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Yes, so thank you very much.

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I'm very excited to be talking to you about this topic, and I hope it will lead to getting us enthused about this

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as I do. Okay. So I'm just going to give a kind of brief overview for the structure of my talk.

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And it starts off by talking about what the national climate fusion is.

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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.

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And how could it possibly do ICF?

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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.

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Try, try again. I'm going to talk about the very initial disappointing setbacks and then the recovery period from that.

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And then the last few years, which have been very exciting in terms of results, as you probably gather from the news.

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And then I'm the third plus mine talking about how we can do even better, an approach that's living with other survivors.

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High gain ICF assignments.

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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,

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which is how we might be able to leverage novel plasma physics to really take the novel plasma

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physics of magnetised weakly collisional plasmas to really kind of make a big step forward.

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And then finally, probably the things most of you are interested in this idea is think about the relation of

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this to inertial fusion energy that's using inertial confinement fusion to deliver energy.

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I'm just going to talk a little bit about what you actually need to solve to make that happen.

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Okay. So very, very soon. It starts off with what's his initial confinement fusion?

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Well, as we've heard, to kind of make fusion happen, what you need to do is combine a very hot plasma.

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One way of doing that, which you've heard about so far, thanks to Michael and Georgia,

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is a magnetic confinement fusion where we're thankfully using a magnetic cage.

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Either tokamak, which celebrates such as Spindle seven X as we've got here,

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and your sense of approach, which I'm going to be talking about, this inertial confinement fusion.

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And that's simply basically what you're doing is you're making fusion reaction happen before the plasma has a chance to escape.

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Now, we actually worked out how to do this in the middle of the last century.

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Using the bombs.

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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.

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Well, as you might imagine, there are a few engineering problems to using nuclear bombs to make power plants.

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Although that didn't actually stop some people trying. But that's just talk for another subject, for another talk.

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So what I'm going to talk about is trying to do the same thing using lasers instead.

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Now, basically, two types of ways of using lasers to make inertial confinement shouldn't happen.

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The first is called Direct Drive ICF.

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The idea here is you take optical lasers and it radiates a spherical capsule containing your fusion fuel, which is a deuterium.

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I'll come back to the exact capsule structure in a sec. And you irradiate the edge of it.

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And this creates rapidly creates a plasma around the edge of the capsule and a bit like hot gas streaming off behind a rocket.

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This causes the whole capsule's compress. And as you can see, you get a lot of transport of thermal energy from the air,

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from the laser in towards the centre when you get in higher density, high temperatures as the compression occurs.

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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,

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Kelvin, and the density at the centre of this, which is about 20 times that's a solid density of LEDs.

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And then if you get to those conditions, this capsule will make a nights and then burn.

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So that's the very basic idea of direct drive, as if as an alternative scheme through the school of indirect drive,

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where you don't drive the the capsule itself with fusion fuel,

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but instead the final phase is inside a gold cylinder as a whole, them which is made of gold behind that material.

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And by irradiating the inside of this whole room with x rays, with the optical lasers, you create a lot of x rays.

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And it's then these x rays that you use to implode the capsule in the same way as with direct drive.

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Use optical lasers to do that.

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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.

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Okay. So just jumping in a bit more, describing what these ICF councils look like.

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So they basically have the following structure in the simplest form.

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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.

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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.

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So you have a layer of fuel. This is usually dirty ice.

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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.

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And then inside that you have to guess and basically you can control the density.

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It's at the main implosion stage by the thickness of the fuel use.

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Now, as you fly the lasers, I've got different times. So we see the initial time.

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This is the size of the capsule. Then as we place, as we find the places, we get a lot of data possible,

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but then the sensor is imploding and then at the very end we end up this highly, much more dense capsule.

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And then if we designed it right,

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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,

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this turns out to be one of the main issues with these instabilities.

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And I'll come back to this in due course. Okay.

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So what's the basic physics that we need to get an ICF capsule's work?

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Well, initially, what role? Fundamentally, we need the heating processes.

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So that's initially the implosion, the compression, and then subsequently the alpha heating,

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the heating by alpha particles released during the reaction of the self-heating to overcome any losses in the system.

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So I said the two main heating mechanisms initially it's the compression that's

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doing PB work and so that that increases the temperature as well as the density.

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And then in addition, once the alpha, once you start getting fusion reactions, if the density of the fuel was high enough,

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these can then actually keep that fuel and you get the kind of self-sustained reaction that's cool alpha you think.

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And then the probably at this earlier stage whilst the implosion is happening, the two main loss mechanisms are radiation.

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So these are X-rays emitted by the hot plasma in the sensor escaping, and then also thermal conduction,

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which is typically coming by electrons away from the hot, hot spot into the cold fuel.

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And just so for ignitions work, we need heating. So obviously better than cooling.

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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.

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So initially the scale of them is about two millimetres in diameter and then one by the time it's imploded.

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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.

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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.

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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,

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I want to use x rays through many of this capsule because surely there's going to

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be some inefficiency by putting my laser energy into this into this whole damn.

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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

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typically about 10% of that laser energy burst into the x rays that then implodes the capsule.

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However, one of the main things that's been I mentioned that's been challenging and it turns out this is more

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challenging for direct drive dress than direct to drive is an indirect drive is the problem of instabilities.

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If you have any either in homogeneity, in the in the laser intensity that you have on the surface Security Council or you

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have any say manufacturing deficiencies on the surface as the implosions happen,

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an instability that you may have learning about the maybe Tyler instability kicks in and this kind of causes the surface to buckle.

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And basically as the surface buckles, this mixes the laser into the centre of the capsule and degrades performance.

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And so this is the kind of earlier experiments. These are what some have done on the nouvelle laser in the mid-nineties already.

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From these X-ray emission images, you can very clearly see these structures developing.

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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,

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they typically end up with more uniform illumination relative to direct drive of the capsule,

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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.

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So this is why well,

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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.

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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.

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You can see in the UK the biggest places is because of the Vulcan.

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There's a round from Bawtry and the wind lies way and it's just all over the place.

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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.

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The national ignition is in Livermore, California. So this is an aerial photograph of the sites.

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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.

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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.

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So it's a pretty mammoth facility. And so here's some kind of kind of more detailed schematic.

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I'm going to be going through the schematic and talking about how the laser works

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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.

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When it fires on this and that laser energy is released to the to the target chamber with a wavelength of 351 nanometres.

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At the moment when the laser is firing, has the power outputs of the entire US national grid.

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I just still find this extraordinary and it has 192 beams that all convergence this very small volume inside this whole room.

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When I Google once preparing this talk, I looked up national instant settings on Twitter.

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I also learned that it's the warp drive for the Enterprise Starship, as you can see from this very realistic photo.

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This is the next target chamber behind this great that you can use these things in multiple ways.

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So how does this work?

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Well, you may recall from your physics studies that the basic principle of lasers is basically leveraging, stimulates the mission of excited atoms.

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So you will remember in a two level system with three basic processes that you and one need to consider.

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So if you have a photon with the right energy coming in with two levels a system,

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an electron sitting in some ground state can be excited up into the higher level simultaneously as well.

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Secondly, if you have an electron that's already sitting in the excited level,

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that can then move down to the lower level and spontaneously emits a photon of the energy between the two levels.

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And then finally,

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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,

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otherwise energy arrives on the electronic at sciences level can fall down,

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and then you end up with two photons emitted with the same energy, but also coherence.

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And for a really good laser, you want lots and lots of coherence and photons.

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And so basically it's the simulated emission process that underpins how lasers work.

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Now it's a little bit more complicated than that. There are certain kind of conditions you need for those actions to work.

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The most important one is population inversion. Okay.

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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.

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Now you will call and this is actually quite an unnatural state. It's the opposite of that.

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It's not a thermodynamic equilibrium. And so this is actually kind of fundamentally why finding lasing materials is quite challenging.

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Achieving this is not something that many materials can do easily.

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There are other conditions.

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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.

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And then finally, you need a sufficiently high pumping rate that is pushing at science's electron electrons, exciting them into this upper level.

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And you need those electrons to sit in that level for long enough.

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And when you put all of these things together to actually achieve it, a two level system that works, you typically need a system.

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So again, it's a medium with it over two levels, like having a sample of a three level laser.

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The NIF laser is actually a full level one.

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And then basically you have two levels within that four level system between which you'll get some more laser action.

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And it's by using these more complicated levels that you can actually manage to achieve population inversion in the immaterial.

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Okay. So what's what how does this work specifically? Well, what we need on this is an item in the phosphate glass.

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I've got a photograph of it. Here is this kind of paint colour.

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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

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mast oscillator which is here it then it's quite a little bit before it's then passed along into the main amplifier base.

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Now the way that the main application occurs is you see that there are these capacitor banks nearby,

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these charge flash lamps, which basically excited lots of electrons into the right level one substation.

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But that's basic idea. And so by having these flash lamps, this enables the mediums to do its thing.

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And then now you can apply the laser up to very high and the very high energies you need.

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And here is a photograph of the the laser base on this.

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Once you've kind of amplified the beings, subsidise energy, you have to do some fine tuning to them.

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There's a kind of complicated set of filtering. You've got company spatial filtering as shown here.

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You polarise the beam.

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That's another level of filtering to make sure that you remove any aberrations in the lenses, get the smoothest possible profiles,

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and then you transport them back along here into the switchyard where the beans are then kind

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of arranged as they need to be before they we then eventually get them in the final optics.

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Now what these so here's a schematic of these final optics and some photographs of them.

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What they're doing here is that the original laser seed is actually infrared light source 1053 nanometres.

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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.

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So relatively efficiently, over 50% convert that infrared light into ultraviolet light.

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That's better with implosions. And so that's done through the station here and you end up with that's the two.

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That's what then gives you the two mega jewels of this and 3519 amazing lights.

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Okay. And then once those are they pass through the final objects, they're all focussed in the centre of the target chamber.

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So this is about ten metres across and some people that's a scale,

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but then all being focussed right into the centre of the chamber since we set disagreements.

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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.

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And the laser beams are coming in each size like this to radiate the sense within into that I the goals,

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as you can tell, probably from the look of the material.

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And they've also got these holes in the side to help kind of diagnose what's going on.

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That's the photograph of the hole I'm holding on the sides.

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And then that's a scale image, comparing the human eyes to see have a sense of how big these things are.

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Actually very small. Then the capsules themselves this even smaller.

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This is a photograph of one use in an experiment. This is about two millimetres across.

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And then the idea here is that you are then schematic of the radiation going in on the inside.

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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.

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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.

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And then you've also got this fills you coming in, which is what fills the DC gas in the centre of the capsule.

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So there are some complications. So beyond the basic picture,

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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.

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And I'll come back to what I mean by that in due course. Okay.

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And then all of the operations this is delivered from a nice central location by the incredibly professional ensemble national staff.

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I've worked with them before and that they're just great.

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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.

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And this a great countdown when the beams about to go. It's really fun. So it an amazing place to do what.

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Okay so what are the key numbers to remember to NIF? Well, so there is this point.

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So I said that the capacitors need to be charged up and this is effectively the wall plug efficiency of NIF.

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And as was mentioned earlier, this is actually not very efficient at the moment. You need 320 mega joules approximately so in the capacitors.

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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.

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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.

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So those are just three numbers to keep in mind and then some key concepts.

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So I'm going to come back to in this talk kind of so the National Academy of Sciences,

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a definition of what ignition is, is basically having more fusion energy out from this than the laser energy.

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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.

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And this is kind of the points at which the kind of fuel is beginning to ignite.

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The heating is coming from the alpha particles, not just the compression, and then the self-heating plasma is one way.

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The fusion energy is much greater than the extra energy. And this is really burning and kind of self-sustaining.

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And then finally and I'll come back to the end result.

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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,

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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.

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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.

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And the goal of this was to just really go will then fire all blazes to get this done.

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And it didn't work. They only achieved the best shots, achieved less than three kilojoules of use an energy ounce.

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The main problem is that they kind of start off with these more cautious thoughts,

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and then when they round up the energy, they actually got degraded performance and subsequent kind of state of the art.

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Simulations of these experiments realised that the main problem were these nasty instabilities.

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Again, you can see that as the implosion occurs though, these structures associated with the tense and the filled tube,

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that as the implication happens, they became worse and worse and worse.

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And so you had really degraded symmetry by the time the implosion happens.

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However, after the kind of disappointing starts, there was a really, I think, really thought thoughtful,

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science driven campaign that's kind of addressed the issues with the emotion experiments.

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So the the low foots was the name of the Triumph. This was the kind of approach adopted by the National Ignition Campaign.

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They changed the shape of the pulse shape for the so-called so-called efforts drive.

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And this was showing stability. And you can see the fusion yields 27 kilojoules.

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They then moved to a different type of a plate.

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So originally they use plastic, then they moved the diamonds and slightly change propulsive against the bigfoots,

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got them up to 55 kilojoules because of the stability, symmetry and energetics.

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And just so I put a kind of phase based on from here. So this is the hot spot energy.

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And when I do this, I'm inside the capsule and this is moving with no al 50 things and not cell facing effects.

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This is a kind of measure performed to key measures of performance. And another one on the Y axis is hotspot pressure.

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We want high energy and high pressure simultaneously.

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What the these improvements mainly managed to do was improve the pressure conditions that were being obtained inside the capsule,

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and there was some improvements of energy, but not that much. So that was the next thing to try to fix.

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So how was that further progress made?

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Well, the most obvious way to try to increase the energy is to increase the capsule size, increase the amounts of fuel.

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And this is increasing this indeed increase the energy, but actually at a cost of increase decrease performance in terms of this pressure metric.

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What went wrong? Well, it turns out that with this new, bigger capsules, the kind of previously carefully tailored laser pulses they have,

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which then combust into a particular radiation drive, and that's the x ray.

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The drive of the x ray was not optimum. The system, the so-called coast time was there for too long.

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So that was one issue. Another issue was that there were these kind of quite significant deficiencies built in the new, larger capsule.

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They hadn't quite optimised for the manufacturing process. And so that degraded the performance.

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And you can see a lot of these and again, more instabilities associated with that.

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So what the team did then was to improve the capsules and redesign the case and then deliver the burning plasma.

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So this was in late 2020, early 2021, really exciting results.

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So these experiments were typically yielding about 170 kilojoules of laser energy,

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which, if you remember, is comparable to the extra energy driving the capsule.

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Hence the burning plasma. So just to show you exactly what these experiments look like,

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so this is a schematic of the precise dimensions of the successful experiment here with the precise dimensions of the goal itself,

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the pulse shape, and then the whole mediation temperature.

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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.

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And this got some attention got into nature, which is a metric that all scientists love.

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And then in terms of just the key science metric here, so just to demonstrate that this assignment really did achieve was burning.

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So basically the key metric is if you can get your plasma burning,

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if the total gain in the fuel is five times the alpha heating, only a fifth of the energy goes into the alphas.

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So you need to have five times that to be on this metric to be burning.

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And these four shots here all achieved over that metric. Hence, this is burning.

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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.

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This is about. Then came the experiment in August 2021, which was a really exciting result.

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This was significant, said. So how was this achieved?

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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,

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hold that laser hits and keep more of the x rays and they then redesign the coast again, improve the quality of the place.

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So again, this is now a diagram of what that again, what that was like.

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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

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temperature because you're now guessing really significant easing on the capsule.

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And then this was the result. So you can now got these even better images, even better temperatures.

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And I mean, the key metric here is the fusion yield that this was 1.3 mega joules.

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These are some neutron and X-ray images from this particular implosion.

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This was probably in the science community one of the most exciting results of all the ones I'm going to talk about,

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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.

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And on the laser energy side, this is still not ignition by the definition, but we're getting pretty close.

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This is point seven of the laser energy. This is about 1.9 mega joules.

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So this was a really exciting results. And just to illustrate this points about the heating.

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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.

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And you can see here that overwhelmingly now the alpha heating is the dominant quantity, keeping things hot.

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And this is overwhelmed, say,

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the conductive losses and then even actually at later times what turns out to be the biggest loss once the ignition has happened,

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then you get the explosion, the kind of offices of the compression expansion cools things down,

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but the alpha casing was able to overcome even that somewhat. Okay.

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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.

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So this is over 500 times improvement and a really exciting achievement.

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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.

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And then. Q As has been mentioned, there were lots of headlines about this.

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BBC At times everyone got quite, quite excited. So that was kind of a good time to be in the field.

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And I just want to make a note here that one of the reasons why I think a lot

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of the scientists are so excited about this is when I started my PhD in 2015,

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I was actually a lot of pessimism that this result would ever be obtains.

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And so to go from that in seven years or six years, I should say,

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to this is kind of a really kind of it was about sun and everyone was I'm very pleased about that.

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So I think, okay, so what happens after August 20, 21?

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Well, there was a appearance on. Well, the key question is, well, how a peaceful is this results?

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And initially it wasn't very repeatable. Unfortunately, there's a lot of variability as it became known.

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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.

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And these were five shots that's followed subsequently on a plot of neutron yield, which is the energy, obviously.

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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.

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This was the variability period you are getting yields, this kind of order of magnitude comparable but smaller by a factor of two six.

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So it was not quite as impressive as previous results.

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The question really is number one. Well, the first is this question, which is what's this on this axis here of placements?

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So it turns out that we were kind of probably just quite lucky on that first

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shot to get very good symmetry and very little mix if you try to replace that,

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given manufacturing designs, things like that, the abrasive mix was much worse and so this degraded the performance.

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For a similar reason. They were kind of more than these low moods asymmetries, these neutron emissions.

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From these summits, you can see that they're not as nice and oracle as the the salt works.

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And then finally, I just want to point out that this phenomenon around this point,

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known as the ignition twist, which is when you're kind of at this point,

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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.

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You can if you get 5% less pressure, you get kind of half or thirds of the energy that you got go sounds.

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So basically this is why even these little changes were enough to really point degrade the performance.

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However, as long as I'm on national team, I've been shown quite good evidence for doing it.

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Times they kind of went back on board and ask, How can we make this more robust?

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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

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of hampered by it and actually make some small changes that can be used to kind of push you over the threshold.

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In particular, there were some redevelopments of the laser technology that I get a little bit on laser energy.

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That's about about 7% more thumb. They went from 1.9 mega joules to 2.5 megatons.

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And then so with this kind of using this little bit of extra energy,

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what they could then do was redesign the capsule, have a thicker a blazer and go for slightly longer laser pulses.

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Both of these factors in a particular place, it gives you more compression.

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And so this should help performance. And so they kind of re optimise trying to do some initial optimisations to kind

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of use this a better capsule that should get more energy to achieve the results.

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And and what they found was that it was good the result of doing this.

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They ended up with fusion yields that were now comparable to the previous record, but not better.

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And again, there were two issues that they identified.

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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.

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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.

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And this was the most of the data show on this spot here.

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You can see it's less symmetric. And this was a slightly unexpected asymmetry.

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That's quite a bit of time to work out what was going on.

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And then the team looks at this, they redesign the laser drive.

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And then the shot that you probably all heard about happened in December 20 Institute.

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So what they basically redistributes is how the laser is,

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what is happening on the inside of the whole rim, and then they manage to get rid of the symmetry.

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And this was the shot that got the 3.15 mega joules from the 2.05 mega joules of laser energy they had.

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Yes. So what's the headline results? Fusion yields the 3.1. mega joules.

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This is now 17 times the extra energy.

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So qualitatively, this is not actually that different from the August 2021 shots, albeit with something more robust.

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However, this one has now gone over the laser energy threshold, and so by the National Academy of Sciences, definition is ignition.

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And now this is up to a 1500 times improvements over in the last year.

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In the last ten years. Okay.

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So that was a really exciting results.

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Then covered lots of headlines, but now the really hot topic in my field is this question How can we do even better?

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How do we go from these gains of 1.5 to Graceland?

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ForeSee, which is the minimum for what you'd need for actual making power generation work.

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Well, there are two approaches to this.

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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.

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Zijlstra Three scientists, you've been really driving the approach with this.

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They are going to continue to optimise the kinds of approach,

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so they're still working on getting better laser X-ray coupling, using more efficient homes,

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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.

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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.

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And with that, you can then scale to larger capsules.

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And because of the ignition cliff, this should go some way to getting gains well beyond the 1.5 that was achieved last December.

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The other approaches asking, which is, I guess what I'm more closely working on is can we leverage plasma physics,

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which in many ways the plasma physics of these equations is not that well understood.

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To design better capsules, just one illustration of the way that which is not very well understood.

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These are some recent experiments reported late last year.

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Similar thing on the NIF and implosion and what they were measured here quite carefully was

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the time time of flights of neutron neutrons being emitted by the implosion of the capsule.

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And then from this the on this experimental team was able to infer the energy spectrum of neutrons being emitted by the plasma.

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And then from this and something about the ions themselves undergoing fusion reactions and what they discovered was very unexpected,

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which is the distribute of the,

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the plasma that they were looking at was not implement dynamic equilibrium and has some very novel less kinetic features like suns out.

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These features are not well model. By just using hydrodynamic fluid codes, you need these more complicated kinetic physics to understand them.

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And because I mean this very basic physics about how the fusion reaction is happening,

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we clearly haven't optimised for that at the moment because we don't really understand that well.

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And that's one aspect. The thing I'm really interested in, however, is magnetic fields,

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which typically in the modelling of this have been ignored, but recently there's been some understanding of that.

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Magnetic fields could actually be really helpful for delivering even better capsules.

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So why do my classic goals matter? And I do experiments. Well, it turns out this magnetic field is a spontaneously generated.

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And if isofix moments are strong enough to monetise the platform's electrons.

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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.

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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,

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you can kind of think of these as a bit like collisions. I'm one of those formulae and those analogies collisional scattering.

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Basically the electron will eventually be deflected and it's these collisions that then mediate transports.

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I'll come back to that. However, if the magnetic fields and there are no magnetic fields in the past,

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when they become strong enough, what you end up with is instead a diagram.

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I'm just saying this is a nickel of electrons instead of being confined to these field lines.

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And this affects fundamentally how such plasmas conduct heats.

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And I'll come back to this.

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So the key parameter for determining when you go from something like this to something like this is a thing called the field parameter.

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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.

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So the giant radius is this kind of the radius of these orbits.

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And then if your path is the length, go to four, which you guess is a fraction of a possible.

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And so these are some relatively recent state of the arts simulations of an inflation in the stagnation phase.

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I'm done by Chris Walsh, who's now at national level.

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And so what you can see here, so this is the density and the temperature.

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And it turns out the kind of the asymmetries you get, even in a relatively good implosion,

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give rise to misaligned density and temperature gradients which generate these strong fields as shown here.

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And this creates all fantasies about what you can see, where this effect starts to matter.

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Why are these magnetic, simple pills and why do they matter?

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Well, it turns out that if you have magnetised electrons, this enables you to suppress heat conduction,

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which is great, because that's one of the main loss mechanisms for these implosions.

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Well, the basic physics underpinning is this physics here, which is basically, if you have a magnetic field,

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this very large scale in order, you can suppress transports across the field lines.

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And that way in these experiments, there's also another effect that's a bit more subtle.

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Once you have these magnetic fields on larger scales, this enables other small scale fields driven by micro instability so much.

383
00:34:31,790 --> 00:34:38,600
And this can actually, it turns out, make suppress the field, suppress its conduction along the field lines, too.

384
00:34:38,790 --> 00:34:43,880
And so now if we can leverage both of these things together, we can suppress a lot of heat conduction in general.

385
00:34:45,500 --> 00:34:50,690
Incidentally, this physics is probably most explored, not so much in the ICF context, but actually in astrophysics.

386
00:34:50,930 --> 00:34:56,000
So this is an image of the temperature profile of the cluster meaning of a galaxy cluster.

387
00:34:56,690 --> 00:35:01,430
And you can see so this is infers by looking at X-ray observations of a galaxy cluster.

388
00:35:01,790 --> 00:35:08,210
And you can basically by looking at different parts of the spectrum of the X-rays, you can then infer these symptoms.

389
00:35:08,630 --> 00:35:11,720
And you can see here that these these images have a lot of structure in them.

390
00:35:12,200 --> 00:35:18,290
At the same time, if you can model these kind of globally ignoring magnetic fields, you wouldn't see any of the structure.

391
00:35:18,290 --> 00:35:19,970
You'd instead have a very smooth profile.

392
00:35:20,240 --> 00:35:25,790
So the fact that there's a lot of structure here is indicative of magnetic fields, all in fact, suppressing the conduction.

393
00:35:27,530 --> 00:35:29,240
Why investigate this possibility now?

394
00:35:29,270 --> 00:35:34,219
Well, in addition to the confusion applications I've just mentioned, it's actually just from a technological perspective,

395
00:35:34,220 --> 00:35:38,630
the perfect time for advancing understanding of these plasmas on these magnetised fasteners.

396
00:35:39,050 --> 00:35:43,310
The first thing is it's now become computationally feasible to do kinetic simulations of these parts.

397
00:35:43,310 --> 00:35:47,930
In this way, you evolve not just kind of macroscopic things, density and temperature in a simulation,

398
00:35:48,110 --> 00:35:53,960
but the very distribution function of the particles themselves. Understanding how different types of particles at different speeds behave.

399
00:35:54,320 --> 00:35:59,240
And so these were some simulations recently investigating exactly the sorts.

400
00:36:00,180 --> 00:36:01,470
Another thing we can now do,

401
00:36:02,100 --> 00:36:07,860
thanks to the kind of increased proliferation of these high energy facilities where you can do experiments that are not just ICF

402
00:36:07,890 --> 00:36:15,720
focussed but also just bespoke and a fundamental part of the experiments you can really now probe of processes like this in the lab.

403
00:36:16,080 --> 00:36:23,910
So during my Ph.D., I worked on a series of experiments investigating the phenomenon of magnetic field amplification, interpreting laser plasmas.

404
00:36:24,240 --> 00:36:28,760
The way the system works is that we irradiated two foils with laser energy.

405
00:36:28,770 --> 00:36:32,700
This is on the omega 60 laser in the US and that creates two jets of plasma.

406
00:36:32,970 --> 00:36:37,440
Those two jets pass through two grids and like water flowing through a grid, this begins to make turbulence.

407
00:36:37,650 --> 00:36:40,650
We then client them together and you end up with a type of plasma in the middle.

408
00:36:40,950 --> 00:36:48,419
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

409
00:36:48,420 --> 00:36:51,719
the kind of basic state of the plasma and in particular the magnetic fields.

410
00:36:51,720 --> 00:36:58,230
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.

411
00:36:58,680 --> 00:37:01,049
So combining these things together,

412
00:37:01,050 --> 00:37:06,390
we can now come up with new models for thermal conduction with these magnetic fields and actually test them in the lab.

413
00:37:08,050 --> 00:37:14,140
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.

414
00:37:15,230 --> 00:37:20,150
So on the theoretical side, it turns out there's a whole zoo of these instabilities, that kind of micro instability.

415
00:37:20,270 --> 00:37:22,370
In mice, we've identified 16.

416
00:37:22,880 --> 00:37:29,180
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.

417
00:37:29,450 --> 00:37:34,880
And so we've worked out now the space based diagram. Which of these instabilities is the one you really need to study?

418
00:37:36,060 --> 00:37:42,660
On the simulation sites. We have been running simulations of these individual instabilities, such as the virus instability,

419
00:37:42,960 --> 00:37:50,250
and we've shown that we can now characterise how transport kind of saturates in these particles when there is a presence.

420
00:37:50,760 --> 00:37:52,559
And finally, we, my colleague,

421
00:37:52,560 --> 00:37:59,460
colleague John and Monica led this really interesting experiment on demonstrating suppression of heat conduction in a laboratory, turbulent plasma.

422
00:37:59,850 --> 00:38:03,000
Again, it's very similar to what I just described to racing in turbulent plasma.

423
00:38:03,120 --> 00:38:06,689
But this was done on the National Ignition Facility, which is also in the field.

424
00:38:06,690 --> 00:38:13,740
Is that even stronger? And what's a Jennifer found was that if you naively ignore magnetic fields involved in thermal conduction,

425
00:38:14,010 --> 00:38:18,540
as we did in the simulations I'm showing here and then local what the temperature of this plasma should look like.

426
00:38:18,810 --> 00:38:20,610
Again, inferred from the X-ray technique.

427
00:38:20,610 --> 00:38:26,610
As I mentioned, in the astrophysical context, you should have very smooth profile like this, but that's what the actual data look like.

428
00:38:26,910 --> 00:38:30,360
You see all these small scale fluctuations and then it was able to show that the difference

429
00:38:30,360 --> 00:38:34,470
between these two is consistent with 100 times decrease in conductivity in this plasma.

430
00:38:34,770 --> 00:38:39,690
So the magnetic fields really suppress thermal conduction processes in this situation.

431
00:38:41,120 --> 00:38:48,560
Okay. So that's I'm talking about the kind of fundamental research on studying how magnetic fields affect conduction in these plasmas.

432
00:38:49,820 --> 00:38:53,390
Now the question is you might ask, well how can we then turn its back into some applications of fusion?

433
00:38:53,600 --> 00:38:59,030
And I think there's been some really promising first steps and this led by another team of different kinds of media and collaborators.

434
00:38:59,270 --> 00:39:05,600
And so they also they've been doing is imposing a background field on the whole when I'm looking something like this.

435
00:39:05,780 --> 00:39:07,729
So what you you've now got the same hologram design.

436
00:39:07,730 --> 00:39:12,920
You have the lasers in the capsule, but now you put a solenoid coil around the outside of your home,

437
00:39:13,370 --> 00:39:18,829
and then you apply a magnetic field that looks like this on the top. And what they found in their preliminary experiments,

438
00:39:18,830 --> 00:39:25,580
which unfortunately they haven't been able to do t experiments yet because of the cryogenic constraints of doing those experiments.

439
00:39:25,580 --> 00:39:31,700
But they have done experiments using deuterium, deuterium, fuel, and they found that with those preliminary experiments,

440
00:39:33,020 --> 00:39:39,110
anything in the magnetic field gives you about temperatures that's about 40% higher and yields are about three times higher.

441
00:39:39,500 --> 00:39:45,530
So this preliminary results is really exciting. And because of how interesting these results have been,

442
00:39:45,530 --> 00:39:51,079
there's now a kind of dedicated plan to do experiments with the same idea and this in the next few years.

443
00:39:51,080 --> 00:39:56,510
And I'm really optimistic that actually this will results in quite significant kind of jumps in the again you can get.

444
00:39:57,790 --> 00:40:00,940
Okay. I'm going. This is my final slide, so I just kind of want to round up.

445
00:40:01,510 --> 00:40:06,770
I just wanted to talk a bit about the natural fusion energy. So we've had all these headlines, these big results.

446
00:40:06,830 --> 00:40:10,530
This has been real progress, but that's still the kind of key question here,

447
00:40:10,540 --> 00:40:17,889
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.

448
00:40:17,890 --> 00:40:23,049
How do we go from this to an actual power plant? Well, I'm going to just highlight five factors here.

449
00:40:23,050 --> 00:40:26,350
This I think you would need to make, that's reality. The first is high gain.

450
00:40:26,740 --> 00:40:30,700
And as I pointed out earlier, it's not just enough to have ignition.

451
00:40:30,700 --> 00:40:35,380
You need to have enough energy to actually make wheel plug efficiency.

452
00:40:36,220 --> 00:40:39,910
And for that, we need these high gains of about over 40.

453
00:40:39,910 --> 00:40:43,720
And I'll come back to why that number is crucial in just a sec.

454
00:40:44,290 --> 00:40:49,810
The second point is the laser efficiency amendment, the wall plug efficiency of the national, which means that AC is only about point 6%.

455
00:40:50,380 --> 00:40:57,910
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.

456
00:40:58,270 --> 00:41:02,530
I'm one way that I think we can overcome and improve the laser efficiency is

457
00:41:02,530 --> 00:41:06,000
that the technology underpinning this is actually quite old in a certain sense.

458
00:41:06,010 --> 00:41:12,010
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.

459
00:41:12,310 --> 00:41:17,470
So probably of the order of 50% now and I think in five years, 20% seems to be on the cards.

460
00:41:17,920 --> 00:41:25,900
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,

461
00:41:26,110 --> 00:41:33,429
what you would then need would be maybe 40 mega joules, and then you'd have a gain of four in terms of energy.

462
00:41:33,430 --> 00:41:40,569
And so the fact of 24th year I mentioned is coming from another thing is of course, these experiments actually make energy.

463
00:41:40,570 --> 00:41:46,030
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.

464
00:41:46,030 --> 00:41:50,590
Was that you, as the current NIF operates, that you'd be doing this once, ten times in seconds.

465
00:41:50,800 --> 00:41:57,940
So we need to work out how to turn something like this, which is 95 very, very intermittently compared to that metric.

466
00:41:57,940 --> 00:42:00,400
As I said, how you turn that into something that fires rapidly.

467
00:42:00,730 --> 00:42:06,550
Again, laser technology can help pair these same high, high efficiency lasers can get much higher shot rates.

468
00:42:06,970 --> 00:42:11,740
That being said, there's never been a mega jewel class diode laser that's been made yet.

469
00:42:11,920 --> 00:42:15,510
So that's still something that needs to be worked on to make sure that works. We are kind of.

470
00:42:17,640 --> 00:42:21,070
Okay. And. The final?

471
00:42:21,310 --> 00:42:24,510
Well, the first thing I want to mention is the simplify the economic target design.

472
00:42:24,520 --> 00:42:27,340
You can see that the targets I talked about are really, really competencies.

473
00:42:28,030 --> 00:42:34,179
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,

474
00:42:34,180 --> 00:42:41,590
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.

475
00:42:41,770 --> 00:42:48,480
I think probably we need to work out how to design simplified targets that you could find ten times a second to work on.

476
00:42:48,820 --> 00:42:56,170
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.

477
00:42:56,170 --> 00:43:01,330
So these things would advance technician schemes, which can work in principle using simple designs.

478
00:43:02,290 --> 00:43:06,099
And then finally there's a lot of work still needs to be done in materials science, particularly, for example.

479
00:43:06,100 --> 00:43:12,370
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.

480
00:43:12,370 --> 00:43:15,850
And so we if we're going to do a high rep rate, we need to get kind of more robust optics.

481
00:43:16,300 --> 00:43:19,959
So I mean, all of these I think the high again, there's an efficiency and a high repetition.

482
00:43:19,960 --> 00:43:23,110
So I think actually we have very good path to solving them.

483
00:43:23,110 --> 00:43:27,730
I think the hardest problem is going to be this thing about the targets this simplifies.

484
00:43:28,510 --> 00:43:33,940
I'm optimistic. It's a problem. I think we can solve it, but I think that's the biggest now anyway.

485
00:43:34,210 --> 00:43:37,540
I think that's what I want to say. Thank you for our attention, because I'd like to take any questions.