Wendelstein 7-X achieves world record for fusion product

June 25, 2018 by Isabella Milch, Max-Planck-Institut für Plasmaphysik (IPP)
View inside the plasma vessel with graphite tile cladding. Credit: IPP, Jan Michael Hosan

In the past experimentation round Wendelstein 7-X achieved higher temperatures and densities of the plasma, longer pulses and the stellarator world record for the fusion product. Moreover, first confirmation for the optimisation concept on which Wendelstein 7-X is based, was obtained. Wendelstein 7-X at Max Planck Institute for Plasma Physics (IPP) in Greifswald, the world's largest fusion device of the stellarator type, is investigating the suitability of this concept for application in power plants.

Unlike in the first experimentation phase 2015/16 the plasma vessel of Wendelstein 7-X has been fitted with interior cladding since September last year. The vessel walls are now covered with graphite tiles, thus allowing higher temperatures and longer plasma discharges. With the so-called divertor it is also possible to control the purity and density of the plasma: The divertor tiles follow the twisted contour of the plasma edge in the form of ten broad strips along the wall of the plasma vessel. In this way, they protect particularly the wall areas onto which the particles escaping from the edge of the plasma ring are made to impinge. Along with impurities, the impinging particles are here neutralised and pumped off.

"First experience with the new wall elements are highly positive", states Professor Dr. Thomas Sunn Pedersen. While by the end of the first campaign pulse lengths of six seconds were being attained, plasmas lasting up to 26 seconds are now being produced. A heating energy of up to 75 megajoules could be fed into the plasma, this being 18 times as much as in the first operation phase without divertor. The heating power could also be increased, this being a prerequisite to high plasma density.

In this way a record value for the fusion product was attained. This product of the ion temperature, plasma density and energy confinement time specifies how close one is getting to the reactor values needed to ignite a plasma. At an ion temperature of about 40 million degrees and a density of 0.8 x 1020 particles per cubic metre Wendelstein 7-X has attained a fusion product affording a good 6 x 1026 degrees x second per cubic metre, the world's stellarator record. "This is an excellent value for a device of this size, achieved, moreover, under realistic conditions, i.e. at a high temperature of the plasma ions", says Professor Sunn Pedersen. The energy confinement time attained, this being a measure of the quality of the thermal insulation of the magnetically confined plasma, indicates with an imposing 200 milliseconds that the numerical optimisation on which Wendelstein 7-X is based might work: "This makes us optimistic for our further work."

The fact that optimisation is taking effect not only in respect of the thermal insulation is testified to by the now completed evaluation of experimental data from the first experimentation phase from December 2015 to March 2016, which has just been reported in Nature Physics. This shows that also the bootstrap current behaves as expected. This electric current is induced by pressure differences in the plasma and could distort the tailored magnetic field. Particles from the plasma edge would then no longer impinge on the right area of the divertor. The bootstrap current in stellarators should therefore be kept as low as possible. Analysis has now confirmed that this has actually been accomplished in the optimised field geometry. "Thus, already during the first experimentation phase important aspects of the optimisation could be verified", states first author Dr. Andreas Dinklage. "More exact and systematic evaluation will ensue in further experiments at much higher heating power and higher plasma pressure."

Wendelstein 7-X attained the Stellarator world record for the fusion product. This product of the ion temperature, plasma density and energy confinement time specifies how close one is getting to the power plant values needed to ignite a plasma. Credit: Graphic: IPP

Since the end of 2017 Wendelstein 7-X has undergone further extensions: These include new measuring equipment and heating systems. Plasma experiments are to be resumed in July. Major extension is planned as of autumn 2018: The present graphite tiles of the divertor are to be replaced by carbon-reinforced carbon components that are additionally water-cooled. They are to make discharges lasting up to 30 minutes possible, during which it can be checked whether Wendelstein 7-X permanently meets its optimisation objectives as well.

Background

The objective of fusion research is to develop a power plant favourable to the climate and environment. Like the sun, it is to derive energy from fusion of atomic nuclei. Because the fusion fire needs temperatures exceeding 100 million degrees to ignite, the fuel, viz. a low-density hydrogen , ought not to come into contact with cold vessel walls. Confined by magnetic fields, it is suspended inside a vacuum chamber with almost no contact.

The magnetic cage of Wendelstein 7-X is produced by a ring of 50 superconducting magnet coils about 3.5 metres high. Their special shapes are the result of elaborate optimisation calculations. Although Wendelstein 7-X will not produce energy, it hopes to prove that stellarators are suitable for application in power plants.

Its aim is to achieve for the first time in a stellarator the quality of confinement afforded by competing devices of the tokamak type. In particular, the device is to demonstrate the essential advantage of stellarators, viz. their capability to operate in continuous mode.

Explore further: Wendelstein 7-X: Second round of experimentation started

More information: et al, Magnetic configuration effects on the Wendelstein 7-X stellarator, Nature Physics (2018). DOI: 10.1038/s41567-018-0141-9

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29 comments

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Hyperfuzzy
1 / 5 (13) Jun 25, 2018
What is being applied cannot ever create fusion sustain-ably; even if successful, fusion releases no energy; the energy is due to the ripples in the field and the motion of charge; so, ... isn't that going at energy backward? oh you think you can use the quite for ... maybe redirect the center? sorry, e=mc^2, nonsense! it'll be find, we got some cool tools, now that we know what we're working with
johnhew
1.3 / 5 (12) Jun 25, 2018
'The objective of fusion research is to develop a power plant favourable to the climate and environment.'

Nope.

Mark Thomas
5 / 5 (18) Jun 25, 2018
Hyperfuzzy and johnhew, a.k.a. clueless. I got a particular laugh out of, "fusion releases no energy." I suppose the sun and those hydrogen bombs don't work either. Both require fusion to produce energy.
Hyperfuzzy
1 / 5 (8) Jun 25, 2018
Hyperfuzzy and johnhew, a.k.a. clueless. I got a particular laugh out of, "fusion releases no energy." I suppose the sun and those hydrogen bombs don't work either. Both require fusion to produce energy.

so, show me.
Hyperfuzzy
1 / 5 (7) Jun 25, 2018
what does the energy look like spectrum, ... e=mc^2; get help
ZoeBell
Jun 26, 2018
This comment has been removed by a moderator.
ZoeBell
Jun 26, 2018
This comment has been removed by a moderator.
TheGhostofOtto1923
1.8 / 5 (5) Jun 26, 2018
They better hurry up and finish ITER before its obsolete. But if this has been obvious to its proponents, maybe it's another indication that it was always meant to be a storage facility rather than a research facility.

After all, its only a few hundred miles away from CERN, well within reach of a next-gen ring capable of producing antimatter by the spoonful.
torbjorn_b_g_larsson
4.3 / 5 (11) Jun 26, 2018
Promising indeed! If they can increase that triple product by going from 0.2 s to 30 minutes plasma - or a factor ~ 10,000 - they will beat the best tokamak (W7X 5 x 10^30 vs JT-60 2 x 10^28 Ksm^-3).

show me
See Wikipedia "fusion". Better yet, attend remedial school.

@ZoeBell: No. Temperature alone is not the problem, Already JET had Q ~ 1 (break even], ITER is designed for Q ~ 10. "The ITER thermonuclear fusion reactor has been designed to produce a fusion plasma equivalent to 500 megawatts of thermal output power for around twenty minutes while 50 megawatts of thermal power are injected into the tokamak," [https://en.wikipe...iki/ITER ]. But it is not going to produce electricity, which is the ultimate goal (" a power plant favourable to the climate and environment").

Also, cold fusion has no results, as expected from nuclear physics.
rrwillsj
1.7 / 5 (6) Jun 26, 2018
cold fusion yesterday.
cold fusion tomorrow.
but never cold fusion today....

What I take away from this article is... That this research is intended to improving the safety factors for a hot fusion reactor. Attempting to protect the containers from deterioration due to the expected extreme energies released.

Finally, someone actually trying to prevent a nuclear disaster. Instead of just sending out glowing publicity about how exceptional the nuclear industries administrators are.
And we damn well better keep paying their salaries. Or else!

Or they are going to walk off in a huff and a snit. Abandoning the whole mess behind for the rest of us to deal with!
ZoeBell
Jun 26, 2018
This comment has been removed by a moderator.
Eikka
5 / 5 (4) Jun 26, 2018
this research is intended to improving the safety factors for a hot fusion reactor.


The point of the 7-X is improving plasma stability to maintain the reaction indefinitely. Ordinary tokamaks run into instabilities which quench the plasma and require re-starting the reactor every couple minutes, which consumes more energy than the reactor manages to produce.

Ordinary tokamaks need to be implausibly huge to get them to run for a useful amount of time - the Russian inventor who came up with the name actually calculated that the donut needs to be kilometers in size to be "naturally" stable.

It's got nothing to do with nuclear safety.
Hyperfuzzy
1 / 5 (6) Jun 26, 2018
we Believe dumb things without logic! Like E=MC^2 = nonsense; the energy is in the vast activity trying to make this true completely without logic statement true. juz a bunch of parrots, they seem to be very fond of stoopid.
ukezi
5 / 5 (1) Jun 26, 2018
@Eikka
Wendelstein is tiny compared to JET, JET has a plasma volume of 200m³, Wendelstein has only 30m³ also at this point Wendelstein doesn't try to do fusion and only does plasma physics with a hydrogen deuterium plasma for radiation protection purposes. You can't upgrade stuff well if it's all radioactive.
Hyperfuzzy
1 / 5 (4) Jun 26, 2018
@Eikka
Wendelstein is tiny compared to JET, JET has a plasma volume of 200m³, Wendelstein has only 30m³ also at this point Wendelstein doesn't try to do fusion and only does plasma physics with a hydrogen deuterium plasma for radiation protection purposes. You can't upgrade stuff well if it's all radioactive.

1st. process not fantasy
Eikka
5 / 5 (4) Jun 26, 2018
Wendelstein is tiny compared to JET


That's the point.

The problem with ordinary tokamaks is that when the plasma goes around the donut, it goes a different distance along the inner and outer diameters, and the magnetic field density is different so the plasma drifts off. It's been said a tokamak is like trying to contain a donut made out of jello by strapping it with rubber bands - you have to hold it very very gingerly or it just falls apart.

The Stellarator twists the plasma as it goes around the donut, which cancels the drift and allows higher plasma density, so the whole thing can be built smaller.
Hyperfuzzy
1 / 5 (2) Jun 26, 2018
Wendelstein is tiny compared to JET


That's the point.

The problem with ordinary tokamaks is that when the plasma goes around the donut, it goes a different distance along the inner and outer diameters, and the magnetic field density is different so the plasma drifts off. It's been said a tokamak is like trying to contain a donut made out of jello by strapping it with rubber bands - you have to hold it very very gingerly or it just falls apart.

The Stellarator twists the plasma as it goes around the donut, which cancels the drift and allows higher plasma density, so the whole thing can be built smaller.

don't laugh
Anuninus
not rated yet Jun 26, 2018
Why people are talking about temperature? We can achieve temperatures even higher than the core of the Sun. The biggest problem with fusion is to sustain the reaction. Perhaps there is another variable that should be taken into consideration?
ZoeBell
Jun 26, 2018
This comment has been removed by a moderator.
Eikka
5 / 5 (4) Jun 27, 2018
yet the fusion reaction runs there with speed few watts per cubic meter ( 6.9 W/m^3 i.e. like heat intensity of compost pile).


Note that the sun is fusing almost exclusively plain hydrogen (proton-proton fusion), whereas fusion reactors use heavy hydrogen (deuterium, tritium) which area easier to fuse.

Da Schneib
5 / 5 (2) Jun 27, 2018
@Eikka and I often disagree, but on this one we're in full agreement. The entire point of the stellarator configuration is to conform to the dynamics of plasma. It makes it easier to magnetically contain it because it's not fighting the containment.
Eikka
5 / 5 (4) Jun 27, 2018
Besides, fusion power is a product of both plasma density and its temperature, which is why the fusion reactors actually run hotter than the core of the sun.

Ideal gas law you know. Temperature is the same as pressure when it comes to the probability of collision in a gas of molecules.
TheGhostofOtto1923
5 / 5 (2) Jun 27, 2018
fusion power is a product of both plasma density and its temperature
The Lawson criterion - "triple product" of density, temperature, and confinement time, nTτE - is the standard determinent of fusion 'power'.
Eikka
not rated yet Jun 27, 2018
Besides, the average power density of the sun's core isn't 6.9 W but about 260 W

The sun is actually quite a crappy fusion reactor, because the high density soup of plasma at the core conducts the heat away. Running a fusion reactor by crushing stuff together by gravity as it turns out is far from "ideal". It's easier to get ions to very high temperatures in near vacuum. The question is just about containment.

Fusion is actually relatively easy to achieve with a particle accelerator. A Farnsworth-Hirsch fusor needs only about 15 keV to initiate D-D fusion - a child can build one on the tabletop from a neon transformer and other bits and bobs - but the device itself is highly inefficient due to various reasons and can't achieve break-even.

Hyperfuzzy
3 / 5 (2) Jun 27, 2018
Does anybody here know what energy is?
Osiris1
not rated yet Jun 27, 2018
Sorry, but I would really love to see a fusion generator/magnetoelectrohydrodynamic rocket. Take us to the stars it would, and if big enough could drive a warp generator.
sascoflame
not rated yet Jul 02, 2018
Max Planck Institutes seem to get everything they do right.
antialias_physorg
not rated yet Jul 02, 2018
Max Planck Institutes seem to get everything they do right.

At least the stuff they publish ;)

Though, yeah...they are usually pretty good at what they do.
Hyperfuzzy
not rated yet Jul 04, 2018
Max Planck Institutes seem to get everything they do right.

At least the stuff they publish ;)

Though, yeah...they are usually pretty good at what they do.

But Planck did not know what it was he seeketh, no dis', hindsight!

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