among institutions for intellectual curiosity and pushing the boundaries of humankind. And yes, I know why they don't... shareholders business plans risk blah blah blah. Reality is just so BORING. Maybe one day we'll find a way…

It is odd that you mention this, unless your name is Karl and were at lunch last Wednesday :-), because it came up as something that companies with big cash hoards might actually be thinking about. Consider the notion that at some point a feasible fusion power plant design becomes "known". Then its a question of money to build one or two or 10. And a company like Google or Apple, with a large cash hoard could jump in, build some plants, power their infrastructure on their own plants and sell excess power to the grid, we even gave a name to the company "Google Power and Packet" :-).

The conversation came up because I was trying to fathom why a company would sit on billions of dollars when they could make more billions with it. This idea, that the future will have sudden insights that will take tremendous capital to exploit to create unassailable leadership positions, is not one I had considered. Fusion power, space opportunities, Etc, might be areas where things suddenly create an entirely new need.

Re: Successful second round of fusion experiments with Wendelstein 7-X

#65

Post by tlb »

If this ends up being the right design for fusion, it may be the most weirdly shaped human artifact, where the shape is fundamental to its operation and not decorative. It's far more complex than a mere turbine blade or venturi. Or can anyone suggest a weirder one? (Define weirdness as the Kolmogorov complexity of the shape, within the precision needed to work properly.)

Re: Successful second round of fusion experiments with Wendelstein 7-X

#66

Post by ChuckMcM »

I love these guys, steadily working through the issues, making steady progress. I think with a slightly different diverter design they could claim to have the worlds first plasma cannon :-).

Pretty insanely complex machine, and really awesome results. Congrats!

Re: Successful second round of fusion experiments with Wendelstein 7-X

#67

Post by Pica_soO »

antocv wrote: post #30
nine_k wrote: post #12

With fusion devices having trouble to confine the plasma for long times, I wonder if a massively-parallel fusion plant woud be feasible. Let's assume that plasma destabilisation does not damage the device, and is a mundane event. Build 10 or even 20 fusion devices (economy of scale!) feeding the common heat buffer, e.g. a large reservoir of a molten salt or metal. Feed conventional turbines off the heat of the heat t…

What is it with physicists and molten salt? Every battery-tech, pro-nuclear, fusion related news have to have somebody chiming in "molten salt". Just an observation.

[dead]

Re: Successful second round of fusion experiments with Wendelstein 7-X

#68

Post by rzzzt »

tlb wrote: post #65

If this ends up being the right design for fusion, it may be the most weirdly shaped human artifact, where the shape is fundamental to its operation and not decorative. It's far more complex than a mere turbine blade or venturi. Or can anyone suggest a weirder one? (Define weirdness as the Kolmogorov complexity of the shape, within the precision needed to work properly.)

David Gelernter has a book on (mostly? not sure if I remember correctly) industrial and software design, in which he brings up the bakelite telephone as an example of such an object. Weird shape - check, functional - check (the handset's size and placement matches the distance between the ears and the mouth). It became a literal icon of itself.

https://en.wikipedia.org/wiki/Model_302_telephone

Re: Successful second round of fusion experiments with Wendelstein 7-X

#69

Post by Obi_Juan_Kenobi »

nine_k wrote: post #44
adrianN wrote: post #18

Earlier quoted context omitted.

Confining the plasma is easier in a larger reactor, so you might be better off building one big reactor instead of 20 small ones.

If confinement is easier in a large machine, why are not very large machines being built? If this is economically infeasible, then again, building piecemeal may be better, in the same way as taking a credit and paying interest on it might be better if you can't secure the upfront sum anyway.

Cost. Building huge magnets and a huge vacuum vessel is simply expensive.

Fusion scales very well with two parameters: size and magnetic field strength.

Size works great, but it's just too expensive. Even if you could justify the costs in theory, ITER is demonstration that the political will to invest that much capital with such a long payoff time just isn't there.

Magnetic field strength is the new hope of the fusion industry: 'Cheap' high temperature superconductors have been commercialized and could make smaller fusion designs practical and economical.

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