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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

#151

Post by jessriedel »

comex wrote: post #77
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.)

> Define weirdness as the Kolmogorov complexity of the shape, within the precision needed to work properly. Well, if the shape is the output of an optimization program, as long as the program itself and its inputs can be simply specified, the shape actually has low Kolmogorov complexity.

True, but you can still formalize the sense in which the object is weird in terms of how long it takes the optimization routine to run. See Bennett's notion of Logical Depth: https://en.wikipedia.org/wiki/Logical_depth

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

#152

Post by pfdietz »

DennisP wrote: post #83
travisoneill1 wrote: post #14

Earlier quoted context omitted.

Private money is coming in now: http://news.mit.edu/2018/mit-newly-formed-company-launch-nov... https://www.lockheedmartin.com/en-us/products/compact-fusion...

Also Helion, TAE (formerly Tri Alpha), First Light Fusion, Tokamak Energy, General Fusion, and others. TAE is the biggest, with over $500M invested so far.

I have to shake my head at TAE, since their approach was brutally critiqued 20 years ago. It turns out being given $500M doesn't let you evade the laws of physics.

https://www.researchgate.net/publication/235032059_Comments_...

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

#153

Post by yholio »

jerf wrote: post #45
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?

If the Stellerator, or any of its descendants, turn out to be the answer to practical fusion, it would have been contingent on vast quantities of computational power being available cheaply. It does not matter how much money you poured into your Stellerator project in 1970, you could never have built the 7-X, because there would have been no way to produce that design in the first place. Personally, I think one of th…

An exact replica of Falcon 9 was impossible 40 years ago, of course. But a replica with 50% lower thrust, 10% lower ISP and 60% it's payload capacity for a similar inflation-adjusted price was certainly possible.

It wasn't the computational revolution that made SpaceX possible, the basic technology is more or less the same as it was in the 60s. The Merlin engine has it's roots in the '90s NASA Fastrac design, evolved for performance and reusability.

SpaceX's success relates to things like market incentives, lean business practices, a fail early and iterate quickly attitude as opposed to "too big to fail" public projects, and so on.

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

#154

Post by pfdietz »

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.

The confinement building of a light water reactor is large because it has to contain large volumes of steam in an accident.

In a molten salt reactor, there is very little volatile material inside the containment building. The salt itself does not have high vapor pressure, even in accident conditions. As a result, the size (and cost) of the containment building can be radically reduced. Moltex's design, for example, reduces the cost (per unit of power output) of the containment building by a factor of 5 vs. LWRs.

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

#155

Post by pfdietz »

theresistor wrote: post #7
chiefalchemist wrote: post #2

"Although Wendelstein 7-X is not designed to generate energy, the device is intended to prove that stellarators are suitable for use in power stations. With Wendelstein 7-X the intention is to achieve for the first time in a stellarator the quality of confinement afforded by competing devices of the tokamak type." This was at the very end. While competition is certainly a positive, this doesn't sound like they're int…

I would say the opposite. Achieving fusion power is so critical to the long term sustainability of human technological civilization that we cannot afford to put all of our eggs in one basket, and hope that we picked the right one.

Fusion power is not critical to long term sustainability. There are perfectly adequate, even superior, alternatives. Fusion has inherent problems that, in my strong opinion, are going to render it uncompetitive against these alternatives.

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

#156

Post by pfdietz »

gus_massa wrote: post #24
chiefalchemist wrote: post #2

"Although Wendelstein 7-X is not designed to generate energy, the device is intended to prove that stellarators are suitable for use in power stations. With Wendelstein 7-X the intention is to achieve for the first time in a stellarator the quality of confinement afforded by competing devices of the tokamak type." This was at the very end. While competition is certainly a positive, this doesn't sound like they're int…

Nobody knows if it's easier to build a commercial fusion power plant with the tokamak design or with the stellarator design or with another of less known competing designs or with another design that nobody has imagined yet. Moreover, perhaps some of these design (including thetokamak and stellarator) perhaps are nice for a lab demo or a model plant that doesn't break even or a tiny scale plant, but they may not scal…

Neither tokamaks nor stellarators appear promising for reaching commercial viability. Both are very complex, very expensive, and will have very poor power density compared to fission reactors (making them much larger for a given power output). It's difficult to see how they could approach the levelized cost of energy that solar and wind have already achieved, never mind the costs of these decades hence.

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

#157

Post by kevin_thibedeau »

btilly wrote: post #138
petra wrote: post #121

Earlier quoted context omitted.

>> when mainframe systems did the job just fine. Didn't people see the value that cheaper/more compute power will give them back than ?

This can be seen as a consequence of https://en.wikipedia.org/wiki/Jevons_paradox . It is called a paradox because seeing it in action usually catches people by surprise. And this is true whether you're talking about the consumption of coal to power factories, or the consumption of electricity to power computing (and in each case the myriad of new uses that efficiency promoted). In Science Fiction over and over again…

"Desk Set" has a job stealing computer with a conversational UI answering reference questions. Ahead of it's time.

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

#158

Post by danielvf »

petra wrote: post #121
wefarrell wrote: post #115

Earlier quoted context omitted.

Pouring in money advances computation. Microprocessors were a direct result of the space race and space weapons systems. No other industry would have justified the trillions of dollars in investment that was required to fit advanced computers into a small space when mainframe systems did the job just fine. Missiles and spaceships required systems that could calculate trajectories and be small enough to launch into sp…

>> when mainframe systems did the job just fine. Didn't people see the value that cheaper/more compute power will give them back than ?

People saw plenty of value in more compute - what they didn’t see the need for was paying an astromical amount more for the same amount of compute to be miniaturized.

For example, in 1964, the ATLAS computer went fully online in Manchester, England. It was the most powerful computer in the world, took up a floor of a university, and the word “supercomputer” was invented to describe it.

The requirements for the Apollo Guidance Computer were to make something with those approximate specs, but take up only 24×12.5×6.5 inches (61×32×17 cm), use 55 watts of power and be ready to fly in 1967. It was a crazy, impossible task.

I’m convinced the AGC was the biggest computing advance after the move general purpose computers.

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

#159

Post by adrianratnapala »

sballin wrote: post #145
saganus wrote: post #5

Does anyone have any idea how do they take pictures of the plasma? That seems quite hard considering the temperatures and the strong magnetic field.

I operate a fast camera at W7-X. It's a normal high-speed camera that records light in the humanly visible range, and the plasma emits in that range and reflects off the walls. IR cameras are most often used to gauge the temperatures of vessel wall components. Our camera looks through a pinhole in the vessel wall, but it sits a few meters away from the machine and gets that view through a bundle of optical fibers. Th…

> Our camera looks through a pinhole in the vessel wall, but it sits a few meters away from the machine and gets that view through a bundle of optical fibers.

Wait, so does this mean that you have a camera obsucra with an array of optical fibres at its back, and then you have an ordinary CCD camera imaging the other end of the fibre array?!?!

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

#160

Post by hyperpallium »

btilly wrote: post #138
petra wrote: post #121

Earlier quoted context omitted.

>> when mainframe systems did the job just fine. Didn't people see the value that cheaper/more compute power will give them back than ?

This can be seen as a consequence of https://en.wikipedia.org/wiki/Jevons_paradox . It is called a paradox because seeing it in action usually catches people by surprise. And this is true whether you're talking about the consumption of coal to power factories, or the consumption of electricity to power computing (and in each case the myriad of new uses that efficiency promoted). In Science Fiction over and over again…

https://wikipedia.org/wiki/The_Feeling_of_Power asimov and manned-missiles
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