Yes, so thank you very much.
I'm very excited to be talking to you about this topic, and I hope it will lead to getting us enthused about this
as I do. Okay. So I'm just going to give a kind of brief overview for the structure of my talk.
And it starts off by talking about what the national climate fusion is.
And I'm going to talk about inertial movement lasers and how this the National Ignition Facility, the NIF, which is the world's largest laser work.
And how could it possibly do ICF?
I'm I'm then I'm going to talk about the story of ICF happiness, which I think you can summarise the things that at first you don't succeed.
Try, try again. I'm going to talk about the very initial disappointing setbacks and then the recovery period from that.
And then the last few years, which have been very exciting in terms of results, as you probably gather from the news.
And then I'm the third plus mine talking about how we can do even better, an approach that's living with other survivors.
High gain ICF assignments.
I'll define what I mean by that in the next five years, and then in particular, I'm going to focus on the approach that I work on, particularly,
which is how we might be able to leverage novel plasma physics to really take the novel plasma
physics of magnetised weakly collisional plasmas to really kind of make a big step forward.
And then finally, probably the things most of you are interested in this idea is think about the relation of
this to inertial fusion energy that's using inertial confinement fusion to deliver energy.
I'm just going to talk a little bit about what you actually need to solve to make that happen.
Okay. So very, very soon. It starts off with what's his initial confinement fusion?
Well, as we've heard, to kind of make fusion happen, what you need to do is combine a very hot plasma.
One way of doing that, which you've heard about so far, thanks to Michael and Georgia,
is a magnetic confinement fusion where we're thankfully using a magnetic cage.
Either tokamak, which celebrates such as Spindle seven X as we've got here,
and your sense of approach, which I'm going to be talking about, this inertial confinement fusion.
And that's simply basically what you're doing is you're making fusion reaction happen before the plasma has a chance to escape.
Now, we actually worked out how to do this in the middle of the last century.
Using the bombs.
And I'm the idea here is that you basically use fission to create this incredibly hot, dense plasma and then the fusion reactions can happen.
Well, as you might imagine, there are a few engineering problems to using nuclear bombs to make power plants.
Although that didn't actually stop some people trying. But that's just talk for another subject, for another talk.
So what I'm going to talk about is trying to do the same thing using lasers instead.
Now, basically, two types of ways of using lasers to make inertial confinement shouldn't happen.
The first is called Direct Drive ICF.
The idea here is you take optical lasers and it radiates a spherical capsule containing your fusion fuel, which is a deuterium.
I'll come back to the exact capsule structure in a sec. And you irradiate the edge of it.
And this creates rapidly creates a plasma around the edge of the capsule and a bit like hot gas streaming off behind a rocket.
This causes the whole capsule's compress. And as you can see, you get a lot of transport of thermal energy from the air,
from the laser in towards the centre when you get in higher density, high temperatures as the compression occurs.
Then we get to the ignition stage. And so at this point you design the good capsule, you have temperatures of about 100 million degrees,
Kelvin, and the density at the centre of this, which is about 20 times that's a solid density of LEDs.
And then if you get to those conditions, this capsule will make a nights and then burn.
So that's the very basic idea of direct drive, as if as an alternative scheme through the school of indirect drive,
where you don't drive the the capsule itself with fusion fuel,
but instead the final phase is inside a gold cylinder as a whole, them which is made of gold behind that material.
And by irradiating the inside of this whole room with x rays, with the optical lasers, you create a lot of x rays.
And it's then these x rays that you use to implode the capsule in the same way as with direct drive.
Use optical lasers to do that.
And I'll discuss in a sec why it says that, you might say, using x rays inside the capsule as opposed to direct drives of the optical laser itself.
Okay. So just jumping in a bit more, describing what these ICF councils look like.
So they basically have the following structure in the simplest form.
So you have what's known as in the Blazer. This is usually a lousy material and there are quite a few subtle reasons this might choose one or another.
Usually at the moment this plastic or diamonds is used to this, and so your radiation is instant onto the onto the blazer and then below that.
So you have a layer of fuel. This is usually dirty ice.
So actually these experiments need to be held in cryogenic conditions until the lasers fire, which is one of the main engineering challenges of them.
And then inside that you have to guess and basically you can control the density.
It's at the main implosion stage by the thickness of the fuel use.
Now, as you fly the lasers, I've got different times. So we see the initial time.
This is the size of the capsule. Then as we place, as we find the places, we get a lot of data possible,
but then the sensor is imploding and then at the very end we end up this highly, much more dense capsule.
And then if we designed it right,
we get to hotspots and ignition and then but I will insist that though this kind of slightly jagged boundary between the vehicle and the plasma,
this turns out to be one of the main issues with these instabilities.
And I'll come back to this in due course. Okay.
So what's the basic physics that we need to get an ICF capsule's work?
Well, initially, what role? Fundamentally, we need the heating processes.
So that's initially the implosion, the compression, and then subsequently the alpha heating,
the heating by alpha particles released during the reaction of the self-heating to overcome any losses in the system.
So I said the two main heating mechanisms initially it's the compression that's
doing PB work and so that that increases the temperature as well as the density.
And then in addition, once the alpha, once you start getting fusion reactions, if the density of the fuel was high enough,
these can then actually keep that fuel and you get the kind of self-sustained reaction that's cool alpha you think.
And then the probably at this earlier stage whilst the implosion is happening, the two main loss mechanisms are radiation.
So these are X-rays emitted by the hot plasma in the sensor escaping, and then also thermal conduction,
which is typically coming by electrons away from the hot, hot spot into the cold fuel.
And just so for ignitions work, we need heating. So obviously better than cooling.
So just to give you an idea of what one of these implosions look like, this is a photograph of an actual capsule used on an implosion.
So initially the scale of them is about two millimetres in diameter and then one by the time it's imploded.
It's like this in the sense of here this is the neutron emission scale of the ice capsule for implosion on this particular shelf life shown here.
So you can see it's about 35 times compression in size. Really, this is less than the width of a human have at this point.
Okay. Now, going back to this direct drive, but this indirect drive you might like, if you look at this thing I want us with,
I want to use x rays through many of this capsule because surely there's going to
be some inefficiency by putting my laser energy into this into this whole damn.
And it's actually a very valid concern. It turns out that when you do this and find these laser beams and you only end up with
typically about 10% of that laser energy burst into the x rays that then implodes the capsule.
However, one of the main things that's been I mentioned that's been challenging and it turns out this is more
challenging for direct drive dress than direct to drive is an indirect drive is the problem of instabilities.
If you have any either in homogeneity, in the in the laser intensity that you have on the surface Security Council or you
have any say manufacturing deficiencies on the surface as the implosions happen,
an instability that you may have learning about the maybe Tyler instability kicks in and this kind of causes the surface to buckle.
And basically as the surface buckles, this mixes the laser into the centre of the capsule and degrades performance.
And so this is the kind of earlier experiments. These are what some have done on the nouvelle laser in the mid-nineties already.
From these X-ray emission images, you can very clearly see these structures developing.
And this is very problematic. And so the one advantage the indirect drive has over this is because of the way that the X-rays are created,
they typically end up with more uniform illumination relative to direct drive of the capsule,
and also because the X-rays, they kind of penetrate in a bit better. And so you end up suppressing instabilities in that way as well.
So this is why well,
one of the reasons why indirect drive has been pursued perhaps a little bit more on the very highest distances as the way to get game.
Okay. So now looking at the world type places, so I've kind of scattered the few of the biggest ones on this map here.
You can see in the UK the biggest places is because of the Vulcan.
There's a round from Bawtry and the wind lies way and it's just all over the place.
But probably the I think it's first of all, the world's really big places are in the US in particular, the one I'm going to be talking about next day.
The national ignition is in Livermore, California. So this is an aerial photograph of the sites.
And then this is the national ignition facility down here. It's about the size of three American football fields that they like to say.
And so in terms of size, that to me is about 180 metres long and 130 metres across, and it's about ten stories high.
So it's a pretty mammoth facility. And so here's some kind of kind of more detailed schematic.
I'm going to be going through the schematic and talking about how the laser works
and the kind of three key facts that the most energetic laser in the world, amendments that this is more than two mega joules of laser energy.
When it fires on this and that laser energy is released to the to the target chamber with a wavelength of 351 nanometres.
At the moment when the laser is firing, has the power outputs of the entire US national grid.
I just still find this extraordinary and it has 192 beams that all convergence this very small volume inside this whole room.
When I Google once preparing this talk, I looked up national instant settings on Twitter.
I also learned that it's the warp drive for the Enterprise Starship, as you can see from this very realistic photo.
This is the next target chamber behind this great that you can use these things in multiple ways.
So how does this work?
Well, you may recall from your physics studies that the basic principle of lasers is basically leveraging, stimulates the mission of excited atoms.
So you will remember in a two level system with three basic processes that you and one need to consider.
So if you have a photon with the right energy coming in with two levels a system,
an electron sitting in some ground state can be excited up into the higher level simultaneously as well.
Secondly, if you have an electron that's already sitting in the excited level,
that can then move down to the lower level and spontaneously emits a photon of the energy between the two levels.
And then finally,
the process that underpins lasers is if you have a system where there's already an excited electron in the upper level and then a photon,
otherwise energy arrives on the electronic at sciences level can fall down,
and then you end up with two photons emitted with the same energy, but also coherence.
And for a really good laser, you want lots and lots of coherence and photons.
And so basically it's the simulated emission process that underpins how lasers work.
Now it's a little bit more complicated than that. There are certain kind of conditions you need for those actions to work.
The most important one is population inversion. Okay.
So the most important one is population inversion, which is you need more power, more electrons sitting in your upper level than your lower level.
Now you will call and this is actually quite an unnatural state. It's the opposite of that.
It's not a thermodynamic equilibrium. And so this is actually kind of fundamentally why finding lasing materials is quite challenging.
Achieving this is not something that many materials can do easily.
There are other conditions.
You typically always need the rates of spontaneous emission to be less than the base of the decay or of the electrons living in your lower level.
And then finally, you need a sufficiently high pumping rate that is pushing at science's electron electrons, exciting them into this upper level.
And you need those electrons to sit in that level for long enough.
And when you put all of these things together to actually achieve it, a two level system that works, you typically need a system.
So again, it's a medium with it over two levels, like having a sample of a three level laser.
The NIF laser is actually a full level one.
And then basically you have two levels within that four level system between which you'll get some more laser action.
And it's by using these more complicated levels that you can actually manage to achieve population inversion in the immaterial.
Okay. So what's what how does this work specifically? Well, what we need on this is an item in the phosphate glass.
I've got a photograph of it. Here is this kind of paint colour.
And basically so at the start what we have so the laser is which and so that's a very weak signal of a few minerals in the
mast oscillator which is here it then it's quite a little bit before it's then passed along into the main amplifier base.
Now the way that the main application occurs is you see that there are these capacitor banks nearby,
these charge flash lamps, which basically excited lots of electrons into the right level one substation.
But that's basic idea. And so by having these flash lamps, this enables the mediums to do its thing.
And then now you can apply the laser up to very high and the very high energies you need.
And here is a photograph of the the laser base on this.
Once you've kind of amplified the beings, subsidise energy, you have to do some fine tuning to them.
There's a kind of complicated set of filtering. You've got company spatial filtering as shown here.
You polarise the beam.
That's another level of filtering to make sure that you remove any aberrations in the lenses, get the smoothest possible profiles,
and then you transport them back along here into the switchyard where the beans are then kind
of arranged as they need to be before they we then eventually get them in the final optics.
Now what these so here's a schematic of these final optics and some photographs of them.
What they're doing here is that the original laser seed is actually infrared light source 1053 nanometres.
But it turns out absorption is typically better if you can go to a short wavelength and so we can use some of those frequency conversion vessels.
So relatively efficiently, over 50% convert that infrared light into ultraviolet light.
That's better with implosions. And so that's done through the station here and you end up with that's the two.
That's what then gives you the two mega jewels of this and 3519 amazing lights.
Okay. And then once those are they pass through the final objects, they're all focussed in the centre of the target chamber.
So this is about ten metres across and some people that's a scale,
but then all being focussed right into the centre of the chamber since we set disagreements.
Okay. So what's the targets themselves? Like the comet? Well, I first I got some images of a poem, so about a centimetre in scale.
And the laser beams are coming in each size like this to radiate the sense within into that I the goals,
as you can tell, probably from the look of the material.
And they've also got these holes in the side to help kind of diagnose what's going on.
That's the photograph of the hole I'm holding on the sides.
And then that's a scale image, comparing the human eyes to see have a sense of how big these things are.
Actually very small. Then the capsules themselves this even smaller.
This is a photograph of one use in an experiment. This is about two millimetres across.
And then the idea here is that you are then schematic of the radiation going in on the inside.
It made it the whole I'm inside the sensor. And then this is a more detailed image here of the actual seven most recent whole rounds.
And like note this is a little bit more complicated. You have to use this thing 2/10 to hold the capsule in the centre.
And then you've also got this fills you coming in, which is what fills the DC gas in the centre of the capsule.
So there are some complications. So beyond the basic picture,
but I hope I'm actually it turns out this complications are going to be quite crucial for making it work, kind of mitigating them.
And I'll come back to what I mean by that in due course. Okay.
And then all of the operations this is delivered from a nice central location by the incredibly professional ensemble national staff.
I've worked with them before and that they're just great.
You'll be pleased to know that there is a nice lots of screens and power bars that charge up at the base is going.
And this a great countdown when the beams about to go. It's really fun. So it an amazing place to do what.
Okay so what are the key numbers to remember to NIF? Well, so there is this point.
So I said that the capacitors need to be charged up and this is effectively the wall plug efficiency of NIF.
And as was mentioned earlier, this is actually not very efficient at the moment. You need 320 mega joules approximately so in the capacitors.
And then this is converted down because the inefficiency to about two mega joules at the laser light being delivered and then with indirect drive.
As I also said, there's also not much efficiency, only about 10% going from the capsule up on the whole ramp into the capsule.
So those are just three numbers to keep in mind and then some key concepts.
So I'm going to come back to in this talk kind of so the National Academy of Sciences,
a definition of what ignition is, is basically having more fusion energy out from this than the laser energy.
So the into the indirect drive on a burning plasma is one in which the fusion energy output from the capsule is greater than the X-ray energy.
And this is kind of the points at which the kind of fuel is beginning to ignite.
The heating is coming from the alpha particles, not just the compression, and then the self-heating plasma is one way.
The fusion energy is much greater than the extra energy. And this is really burning and kind of self-sustaining.
And then finally and I'll come back to the end result.
What you really need, if you want, if it ever work, is the fusion energy out to be greater than the wall plug energy in,
which I mean, that tells you that there was quite a difference between these two. And I'll come back to this at the end of the talk.
Okay. So let's start off with the kind of the first attempts to make unsafe happen with the national ignition campaign between 2009 and 12.
And the goal of this was to just really go will then fire all blazes to get this done.
And it didn't work. They only achieved the best shots, achieved less than three kilojoules of use an energy ounce.
The main problem is that they kind of start off with these more cautious thoughts,
and then when they round up the energy, they actually got degraded performance and subsequent kind of state of the art.
Simulations of these experiments realised that the main problem were these nasty instabilities.
Again, you can see that as the implosion occurs though, these structures associated with the tense and the filled tube,
that as the implication happens, they became worse and worse and worse.
And so you had really degraded symmetry by the time the implosion happens.
However, after the kind of disappointing starts, there was a really, I think, really thought thoughtful,
science driven campaign that's kind of addressed the issues with the emotion experiments.
So the the low foots was the name of the Triumph. This was the kind of approach adopted by the National Ignition Campaign.
They changed the shape of the pulse shape for the so-called so-called efforts drive.
And this was showing stability. And you can see the fusion yields 27 kilojoules.
They then moved to a different type of a plate.
So originally they use plastic, then they moved the diamonds and slightly change propulsive against the bigfoots,
got them up to 55 kilojoules because of the stability, symmetry and energetics.
And just so I put a kind of phase based on from here. So this is the hot spot energy.
And when I do this, I'm inside the capsule and this is moving with no al 50 things and not cell facing effects.
This is a kind of measure performed to key measures of performance. And another one on the Y axis is hotspot pressure.
We want high energy and high pressure simultaneously.
What the these improvements mainly managed to do was improve the pressure conditions that were being obtained inside the capsule,
and there was some improvements of energy, but not that much. So that was the next thing to try to fix.
So how was that further progress made?
Well, the most obvious way to try to increase the energy is to increase the capsule size, increase the amounts of fuel.
And this is increasing this indeed increase the energy, but actually at a cost of increase decrease performance in terms of this pressure metric.
What went wrong? Well, it turns out that with this new, bigger capsules, the kind of previously carefully tailored laser pulses they have,
which then combust into a particular radiation drive, and that's the x ray.
The drive of the x ray was not optimum. The system, the so-called coast time was there for too long.
So that was one issue. Another issue was that there were these kind of quite significant deficiencies built in the new, larger capsule.
They hadn't quite optimised for the manufacturing process. And so that degraded the performance.
And you can see a lot of these and again, more instabilities associated with that.
So what the team did then was to improve the capsules and redesign the case and then deliver the burning plasma.
So this was in late 2020, early 2021, really exciting results.
So these experiments were typically yielding about 170 kilojoules of laser energy,
which, if you remember, is comparable to the extra energy driving the capsule.
Hence the burning plasma. So just to show you exactly what these experiments look like,
so this is a schematic of the precise dimensions of the successful experiment here with the precise dimensions of the goal itself,
the pulse shape, and then the whole mediation temperature.
And then, as you can see, you are now at the same pressures you were at before, but with the same energies that this large capsule had delivered.
And this got some attention got into nature, which is a metric that all scientists love.
And then in terms of just the key science metric here, so just to demonstrate that this assignment really did achieve was burning.
So basically the key metric is if you can get your plasma burning,
if the total gain in the fuel is five times the alpha heating, only a fifth of the energy goes into the alphas.
So you need to have five times that to be on this metric to be burning.
And these four shots here all achieved over that metric. Hence, this is burning.
I'm calling it the kind of peacekeeping at the the alpha meeting of the possible of the plasma is now comparable as the external.
This is about. Then came the experiment in August 2021, which was a really exciting result.
This was significant, said. So how was this achieved?
Well, what was that? What happened was we would use the site. Well, the team at Livermore, I should say, reduced the size of the engines,
hold that laser hits and keep more of the x rays and they then redesign the coast again, improve the quality of the place.
So again, this is now a diagram of what that again, what that was like.
It looks like the laser pulse and the radiation temperature. And you can see that this this is a quantum take up at the end of the radiation
temperature because you're now guessing really significant easing on the capsule.
And then this was the result. So you can now got these even better images, even better temperatures.
And I mean, the key metric here is the fusion yield that this was 1.3 mega joules.
These are some neutron and X-ray images from this particular implosion.
This was probably in the science community one of the most exciting results of all the ones I'm going to talk about,
because this was the first time we had kind of much more of a fusion energy out from the X-ray, energy driving the capsule four times eight.
And on the laser energy side, this is still not ignition by the definition, but we're getting pretty close.
This is point seven of the laser energy. This is about 1.9 mega joules.
So this was a really exciting results. And just to illustrate this points about the heating.
So for these after this was done, some detailed analysis was done of kind of the relative contributions of different types of heating and losses.
And you can see here that overwhelmingly now the alpha heating is the dominant quantity, keeping things hot.
And this is overwhelmed, say,
the conductive losses and then even actually at later times what turns out to be the biggest loss once the ignition has happened,
then you get the explosion, the kind of offices of the compression expansion cools things down,
but the alpha casing was able to overcome even that somewhat. Okay.
So if we just pause and take stock here. So since the national election campaign, we've now gone from 2.5 petajoules to 1.35.
So this is over 500 times improvement and a really exciting achievement.
And it was kind of done by carefully working out all of these. I kind of ironed out all these issues with the initial and I see design.
And then. Q As has been mentioned, there were lots of headlines about this.
BBC At times everyone got quite, quite excited. So that was kind of a good time to be in the field.
And I just want to make a note here that one of the reasons why I think a lot
of the scientists are so excited about this is when I started my PhD in 2015,
I was actually a lot of pessimism that this result would ever be obtains.
And so to go from that in seven years or six years, I should say,
to this is kind of a really kind of it was about sun and everyone was I'm very pleased about that.
So I think, okay, so what happens after August 20, 21?
Well, there was a appearance on. Well, the key question is, well, how a peaceful is this results?
And initially it wasn't very repeatable. Unfortunately, there's a lot of variability as it became known.
So what I'm saying here, so this is the kind of the big shot that got the very high energy yield, 1.3 mega joules.
And these were five shots that's followed subsequently on a plot of neutron yield, which is the energy, obviously.
And then I'll come back to what they consider in the other accesses and set and then just what this looks like in function of time.
This was the variability period you are getting yields, this kind of order of magnitude comparable but smaller by a factor of two six.
So it was not quite as impressive as previous results.
The question really is number one. Well, the first is this question, which is what's this on this axis here of placements?
So it turns out that we were kind of probably just quite lucky on that first
shot to get very good symmetry and very little mix if you try to replace that,
given manufacturing designs, things like that, the abrasive mix was much worse and so this degraded the performance.
For a similar reason. They were kind of more than these low moods asymmetries, these neutron emissions.
From these summits, you can see that they're not as nice and oracle as the the salt works.
And then finally, I just want to point out that this phenomenon around this point,
known as the ignition twist, which is when you're kind of at this point,
when you're getting this done in quite small changes in the input performance, then it's a very different kind of large changes in the energy out.
You can if you get 5% less pressure, you get kind of half or thirds of the energy that you got go sounds.
So basically this is why even these little changes were enough to really point degrade the performance.
However, as long as I'm on national team, I've been shown quite good evidence for doing it.
Times they kind of went back on board and ask, How can we make this more robust?
How can we overcome variability? And what was probably the really big thing was I decided to take advantage of the innocent life rather than be kind
of hampered by it and actually make some small changes that can be used to kind of push you over the threshold.
In particular, there were some redevelopments of the laser technology that I get a little bit on laser energy.
That's about about 7% more thumb. They went from 1.9 mega joules to 2.5 megatons.
And then so with this kind of using this little bit of extra energy,
what they could then do was redesign the capsule, have a thicker a blazer and go for slightly longer laser pulses.
Both of these factors in a particular place, it gives you more compression.
And so this should help performance. And so they kind of re optimise trying to do some initial optimisations to kind
of use this a better capsule that should get more energy to achieve the results.
And and what they found was that it was good the result of doing this.
They ended up with fusion yields that were now comparable to the previous record, but not better.
And again, there were two issues that they identified.
The first was same capsule manufacturing issues. You can see these kind of impurities in the in the shell of the of the HTC Diamond shell.
Again, that came up because they now were changing the thickness again. And then also, you can see that this was the shot, the 1.3 mega joules.
And this was the most of the data show on this spot here.
You can see it's less symmetric. And this was a slightly unexpected asymmetry.
That's quite a bit of time to work out what was going on.
And then the team looks at this, they redesign the laser drive.
And then the shot that you probably all heard about happened in December 20 Institute.
So what they basically redistributes is how the laser is,
what is happening on the inside of the whole rim, and then they manage to get rid of the symmetry.
And this was the shot that got the 3.15 mega joules from the 2.05 mega joules of laser energy they had.
Yes. So what's the headline results? Fusion yields the 3.1. mega joules.
This is now 17 times the extra energy.
So qualitatively, this is not actually that different from the August 2021 shots, albeit with something more robust.
However, this one has now gone over the laser energy threshold, and so by the National Academy of Sciences, definition is ignition.
And now this is up to a 1500 times improvements over in the last year.
In the last ten years. Okay.
So that was a really exciting results.
Then covered lots of headlines, but now the really hot topic in my field is this question How can we do even better?
How do we go from these gains of 1.5 to Graceland?
ForeSee, which is the minimum for what you'd need for actual making power generation work.
Well, there are two approaches to this.
The first, which is the approach that the team at the National Lab and a few key people in my hurricane and literature, and I'm.
Zijlstra Three scientists, you've been really driving the approach with this.
They are going to continue to optimise the kinds of approach,
so they're still working on getting better laser X-ray coupling, using more efficient homes,
achieving high compression by further shaping the pulse to get kind of every little drip out of what you can get with the current system.
And then finally using their now plans to refurbish the laser to go to 2.5 to 3 mega joules over the next few years.
And with that, you can then scale to larger capsules.
And because of the ignition cliff, this should go some way to getting gains well beyond the 1.5 that was achieved last December.
The other approaches asking, which is, I guess what I'm more closely working on is can we leverage plasma physics,
which in many ways the plasma physics of these equations is not that well understood.
To design better capsules, just one illustration of the way that which is not very well understood.
These are some recent experiments reported late last year.
Similar thing on the NIF and implosion and what they were measured here quite carefully was
the time time of flights of neutron neutrons being emitted by the implosion of the capsule.
And then from this the on this experimental team was able to infer the energy spectrum of neutrons being emitted by the plasma.
And then from this and something about the ions themselves undergoing fusion reactions and what they discovered was very unexpected,
which is the distribute of the,
the plasma that they were looking at was not implement dynamic equilibrium and has some very novel less kinetic features like suns out.
These features are not well model. By just using hydrodynamic fluid codes, you need these more complicated kinetic physics to understand them.
And because I mean this very basic physics about how the fusion reaction is happening,
we clearly haven't optimised for that at the moment because we don't really understand that well.
And that's one aspect. The thing I'm really interested in, however, is magnetic fields,
which typically in the modelling of this have been ignored, but recently there's been some understanding of that.
Magnetic fields could actually be really helpful for delivering even better capsules.
So why do my classic goals matter? And I do experiments. Well, it turns out this magnetic field is a spontaneously generated.
And if isofix moments are strong enough to monetise the platform's electrons.
What do I mean by that? Well, in a completely on market size plasma, I have an electron detector here and it's just wandering around.
What happens is, due to encountering kind of fluctuations in the electric field on the microscopic scale in the plasma due to the other electrons,
you can kind of think of these as a bit like collisions. I'm one of those formulae and those analogies collisional scattering.
Basically the electron will eventually be deflected and it's these collisions that then mediate transports.
I'll come back to that. However, if the magnetic fields and there are no magnetic fields in the past,
when they become strong enough, what you end up with is instead a diagram.
I'm just saying this is a nickel of electrons instead of being confined to these field lines.
And this affects fundamentally how such plasmas conduct heats.
And I'll come back to this.
So the key parameter for determining when you go from something like this to something like this is a thing called the field parameter.
It's basically the ratio of what's called the memory path, if you think back to a physics phase divided by the gyro radius.
So the giant radius is this kind of the radius of these orbits.
And then if your path is the length, go to four, which you guess is a fraction of a possible.
And so these are some relatively recent state of the arts simulations of an inflation in the stagnation phase.
I'm done by Chris Walsh, who's now at national level.
And so what you can see here, so this is the density and the temperature.
And it turns out the kind of the asymmetries you get, even in a relatively good implosion,
give rise to misaligned density and temperature gradients which generate these strong fields as shown here.
And this creates all fantasies about what you can see, where this effect starts to matter.
Why are these magnetic, simple pills and why do they matter?
Well, it turns out that if you have magnetised electrons, this enables you to suppress heat conduction,
which is great, because that's one of the main loss mechanisms for these implosions.
Well, the basic physics underpinning is this physics here, which is basically, if you have a magnetic field,
this very large scale in order, you can suppress transports across the field lines.
And that way in these experiments, there's also another effect that's a bit more subtle.
Once you have these magnetic fields on larger scales, this enables other small scale fields driven by micro instability so much.
And this can actually, it turns out, make suppress the field, suppress its conduction along the field lines, too.
And so now if we can leverage both of these things together, we can suppress a lot of heat conduction in general.
Incidentally, this physics is probably most explored, not so much in the ICF context, but actually in astrophysics.
So this is an image of the temperature profile of the cluster meaning of a galaxy cluster.
And you can see so this is infers by looking at X-ray observations of a galaxy cluster.
And you can basically by looking at different parts of the spectrum of the X-rays, you can then infer these symptoms.
And you can see here that these these images have a lot of structure in them.
At the same time, if you can model these kind of globally ignoring magnetic fields, you wouldn't see any of the structure.
You'd instead have a very smooth profile.
So the fact that there's a lot of structure here is indicative of magnetic fields, all in fact, suppressing the conduction.
Why investigate this possibility now?
Well, in addition to the confusion applications I've just mentioned, it's actually just from a technological perspective,
the perfect time for advancing understanding of these plasmas on these magnetised fasteners.
The first thing is it's now become computationally feasible to do kinetic simulations of these parts.
In this way, you evolve not just kind of macroscopic things, density and temperature in a simulation,
but the very distribution function of the particles themselves. Understanding how different types of particles at different speeds behave.
And so these were some simulations recently investigating exactly the sorts.
Another thing we can now do,
thanks to the kind of increased proliferation of these high energy facilities where you can do experiments that are not just ICF
focussed but also just bespoke and a fundamental part of the experiments you can really now probe of processes like this in the lab.
So during my Ph.D., I worked on a series of experiments investigating the phenomenon of magnetic field amplification, interpreting laser plasmas.
The way the system works is that we irradiated two foils with laser energy.
This is on the omega 60 laser in the US and that creates two jets of plasma.
Those two jets pass through two grids and like water flowing through a grid, this begins to make turbulence.
We then client them together and you end up with a type of plasma in the middle.
And here are some X-ray emission images showing that turbulence. And then what we did is we use some very specialised diagnostics to measure
the kind of basic state of the plasma and in particular the magnetic fields.
And you can see that you get these very complicated structures merging and emerging in this plasma, which we were able to diagnose in some depth.
So combining these things together,
we can now come up with new models for thermal conduction with these magnetic fields and actually test them in the lab.
What have we done so far on this? Well, I'm not going to detail, but we've done a combination of some theoretical numerical and experimental studies.
So on the theoretical side, it turns out there's a whole zoo of these instabilities, that kind of micro instability.
In mice, we've identified 16.
And so you really need to classify them very carefully and work out which one matters as a function of how dense you'll find some is or hypotheses.
And so we've worked out now the space based diagram. Which of these instabilities is the one you really need to study?
On the simulation sites. We have been running simulations of these individual instabilities, such as the virus instability,
and we've shown that we can now characterise how transport kind of saturates in these particles when there is a presence.
And finally, we, my colleague,
colleague John and Monica led this really interesting experiment on demonstrating suppression of heat conduction in a laboratory, turbulent plasma.
Again, it's very similar to what I just described to racing in turbulent plasma.
But this was done on the National Ignition Facility, which is also in the field.
Is that even stronger? And what's a Jennifer found was that if you naively ignore magnetic fields involved in thermal conduction,
as we did in the simulations I'm showing here and then local what the temperature of this plasma should look like.
Again, inferred from the X-ray technique.
As I mentioned, in the astrophysical context, you should have very smooth profile like this, but that's what the actual data look like.
You see all these small scale fluctuations and then it was able to show that the difference
between these two is consistent with 100 times decrease in conductivity in this plasma.
So the magnetic fields really suppress thermal conduction processes in this situation.
Okay. So that's I'm talking about the kind of fundamental research on studying how magnetic fields affect conduction in these plasmas.
Now the question is you might ask, well how can we then turn its back into some applications of fusion?
And I think there's been some really promising first steps and this led by another team of different kinds of media and collaborators.
And so they also they've been doing is imposing a background field on the whole when I'm looking something like this.
So what you you've now got the same hologram design.
You have the lasers in the capsule, but now you put a solenoid coil around the outside of your home,
and then you apply a magnetic field that looks like this on the top. And what they found in their preliminary experiments,
which unfortunately they haven't been able to do t experiments yet because of the cryogenic constraints of doing those experiments.
But they have done experiments using deuterium, deuterium, fuel, and they found that with those preliminary experiments,
anything in the magnetic field gives you about temperatures that's about 40% higher and yields are about three times higher.
So this preliminary results is really exciting. And because of how interesting these results have been,
there's now a kind of dedicated plan to do experiments with the same idea and this in the next few years.
And I'm really optimistic that actually this will results in quite significant kind of jumps in the again you can get.
Okay. I'm going. This is my final slide, so I just kind of want to round up.
I just wanted to talk a bit about the natural fusion energy. So we've had all these headlines, these big results.
This has been real progress, but that's still the kind of key question here,
which is what would need to happen to make a national fusion energy system using a national component fusion as an energy source, as a reality.
How do we go from this to an actual power plant? Well, I'm going to just highlight five factors here.
This I think you would need to make, that's reality. The first is high gain.
And as I pointed out earlier, it's not just enough to have ignition.
You need to have enough energy to actually make wheel plug efficiency.
And for that, we need these high gains of about over 40.
And I'll come back to why that number is crucial in just a sec.
The second point is the laser efficiency amendment, the wall plug efficiency of the national, which means that AC is only about point 6%.
That means that if you want a power, you need to be getting 600 or even a gigajoule of energy out, which is way beyond where we are now.
I'm one way that I think we can overcome and improve the laser efficiency is
that the technology underpinning this is actually quite old in a certain sense.
It's using these elements which are not very efficient, though. Now it's this new diamond places that have a much higher plug efficiency.
So probably of the order of 50% now and I think in five years, 20% seems to be on the cards.
So that will go a long way to overcoming this issue of what if we have a 20% laser efficiency laser with two mega joules,
what you would then need would be maybe 40 mega joules, and then you'd have a gain of four in terms of energy.
And so the fact of 24th year I mentioned is coming from another thing is of course, these experiments actually make energy.
You need to be having doing this consistently. The idea with international fusion energy is that you wouldn't be doing this once every time.
Was that you, as the current NIF operates, that you'd be doing this once, ten times in seconds.
So we need to work out how to turn something like this, which is 95 very, very intermittently compared to that metric.
As I said, how you turn that into something that fires rapidly.
Again, laser technology can help pair these same high, high efficiency lasers can get much higher shot rates.
That being said, there's never been a mega jewel class diode laser that's been made yet.
So that's still something that needs to be worked on to make sure that works. We are kind of.
Okay. And. The final?
Well, the first thing I want to mention is the simplify the economic target design.
You can see that the targets I talked about are really, really competencies.
And the idea that we're going to try to make precision ten of these seconds in the right place is a really difficult technological challenge,
to put it mildly. So, I mean, to be frank, I think there are people who are working on exactly this problem, some private companies looking at this.
I think probably we need to work out how to design simplified targets that you could find ten times a second to work on.
And that's the well, people looking at such a piece of noisy work say I was thinking about how you might do that and how what schemes would do that.
So these things would advance technician schemes, which can work in principle using simple designs.
And then finally there's a lot of work still needs to be done in materials science, particularly, for example.
It turns out when you get these very high gain experiments that can damage the optics of the lasers themselves over a kind of a period.
And so we if we're going to do a high rep rate, we need to get kind of more robust optics.
So I mean, all of these I think the high again, there's an efficiency and a high repetition.
So I think actually we have very good path to solving them.
I think the hardest problem is going to be this thing about the targets this simplifies.
I'm optimistic. It's a problem. I think we can solve it, but I think that's the biggest now anyway.
I think that's what I want to say. Thank you for our attention, because I'd like to take any questions.