Wendelstein 7-X stellarator getting ready for the next phase of operation [pdf]

http://www.ipp.mpg.de/4206699/013_April_2017_eng.pdf

by clon • 9 years ago

122 54 9 years ago

ipp.mpg.de

mandelken• 9 years ago

only 10 years too late..

Gravityloss• 9 years ago

The earlier, the better. Can someone say at what point we should stop trying?

rb1• 9 years ago

The point when the black line on the graph goes below 0 http://i.imgur.com/sjH5r.jpg

(from: https://hardware.slashdot.org/story/12/04/11/0435231/mit-fus...)

Cerium• 9 years ago

The best time to plant a tree was 20 years ago. The second best time is today.

DesiLurker3• 9 years ago

my prediction is we'll have fusion net positive within a decade of when alternative energy's growth is significant enough to show up in fossil fuel economy's future projection.

oh and no its not too late. if you have cheap and plentiful energy from fusion you can take on massive geoengineering projects to reverse global warming. its a whole another ballgame!

zlynx3• 9 years ago

But where are you putting the waste heat from everybody's personal Mr. Fusion reactor?

Just imagine if everybody on Earth has a personal, nearly free 10 megawatt generator. Flying cars. Laser weapons. Direct desalination of seawater in coastal cities. Stomping around in powered exoskeleton suits.

Anyway, it would be awesome. But where do we put all the heat?

mrfusion• 9 years ago

What's the next phase? When does it start?

(I don't know if there's a problem with my reading comprehension or what?)

clon• 9 years ago

From the source:

In preparation for the next operation phase (OP 1.2a), which is scheduled to start in late summer of this year, the limiter structures have been replaced by a test divertor and all graphite tiles on the baffles and wall protection elements have been installed. This will allow the use of more heating power and access to the required magnetic field configurations.

ZenoArrow• 9 years ago

There's no specific date mentioned, but the PDF does mention 'late summer' of this year.

Looks like they're about halfway along with preparing the graphite tiles for the next phase (4500 out of 8000).

colonelxc• 9 years ago

Home page for the project, which provides some higher level details: http://www.ipp.mpg.de/w7x

shaqbert• 9 years ago

Wendelstein 7-x is really not fusion research, but plasma physics research. At the energy/temperature levels and magnetic field strength this machine is operating, plasma is showing all kinds of undesirable behavior, such as turbulence, radial forces... a little bit like the storms on Jupiter. This imposes many challenges, because as soon as the plasma escapes the magnetic field and touches the vessel, it rapidly cools - ending any potential fusion.

Wendelstein's goal is to find out the viability of the stellarator concept, to see if it could be on par with the Tokamak concept, which so far have shown a better ratio of energy invested and energy won back, but come with their own bag of problems.

What the folks at Wendelstein are doing is a step by step verification of some of the hypothesis. There is this excellent 3h podcast with the scientific leader of Wendelstein [0], unfortunately it is in German. It is fascinating to hear their story on how they build this ultra complex piece of kit. The current change is the shielding of the vessel, which now permits higher energy levels and longer runs. Their long term goal is to operate at 100m K for 30 min.

Regarding the "when we should stop trying" and "it is 30 years out" adage: There has been great progress made in improving the ratio of energy invested and energy won back, the G-factor. Right now no fusion reactor is crossing the G > 1 limit. But Iter would be design to yield about G = 5. Newer designs using high temperature superconductors could even yield G > 10 with a smaller footprint. For more on the current state of fusion research, this video [1] from MIT is fantastic, albeit 1h long.

[0] http://alternativlos.org/36/

[1] https://youtu.be/L0KuAx1COEk?t=37m23s

sandworm1012• 9 years ago

But how much of that G > 1 energy has ever been harvested? I get the impression that very little is being done in regards to extracting energy from a sustained fusion reaction. We can't put solar panels in there, nor can I see how one would extract heat given the cooling needs of the magnets. Is there some sort of medium that we can use to pipe heat energy out of this plasma without destroying it?

PhasmaFelis• 9 years ago

But how much of that G > 1 energy has ever been harvested?

None, because we haven't achieved G > 1 yet. :)

Per https://physics.stackexchange.com/questions/70209/how-is-ene..., hydrogen fusion produces helium and neutrons; neutrons are unaffected by magnetic fields, so they escape confinement and impact the reactor walls, heating them. The heat is simply vented in current test rigs, but in a working model it can be used to produce steam to power generators. That's specifically for tokamaks, but I would guess the process is similar for stellarators.

vilhelm_s3• 9 years ago

The inner surface of the Wendelstein plasma vessel is water-cooled (it has to be, or it would eventually melt), so in the future you could drive a generator from the cooling system.

There is a separate engineering problem about how to keep the plasma vessel from warming the magnets (which need be near absolute zero). In the Wendelstein this works by putting most of the device inside a vacuum, to provide better thermal isolation. So the full system is a vacuum chamber which contains the magnets which wrap around the plasma vessel which wraps around the plasma.

There is an article about the cooling system here: https://www.ipp.mpg.de/ippcms/eng/presse/pi/02_10_pi

DesiLurker3• 9 years ago

almost all of fusion development is basically plasma physics research. nuclear fusion itself is known science, its the plasma containment & stabilizing that hard. so you can sustain the fusion & get positive yield.

that said I'd much prefer all the money being burnt on ITER/tokamak would be better spent by spreading the bets into exploring concepts like W7 or inertial confinement or even MIT ARC kind of efforts. Grand efforts like ITER are just ensuring fusion is always 30 years out.

My personal prediction is that we'll have fusion positive yield within a decade of when alternative energy becomes a significant portion (say 25% .. & growing) of total energy mix.

zlynx3• 9 years ago

There really are physics that only work at very large scale, such as stars and black holes.

It may be that we can only get fusion power generation working in huge reactors like ITER. It's also a good attempt at getting many countries working together. Ideally, more big brains working together will have better ideas and results.

There's downsides to ITER too of course. But I think it's worth working on.

Yizahi2• 9 years ago

Except when stellarator starts doing longer runs and requires more hardened materials (like ITER) and when we need more instrumentation in the containment walls (like ITER) and when we need to actually plan to harvest energy from it (like ITER) and somewhere at that point someone proposes yet another concept for fusion reactor, modern and not dragged down by all that "practical" stuff. Also fusion is not 30 years away, it is likely more, after ITER we'll have DEMO, that would take many years again and only after that we may have first practical reactors running.

boznz3• 9 years ago

Got a friend at ITAR, when I asked him how many people work there, he said about 10%

mozumder2• 9 years ago

So, assuming these work great.. what are the next steps to get fusion energy production?

Are there fundamental limits that prevent these designs from producing a commercially profitable neighborhood reactor for, say $1 million?

Actually, what's the smallest scale possible for these stellerators? Can one be produced table-top sized, to say, power a ship or train or even a car?

So many questions...

vilhelm_s3• 9 years ago

The smallest scale is basically the same as for tokamaks (the advantage is that you can operate a stellarator continuously, while a tokamak is pulsed which may be less convenient for power generation).

The scale is mostly limited by magnetic field strength. With ordinary superconducting magnets they get pretty big (the planned ITER reactor will weigh 5,116 tonnes). Some people say that new high-temperature superconductors will enable stronger magnets and hence smaller reactors (http://news.mit.edu/2017/brandon-sorbom-designing-fusion-fut...).

mozumder2• 9 years ago

looking more into this, it looks like the minimum size limit is the wall that absorbs the free neutrons from the De-Tr reactions. It looks like it'll always be some minimum size due to the energy of the released neutrons.

phkahler• 9 years ago

And just the other day we had a link here where a retired physicist was saying fusion is not likely to work, and if it does it will produce radioactive waste much like fission.

I propose we make a reactor large enough to use gravitational confinement and get the energy out via electromagnetic radiation. We could make it safe by having it operate in vacuum at a safe distance from the earth.

mschuster91• 9 years ago

We could make it safe by having it operate in vacuum at a safe distance from the earth.

And if the thing happens to be rotated even by a milli-arc, for example due to asteroid strike or a simple software error, the receiving area will be fried by microwave. Or hackers might want to introduce a deliberate rotation to use it as an orbital based frying weapon. No thanks, that's way too risky.

bicubic• 9 years ago

He's talking about the sun. We already have a giant fusion reactor that we're not using.

yorwba• 9 years ago

Your parent comment is a joke about the sun as a fusion reactor, in case you couldn't tell.

The actual failure case to be worried about is that the reactor blows up towards the end of its life cycle.

the_rosentotter• 9 years ago

This criticism is usually brought up with this kind of energy transfer (solar beamed down from orbit etc.). But would it not be rather simple to build in some kind of feedback mechanism, where the ground station beams back at the orbital unit as long as it is receiving an incoming beam?

It would act as a switch, where, as soon as the incoming beam stops, the feedback stops and the orbital transmitter would stop too, e.g. if the energy beam went out of position.

nick_2• 9 years ago

What if we made a really really huge one? I'm talking 15 × 10^28 kg worth of hydrogen. At that size it would start and maintain itself. We could place it far enough away that we could harness its output safely here on earth with solar cells!

Will_Parker• 9 years ago

The problem is, something that massive would affect the motion of the Earth itself.

hossbeast• 9 years ago

And we won't have to solve the problem of plasma confinement!

zardo• 9 years ago

It would bombard the Earth with dangerous levels of radiation.

I suppose it could work, we would just need to be careful about atmospheric composition to manage radiative cooling, and block some harmful em frequencies. But I don't foresee any problems with that.

vilhelm_s3• 9 years ago

The radioactive waste is quite unlike fission. Fusion reactors will generate low-level radioactive waste (from parts of the machines being irradiated), but fission generates high-level waste which must be sealed of for thousands of years (from fission products).

pacificmint• 9 years ago

And just the other day we had a link here where a retired physicist was saying fusion is not likely to work, and if it does it will produce radioactive waste much like fission.

He didn't really say it won't work, he mostly just said it wouldn't be as clean as people think it will be. But you are right, it does put news like this one into perspective.

Link to the HN discussion from two days ago: https://news.ycombinator.com/item?id=14202488

devrandomguy• 9 years ago

I support your plan, and present a proposal for phase two: control and efficiency improvements.

The density of the plasma determines the rate of fusion, and is itself determined partly by temperature. If we were to reflect a significant fraction of the emitted radiation back, then the plasma and its surrounding gas should expand, reducing pressure on the fusing core. That should in turn reduce the rate of fusion, lowering fuel consumption.

In theory, we could even diffuse the entire hydrogen supply into a warm cloud that is not dense enough to fuse at all, and store this until we need more heat. As the system cools, it will contract, eventually reigniting itself.

Even if we fail and die, it will still reignite itself, which clearly demonstrates the inherent safety of my proposal.

janemanos• 9 years ago

Back in the sixties some scientist said "Fusion is ready in 20 years", then in the eighties some others said it again, and in the 2000's the next ones... but hey, I don't care how long it will take as long as humankind strives for such stuff I'm fine

twic• 9 years ago

Meanwhile, in boring-shaped fusion reactor news, boringly-named Tokamak Energy switched on their new reactor, the ST40, today:

http://www.world-nuclear-news.org/NN-Tokamak-Energy-turns-on...

They only switched it on for a 'glow discharge test', but hey:

https://www.youtube.com/watch?v=YNrhTYhUXJc

Reactor teardown, sort of:

https://www.youtube.com/watch?v=jRyUWOUk_48

boznz3• 9 years ago

Thanks for the links

Wendelstein 7-X stellarator getting ready for the next phase of operation [pdf]

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