It's a great privilege to be here. I gave a theoretical physics colloquium last week where I presented the theoretical underpinnings of today's talk.
So today that would be very little theory. A more focussed on experimental program.
Let's see. Fusion.
If you want to do fusion, not atmospheric pressure, you need a confinement time of the order of seconds.
The confinement time is the energy of the plasma divided by the heating power that you need to sustain this energy.
So it's the characteristic time scale on which the plasma would cool down if
you turned off the heating needs to be of the order of a couple of seconds.
And to achieve fusion, you need a temperature of ten KB or so, which means the thermal velocity of the ions exceeds 2000 kilometres per second.
So if you don't confine it there, the lifetime of confinement, I would be less than a microsecond.
Therefore you use magnetic fields. As I'm sure you know, the magnetic field charge charges can essentially only move along the field.
Across the field,
they move in tightly wound spirals with a jar radius of the order of equal to the perpendicular velocity component divided by the gyro frequency,
which is charged ten times field of a mass. So the magnetic field confines the particles in two of the three dimensions.
And the obvious way to provide confinement in the third dimension is to is to band the magnetic field into a ring.
But that doesn't quite work. If you do that and you max, the radius of the field capital are be much larger than the gyrus gyro radius obviously.
So you have a small parameter rho store which is in practice of its orbit and to the minus three,
then the magnetic field is necessarily non-uniform, so the particles do not anymore.
Exactly. Follow follow the three lines. Plus a gyration.
In addition, the velocity vector,
the time average velocity vector consists not only of the parallel velocity and only the fields of B or C undetectable on the field.
There is also a slower, slower by a factor rho star drift.
Perpendicular to the field lines and perpendicular to the field strength.
So that's a slow drift. We're just starting to see orders of magnitude slower than done the pilot motion.
So if you just band the field into a ring, it will the particles will slowly drift in the vertical direction.
This gravity is obviously directed inwards in doing so. That's a conserved quantity that we like to say.
It's the magnetic moment of the current loop that the particle makes.
So the confinement time for such a device would then be, roughly speaking, if the length,
the device divided by the drift velocity, which is one factor roast, are smaller than the thermal velocity.
But so you've gained three orders of magnitude in confinement time.
But you need another to order something or to. So the way to get sacked.
So what we need is second order confinement. Second order in row.
The most popular way of achieving that is to bend the magnetic field.
It's so that it spirals around a Troilus surface, such as it's called the Tokamak.
The idea is, was due to Tom and Sakharov in 1951, but others conceived of the idea simultaneously.
So in a tokamak, you drive a current of order of mega amperes,
which then produces a pole oil field that adds to the toroidal field and makes the field spiral around the plasma.
What then happens can be illustrated by my movie here.
So. So this is a movie about a part of an orbit.
So as you see, the particle orbit, the particle state follow the magnetic surface, trace off by the field lines of magnetic fields.
It's colour coded to it's colour coded out.
The the drift is vertical, but, but the particle drifts into the plasma as much as it drifts out of it.
And in this way, you get the second order component. But.
Yeah, but you have to drive this current. And there is no obvious way of driving a car in steady state and a plasma.
And that current can, of course, can be the source of instabilities, of violent instabilities.
The Tokamak was not what was not exclusively invented by Tom and.
Several other people have the same idea because in the 1950s, the fusion program in Russia of the Soviet Union,
in the UK and in the US was classified, which had the consequence.
That work was parallel. Work was paralysed.
The same invention, the same ideas were conceived in many different places.
It also had advantages. If you talk to people from that era, they will tell you you never had to go to conferences, didn't have to publish.
You didn't have to fight for recognition because there was none.
The only thing that mattered was to get the right answer. There was no government, so there was no.
So most of the ideas infused in the world at that time were held by several people independently of each other.
But there was one one exception.
This clever chap, Lyman Spitzer of 36, was head of astrophysics in Princeton,
and so great pioneer of the study of the interstellar medium and also the father of the Hubble Space Telescope.
Later, he had a unique idea that nobody else had the quality to stellarator.
In the stellarator. You also twist the magnetic field lines, but you do it with the help of external coils, not by a plasma current.
So this is the classical stellarator of of Spitzer.
The magnetic field is produced by two kinds.
Of course, you have these toroidal magnetic field coils, just as in the Tokamak, which produces quite a few like this.
And in addition, you have these helical coils which carry current in alternate directions like this that makes
the magnetic field lines twist around the Taurus like this so that they trace out the surface.
And on the surface, the magnetic particles move and just seem to talk a lot.
They are confined because the drifted approximately vertical.
The particle, the particle drifts into the magnetic surface.
That's the surface trace off other fields as much as it drifts out.
So you don't have to drive a current in the place where you have a steady state confinement device for plasma.
But it is a bit counterintuitive that that would be possible at first.
First of all, if we are so the magnetic field is twisted, as you saw in this in this figure, this twisted if I take this magnetic surface.
This purple surface. And unwrap it. So this is the toroidal angle.
That's the long way around the quartz to follow along a following feedline periodically.
So you follow the feedline like this. It comes back here and it gradually winds around the tours.
I can define a rotational transform. Spitzer called it as the winding number of those few nights.
But it is counterintuitive that that should be possible for.
Let's consider this this picture again.
Let us. Integrate the magnetic field around such a contour since there is no current in the plasma.
The answer is zero. Suggesting that there is no average magnetic field in this direction.
And yet. Spitzer realised the magnetic field lines do spiral around the Taurus.
So what is the average feel then? Well, it turns out that there are two kinds of averages.
This average is different from the eye out on the winding number average.
If you write it in a clever set of coordinates,
you find that one is the average of the covariant pull of vital component and the other is the average of the contraband component.
Another way of seeing this is to go back to the Tokamak.
It's a field in the Tokamak. And let's define an integration contour that starts on a few lines and goes
perpendicular to two of the few lines until you come back to the original field,
and then you go back to where you started along the V line.
So it runs perpendicular to be up to here and then it goes along. B. Now again, let's calculate.
This can be integral or be. It must be clear to me, you know how steam closed current.
But the first bit of the control, the one that goes from here to the here, which is perpendicular to be, makes no contribution.
So you realise that the lengths that you have to go along the field is proportional to the current, then to the current.
So in a stellarator this means that the perpendicular is closed on themselves.
There is no such aspect. So purely a geometric way of formal,
formal acting spritzers inside is that if you draw the field lines on the magnetic surface and the perpendicular ice,
then the field lines spiral around the Taurus. If you follow a few line here, you'll notice that it's started by as well as the cross.
But the perpendicular do not spiral. They're closed on themselves.
And this is the slightly counterintuitive fact that this should be possible.
It is an early realisation of what later became a geometric phases in physics.
The Berry Face is the most famous example of it, but there are others that are even ones.
But this is one one of the first. It's not the first realisation of it, but it's it's one of the first ones.
The same thing happens,
I believe if you send polarised light down a and an optical fibre which you twist in space when it and if you make it come back to itself,
the polarisation has shifted by an angle so you can prove mathematically that are exactly three ways of twisting magnetic fields.
This follows just for maximum sequential.
You can you can calculate this winding a number iota up close to the innermost feeling called the magnetic axis as an integral.
And you can show that in the right ones around the Taurus, and you'll find that this one number is the sum of three terms.
The first one is the current. That's what's used in the Tokamak to twist lines.
But then there are two other terms. So just the current density here. First you have Tao.
Tao is the course of this innermost magnetic field line.
So the torsion is a concept from differential geometry that characterises how much a curve deviates from lying in a plane.
So capped by here is the curvature vector, which points inwards.
If you take the curvature vector and cross it with the with the tangent vector, you get a vector that's perpendicular to both.
And if, um. Um.
Well, if you do this, you get that to get the torso. The third way of twisting a funny line is the following.
If you cut the magnetic surface like this, it's necessarily necessarily elliptical in the centre with a major axis and a minor axis.
If you left a cross section of that ellipse, rotate as you go around the Taurus.
Then so do you. Here is the angle, the tilting angle of the ellipse.
If that, um. If if there's ellipticity on that tilting angle, that tilt moves systematically in one direction.
It drags the fields field with it. You can understand this by thinking of water.
That's a perfect mathematical analogy between three lines and streamlines, you know, in in an in an ideal fluid.
Suppose you build a pipe with elliptical cross-section and you you make that cross-section rotate along the pipe, then the then the streamlines.
The water will also rotate. Although even if there's no vorticity in the water.
Miles can rotate without vorticity. Magnetic fields can rotate without current.
It's a perfect mathematical analogy. So knowing this now that it's how to twist magnetic fields, people went off and built stellar reactors.
Now you can do anything your heart desires. You can think of all sorts of weird, stellar ideas.
This is the largest one in the world. Prior to our experiment. It's called a large helical device.
It's in Japan. What you see is a magnetic surface here with the field strength colour coded.
This is the set of coins that produces it. So you have.
So this is not a classical stellarator. It's not if debate with Spitzer's idea.
There's no there are no Royal Enfield coins.
Instead, there are these pull oil field calls, this circle of things, and there are two helical coils carrying current in the same direction.
That also works has the largest stellarator in Europe.
Prior experiment. It's called T.J. two. It's in Madrid.
This is the. A magnetic surface with the strength colour coded again.
This is the strange set of coins that produces it.
It's rather artistic. So this is from the country of Salvador Dali, of course.
So this film, this it's created by by a red and blue card in the cemetery which are tightly wound around each other and by this circular green course.
In addition to the large football field courts. So you can go.
So there are wonderful, stellar writers around the world,
but they all suffer from a basic problem that has to do with particle or particle orbits that are different from the ones I showed you earlier.
Remember, the magnetic moment is constant and these perps squared over to be the perp is
the component of the velocity vector that's perpendicular demographically.
The energy source. A constant, of course. So.
So these two conserved quantities implies that B is equal to each of the new.
Implying that a a particle can never penetrate into a region with a magnetic field strength larger than that of AMU.
And this is, of course, the basis for trapping of charged particles in the magnetosphere, the Van Allen belts.
Particles with large enough, you can't go into regions of large field strength.
If we look at the particle orbits in a tokamak,
this means that there are orbits that do this that are reflected by the large magnetic field strength that that prevents on the inboard side,
the Taurus, these particles, they stay on them on the magnetic surface that we see here, so that they are, well, confined.
And bounce back and forth. But when confined by the magnetic field still, but in a stellarator, it's just different.
So first of all, the the mathematical reason for this is that there is the third constant of the motion in addition to EMU due to the symmetry.
So there are three constants of the motion and therefore the Hamiltonian describing this part of the most integral in a stellarator.
It's different. Let's look at the particle of motion on a magnetic surface again in the large helical device in Japan.
So this is the same orbit as I showed you before, and it does exactly what Spitzer realised it would do.
But then there is this second class of orbits that we didn't think of as prime time to realise this.
Ten, 15 years after that, the trapped particle orbits.
They bounce back and forth along the field and they drift slowly across it.
The drift is no longer compensated by the helical emotion and the particles drift out.
So the trapped orbits would drift out of a generic stellarator and therefore the confinement is pretty bad.
In practice, particles collide before they're drifted out.
So those are shorter timescales after the collision frequency. So let's estimate the diffusion coefficient.
So what will happen is that the particle, the particle follows a magnetic field line where the field strength bar is roughly like this.
These little magnetic wells, when it is trapped in one of those swells, it drifts vertically.
But then it collides with another particle and it's scattered into another type of orbit.
Circulating orbit, perhaps.
So then it's welcome, fine for a while until it collides again and it becomes trapped somewhere else, and then it perhaps drifts into the surface.
And in this way the it undergoes a random walk, sometimes drifting inward, sometimes drifting outwards.
The step length of that random walk is equal to the drift velocity times.
The step time and the step time is sort of the collision frequency, the inverse collision frequency.
So if you add the number of participating particles of this, the number of particles trapped in these events.
So if you estimate the diffusion coefficient by multiplying the number of participating particles,
when this fraction of such particles divided with the delta all squared over delta t,
we get a diffusion coefficient that scales with a square of the drift velocity and inversely with the collision frequency.
The collision frequency. Gives us energy to the minus three halves at high energies.
So if he works like this, the drift velocity is proportional to the temperature or to the energy of a particle.
So the this diffusion coefficient is proportional to temperature to the seven halves.
So in the hot plasma, it causes enormous loss.
So in practice, in an experiment, it means you can heat the plasma up to a certain temperature and then you just hit a brick wall.
You just can't get it any hotter. And this has been plaguing all Stellarator experiments for decades.
And these losses tend to predominate over turbulent losses, which are that in addition.
You can do a proper transport theory by solving a kinetic equation for these particles, but I won't go into that.
So our new experiment balanced on seven X in Germany.
It's one of the largest physics experiments that have ever been constructed in Germany, and it aims to solve this problem.
It is remarkably and perhaps uniquely theory driven.
This is what has been done. An attempt has been to optimise the magnetic field.
The magnetic field near Taurus is defined uniquely by the surface of the of the boundary.
If you can close a magnetic field in a trial, in a trial region with the boundary of given shape, you have uniquely defined what the few lines are.
So you can you can play with that boundary, see what you feel you get, and try to reduce the number of particles that drift out of the device.
Until you are and when you are happy with that feed, you can on a second surface find the current distribution that would produce that feed.
There's always such a current distribution that you can be scrutinised, that kind of distribution to find magnetic field coins that will do it.
This is the result for Palestine seven x. So the result that is the shape of a plasma with feedbacks that you are happy with.
And magnetic field coils that produce this shape.
This only became possible with the advent of super quantum computers in the late eighties.
So in London's time, seven x an attempt has been made to optimise the field for small transport, but not only for that.
There is also a list of other criteria. One of the once good nested magnetic surfaces.
How to show you a picture of that in a minute. Good finite pressure equilibrium.
The plasma influences equally. It changes the occurrence in the plasma that affects the magnetic field.
One wants to minimise the back reaction of the plasma on the field.
One wants to optimise stability and one wants to end up with coins that are buildable that are not too complicated.
Their shape. You might think these are very complicated, but they are very simple compared with some other types of satellite records.
And they are modular, unlike those of the classical stellarator.
They don't go all the way around the Taurus. So they are much smaller.
They can be put on the back of a lorry. They don't have to be wound on the side.
To try to convince you that this works. Let me show you particle orbits on the magnetic surface in this device.
So here again, it's a little orbit that circulates around the tourists.
Again, it's very well confined. It stays on the surface.
It started to pop. But let's now zoom in on a trapped particle orbit in orbit that just gets reflected by the stars.
It doesn't drift out to the device. It drifts around and stays on average on the magnetic surface where it started.
And in this way. So then that happens for the great majority of all orbits because make it happen for for all orbits.
One can show that mathematically you can make it happen for the great majority of them.
And in this way one can reduce the diffusion. Can efficient. Can you reduce it enough?
Well, there is a technique that will always be a temperature above which those few unconfined orbits will dominate the transport.
You can calculate the the temperature above which that diffusion coefficient gets larger than a previous time values like one square metre per second.
That's typically what turbulence does for the plasma anyway.
And you find the prediction is that you one should get up to five KB or so depending on the density.
I remind you that this diffusion coefficient we found was inversely proportional to the density.
It's all the same proportion to the square of the magnetic field strength and the radius of the device.
So this transporter is small enough that if one scales it up to the size which a fusion power plant would have to have,
the confinement is good enough.
The device is not had not only been optimised for good confinement magnetic field on some trajectories without much coding system,
they can be chaotic. Of the few lines that correspond to particle orbits with particles of zero mass, so they are therefore Hamiltonian.
And as Hamiltonian systems they can exhibit chaos that can.
The defeat came from Ireland. So that that happens if you don't watch out.
So this is this is a puncture plot to carry a plot of the field in a cross-section of abandoned flights of the next where we have optimised the field.
You see chaotic felines in the edge here and you see a chain of magnetic islands.
So. So here the particles can move freely from the inside of the island to the outside of the island, along the beach and around the course.
So the red region here doesn't provide any confinement.
So the field has been carefully designed to avoid such things happening.
And this is the result. This is the result of a heroic German engineering effort that's been made.
But. To construct this device.
It's. The plasma vault. So this is a normal size person.
It has a plasma volume of 30 cubic metres. It's a major radius of five and a half metres metres.
A minor radius ten times smaller. A magnetic field of three Tesla.
So the field energy is nearly gigajoule. This field is created by these superconducting coils, weird shapes.
There are 70 of them. 50 non-playing, their coils and 20 additional play.
They're quite strong. Experimental flexibility to the device. They are superconducting so they can produce plasma for up to 30 minutes.
It's just a cooling plasma that that limits the life.
The cell sets this this limit. The plasma heated by various heating systems,
most mostly microwaves of two different frequencies resonating with this electrons and the subsequent electrical motion.
And this is what it looks from the inside. I'll try to explain. So explain the device.
So first there is the plasma surface, right?
That's the shape. Powered by optimisation.
So this is where the theoreticians job is done. So I feel qualified to talk about everything that comes now.
So in well-defined places, the field lines hit the wall.
Somewhere, the energy must come out of the of the device that happens at these so-called diverter targets.
They're actively cooled to withstand heat fluxes up to ten megawatts per square metre.
That's a fifth of the energy flux on the surface of the sun, but it can be done by pumping a lot of water, essentially.
So this is the way it happens.
If you take a cross-sectional magnetic field and a puncture plot, the magnetic islands at the edge, which have been designed to be there,
and they are and they are cut by this diabolical place, by these target plates for the plasma when it leaks out to the field.
Here it comes on to on to a few lines corresponding to these islands.
And they hit these flights, which are designed to withstand.
So yeah, I'm going to think I should add that that's a category.
Then that's the vacuum vessel, of course. The vacuum vessel is a piece of our of welding art, one can say.
Fantastic feat of engineering. I think outside the vacuum vessel cover is odd because this is the most expensive chip of the device, €80 million.
I think they cost the 70 of these magnetic field coils.
Niobium, titanium. Which was just about fit around the vacuum.
So they had to be threaded upon it carefully.
Huge forces on on these coins.
Hot water, 100 tons. So they are own bolted into this central support structure.
Steve. Then is a cry a start to keep to the field.
The coin's cool, of course. So this is another.
Piece of engineering that almost more holes in this stuff than there is metal.
It's a very wobbly thing. Is there 254 ports?
It looks like that.
So which then to go to both the outer vessel on the inner vessel of three metres long and this is what the device looked like a few years ago.
So you see here that the inner.
Vacuum vessel, the coils, lots of cooling pipes and the aftermath after cries that you don't miss in a misguided effort to save money.
The crisis that was made as small as possible.
Which seemed like a good idea at the time, but it left almost no room for for all the pipes that had to go.
So then then a team of 20 people had to use cat software to root these pipes so that
they don't collide with with each other when the when the device is cooled down.
This is slightly like the one that Chrysler has been added.
There's certainly some rather difficult working conditions that you can set a war plan that's obviously protecting what you see.
Some of the cooling pipes here. Lots of scaffolding, of course.
The device was started to be commissioned in the middle of 2014.
I'll show you a little movie of the assembly.
Let's see. The device is pentagonal.
It consists of of of five modules.
This is the first half module is in the vacuum vessel and the and the cords being threaded upon it one by one by this special machinery.
One after another. So there are seven coins in one half module.
Now the first half module is ready. Lifted it somewhere else, bolted into another half module.
And then the cooling pipes are added. I'll do the entire module as it is being lifted into the Taurus.
Who comes into the vacuum vessel? The lower part of the vacuum vessel here.
The top pockets are dead. It's put into position.
This is from above. You see a lot of activity in module after module coming into place this year as another bit of the year of the Christ.
And that's the last module. Lots of scaffolding, lots of pipes, lots of ports being run to the sea from above again.
And you see how many? So that that that took ten years.
That was ten years. And one minute if this.
So then about a year ago, the most dramatic moment I think, of the commissioning went away when they started cooling down the Croisette.
So it's 530 tons of mass to that is to be called the cryogenic temperatures.
It's a11 and a half megawatt helium cooling, cooling, cooling plant.
And then you hope that there are no cold leaks. But afterward, there are 5000 welds in the cryo stuff and each of them has to be tight.
And co leaks are the other worst nightmare of leaks that only appear when the
device is cold and disappear when you heat up the device to go look for them.
But it all went very smoothly in one month's time. It cooled down the device.
Everybody was was terribly nervous.
And this was the final plunge the following week, down to four Kelvin, ten to the minus seven millibars.
Ice pressure. No leaks. There were leaks afterwards in the quiet start.
In the in the there there were there were leaks in, in less critical components like the pumping ducts.
Um, that, that we knew could be repaired afterwards.
So that, so that, that, that only took a few weeks.
And then in the summer, filling measurements could be made. So these magnetic everything has been mounted with mm.
Precision. To make sure the magnetic field is is as close as possibly possible to the design value and it can be measured.
This shows this picture shows the principle of it. So here are a few lines.
The coin points, obviously, if you insert a cathode into a low pressure, but not desperately low pressure vessel.
So you have to have some gas in it. You don't need much more than that to keep inside a cathode.
It will emit an electron beam along the feet, which you can detect.
For instance, if that's enough gas, that gas will light up along the field line where the electrons travel.
Or you can put a fluorescent rod intersecting the beam and make your point.
Carry a plot of the field. Then you can swing the electron emitter and the fluorescent ROC and see what happens.
So this is the device we have these manipulators.
So you're inside a cathode with one of them, a fluorescent rod or not with the other one.
And you see what the electron beam does. And you get pictures like this.
So this is a picture of an electron beam propagating in the in the air,
essentially moist air at low pressure on the toys that goes up around the mile 25 times around the Taurus.
You can actually see the magnetic field. We have funded projects.
So it looks like the fee lines are noted.
So some of these pictures look really strange. You can compare this with with your predictions, of course.
Or you can do it. You can have this fluorescent rod.
That lights up when when the electron beam intersects it.
And you can take pictures of these feedlots and the price and load with long exposure targets to get pictures like this.
So here you see magnetic felines going around the tourists and an intentionally created magnetic island.
Five over six Ireland. So this is when the when the winding number is exactly equal to five over six.
This provides an extremely. Accurate measurement of that magnetic field line component down to one part, ten to the minus five.
To my knowledge, it's the first time that the topology with magnetic field has been measured that accurately
the topology of a magnetic field that's 30 metres across measure to this position.
And you can of this is this is this is a pop culture plot done with experiment.
And you can compare that with your calculations.
The feed the build machine has to be carefully been scanned, put in to the computer so it can calculate what the field should look like.
And it. And it agrees. Exactly.
Then you can crank up the debt. You can increase the current. For the coins, the coins are subject to huge forces.
They don't. And they try to be more become more planar as you increase the the current the state of lowest energy is a circle is a plain circle.
That's what they want to be. And you do that when they become more plane, that reduces the widening number, the rotation and transform the field.
And these islands move the surface on which the widening number is equal to five six moves outward when you do that.
So this here you see this chain of magnetic islands with different field strengths.
You see if moving out from the red one to the green one as you increase the field strength.
And you can compare that with the calculated elastic, the formation of the cards, and see that they deform as you expect them,
that they are properly bolted onto the central support structure and that also increase.
So that's quite an element model of the entire US built machine where this can be done.
And then we finally, after waiting for six months or more, most got permission from the radiation protection authorities to have first class mass.
So on the 9th of December. We had invited the press to come and look at our first plasma.
We had made some the night before, actually, and there were 11 camera teams in the control room.
You don't want to. So this is the first pass by a temperature of a million degrees, 180 lifetime for 20 milliseconds.
So the there are lots of impurities, lots of impurities in the walls that you need to get rid of by successive plasma
so that those impurities flow into the plasma and to extinguish it after a while.
This is a movie. It's very faint. It's from last week of a more recent plasma.
You see the plasma rotating like this,
which is like from from hydrogen and from from from impurities that move inwards and eventually extinguish the plasma.
I'm. My Final View graph are just the parameters achieved to date as of yesterday or so.
So. The heating power is up to five megawatts.
It will be much higher in the future. Plus, my lifetime output of 15 times longer than the first estimate.
Estimation gets cleaner and cleaner. And extreme temperatures up to eight kilowatts.
I am temperature's about a 10th that so the all the heating is in the electron
channel and the items get heated by the electrons because of the large mass ratio.
The temperature equilibration time between the electrons on the ions is longer than the discharge time.
So for densities up to ten to the 20.
So this is an example of a series of temperature and density profiles across the plasma.
So you see in the beginning. So you have temperature locked out and then the temperature rises, the density first goes up and then it goes down.
So the best for after 200 milliseconds or so is the.
It's this light blue one where you have a whites ten to the 20 metres per square and particles per cubic metre.
That's just what you want for fusion. You want it to be about three times hotter than that we have here.
So you see the temperature of that being about four kilowatts.
And for those of you a plasma physicist, we may even see it.
To find that pressure with the plasma making the field expand its potential problem of shift because this this.
China is recording a high temperature on the central line.
So to summarise then, the Stellarator concept will now be put to a definitive test and the voltage line seven x.
The device has been completely decommissioned and taken into operation.
Last month we will have a first hydrogen plasmas.
Next week we invited a physical chemist to push the button. We hope that this will verify that the fusion great plasma confinement device can be
provided by a STELLARATOR And it will be very interesting to compare confinement,
turbulence and general performance to that of other fusion devices.
Thank you.