Fusion – Ria Lina, Yasmin Andrew and Howard Wilson

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Hello, I'm Brian Cox. I'm Robin Inks, and this is the Infinite Mancish Cage because today we are in Manchester, which is home, in case you don't know, to some of Brian's favorite childhood bus routes.

Those of you who are regular listeners will know before Brian started getting involved with the stars, he was an avid bus spotter. So, what was your favorite?

You're coming in from Oldham, you've got you've put on all your kind of Robert Smith makeup. Perhaps you're going to Gilly's Rock World.

No, Cloud 9. You're not going to Gilly's Rock World.
Cloud 9 in Berlin it was. And it was the 24 bus by the way that went from Chatterton to Manchester, Piccadilly bus station.

What was it about the 24 that really impressed you? It was the bus that went where I wanted to go from.

Today we're asking nuclear fusion when will it be ready? What makes fusion reactors so hard to build when the sun built itself using only gravity? What are are the breakthroughs we're waiting for?

To help us understand the challenges, the innovations, and the future benefits, we are joined by a fusion scientist with an interest in magnetic confinement, a plasma scientist with an interest in spherical tokamak innovations, and a forensic comedian with an interest in viruses and puns.

And they are. My name is Howard Wilson.
I'm the Director for Science and Technology at UK Industrial Fusion Solutions, which is the organisation that's leading the delivery of

STEPs. STEP is the spherical tokamak for energy production, the UK's first fusion pilot plant here on Earth.

I started in Fusion in 1988, and about six months later, there was the announcement of Cold Fusion. We were asked to give an example of

what we think is a crazy energy source, and I will put Cold Fusion in that box. I'm Yasmin Andrew, and I'm a senior teaching fellow at Imperial College London.

I'm a plasma physicist, and I've been working on magnetic confinement fusion for the last 30 years. Do you want the unusual energy source?

Yes, so this is more strange: was this idea of sending a satellite into space while just above Earth and then making use of the solar wind to drive an electric current and then use then beaming that electric current back down to Earth using a laser.

I don't know where they've gone with that. It's over-complicated, isn't it? It's very complicated, and the optics aren't up to it, apparently.

Is it because when you're looking for finance, if you just say and lasers, people go, oh, that sounds brilliant, yeah. They don't hear the rest, do they? They just hear lasers.

But more plausible than cold fusion. Does that mean I'm winning?

Hi, I'm Mia Lina. I'm a comedian and lapsed forensic scientist and virologist.

And I don't understand why we're even investigating fusion when we already have the technology of hamster wheels that we could do at a size large enough to put all the children with ADHD in them.

And this is our panel.

Actually. Howard, I need to ask you first, when you said to your friends I've just joined steps, in many ways were they then disappointed?

There is a Howard in a boy band, I believe. Yeah, there is.
It wasn't me. You're a fantastic conflagration of montage of boy bands with your steps element and also your take that element.

I thought that was like the 12-step program.

And I was waiting for him to come and like apologise to all of us.

Howard, you mentioned cold fusion there.

The first question was to describe what fusion is, but maybe in that context, because many people might not know why cold fusion is, your choice is a ridiculous energy source.

Should we start with what fusion is? Yeah, and then why do you realise how ridiculous cold fusion is? So fusion is the process that powers the stars, powers our own star, the sun.

You take the light elements, hydrogen, really the light end of the periodic table, or isotopes of of hydrogen, heavy forms of hydrogen.

And if you push them together close enough such that the nuclei that sit in the middle of the atom get those nuclei to touch each other, there is a significant probability that they will fuse to create something heavier, a heavier element, and they release energy at the same time.

And that's the energy that powers the Sun.

It's actually the process whereby all of you are made, because you start off with the light elements from the Big Bang, and it's through the fusion process that the heavier elements that we're made up from come from.

So it's absolutely fundamental in terms of energy, because it's where the sun gets its energy from, and it's fundamental in terms of our being, where our materials come from.

So, how do you get two nuclei close enough together? That doesn't sound like a hard thing. Well, it is, because they're both positively charged.
They don't want to come close together.

And so, you've got to get enough energy in them to overcome what we call the Coulomb propulsion that like charges repel.

That takes a lot of energy, and we tend to do it just by heating it to ridiculous temperatures. So, the temperature at the center of the sun is what, about 10 million degrees centigrade or so.

The Sun is a fusion reactor power plant, but it's not a very efficient one. We have to achieve temperatures at 10 times that temperature to get these nuclei to get close enough together.

Why do cold fusion think they're going to get these nuclei to come close enough together at room temperature?

And there was an argument that by putting them in a particular metal palladium and passing the current through them that they would come close enough together to fuse.

It didn't sound plausible, and it wasn't true. It's because energy from the palladium again has such a showbiz air.
There's something about you.

Now, Yasmin, most people, when you think of nuclear power, probably think of nuclear fission. So, what's the difference? So, fission is the opposite process.

So, to what I was just described, where you take a very large radioactive nucleus, which is unstable, and then it will break down into smaller particles, and it's the same effect as the binding energy of the nucleus that's released in that decay.

And the two smaller particles are released with energy. So, So it's the exact opposite process.

So you're saying that you release energy when you stick hydrogen together to make deuterium or helium, and you release energy when you split uranium up to make lighter elements. So why?

So it's down to mass-energy equivalence. So in the case of fusion, the sum of the starting nuclei is less than the starting mass, and so that difference in mass is released as energy.

And it's the same process in fission. So it's the mass-energy equivalence equals mc squared, which I think is the most famous of physics equations, and people will be familiar with.

What makes something unstable then? Are we talking about basically as it increases in size, the stability decreases? So hydrogen is very simple in terms of its structure and then

stable. Yes, exactly.
So when it becomes very large, and then the forces that are required to keep many of the nuclear particles together, the more energy is needed to create that nucleus.

So it is inherently unstable.

So hydrogen or helium that's used for fusion is opposite, which is one of the reasons it's so difficult because they are stable and you're almost having to force them to fuse.

One of the other differences between the exact opposites of them is if you look at the fission reaction, as long as you put sufficient fissile heavy material together, like uranium, you put enough there and start the fission reaction.

It is self-sustaining. If you have more than the critical mass, it will run away unless you do things to it.

So, in a fusion plant, perfectly safe, but you, the operator, have to put control rods in to soak up these neutrons to stop the reaction happening. I'll just say you said fusion plant.

Fission plant, sorry.

Again, listening to your classic music hall routine: fission, fusion, fusion, fission.

How do you feel, Rhea, about because

your forensic science you're fascinated by, viruses you're fascinated by.

You know, my mind does get very easily bamboozled by physics because the scale that you're dealing on is so kind of fascinating to try and create a picture of it.

How do you generally, as you hear these ideas bouncing around? I have so many questions right now.

Question number one, if it needs that much heat in order to release energy, you're using energy to create energy, it feels inefficient. I don't understand why we're heading towards fusion.

The amount of heat that we're using to fuse two hydrogen atoms together is still less than what it would release. Yeah, that's incredible.
It's a key question.

So we have to create conditions such that you put sufficient heat into the plasma that it will start to burn. This is what we call a burning plasma.
So it will be self-sustaining.

It will no longer require external heating. And in fact, it will start to produce net heat.
Until it runs out of hydrogen atoms. Yeah, and then it'll just be helium plasma.

You keep supplying the hydrogen as it's running. You're trying to get the helium out as the

helium. Just like, come on, have some more hydrogen.
Come on. Yeah.

And it just sits there and keeps

it. You need to fuel it for as long as you want it to burn.
It's essentially the same as the sun, right? The sun is a self-sustaining fusion reaction.

But we've all been told that the sun's going to run out at some point and the world. Right, so it isn't.
Five billion years.

You say that, but it'll come around in no time.

There was a very famous story of Patrick Moore, where he said that he was giving a lecture, and he said that.

He said, five billion years, the sun will run out of fuel, it'll swell up, it may engulf the earth. And someone did say, Did you say five million or or five billion?

I've got, you know, I.

And he did say, Yeah, we'll all set our own business. It doesn't matter.

But it is that thing about time, isn't it? That you go, the first billion years went really slow, but my God, the last four billion just raced past. That's what happens as you get older, don't you?

Time means something different. I mean, that was my second question.

I mean, if the sun is just constantly creating helium, if it could speak, would it sound like this the whole time, like it ate out of a balloon? See, I wanted you to do that voice.

I wanted you to start with the, you want some more hydrogen, and go, oh, you want some more helium.

I was hoping that was where that was going to go, and then we would go across the whole periodic table. And I think deuterium probably kills us.
I don't know, but yeah. The first question.

Until we get to America. Oh my god, aren't we amazing?

We should say, first of all, it's not hydrogen that we use as a fuel. Is it in the reactors that we have now?

We could do. You could, in principle, but the conditions you need are even more extreme if you use pure hydrogen.

So we use two heavy forms of hydrogen, one's called deuterium, which sounds fancy, but actually there's loads of it. It's everywhere.
One in every 6,000 hydrogens is, in fact, deuterium.

And if you think about all the water in the world, all the H2O in the world, one in 6,000 of those H's is actually a D. So there's loads of deuterium.
So we're full of deuterium.

Absolutely ram full of it. Yeah, yeah.
Yeah, absolutely.

What a great insult.

And then the other one we use is tritium. It's not stable and it will decay, but 12 12 years.

It's got a half-life of about 12 years, which means if you have a jar of tritium, go away for 12 years, come back again, half of it's gone, half of it's decayed into something else.

So tritium is really rare. There are sources of it, but it does mean we have to manufacture it within the plant, and we may come back to that later.

But that's the reaction that we use, deuterium and tritium, because although it's still hard, it's not easy to get something to 200 million degrees and hold it here on Earth.

We all know that, don't we?

So it's not an easy thing to do, but it's the easiest easiest fusion reaction to do. And it gives you helium, as we've been discussing, and it throws out a neutron as well.

It's the energy of the neutron that throws out that we will capture basically boil water and drive turbines for surface. So that's the self-sustaining reaction.
It's the helium going back in. Yeah.

So the helium has one-fifth of the fusion energy, the neutron has four-fifths of the fusion energy.

The helium stays inside the deuterium and tritium and gives up its energy to the deuterium and tritium. So once you've got it going, the helium that's produced keeps it going.
Really?

Just to double-check, this is all with consent, right? We're not just forcing these atoms together against their will.

It is against their will, isn't it? Forcing them together against their will. I don't know if this is the same thing.
And they have a strong will.

So, Yasmin, so fusion, probably most people have heard of it. There's almost a joke, isn't there? It's always 20 years away.
But it is often presented as the holy grail of energy production.

So, I suppose that there are two questions there: which is

why is it always, why does it always appear to be decades away? And why is it the Holy Grail? So, I think it is a limitless source of energy, and so that's why it's the Holy Grail.

So, if it's achieved and it's controlled and it can be hooked up to the grid, it has vast potential for society, for electricity generation, for many of humanity's problems in terms of inequalities for electricity access.

And it doesn't require a lot of fuel. Part of the fuel that we need is very abundant, easily accessible.
Personally, I think it's been underfunded for many, many years. It wasn't fashionable.

So, they had fission. There was no reason to fund fusion research.
And so, you know,

we've been doing that research for a long time. I think for quite some time, it wasn't very much in the spotlight.
It has had decades of funding, but at a relatively low level, I would say.

And so, I think when you compare the amount of funding or the efforts that were put into developing fission when that energy source was needed, it's not really comparable.

So, you can start to see it now. The focus is definitely shifting.
I think there is an awareness that fusion is needed.

The funding of the research has started to change, and so now it's becoming much more serious.

And so, now if the efforts are there and we're able to grow the community and we have many strands of fusion research, I think there is hope that it can be developed and on the grid and in a controlled way.

So, is that basically that because we're now seeing the implications of climate change, now it's actually becoming a reality? Is that what has finally kind of sped it up in terms of the market?

I think this recognition that oil and gas will run out. I'm not sure if it's actually embedded in concerns about climate change.

I mean, for me, obviously, that's a huge one, and that's again another appeal for fusion. Fossil fuels are not never-ending, and

a replacement is needed.

We need a continuous source of energy that renewables and sustainable energy is very important, but I don't think it's going to fill the gap that fission will until fusion is ready.

And when fusion is ready, it looks like it would take the place of, for example, fission, which has its own problems.

And that's in about 20 years' time, is that right?

Yeah.

Rhea,

you had a question.

No, I was just going to apologise for the lack of funding. I think we've been spending it all this time on vaccine research, but as we all know, that's come to nothing.
So I'm really sorry.

Have you been taking your paracetamol again?

No, because I'm not pregnant.

So, can I add a perspective on this? I think think fusion is difficult and fusion is expensive. The research associated with it is expensive.

And so, there's been a big view that actually fusion will be ready when we need it.

And I think a large number of politicians and the general public understand that we do need it for climate change and we do need it for energy security.

And that's something that's been particularly important and risen in priority over the last four or five years, for example. And so, people now go, Yes, we do need it.

And you'll have seen over the last five, six years, as people have gone, yes, we need it, you'll see a lot more private investment going in, billions and billions of pounds, and that funding is now starting to accelerate the process.

And we are starting to see

fusion power plants on the horizon in the next decade or so, at least in a prototype sense that demonstrates that it's feasible.

How many different technologies are there? Because essentially the point is you have to stick some deuterium and tritium together, so hydrogen basically.

How many different ways are there of doing that?

There

hundreds, but actually, they can be categorized as two.

One is inertial confinement fusion, one is magnetic confinement fusion. They're both trying to do the same thing.
To do fusion, you need a sufficiently high density,

you need actually a certain temperature, this 200 million degrees, and you need to be able to confine your fuel for long enough.

You need a good enough system to be able to hold the heat in sufficiently well, sufficiently insulating system.

And so, you have this so-called triple product of density, temperature, and confinement time.

Inertial fusion, they take a small pellet of deuterium and tritium, about a millimeter or so in diameter, and they coat it with something, something heavy typically, and they put it in the size of a big chamber, probably not that much smaller than this room, actually.

And they focus a large number of lasers, like 200 lasers or so, on this poor little pellet, 200 of the world's biggest lasers. And that basically burns off that coating from the deuterium and tritium.

And as it blasts away, it pushes on the deuterium and tritium, compresses it to really high densities, like a thousand times solid density.

It's like taking a brick that a building is made out of and just squeezing it down to a Lego brick. So you get really, really high density.

You get the temperature as you compress it, but it has really short confinement time because there's nothing holding it there.

The only confinement time is associated with the inertia of the fuel, so it's like billionths of a second. But that product of density and temperature can, in principle, get you to fusion power.

And they demonstrated demonstrated it once with one shot a day kind of thing.

They would need to do that 10 times a second in order to deliver fusion power, and much, much more cheaply than they're doing at the moment. So that's inertial fusion.

And then magnetic fusion uses the fact that if you heat something to 200 million degrees, it doesn't look like the matter in this room, it looks like something called a plasma.

So if you take water, for example, you know the three states of matter we're familiar with, solid, liquid, gas.

Take water, solid state is ice, heat it, it melts, you get water, heat that, it mat that it vaporizes, you get seam. Now keep heating it.

Your water, your H2O bonds split apart because you're putting so much energy into it, your H2s become split into individual atoms.

If you keep heating it, it gets so energetic that the electrons surrounding the nucleus effectively boil off that central nucleus, and you're left with this big ionized gas of positively charged nuclei and negatively charged electrons.

The whole thing is still neutral because you haven't made any charge, but now you've got charged particles in there. And that charged particle gas behaves very differently to the gas that

we have in this room. And that's a plasma.
Fascinating. I've spent my life doing it.
But it's what we have to study in fusion to make fusion happen.

Now, because the plasma has charged particles, we can hold onto it in magnetic fields. It's lower density, much longer confinement times, and the temperature is the same in both of them.

And magnetic confinement is holding that plasma for much longer time scales to create the fusion process.

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Yasmin,

so your expertise, a plasma physicist, initially.

So the problems we have building fusion reactors or the confinement reactors are essentially associated with controlling that gas, which would seem, as you described it, Howard, to be quite easy.

You just stick it in a magnetic bottle or something and it just sits there. So Howard's described that really nicely, so how you create the plasma.

So, essentially, you need some way to ionise the gas.

And one that people are familiar with would be the neon lights. So, you have the different colours of neon lights, and those are plasmas.

Essentially, they're low-temperature plasmas, and they will have created those by running an electric current through the gas, and that's enough to ionise it.

For fusion, we need to heat that plasma up to the very high temperatures needed to actually bring the positive nuclei close together.

So, then you're going into high-temperature plasmas, and that's where the temperatures that are needed for fusion to happen. You couldn't have such a hot plasma in contact with a wall.

So you could put a magnetic field in it, and then the plasmas, because they're charged particles in the presence of a magnetic field, they start to do really interesting things and they spiral around the magnetic field and it essentially traps them.

So that's a great way of moving the plasma away from the walls of whatever you're containing it in. So then you're reducing the problem of melting the walls, the vessel.

But you also need to keep the particles in the same place for long enough for fusion to happen. And so if you're constantly leaking particles, it's just much less likelihood of fusion taking place.

So they solve that problem by taking our magnetic fields and basically joining them up at the end. So you have this infinite way round a doughnut-shaped vessel.
So you're reducing those end losses.

But because you now have what we call a toroidal geometry, so you have this doughnut-like geometry,

it causes other losses outwards towards the vessel. So, again, the confinement is not perfect.

And then the really important thing is we have a very high temperature gradient between the middle of the plasma where we're trying to get the temperatures high enough for fusion to happen.

So, if you imagine we've got tens of millions of degrees at the center of the plasma in this doughnut, and then the walls of the on jet, I think, for example, was a big experiment near Oxford.

The walls were held at 300 degrees centigrade. So there's a massive temperature gradient between the middle of the plasma and the edge of the plasma.

And what's the distance there that we talked about? That was three metres, radio.

So whenever you have these huge temperature gradients, I mean, you end up with something called turbulence. And turbulence introduces plasma losses.
So again, it influences confinement.

Can I recommend you maybe need to watch more Star Trek? Because they're always getting breaches in the plasma manifold.

And they seem to manage it.

We'll walk after it. We'll have a look.

I mean, we should look at Voyager. They got all the way home from the Delta Quadrant, all right?

It's not, wasn't it a spore drive or something? It wasn't, they didn't use spores. Oh, oh, I'm in pain.
I'm in pain.

I'm not familiar. I'm not familiar with that.
No, that was discovery. That was discovered.
Oh, that's discovery art.

We don't know. Brian, you look like an idiot.

What was the spore drive then? The spore drive was

was a ship that we don't talk about that transported along mythelial networks and then ended up very far in the future, even though it's all in the future, but even further in the future, with Spock's sister on it, who now he then never mentioned again because

he didn't know he had her when he first started.

But there's a lot of show business, because each time there's a little moment in this conversation.

So we started off with steps, then we had palladium, then you bring in neon, and then I noticed when you say particle loss, you do jazz hands. So I feel

that it's the most show-busy physics episode we've done yet, I reckon. Howard, so getting back to the point.

It sounds like at least a simple problem to state, which is we'd like to create a plasma, if that's the kind of fusion we're talking about, and we'd like to confine it.

We'd like to hold it long enough, essentially. So why can't we just solve it? We know that fusion works because we see the sun doing it all the time.

We know the conditions we have to achieve to make fusion work. What we have been struggling with over the decades is how to achieve those conditions.

And before the fusion process takes over, one has to put in enough energy to spark it up. That churns the plasma up and that generates this turbulence.
Now, the turbulence is a really complex thing.

You'll have pictures in your head about turbulence at the bottom of a waterfall, for example, and that's already pretty difficult.

If you just look at all the different structures that appear in the bottom of a waterfall, big eddies, small eddies. You can imagine trying to understand that is a very difficult thing.

We can understand that, but a plasma turbulence is different again because it has that physics, so it does have those sorts of churning away, the same as water would have.

But in a plasma, remember, the particles are charged, and we are holding onto those charges with a magnetic field.

And if those charged particles start jiggling around, as they would with turbulence, your charged particle jiggles around.

If you move two charges relative to each other, you create an electric field. So jiggling charged particles around jiggles your electric field.

You can also jiggle the magnetic field, and those jiggling electric fields and jiggling magnetic fields feed back on the particles. And they feed back on them in a very special way.

And the best way to think about this is to go to the beach and watch a surfer. And if you watch a surfer, and if the surfer does not paddle,

the wave will just go under them and they'll bob up and down. They're not tapping any of the energy of the wave at all.

If a surfer paddles to match their speed with the wave, what we call a resonance, the wave will pick the surfer up and take them into shore.

And the surfer is tapping the energy of the wave, or the particle, who's a surfer, is tapping the energy of the wave. Those resonances are happening all the time in plasma physics.

And that interaction between energy in the wave and energy in the particles is happening all the time from all of these different resonances.

But to understand those resonances, you not only have to understand where all the particles are, which is what you have to do for water, you also have to understand what their velocities are, which direction they're going in, how fast they're going.

And so, there's a whole there's another three dimensions there. It becomes a six-dimensional problem.
There isn't a computer in the world that can solve that problem.

And so, we have a whole bunch of very clever theoretical models which reduce the dimensionality of that to make them tractable on today's computers.

And so, we are starting to be able to predict what the turbulence will be and what the consequences of that turbulence are for the heat and particles leaking out through the magnetic field, and starting to be able to design our tokamaks, as these machines are called, or stellarators, you might think as well.

We can start to understand how best to design those so we can minimize that turbulence.

I will make a not-so-bold statement: if it wasn't for plasma turbulence, fusion would have been working decades ago.

Up to the point that we are now, it's been because it's really difficult to simulate.

So, we're just about managing to do it now. So, it's had to be experimental.

So, JET, maybe you could talk a bit about JET, which was a world-leading experiment

there's a really cool fact about jet, actually, is that jet reaches these temperatures. We can do 200 million degrees.
That is the hottest place in the solar system in Oxfordshire.

So, that's a really cool statement. But, yeah, so how do you do an experiment in something that's 200 degrees centigrade?

How do you see what's inside those plasmas? And we use lasers. You fire the laser in, and temperature, the temperature of a gas is how much your particles are jiggling about.

If you heat it up, the particles jiggle around more and more and more. So, So now, if you fire a laser into your plasma and it hits a jiggling particle, it will scatter off that particle.

And so you fire your light in at a very fixed frequency.

When you measure it coming out, you find that there's a width of frequencies that come out, and that width of frequencies tells you about the temperature.

But it's far from easy to do the experiments, it's far from easy to do the simulations. We need to do both and combine the two.
So, JET, you said it's about what, three meters?

Yes, three meters measure radius. And then,

so JET stands for the, it started as the Joint European Taurus. And ETA is the international, it originally was called the International Thermonuclear Experimental.

Was it reactor? It was reactor. They used the word reactor.
It's not a reactor, it's an experiment.

And that, I think, is five metres.

Six, okay.

It's very big,

five c metre, so it's it's a theatre-sized thing.

It's a big object. So we have known for a long time that for the magnetic technology that was available, that this much larger machine was required to reach the confinement.

So, the plasma is contained in something called a vacuum vessel. So, it's a metal doughnut-shaped vessel, and it is usually built in eight different parts.

And if they're being built by different people, they have to fit, and the tolerances are very, very small, so even just a few millimeters out on the welding, I think, can cause problems and they don't perfectly fit, because you have to create a very high vacuum in there.

There can't be any leaking.

Can I go back a step just going back to turbulence? First of all, you said it's a six-dimensional problem. So, what exactly are the six dimensions?

You've got the three dimensions that we're living in here, and then the other three dimensions that you have to

length, width, depth. Yeah, that

of the confinement or of the body.

Of the plasma, the same as in this room, but then the other one we're still pretty familiar with, it's just the velocity dimension. So, you have to know which ways the particles are going.

So, there's another three dimensions about where you can move. So, you can say, I'm here at any one position, at any one time, and give a spatial dimension about where you are now.

So you give your coordinates in this room.

But now you might be moving in a certain direction, and you could be moving that way, that way, or that way. And that's another three dimensions.

It's just three more pieces of information that we need to know about your position. Not just where you are, it's what direction are you moving in as well.
And that's six? That's six.

Your three spatial. Is there anyone else in the room, or is that like

the first three?

Six numbers per particle. So, this is what is determining the turbulence that you're trying to research and resolve.

And am I right that you said that the larger the torus, the less problematic the turbulence is? No, so the plasma becomes large enough that the confinement is better.

There's greater likelihood of fusion. You should say it's not obvious, is it? That if you go, because people might be thinking, it should be obvious.

You go bigger, it's easier, but that was a difficult problem, right? It wasn't, it took a while to realise that, didn't it?

Right, so there's been a lot of what we call cross-machine scalings that are looking at the effect of changing the size of the m machine.

So that is an empirical scaling which has shown that the confinement improves as the plasma size gets bigger. Purely experimental, it's purely experimental.

The new technology that will make a big difference is the high-temperature superconductivity for the coils.

So the magnetic fields we can apply to these experiments, it was always limited by the use of copper coils.

So with the advent of high-temperature superconducting coils, it's now possible to have much higher magnetic fields on tokamaks. And so, that's a route to improving confinement.

So, that's a fairly recent development. They started work on that in the late 80s, but I think we've only seen actual application of it really in the last 10 years.

You know, what I find really interesting about this is that it's an example, and there aren't many examples, I think, of engineering that's so difficult that we have to learn so many things that it takes decades.

As you said,

this magnet technology, we discover it in the 80s or the properties of these materials, but it takes 30 years to implement.

I suppose there's a natural question is why is that? You gave one example which was just the amount we invest in it, but I think could you speak on how difficult these technologies are?

And there are quite a lot of them that you need to build one of these reactors.

If you think about taking something right from first discovery right through to final delivery, people are really excited about the discovery thing because you're pushing the frontier of human knowledge.

You get a lot of investment and a lot of your brightest minds looking at that. Then go to the other end of the scale where you're actually bringing it to the market.

There's also a lot of interest to that. It's usually different people, it's usually people who are interested in making money because it's sufficiently developed.

And so that also attracts a lot of money and it attracts a lot of bright minds.

That bit between is even called the valley of death because you have to still have to keep investing and you still have to get clever people working on it to take it from the lab through to the final marketplace.

It's a little bit of a thankless task because you don't get big high-profile papers, you don't get to sit on the stage with Brian Cox.

And so it can fail because you can run out of interest, you can run out of resource. And so that is what takes a lot of the time is taking it from an idea to a commercially viable product.

And this is where fusion now is. We have done it in the lab, they're big labs, and we are now trying to commercialize it.

You can't reproduce the conditions in a fusion reactor until you've got a fusion reactor.

So we are going to be relying on simulations, and we're going to have to use those simulations to be able to predict what's happening. But we need to be confident those simulations are right.

And so you need to be able to test it against experiment. And the skill of the scientist is designing that experiment to test your theory.

So, what I what what what I think that we need to do is to not just think about doing simulations and doing experiments and occasionally comparing them to validate them, but actually do the whole thing together.

Integrate the two things together, the simulation capability, the virtual world, with the real experimental world to give you a capability that will be able to be drive you through this valley of death faster.

I have to pick up on Howard's point. I think I agree with him him 100%.

As an experimentalist, I've always enjoyed working with theorists because what's interesting for me is taking a really cool idea, a really cool theory. Can we test this?

Can I design an experiment that will look into this and see how valid it is? Does it explain what we're seeing?

And I thought it was very interesting what Howard said, which is one of the challenges, in order to do experiments on plasmas at scale, you have to build the thing you want to do the experiments to tell you how to build.

If the only way to do the experiment is to build a fusion reactor.

That is one of the problems, I guess. It is one of the challenges, yeah, yeah, because you can't reproduce the conditions on Earth.

And it's not just about the plasma, it's about the neutrons that are produced as well. Rio, how's your mind been through this conversation?

Well, actually, I'm going to be honest with you, I've been thinking about the turbulence issue, and I was thinking about water slides. Have you just tried tilting the torus? You know, think about it.

When you're in a water park and you're all sitting in your own little rubber rings and it's just like that river thing and you go through, and it's really slow, and you all bump into each other, and it's just a bit rubbish, right?

But then you go and you take your rubber ring up to the top of the slide, and that's really good because gravity is whooshing you down, and all the water is going in the same direction.

So, I'm figuring that that's your issue: your torus is flat, and you just need to tilt it on an angle so that we get some gravity. Do you know what I mean? Like, just get that whoosh going.

Yeah, I think that, no, I agree. Yeah,

I think we are seeing the beginning of the movie about when you won the Nobel Prize in 2037 and you're still working on that thing.

No, no, how it's theoretical.

It's a really good point. So that whoosh that you're talking about, where it's going round the doughnut, exists, and it's really important to the...

I'll take the job. It's fine.

I'll probably finish it.

We'll get it going. You get me on board.
We'll do this by 2033. I'm telling you.
So you're saying that's a good thing. So that whoosh does suppress the turbo.

It tears the turbines apart.

I am wasted in comedy.

Someone's just won a free pass to Thorpe Park, haven't they, for a lifetime?

Just very quickly, because we are at the end, but I'd just like to finish by. So what is the future that you envisage? So let's say that these go to plan and ETAWorks and STEP works.

So by, let's say, 2050, let's say, so twenty-five years' time,

how much of the energy that we use on the grid would you envision would be coming from fusion? So I think twenty fifty we will see STEP operating.

It will start operating in twenty forty and during that decade we will put net power onto the grid. And that's but not in a commercial sense.

We'll put a a few hundred megawatts of power onto the grid. And that's in Oxford.

And that no, that's in North Nottinghamshire, West Burton, which is where I'm based, which is a disused coal-fired power station.

So I look outside my window and there's the big cooling towers from the coal pipe, and they're pretty cool.

I realize why now why the g I thought they were cold cooling towers because they were cooling water but they're cool.

So they will they will come down in a in about a year or so's time, two years' time, and they will be replaced by a step fusion. So that will be putting electricity onto the grid.

That will just demonstrate that we can do it. And then also during the twenty forties we'll be designing that first fleet of commercial plants.

And those commercial plants should come online if you're really ambitious and really went for it, really pushed for it in the twenty fifties. And then our our power.

It's a large fraction of the power. No, it's not going to be large, it'll grow up slowly.
It will take you of the order of 10 years to build one, just as it does with a fission plant.

When you've got them, the fuel is seawater, basically.

The fuel is seawater and lithium. So we didn't talk about the bridium, but you get the tritium by reacting the neutron that comes flying out of the reaction.

You react it with lithium, and that lithium produces the tritium that goes back into the fusion plant.

So your raw elements are deuterium that you get out of water and lithium that you get out of the ground.

And you all have it in your pockets now now in your mobile phone batteries, your laptop batteries. And there's a really nice little picture that we give about how much fuel there is in the world.

And the picture that's often used is: if you take all the deuterium that's in a bath full of seawater,

and if you take the lithium that's in maybe one, maybe two laptop batteries, and you do fusion with it instead of having a bath and instead of using your laptop, that will give you your full lifetime's electricity needs: the lithium in two laptop batteries, and the deuterium in a bath full of seawater.

So that's why we want to do it.

It's a smellier world, but a happier one. So Yasmin, so would you concur with those?

Absolutely. I mean, I think it is coming.
I think we have real evidence. There's been huge breakthroughs actually over the last five years.
So we had the

big results actually from the National Ignition Facility in Lawrence Livermore, the lab in California, where they had net fusion.

And then we had major results from JET and the Joint European Tourists in the last last few years, where they were able to show significant energy from fusion reactions over five, six seconds.

So, in terms of demonstration of the principle, and they did that twice actually in the last couple of years, so there's been real demonstration of the principles of fusion, and there's been massive change, I think, overcoming many of the challenges.

We've demonstrated it, and the plasma results are running longer than ever before. And Rhea, does it frustrate you? Because it often frustrates me

when you hear the numbers. So, you say, well, essentially, some seawater and some lithium, and you power your whole life, you can see cities are powered with not much of this stuff.

Does it frustrate you that we don't invest and we don't move as fast as we could do? No, I think

it's a bigger question than that, isn't it? Funding, it's all about education. We don't fund it because we don't know about it.

We don't know to ask for it, and we don't know to say, actually, can you stop spending money on, I don't know, fantasy football, and can we please start funding fusion? That's the problem.

Is that, you know, we're not even really taught about fusion in school very much.

We're taught about fission, definitely, but we're not, you know, we're not taught it at this level to say, by the way, laptop and a bath,

and we'll get you another laptop. You know.

There's a lot that needs funding, and there aren't a lot of people that understand that that's really where the money should go, or believe that that's where the money should go.

And that's a much bigger problem than this show.

Is that next episode? Is all of economics? No, the next episode is just a recording of the sounds you make as you go down different water slides. It's just a whole, it's going to be great fun.

We asked the audience a question as well. We asked them, what do you think is the greatest untapped energy source in the world? Ria, what have you got? I have three that go together.

Here we go: underground water, because springs can only get better. Excellent, yep.

Caber tossing at the Highland Games, because flings can only get better. Well done, everyone, again.
And deep sea thermal vents because things can only get wetter.

Or tidal energy because the moon should earn its keep.

The crackling electric tension of every man looking straight ahead in a crowded urinal.

I think we'll end on that one.

Thank you so much to our fantastic panel, Yasmin Andrews, Howard Wilson and Ria Lina.

Next week, our episode, we're going to be gazing up at the sky and finding elephants, or maybe dogs, or maybe the wispy face of Brian Cox formed out of the vapor of the Nimbostratus cloud above us.

Well, basically, we're going to be talking about clouds and what we see in clouds, but probably not that.

But there is currently statistics to suggest that you are now seeing more in water vapor patterns than Jesus.

I think that's entirely appropriate. Good night.
Good night.

In the infinite monkey cage.

In the infinite monkey cage.

Till now, nice again.

Hi, I'm Phil Wang, and this is a podcast to podcast trailer for a different podcast than this podcast that you've listened to or are going to listen to.

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The podcast I'm talking about is Comedy of the Week, which takes choice episodes from BBC sitcoms, sketch shows, podcasts, and panel shows, including my own show, Unspeakable, and puts them all into one podcast.

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