Fusion: How to Put the Sun in a Magnetic Bottle - with Ian Chapman

so my name is Ian Chapman I'm from the column Center for Fusion Energi I imagine most of you have heard about Fusion this is the the best the only working fusion reactor that we have in our solar system at the moment beautiful and produced most of the energy that we use in our lives today the one thing I want you to take away from this beautiful movie of the Sun is how turbulent it is how much is going on so it's very not key essent it's really moving around all over the place you see these these flares these beautiful filaments erupting from the surface of the Sun you see that there's turbulence going on all of the time and that's essentially what we're trying to do in the study of nuclear fusion is to take something like that a plasma like the Sun is and put it in a bottle here on earth and perhaps the biggest challenge is dealing with this instability dealing with the fact that it's wobbling around all over the place now you would probably if I asked you where's the hottest place in the solar system almost all of you would say the Sun in fact the hottest place in the solar system is this hangar in the middle of farmland in Oxfordshire so every day more or less we generate fuel which we take - ten times hotter than the center of the Sun 150 million degrees C and that sounds ridiculous and it sounds completely ridiculous that you could even imagine doing something like that actually that's the easy bit so heating it up is not a big problem confining it and keeping it stationary that is a big problem and that's basically the the nature of this talk I'm going to talk about what we're doing day to day trying to take the Sun take the diffusion which is going on in the middle of the Sun and replicate that here on earth in a magnetic bottle a cage to keep the fuel steady and stationary so as I say a lot of you will have heard of fusion and probably a lot of you will have heard the the long foretold so CIM stance the fusion is always 30 years away as prelude to the questions which come at the end I will not give you an answer if you ask me how long till fusion another another it was very interesting to hear Chris say that a lot of his friends say why are you wasting your time doing that because I get exactly the same thing in a completely different sphere so maybe this is just the nature of science so through this the course of this talk what I hope that you'll come away with is a feeling for some of the progress which is actually being made in this field so fusion always has been and always has offered this wonderful promise to mankind that we can find a fuel source which is effectively limitless but it's really difficult to do right and so there's this joke about being thirty years away so I hope that I give you convey some of the progress which is being made in this field I'm going to actually show you some science and show you one of the technical challenges that I deal with day to day and then I'll tell you about where the field is going and where we're going over the next sort of 30 years so fusion actually nearly a century ago that Eddington realized how the Sun was powered what gave the Sun its energy this reservoir can scarcely be other than the subatomic energy which exists abundant in all matter we sometimes dream that man will one day learn how to release it and use it for his own service the store is well not inexhaustible if only it could be tapped and I really love this quotation because of that last bit if only it could be tapped and that's effectively what my job is and what all the people that work in our community are doing with trying to replicate that trying to tap that source for mankind's mankind's use now what we do is we take two isotopes of hydrogen here deuterium which is heavy hydrogen and tritium which is even heavier hydrogen we take those two isotopes and we force them together you force them at extreme speeds force these isotopes together at which point they'll fuse they join together now this is the only formula I show you in the talk from Einstein a equals MC squared the mass of these two things the reactants the deuterium and the tritium on the left hand side is less and the mass of the products on the right-hand side sorry is more than the mass of the products on the right-hand side get it the right way around right so you have a helium here in alpha particle and a neutron and the neutron takes most of the energy but the fact that there's a difference in the mass means that you get an energy and actually the the the energy produced when you fuse deuterium and tritium here's extremely high yield so it's a very very large amount of energy which comes out of fusion compared to out of nuclear fission which we have in working reactors today so in fact if you actually do some simple numbers and work out how much energy is released with just one mole which is a few grams of the reactants you produce a tera Joule of energy that would be enough energy for me for the rest of my life and and that we can get from relatively abundant fuel and not very much of it so a bathtub of water and the lithium out of two laptop batteries that would be enough fuel for me for the rest of my life more or less and that's assuming that I'm American and I burn my fuel at 10 to 20 kilowatt hours as well so maybe is 120 years worth of fuel if you compare that with how we typically get our fuel at the moment and our energy from coal it's equivalent to about 1600 wheelbarrows the very scientific unit of wheelbarrows of coal so it gives you some sort of indication of the the difference in yield we're talking about a few grams of fuel compared to a mountain of fuel so the yield is extremely high so you don't need a lot of fuel and the fuel is more or less relatively abundant so water obviously we have plenty of water and lithium there's a lot of lithium in the Earth's crust and we can continue mining that and not using it in laptop batteries but using it for this now there's always a but so that sounds wonderful but Fusion is really really hard and the fact that fusion is really really hard is because we don't have the benefit of gravity so the Sun is enormous thing out in space has gravity pulling the fuel together and compressing the fuel to make the fusion happen we don't have gravity so we have to use we have to make the fuel even more energetic the deuterium and the tritium both positively charged and you'll remember from our level chemistry that positively charged things will repel one another so in order to get them close enough you have to get them really really close sort of 10 to the minus 14 meters which is inconceivably close in order to get them that close you need to make them extremely energetic so that they can overcome that repulsion and if you get them that close you can get them that hot then they get close and then they fuse and when they fuse they release this energy now because you don't have gravity to help you whereas the Sun has gravity and in the middle of the sun's about 15 million degrees we don't have gravity we instead have to go to about 150 million degrees and at that point the fuel has turned into the fourth state of matter so called plasma so you go solid to liquid more energy turns it into a gas more energy turns it into a plasma and when you when you're in a plasma so a plasma is what is ionized and all of the particles are charged we have ions and electrons they're all charged they will all feel a magnetic field and that's the one thing which we do have in our benefit here is that they will feel a magnetic field so we can put them in a magnetic field and they will follow the magnetic field lines and they will be confined by the magnetic field and that's what we do so how do we harness fusion how do we try to do that here on earth when we don't have gravity we can't just put the Sun in leafy oxfordshire so instead we use magnetic coils so you'll be familiar with this if you pass a current through a wire so here you see a coil of wire we pass a current through this coil of wire in and out around this coil that that current passing through that wire will generate a magnetic field the magnetic field is perpendicular to where the current is flowing so when you have a coil like this it produces a magnetic field through it so the fact that you now have like a line of magnetic field there means that the particles the electrons and the ions will follow that magnetic field and okay next step we just bend it round on itself so we take our coil we bend it round on itself and then in principle the fuel will just keep going round yeah just keep circulating round and round around and that's ostensibly the confinement device that we use it's it's slightly more complicated than that but not a great deal more complicate so let me walk you through it you have these big blue coils here what we call toroidal field coils I'll explain that in a minute so they're sort of D shaped coils and you put them in a ring then you pass a current very large current through these coils and that induces a magnetic field that magnetic field is then going the long way around this doughnut the toroidal direction the long way around a torus and that is there where we put the fuel so this pink doughnut shape is actually the fuel and that the ions and the electrons largely move around this doughnut now it turns out that due to slight complications in the nature of that field in the the geometry of the field those ions electrons drift apart and they'll move up and they'll move down and they'll end up being lost so whilst that whilst that toroidal field is a good confinement it's not perfectly confining so we need to do better than that so what we do is we put a solenoid down the middle here the primary winding of the transformer transformer the thing at the end of your street where it takes the voltage from the grid and then puts in a voltage that you can use in your house so you there's a lot of coils of wire going around this solenoid down the middle you pass a current through this many many mega amps through this wire that insert itself will induce a current in the short in the secondary winding of the transformer which is the fuel so you then end up passing a current through the fuel so the fuel is now confined on the magnetic field going this way and is also carrying current now the fact that you've induced the current this way that that current itself will also induce a magnetic field now remember the magnetic field is perpendicular so it will go the short way around the doughnut so you now have two magnetic fields join together one that goes the long way around and one that goes the short way around they together produce a helical field and this helical field is a very good confining field and that then keeps the particles keeps the energetic ions and electrons very well confined and on the next one I'll show you a movie of this I got one of my students to initiate a bunch of particles at this point here so they come in from this injector they're ionized at this point when they turn into plasma and you've got and electrons and then if you just play the movie you'll see how those particles move in the presence of this confining field and you'll see that they effectively circulate most of them keep going in the same direction they circulate round and round if you're if you've got good eyes you might spot one or two that end up bouncing so they go most of the way around and then at some point they'll just bounce and go back on themselves but they're still confined so even if they're going in a reverse direction they're still they're still trapped within the vessel so those those particles are welcome fine and they'll stay there for many many many thousands of millions of turns so that's the basic premise that's what we're trying to achieve so how are we doing so as I say fusions always thirty years away why is it always thirty years away so if you go back effectively a generation to the 70s and 80s Cullum which is a showed you the picture at the start is an old aircraft base in the middle of Oxfordshire so we now have the world's biggest at the moment world's biggest fusion experiment there but it started right back in the 70s and 80s or even before that in fact when when fusion was Declassified but these are some of the first toroidal chambers that we had so you can see here these coils and you pass a current through these coils which induces the field the long way around that doughnut now this was just sat on a tabletop about this size to give you some concept of the scale you can see a man here so this is a very small hands-on capacitor bank fed machine the fuel was only confined for very very short fractions of a second sort of microseconds didn't last very long but it was enough to prove the principle that the tokamak could hold the fuel could contain the fuel I dag but I dug back through the archives a column to look at how the data analysis was done in this old machine I really like I really like this this particular page that I found because the date here is my wife's date of birth so it tells me that really is a generation ago and this is how this is how the data analysis was done so these are oscilloscope traces and sort of handwritten scrawl on the side and that's how that's how data analysis was done in the 70s and 80s this is where we are today so it's a slight advance you would say in that period of time this is that the world's biggest fusion experiment the moment called the joint European torus this is a an experiment that operated here in the UK on behalf of Europe so who knows what happens in four months time but nominally today whilst we are in Europe we operate it on behalf of all of our European partners and they participate as well of course and regularly come to do experiments this machine is now a lot bigger in scale so there is no man but okay so this cubicle up here is about the same size as a fridge freezer so it's about my height about the same size as me if I put on a bit of beef so this is this is roughly a man to give you some sort of concept of scale and this is a much bigger machine now than we were looking at also the technology has advanced a huge way so that first machine Tasca that I showed you was just powered by capacitor banks very very short pulse very very cheap and dirty to put together in jet the the technology has advanced such a long way but all of that the machine has many many tens of thousands of components were all installed recently with robotic engineering remote handling so here's a man in the loop this guy sits about 50 meters away from the machine and never picks up an actual screwdriver but he controls this snake which comes in and winds its way around the vessel and there's actually two of these one comes in the other side one is the slave and holds all the tools and all the components that you need and this guy here the robot has a bunch of cameras and installs all of the tiles and components in the vessel and I'll show you the complexity of the vessel so you can see just how many small tiny components there are at the bottom there's literally hundreds of thousands of these tiles all the way around all installed by this guy with these cameras and the man in the loop so it shows you how far the field has come when you compare the oscilloscope traces to an ability to be able to do that and refit the entire vessel remotely with robots like that so the best that the field has moved on a great deal and it works okay so so in 1997 which was the last time that the community fused deuterium and tritium most of the time we just used deuterium tritium is very expensive so we don't use tritium very often in a reactor we would breed it ourselves so it would be self-sufficient so you wouldn't have to worry about the cost but in here in our current day machines we don't breed it and therefore we have to get it from other sources it's a commodity it's very expensive we don't do it very often however when we did do it you see that we produce 16 megawatts here in jet 16 megawatts a reasonable amount of energy it's ok it's not commercial you certainly wouldn't ever put that that onto the grid but it's a reasonable amount of energy the big problem is that that 16 megawatts was generated having put 25 megawatts into the machine alright so nobody's going to pay you to do that now really that's just a question of scale if you build the reactor bigger it will confine the fuel for much longer and the fusion yield which comes out is much much higher so effectively what we need to do is build a bigger machine and that's what what is happening at the moment we are building what almost to scale that version of jet that will be I hope operational within the next 10 years and that instead of putting in 25 in getting out 16 in the next step device will put in 50 and get out 500 and that's the aim of the machine so it's not it's not going to put electricity onto the grid it's not designed to do that it is an experiment it's a proof of principle if you can prove the principle and we get as we predict we'll get 500 megawatts out at that point I hope the industry gets excited about this and starts being serious about building reactors but you know this is experimental science we have to show that it works first we have absolute confidence that we've designed it correctly and that we understand enough of the processes which are going on for that to be true but we still have to demonstrate it and that's where that's the big challenge for us over then two years is to demonstrate exactly that so in preparation for that and I will tell you about that machine in a minute but in preparation for that I thought I'd give you an example of one of the technical challenges that we have every day now if you remember back at the start I showed you that movie of the Sun and the Sun was moving around all over the place it's very turbulent had these beautiful filaments coming out of it now that's a plasma at extreme temperatures lo and behold when we do it in the laboratory and we generate a plasma extreme temperatures we get very similar phenomena so you can see these filaments these connected filaments bursting out at the edge if I just freeze that so you can see it really is a continuous filament there and it's very well aligned along the magnetic field just as these things happen in the Sun they follow the magnetic field now these things whilst aesthetically beautiful are a bit of a pain in the arse I must say in that they take with them a significant amount of energy so that that burst that eruption can take with it a few percent of the stored energy of the whole fuel so on the next step device that we're building this one that's being built in the South of France every time that happens and we think it will probably happen a few times a second every time it happens it could take 20 mega joules in 500 microseconds so this is huge heat flux that we put a heat flux on to the vessel walls which the the materials that the vessel is built from will not withstand so you'd end up melting parts local parts of your reactor and clearly this is not acceptable the regulator will not accept this and nor should the investors so we need to find a way of dealing with this so we have to you know instead of releasing about 20 mega joules we have to find a way that every time one of those things happens it only reduces one mega Joule and you know we've tried doing this we've had lots of different ways of lots of different ideas of doing this the most successful I would say is to deliberately degrade to the confinement to make it that the fuel locally worse confined now so we had one demonstration with a glass of water I'm going to go to an even cheaper because we're in government austerity times demonstration with literally no expense spent and ask you to use your imagination so what's happening here is it's I like to use the analogy of a pan of water so you put a pan of water on a stove in your kitchen turn on the gas and start heating it up and that's what we're doing in a fusion reactor with plowing energy in and making it hot in the middle so the water is getting hotter and hotter and hotter now you put the lid on that pan of water at some point the pressure is going to get too big yeah so you'll see this more and more steam between the water and the lid and eventually that pressure that steam pressure will get so big that it will cause the lid to pop off and there'll be a local excursion of steam out of the pad and that's roughly what's going on here so we've confined the fuel so well the fuel is so well confined within our magnetic bottle and we're heating it we're making it hotter and hotter and hotter at some point the pressure just gets too big and you get one of these bursts one of these filaments are up ting out at the edge and taking some of the pressure away now what do you do in your kitchen if you want to stop that happening you either turn down the gas and then the water gets cooler now we don't want to do that we don't want the water to get cooler because we need the fuel to be really hot to make the fusion happen it needs to be really hot so that's not an option so that what you can do though is you can open the valve on the lid or put a spoon under the lid so that the steam just comes out seeps out gently and that's effectively what we want to do in a fusion reactor - you want to find a way that you keep the confinement really good in the center and that the hot but the bit in the middle of the fuel is really really hot so the fusion is still happening but that you make the confinement slightly worse at the edge so that it's allowed the pressure is allowed to seep out gently so you don't get these explosive releases you get a gentle release and that's what this court these coils do so eater is planning to have these green coils here there's 27 of them these are installed inside the vessel and the idea is that they apply a very local small field right at the edge so right at the edge of the fuel they make the confinement worse so conceptually that makes sense so we needed to test it and see if it actually works so this is our machine in the in the UK that that's just for the UK we have we installed 18 of these little coils on the inside of the vessel to see if the predictions that you could make the confinement slightly worse at the edge actually worked if that actually happens now when you apply these very small local fields you get these sort of tangled structures at the edge so this is a prediction that we made about 10 years ago but if you apply one of these small confining fields you'll get funny structures at the edge here like lobe structures down at the edge now most people in the community thought okay that's mathematically what happens but that's never going to happen you're never going to see a plasma which has these sort of funny little fingers sticking out of it and I must say me too I didn't believe that that would possibly happen so we did it we put these coils in and then we tried to make measurements of it and if you just play the movie on the right hand side you'll see at the top here this is when we put current into the coils and when we do so you really do see these fingers and these lobes sticking out at the edge and this to me is how science should be done you have an idea you think this is a way that we can fix this problem that we've got you develop a theory you make a prediction for what will happen if you apply this technique then you apply the technique and lo and behold you get extremely good agreement between what happens empirically and what you predicted in the first place and it gives you some confidence then that you can extrapolate this to the next the next big machine that we have to build so I like to show that because I think it's how science should work so now I just close with a little bit about eater that eater is the next big machine the one that is being built at the moment we expect to be operational in about 20-25 something like that so that a decade from now it's being built in the South of France in Provence I know it's terrible our scientists we're going to have to go and work in bronze eita is extraordinary in many ways it's a bureaucratic nightmare but it is hugely exciting my personal opinion is that this is probably the biggest most exciting science experiment that's ever been done it's certainly the the biggest in terms of cost it's also the biggest in terms of collaboration so at the top there if you're good with flags you can see all the partners who are investing real cash into this project and you'll see that that represents well over half the world's population this is probably the biggest collaboration there's ever been actually these people genuinely collaborating because there's some countries there that you don't naturally trust each other and don't naturally work together but they are genuinely working together on this because it's such a big issue and it's so important to all of those members some of those members have things written into their constitution that they will deliver fusion so they're very very serious about it and very invested so this is what Ito will look like so I've got my standard man this is jet standard man standard man here so you can see the men at the same scale it gives you some idea of just how big this thing is all right so it's a pretty big serious piece of kit and it comes with a big price tag and it's very very complicated desert the design and build which is why it's still probably 10 years away but it is being built this was the first time I went to Provence to see the site I took this picture because it was just a hole in the ground right the hollowed ground doesn't sound very exciting but when you see the scale of the hole in the ground and see these man abseiling down to put some dynamite at the bottom it felt more impressive eventually that that hole in the ground two years later became they poured concrete into it and put seismic protection in because you're building something which is upwards of 15 billion pounds so it's extremely expensive and in all wisdom you've built it in a slightly seismically active area so you have to have these protection plates at the bottom to make sure that nothing bad happens to your very large investment about a year later this is now looking down from the top to give you some scale this is about 80 metres up about 120 metres across ultimately it will come about 80 metres out of the ground is a huge amount of concrete a lot of concrete seven and a half thousand tons of steel I always tell people it's like Wembley it's roughly the same amount of steel is roughly the same dimensions as when bleagh and like Wembley it's roughly two times over-budget and roughly two times late so but it will happen okay will happen and slowly it's now coming out the ground so you can you can at this stage begin to see the shape of the machine so all of these wire cages here are where the coils will sit so you'll have those coils going the long way around to give you the magnetic cage this bit in the middle is where the solenoid will sit to induce the current in the plasma and it's slowly beginning to look like what we think of as a as a tokamak as a confining device just bringing things to eater is a big issue so these are big coils big big coils now it's not on the coast and these coils are being built all around the world and you then have to get them to Marseille Harbor and then get them to site which is about 60 miles away so they have to go on this beast which has got 32 axles for wheels across takes 800 tonnes moves at a whopping 4 mile an hour and takes 4 nights and obviously they do it overnight to not otherwise it would be worse than the French farmers so they do it overnight to get things to site now I said at the start how this is a huge collaboration being a huge collaboration means the project will actually happen because none of the partners would have paid for it on their own but it does add complexity because all of the partners rightly so all of the partners want to know they want to keep some of the intellectual property they want to know how to do this on their own so if eater works and I truly believe it'll will work when eater works then any one of those partners will want to build their own power plant and they won't want to say ok the coils were built by the u.s. we're now beholden to the u.s. to build the coils for instance so this is very open everything is open everything is published sharing of the intellectual t now conceptually that sounds great in practice it's not so perfect in that if you were designing a assembly project like this any sensible same person would say I've got 18 and I use the coils as well as an example because they're one of the biggest bits of kit I've got 18 of these I will say to engineering company X please build me 18 to the same specification now that's not the way this project is designed naturally because all partners want a share of this so instead you have multiple places in multiple countries building these coils which ultimately have to come out to the same specification and then you have the lead legal ramifications of ensuring the specification is exactly the same and if it's not who pays who what so it becomes far more complicated and and I use a coils as an example here you see the conductor this is the largest procurement of superconductor strand ever is being built by six of the seven different partners then it is shipped from wherever it's built the conductor is jacketed is then shipped to two different sites to be put on coils and then the cases for those coils are built in a different site those two things are then taken to an oven a great big oven where they're baked in two different sites again so you have this huge circulation of effort and and duplication of effort going on to satisfy the way the project was conceived so show you some examples of that this is a jacketing bench where the superconducting coil is made this is one that's in Florida for perfectly perfectly level for Miles bench to jacket these coils that that in itself is a big engineering project and here's that done again in China so you don't just do it once you do it multiple times once you've built that superconducting strand and you've put it onto the coil you then have to bake it baking it because the coil is so big means you have to have an oven big enough to put the coil in so this is now a 50 meter by 20 meter oven so just that is a big engineering project that takes years to build but you do it twice so this gives you some idea of the complexity of doing something which is a collaboration between all those partners and is the first of a car find huge really big science has huge potential but is very difficult ultimately the aim of this device is that as I say it will produce about 10 times more energy out than put in so we'll put 50 megawatts in to heat the fuel in the first place once the fuel is hot and the fusion is happening it will produce about 500 megawatts out now 100 megawatts of that is in the the alpha-particle this helium for this is charged so this will also feel the magnetic field so it will stay within the magnetic field so that hundred megawatts produced from the fusion reaction stays there and then heats the bulk fuel so it happens that it's when this is born this product is born a much higher temperature than the bulk fuel so when it's born it's very energetic and through collisions it just passes on its energy to the rest of the fuel so it's self heating so you need to put some energy in to get it going but once you've got it going it's self heating the rest of the energy the other 400 comes out with neutrons neutrons are neutral they do not feel the field they just go out of the vessel and then those neutrons are absorbed in a blanket ultimately turn water into steam steam turns turbines in exactly the same way as a fission plant works or a coal plant works so the efficiencies are roughly the same and what comes after Rita so as I say eater is an experiment it will not put power onto the grid but of course we're planning for what happens after it we have designs for how you would scale that up so 8 is about 500 megawatts now 500 megawatts is not that much in fact it's very small in terms of reactors if you look at a fission reactor or a coal plant that these are usually one or two gigawatts so you need to be bigger still so we have a design for a demonstration reactor which you know with a trailing wind and the right investment we could build by the 2050s I would guess something like that which is a bit bigger still Vanita eat is quite big it's a bit bigger still surround six meters across it's about nine meters across so it scaled up a bit more and that gives you a bigger yield so you could imagine building one of these about a gigawatt Electric in parallel this will be very expensive right this would be tens of billions to build one of these units so in parallel the UK has a program to try and look at can we make fusion smaller and cheaper so one seater works and eater is a real proof of principle can you do that in a more compact way and we've got various ideas that we're testing out at the moment we're just just completing the upgrade of one of our machines in Oxfordshire which is to test this out and see if you can find ways of having something which is really really hot as I remind you ten times hotter than the center of the Sun but do it in an even more compact device now there are challenges with doing that you have extremely high heat fluxes to deal with these sort of heat fluxes are significantly more than you might get on a reentrant space shuttle and a space shuttle is designed to melt so that gives you some idea of the heat fluxes that we're talking about but we've got ideas of how we're going to test that out and that's exactly what we're doing this this device at the moment is to test some of those ideas so I will close there I'd say fusion is safe fusion has more or less no long long-lived radioactive waste legacy the fuel is relatively abundant there's no carbon produced from it it can in principle be a continuous supply so it's not like other renewables where you have to wait for the Sun to shine or the wind to blow it's in principle continuous and it doesn't use very much land but it's really really hard so Eddington said a century ago we sometimes dream that man will one day learn how to release it and use it for his own service now that dream is still there we're still trying really hard to do it we've just got to finish the job thank you for your time and if you're interested please look you you

Channel: The Royal Institution

Views: 703,894

Rating: 4.8370695 out of 5

Keywords: Ri, Royal Institution, fusion, energy, nuclear fusion, fission, sun, power, ian chapman, solar, power of the sun

Id: zn1SJOPgewo

Length: 35min 0sec (2100 seconds)

Published: Wed Jun 08 2016

Reddit Comments

[u/cortjest]

This was a fun watch. Good learn. He refused to say "fusion is 30 years away," but stated the facts of the current field and future plans.

TIL: the collaboration and duplication of efforts to prevent a monopoly costs more today, but is an investment into the future.