1 00:00:00,650 --> 00:00:07,940 Hello at the centre of the sun, this very moment, millions of tons of hydrogen have been transformed into helium, 2 00:00:07,940 --> 00:00:14,270 releasing a huge amount of energy, the physical process by which this occurs is known as nuclear fusion. 3 00:00:14,270 --> 00:00:18,590 And the prospects of using this miraculous property of the natural world to generate 4 00:00:18,590 --> 00:00:24,200 clean power on earth has preoccupied scientists and entrepreneurs for over 60 years. 5 00:00:24,200 --> 00:00:28,130 Yet despite huge international collaboration and investment, 6 00:00:28,130 --> 00:00:34,850 no terrestrial nuclear fusion device has yet been able to produce more energy than it consumes. 7 00:00:34,850 --> 00:00:38,600 This, notwithstanding, the progress over this period, has been immense, 8 00:00:38,600 --> 00:00:44,480 and the 21st century will most likely see the first economically viable fusion power plant. 9 00:00:44,480 --> 00:00:51,080 With me to discuss the past, present and future of nuclear fusion research are Dr. Justin Ball, 10 00:00:51,080 --> 00:00:57,890 originally graduate medical student in theoretical physics from Wooster College and now a postdoc hopeful Valerian Chen, 11 00:00:57,890 --> 00:01:05,870 additional student immersion college, also in theoretical physics, and Jason Parisi, medical student at Merton College, also in theoretical physics. 12 00:01:05,870 --> 00:01:07,400 Thank you very much for joining me. 13 00:01:07,400 --> 00:01:15,170 Perhaps just for laymen like myself, we could start with a description of what the basic process of nuclear fusion is. 14 00:01:15,170 --> 00:01:17,480 Jason, do you fancy taking it up for us short? 15 00:01:17,480 --> 00:01:26,810 So fusion is the process whereby you take very light atomic nuclei and you literally just fusion about fuse them together. 16 00:01:26,810 --> 00:01:32,300 So, for example, the sun takes hydrogen nuclei and it fuses them together. 17 00:01:32,300 --> 00:01:35,750 And in that process you produce energy. 18 00:01:35,750 --> 00:01:43,250 It is the opposite of fission whereby in fission, instead of having two very light nuclei and fusing them together, 19 00:01:43,250 --> 00:01:49,880 fission is whereby you have a very heavy, unstable nucleus and you launch a neutron at it. 20 00:01:49,880 --> 00:01:57,080 The fissionable nucleus will absorb the neutrons and split into two small units and that will release energy as well. 21 00:01:57,080 --> 00:02:04,820 The reason that fusion releases energy is actually because the two separate let's say, for example, I'm talking about hydrogen fusion. 22 00:02:04,820 --> 00:02:12,800 The two separate hydrogen nuclei are actually heavier than the new heavier nucleus that it will create after effusions. 23 00:02:12,800 --> 00:02:19,550 And because energy has to be consolidated. So the individual hydrogen lighter than the individual helium. 24 00:02:19,550 --> 00:02:24,320 So that idea combined the heavier. Yes, that's ironic. Exactly. 25 00:02:24,320 --> 00:02:34,040 So actually, in 1920, Francis Asten discovered that actually two hydrogen nuclei separately, but she went terroris heavier than the new helium guy. 26 00:02:34,040 --> 00:02:38,780 And that means through Einstein's very famous equation, equals MC squared. 27 00:02:38,780 --> 00:02:44,060 You can actually see that that difference in mass will release energy in some form. 28 00:02:44,060 --> 00:02:48,830 And usually that's in the form of kinetic energy for some particle moving off. 29 00:02:48,830 --> 00:02:50,990 OK, thank you. That that was very clear. 30 00:02:50,990 --> 00:03:00,290 And so I guess these are two very different kinds of nuclear processes, one of which we've been able for 60 years to use for producing energy. 31 00:03:00,290 --> 00:03:06,770 Novela, and could you describe to us how fish plant would differ from a from a fusion plant? 32 00:03:06,770 --> 00:03:10,220 What are the main principles of efficient plants? Which are we stick to that. 33 00:03:10,220 --> 00:03:17,180 So very loosely speaking, what you have in an efficient plant is a cell where you have all this fissile material, 34 00:03:17,180 --> 00:03:22,730 the fuel in it, and you control the rate of reaction by putting in rods, slow it down. 35 00:03:22,730 --> 00:03:31,640 So when if you didn't have the right and you just had this material decay spontaneously creating some neutrons and you create to create one in one, 36 00:03:31,640 --> 00:03:35,600 each one, for example, you would care some several neutrons to come out. 37 00:03:35,600 --> 00:03:41,300 And these neutrons have quite a bit of energy into other nuclei and they do decay. 38 00:03:41,300 --> 00:03:45,890 So it's like a domino effect. And this runs away and you have an explosion which you don't want. 39 00:03:45,890 --> 00:03:50,360 You want something controlled release of power. So what you do is you put in. 40 00:03:50,360 --> 00:03:55,850 Right. So you put in like basically a wall because it's the fashionable thing to talk about. 41 00:03:55,850 --> 00:04:02,120 It is designed to slow down the rate of reaction to a system that you still have. 42 00:04:02,120 --> 00:04:06,500 It still runs that you still create lots of heat, but it doesn't go out of control. 43 00:04:06,500 --> 00:04:11,750 And this can be done at room temperature just in the plant as it is. 44 00:04:11,750 --> 00:04:17,630 Of course, its energy then boils water and drives a turbine. But everything else of that has been done since the Industrial Revolution. 45 00:04:17,630 --> 00:04:23,750 That's how you create the fires. The only difference here is cool or efficient power. 46 00:04:23,750 --> 00:04:29,180 Now, we fusion light years need these light elements to come close enough to join together 47 00:04:29,180 --> 00:04:34,130 to make it become heavier elements and therefore release some of the energy. 48 00:04:34,130 --> 00:04:40,640 And in order for them to come close enough, you need to have a lot of energy to begin with because you see, in the previous case, 49 00:04:40,640 --> 00:04:46,040 these neutrons had no charge so they could approach the nucleus positively, touch and not feel any force at all. 50 00:04:46,040 --> 00:04:51,950 So they don't care about the title and you just fly into the nucleus and things happen. 51 00:04:51,950 --> 00:04:56,180 Now you have two protons they both have charged, both positively charged. 52 00:04:56,180 --> 00:05:00,180 How are you going to get to stick together or touch others who are? 53 00:05:00,180 --> 00:05:08,430 So you need a lot of energy and love, energy needs a large temperature, and if you want to reach these temperatures, in fact, 54 00:05:08,430 --> 00:05:15,270 if you want to do it efficiently and power plant skills, these temperatures to be hotter than the centre of the sun. 55 00:05:15,270 --> 00:05:20,730 And that's the challenge. And the great thing about fusion is that I like fission, which is quite strange. 56 00:05:20,730 --> 00:05:25,290 You have all the fuel at once. So it means that if it goes, it burns all of it. 57 00:05:25,290 --> 00:05:29,430 And all of the energy is released once a few years worth of energy just released at once. The Fusion. 58 00:05:29,430 --> 00:05:35,700 On the other hand, you pump the fuel to gas it. So it's more like a normal way of creating energy that you start to get fuel outside. 59 00:05:35,700 --> 00:05:42,450 You put it in the chamber when you need it. So when we supply, then the reaction stops and it would explode. 60 00:05:42,450 --> 00:05:49,860 OK, so what I'm sensing is that with a fission power plant, you have this very unstable material that will decay. 61 00:05:49,860 --> 00:05:56,310 Really heat into the challenge, which was overcome some years ago, was to control the reactions of people reacting or once. 62 00:05:56,310 --> 00:06:03,900 But you're telling me that with a fusion power plant, the difficulty is to get the material hot enough for the nuclear process to happen at all. 63 00:06:03,900 --> 00:06:07,530 Yes, this saying. So just what sort of temperatures are we talking about? 64 00:06:07,530 --> 00:06:11,100 We said hotter than the centre of the sun. But what sort of numbers do these mean? 65 00:06:11,100 --> 00:06:16,770 Yes, this is around one hundred and fifty million degrees Celsius or Fahrenheit. 66 00:06:16,770 --> 00:06:24,240 Really, the scale doesn't matter too much at these insane temperatures. So the material was hydrogen material. 67 00:06:24,240 --> 00:06:28,530 That's not a gas at a temperature. What was the name for? 68 00:06:28,530 --> 00:06:37,770 So if you start off with the solid material, so solid hydrogen, you know, you have lots of bonds connecting the different atoms, molecules. 69 00:06:37,770 --> 00:06:44,190 And then as you heat it up, eventually you start to break the inner molecule bonds to produce a liquid heated up more. 70 00:06:44,190 --> 00:06:50,160 You completely break all of these bonds and you have a gas of just different molecules flying around in the air. 71 00:06:50,160 --> 00:06:51,870 And then if you heat it up even more, 72 00:06:51,870 --> 00:06:59,760 eventually you can break the connexion of the nuclei in your atoms with the electrons that are orbiting around your atom. 73 00:06:59,760 --> 00:07:04,020 And so when the thermal energy that's in your system, so, you know, 74 00:07:04,020 --> 00:07:09,270 you have all these atoms flying around when there's so much energy in the atoms flying around, 75 00:07:09,270 --> 00:07:13,890 that is similar energy to how much it takes to look to liberate an electron. 76 00:07:13,890 --> 00:07:17,760 Then you can get a plasma, which is a different state of matter, 77 00:07:17,760 --> 00:07:26,850 where you have free flowing nuclei and you have free electrons are going their own independent ways and and functioning independently. 78 00:07:26,850 --> 00:07:34,230 So the hydrogen is in a plasma state. Yes. So at these temperatures, like in the sun, the fuel is in a plasma state. 79 00:07:34,230 --> 00:07:40,140 We have free electrons and free free nuclei. So it doesn't no longer make sense to talk about an individual atom. 80 00:07:40,140 --> 00:07:45,210 In that sense, you have nuclei and electrons, but you no longer have gravity. 81 00:07:45,210 --> 00:07:49,110 So let's talk a little bit about the history of nuclear fusion. 82 00:07:49,110 --> 00:07:55,690 You mentioned that in 1920 there was this discovery of a difference in maths that the two hydrogens 83 00:07:55,690 --> 00:07:59,910 sum together separately were heavier than the helium they would create when they combined. 84 00:07:59,910 --> 00:08:05,550 What were the theoretical developments happened in the 20s and 30s? 85 00:08:05,550 --> 00:08:11,070 Sure. So in 1920, Einstein actually figured out that there was this change in mass. 86 00:08:11,070 --> 00:08:14,790 When you fusion things together that was actually a serendipitous discovery. 87 00:08:14,790 --> 00:08:19,980 Wasn't was an intentional, intentional, which is always kind of fun and science that often happens. 88 00:08:19,980 --> 00:08:27,390 And then I think later that year, Rutherford took that together and said, wow, actually, it's not gravity that heats up the sun. 89 00:08:27,390 --> 00:08:31,980 It's not it's not meteors striking the surface. It's not definitely not chemical. 90 00:08:31,980 --> 00:08:34,170 It's actually fusion that powers the sun. 91 00:08:34,170 --> 00:08:38,890 Until that point of Rutherford, people felt that it was ordinary chemical reactions that we might see right now. 92 00:08:38,890 --> 00:08:47,040 If there was power powering the sun, why was there this change? What paradox could be explained by it just being chemical reactions from the sun? 93 00:08:47,040 --> 00:08:54,900 Yeah, that's a fascinating question. So it was actually back in the late 60s that people really started to think about how old is the sun. 94 00:08:54,900 --> 00:09:02,820 One of the main reasons for that is because biologists such as Darwin were actually coming to say, actually, how old is the earth? 95 00:09:02,820 --> 00:09:06,540 And looking at like they did very kind of back of the envelope calculations 96 00:09:06,540 --> 00:09:13,050 just to see like how long does it take for this kind of level of complexity, like human beings or mammals or whatever, to evolve? 97 00:09:13,050 --> 00:09:20,730 And they came up with like hundreds of millions of years. Now, if you take the most energetic chemical reaction you can imagine and, 98 00:09:20,730 --> 00:09:24,720 you know, the mass of the sun, we people knew the mass of the sun back in 1850. 99 00:09:24,720 --> 00:09:31,350 So it's pretty easy to figure out then. So you take the most energetic chemical reaction, the sun with its mass, 100 00:09:31,350 --> 00:09:39,300 which is about 10 to the 30 kilograms and its current power output would only last a few thousand years, which is crazy if you think about it. 101 00:09:39,300 --> 00:09:48,690 So that even the most devout Christians at the time, like Lord Kelvin, no way can it be chemical reactions that's powering it. 102 00:09:48,690 --> 00:09:51,960 So there are two other key theories that people thought about. 103 00:09:51,960 --> 00:10:00,110 The first was that the sun would kind of contract under its own gravity and that would heat it up and. 104 00:10:00,110 --> 00:10:08,570 A little bit, and that would cause it to radiate and by continuously doing that, you would get a lifetime of about 30 million years for the sun. 105 00:10:08,570 --> 00:10:17,600 And also another theory was that like loads of meteors and asteroids were kind of consistently striking the surface of the sun heating up. 106 00:10:17,600 --> 00:10:25,310 And that also gave tens of billions of years. So lots of physicists were kind of satisfied with that to some extent. 107 00:10:25,310 --> 00:10:34,940 Kelvin really liked the meteoric theory, for example, but biologists and geologists who were looking at rocks and how they were were not satisfied. 108 00:10:34,940 --> 00:10:40,790 So there was this tension between hanging. The physics is telling us the sun is only tens of millions of years old. 109 00:10:40,790 --> 00:10:46,580 But the geologists and biologists telling us the earth is at least hundreds of billions of years old. 110 00:10:46,580 --> 00:10:50,960 And obviously everyone assumed that the sun has to be at least as old as the Earth. 111 00:10:50,960 --> 00:10:55,130 And therefore, there was the tension. That's really interesting. 112 00:10:55,130 --> 00:11:00,660 After the 1920s, people who felt that the nuclear fusion process was behind the sun, just a number, right. 113 00:11:00,660 --> 00:11:06,140 That in the 1930s there was more progress made about the actual details of the nuclear processes. 114 00:11:06,140 --> 00:11:14,210 Yeah, that's correct. So there is a famous paper by Hans-Peter where he laid out all of the detailed fusion reactions that were going on. 115 00:11:14,210 --> 00:11:21,890 So from starting with just using normal hydrogen and then on to form progressively heavier elements. 116 00:11:21,890 --> 00:11:28,370 Right. And so all of these processes, starting with hydrogen and ending with elements like oxygen and carbon, 117 00:11:28,370 --> 00:11:33,500 were mapped out the exact process by which stars or somebodies have your elements. 118 00:11:33,500 --> 00:11:36,380 Maybe we could nail down my own understanding at least. 119 00:11:36,380 --> 00:11:44,540 Why is it a good idea to collide these very small elements, whereas in fission we're splitting apart very big elements. 120 00:11:44,540 --> 00:11:51,470 Yeah. So it gets back to what we said earlier, that if you combine really small elements, you can produce atom, 121 00:11:51,470 --> 00:11:56,240 that it weighs less than the the mass of what you initially put in to produce energy. 122 00:11:56,240 --> 00:12:01,670 And so the really light elements are easiest because they have the lowest electric charge. 123 00:12:01,670 --> 00:12:11,040 So basically you're trying to get these two nuclei to stick together. But the electric repulsion, you know, the positive charges repel each other. 124 00:12:11,040 --> 00:12:16,730 And so the lightest elements have the lowest electric charge. So it's easiest to bring them together. 125 00:12:16,730 --> 00:12:24,200 And the more stable nuclei, ironically possible because anything bigger wants to break into smaller, 126 00:12:24,200 --> 00:12:27,810 smaller nuclei because the electrostatic repulsion in the nucleus is high. 127 00:12:27,810 --> 00:12:33,850 Anything smaller wants to become bigger because he wants to have more other nuclear arms around it. 128 00:12:33,850 --> 00:12:38,510 So so nuclear forces stabilise it. In a way, this is like groups of friends. 129 00:12:38,510 --> 00:12:42,320 So when you are two people in a room, you have two of you in a room. 130 00:12:42,320 --> 00:12:48,050 You need to overcome the awkwardness, which is like the repulsions. You want to find a nucleus. 131 00:12:48,050 --> 00:12:51,680 If I do come close enough to have a conversation and start the bonds of friendship. 132 00:12:51,680 --> 00:12:55,100 On the other hand, if the group is big, it's very difficult to coordinate things. 133 00:12:55,100 --> 00:13:01,220 People get left out and so the awkwardness dominates and the group breaks up into smaller groups. 134 00:13:01,220 --> 00:13:06,920 And eventually you settle on the number which you can find it by force nuclei. 135 00:13:06,920 --> 00:13:13,850 It's numbers bigger. And so the same thing happens with elements that everybody wants to become. 136 00:13:13,850 --> 00:13:20,720 Nicole and are the. OK, so this is free, but of course, very well documented that there was lots of nuclear research. 137 00:13:20,720 --> 00:13:26,270 That was during the war, culminating in the Hiroshima and Nagasaki bombs, which were fission bombs. 138 00:13:26,270 --> 00:13:33,650 But your time period is really quite interesting story about what happened after the war when people tried to use these for the military uses, 139 00:13:33,650 --> 00:13:40,520 but also for power. Justin, you were telling me about this particular Argentinean scientist and this story to do with you. 140 00:13:40,520 --> 00:13:45,260 Yeah, yeah. So right after the war, there is a lot of optimism of the nuclear power. 141 00:13:45,260 --> 00:13:53,270 And so people knew about fusion. And immediately following the war, there is a lot of work on employing fusion in nuclear weapons. 142 00:13:53,270 --> 00:14:00,980 So during the war, we reduced fission weapons that we wanted to apply it to fusion weapons. 143 00:14:00,980 --> 00:14:07,670 And there wasn't initially a lot of investigation into using fusion to produce electricity for peaceful means. 144 00:14:07,670 --> 00:14:14,270 But there is a famous event now where an Argentinean scientist named Ronald Richter, 145 00:14:14,270 --> 00:14:20,810 um, you know, in this kind of mad scientist lab on an island in Argentina, 146 00:14:20,810 --> 00:14:25,970 claimed to have achieved fusion and claimed that he was going to bring unlimited energy to the world. 147 00:14:25,970 --> 00:14:31,910 And this cut the the eye of the president of Argentina who who made this grand declaration 148 00:14:31,910 --> 00:14:37,370 and so naturally was picked up by all sorts of papers around the world making headlines, 149 00:14:37,370 --> 00:14:44,840 which caught the attention of physicists, especially Spitzer, who is a plasma physicist working at Princeton at the time. 150 00:14:44,840 --> 00:14:49,760 And so he immediately thought through so through this. And so this method wouldn't work. 151 00:14:49,760 --> 00:14:54,740 But it prompted a question like, can you do this and what are what are the best ways to do it? 152 00:14:54,740 --> 00:15:00,500 And so he immediately started thinking about ways to produce fusion energy. 153 00:15:00,500 --> 00:15:02,090 And several years later, 154 00:15:02,090 --> 00:15:11,120 founded the famous Princeton plasma physics lab and invented one of the most promising devices that we still use today called the stallholder Drayson, 155 00:15:11,120 --> 00:15:19,850 this research has been done after the war. Was this done as a larger global collaboration as things are being done now or was it slightly different? 156 00:15:19,850 --> 00:15:30,260 So actually, fusion energy research was classified and in the United States it was called Project Matterhorn, as far as I understand. 157 00:15:30,260 --> 00:15:32,330 However, as we can see nowadays, 158 00:15:32,330 --> 00:15:39,950 the problem of controlled thermonuclear fusion reactions to generate electricity is a lot harder than that of fission. 159 00:15:39,950 --> 00:15:44,240 And so the scientists realise that like even the collective power of the United States, 160 00:15:44,240 --> 00:15:49,490 the Soviet Union individually isn't going to be able to solve this problem quickly. 161 00:15:49,490 --> 00:15:58,280 So there's a very famous fusion conference or the Geneva conference where physicists from the Soviet Union in the United States, 162 00:15:58,280 --> 00:16:04,550 the U.K. and a few other places got together and actually compared what kind of theory they were using, 163 00:16:04,550 --> 00:16:08,660 what kind of devices they were using, and are some really interesting things. 164 00:16:08,660 --> 00:16:15,320 Like what was I think really interesting was not the differences, but actually the similarities between the approaches they were taking. 165 00:16:15,320 --> 00:16:22,610 And that was really quite promising. And to some extent and it showed that actually everyone was thinking the same way about things. 166 00:16:22,610 --> 00:16:28,670 And yet so to this day, fusion research, at least for energy purposes, for peaceful energy purposes, 167 00:16:28,670 --> 00:16:33,170 has always been an area in which international collaboration has thrived, 168 00:16:33,170 --> 00:16:38,580 particularly between allies during the Cold War, between the Russians and the Americans. 169 00:16:38,580 --> 00:16:47,000 What is this related to the fact that unlike nuclear fission, nuclear fusion by itself does not lead to a nuclear bomb? 170 00:16:47,000 --> 00:16:58,280 Yeah, that's that's a great point. So actually, every single nuclear weapon that exists today has at least a fission core, 171 00:16:58,280 --> 00:17:03,230 which means that you need to have you need to understand fission before you can make a nuclear weapon. 172 00:17:03,230 --> 00:17:05,510 On the other hand, if you just had a fusion plant, 173 00:17:05,510 --> 00:17:14,650 you can't make a pure fusion weapon because you would need to understand the fissile material as well before that to make the weapon. 174 00:17:14,650 --> 00:17:22,120 OK, so it's about time to bite the bullet as a human species, we've been trying to do this for 60 years, in which time we've got to the moon. 175 00:17:22,120 --> 00:17:26,770 We've invented nuclear fission reactors, we invented the Internet bubble, 176 00:17:26,770 --> 00:17:32,330 and we still don't have a nuclear fusion plant that produces electricity for Larin. 177 00:17:32,330 --> 00:17:36,640 What are the challenges that mean that this has been a very hard problem? 178 00:17:36,640 --> 00:17:40,550 Well, as we've discussed, it's not like a fusion can happen. 179 00:17:40,550 --> 00:17:47,740 You need really high temperatures in the core of the device where the nuclear fusing as well. 180 00:17:47,740 --> 00:17:52,360 However, at the edge of your reactor, the part which faces the wall, 181 00:17:52,360 --> 00:17:59,980 you don't want it to be particularly hot because it's going to melt the material and you have something like hundreds of million, 182 00:17:59,980 --> 00:18:08,680 100 million degrees in the middle. And material that we know today, as far as I understand, a few thousand degrees is pretty much limited. 183 00:18:08,680 --> 00:18:12,490 So you have massive temperature differences between the two. 184 00:18:12,490 --> 00:18:20,830 And the question is, how do you maintain this? How do you make the middle hotter and the outside just as cool as before? 185 00:18:20,830 --> 00:18:24,010 And there are various physics and technology problems to it. 186 00:18:24,010 --> 00:18:30,860 So, of course, on the technology side, you want material which does melt and all the physics side. 187 00:18:30,860 --> 00:18:36,590 You want to understand that we hit it out from the inside, 188 00:18:36,590 --> 00:18:41,520 out from the inside of what is that is the first time I heard the word in the podcast, but it can be a very important word. 189 00:18:41,520 --> 00:18:50,570 So we should just so a Tokamak is so to talk about is one of the leading contenders for fusion power today. 190 00:18:50,570 --> 00:18:52,850 And the way it works is that you have a doughnut, 191 00:18:52,850 --> 00:18:59,600 basically something that's shaped like a doughnut and you put magnetic coils on the outside of what these magnetic coils do. 192 00:18:59,600 --> 00:19:08,660 Stay the hold the plasma and confided, as we say in place to this, prevents plasma from touching the wall, mostly speaking. 193 00:19:08,660 --> 00:19:13,430 And so essentially keeping it suspended from everything else. 194 00:19:13,430 --> 00:19:17,900 And then you try to heat it up because the plasma is charged. 195 00:19:17,900 --> 00:19:26,570 It will be contained by the magnetic field and because it has particles that it turns out follow the fuel lines. 196 00:19:26,570 --> 00:19:32,960 So if you engineer your lines in a certain way, the particles will not go from one field to another. 197 00:19:32,960 --> 00:19:36,540 What it does happen, but it's low compared to moving along the fuel line. 198 00:19:36,540 --> 00:19:42,710 So you try to keep this very few lines and keep the particles from moving outwards. 199 00:19:42,710 --> 00:19:51,360 And in fact, using magnetic fields to confine energy is this is basically an installation of insulating your muscles. 200 00:19:51,360 --> 00:19:59,690 He doesn't move out. Installation, if I remember correctly, is about 10000 times better than the tiles on the space ship, 201 00:19:59,690 --> 00:20:04,720 which prevents the crew from flying during re-entry, of course, in space. 202 00:20:04,720 --> 00:20:09,350 And I think feels like that is going to come up. 203 00:20:09,350 --> 00:20:18,290 OK, so just going to just there are these great challenges of containing the material and getting it to a high enough temperature, 204 00:20:18,290 --> 00:20:21,980 but that does one more thing that's required to get fusion to happen. 205 00:20:21,980 --> 00:20:24,620 I remember you telling me about these three things that were important. Yeah. 206 00:20:24,620 --> 00:20:34,010 So to get, you know, a viable fusion power plant to get your fuel such that it can produce a lot of fusion power, you need three things. 207 00:20:34,010 --> 00:20:38,150 You need enough particles. Right, because you want to combine the particles to fuse. 208 00:20:38,150 --> 00:20:45,290 You need them to be hot enough. So you need to see really high temperatures because otherwise they're just bounce off of each other without sticking. 209 00:20:45,290 --> 00:20:51,500 And then you need confinement. So you need density, temperature and confinement. 210 00:20:51,500 --> 00:20:56,720 So again, enough particles that are hot enough and you need to keep them in the same place for long enough. 211 00:20:56,720 --> 00:21:02,840 And if you can do these three things sufficiently well, then no matter what scheme you use, 212 00:21:02,840 --> 00:21:06,740 you're going to you're going to be good at your produce fusion power from this. 213 00:21:06,740 --> 00:21:12,840 And there's a way of measuring progress of the scientific community on all of these three goals. 214 00:21:12,840 --> 00:21:22,970 Yeah. So this is the multiplication of density times, temperature three times confinement is referred to in infusion as the triple product. 215 00:21:22,970 --> 00:21:27,770 And this is kind of the fundamental metric for performance of our devices. 216 00:21:27,770 --> 00:21:32,630 And so if you look at where we were in the 1950s when research was first starting, 217 00:21:32,630 --> 00:21:38,300 and then look at how the triple product of our devices changed with time, 218 00:21:38,300 --> 00:21:46,130 you'll see that between the 50s and the 90s, they said, I guess fusion was progressing extremely rapidly. 219 00:21:46,130 --> 00:21:48,680 It actually outperformed the famous Moore's Law. 220 00:21:48,680 --> 00:21:56,300 So basically, the the triple problem was increasing faster than computer performance is increasing, which is really impressive. 221 00:21:56,300 --> 00:22:03,950 There is, as you mentioned, up until the 90s, there has been a slight slowdown in progress, at least in terms of the triple products measure. 222 00:22:03,950 --> 00:22:06,680 Yes and no. So actually, 223 00:22:06,680 --> 00:22:15,680 an interesting point is that we've only ever actually run the kind of fuel that we expect will power the first generation fusion reactors, 224 00:22:15,680 --> 00:22:19,490 which is deuterium and tritium. These are two isotopes of hydrogen. 225 00:22:19,490 --> 00:22:26,750 We've only run this in two separate documents, one to talk about called FDR in Princeton and one at the talk, 226 00:22:26,750 --> 00:22:30,140 Michael Jet in the U.K., actually six miles down the road from here. 227 00:22:30,140 --> 00:22:34,850 So we've only actually had a few chances to properly verify this. 228 00:22:34,850 --> 00:22:42,530 All the rest of the Tokamak used to term to Treasury usually now, actually, even though you don't get fusion power out of that or very much, 229 00:22:42,530 --> 00:22:46,220 you can kind of say, OK, by making a determinate here and running this Tokamak. 230 00:22:46,220 --> 00:22:50,750 But what would it look like if it were to him? Tritium, because the triple product, as you said, 231 00:22:50,750 --> 00:22:57,560 to term tritium and we have got some talkbacks that have actually improved quite substantially in the past 10 years, 232 00:22:57,560 --> 00:23:01,100 although it is true that progress has slowed. 233 00:23:01,100 --> 00:23:08,420 And that's because basically we're all working on ITER, which we'll talk about later, I'm sure, which is the world's largest Tokamak. 234 00:23:08,420 --> 00:23:14,500 And when that comes online, I think the progress will continue in the triple product quite substantially. 235 00:23:14,500 --> 00:23:19,730 Yeah, kind of jump in. So progress seems to have kind of stalled in the 1990s, 236 00:23:19,730 --> 00:23:25,880 but it's kind of because the entire community is is contributing to this one large experiment, ITER. 237 00:23:25,880 --> 00:23:29,210 And so, you know, this this experiment takes a long time to build. 238 00:23:29,210 --> 00:23:37,450 So we're hopeful that. If we wait, then we'll get a payoff and we'll see a very big improvement in either, but this is an experiment. 239 00:23:37,450 --> 00:23:42,390 So please forgive me if this is not a good analogy, but would you say that for the nuclear fusion community, 240 00:23:42,390 --> 00:23:48,580 the building of ITER is analogous to what the building of, say, the LHC was to be part of this museum? 241 00:23:48,580 --> 00:23:52,500 Yes. Yeah, yeah. Well, let's talk about it now. 242 00:23:52,500 --> 00:23:59,730 So it is a very, very large Tokamak nuclear fusion device that is currently being built in the south of France. 243 00:23:59,730 --> 00:24:09,570 Yes. And it has to be so big because there are certain issues, things related to all of your research so that it wants to come in for Larry. 244 00:24:09,570 --> 00:24:14,970 Tell me why it has to be so big or why it's been so big of this. 245 00:24:14,970 --> 00:24:21,720 I think to me at least, the simplest way to understand this is about surface area to volume ratio. 246 00:24:21,720 --> 00:24:28,590 So if you have lots of surface area and the same volume, you're going to lose heat very quickly. 247 00:24:28,590 --> 00:24:36,150 But if you increase the volume, then you have less surface area per unit volume and then you lose heat more slowly. 248 00:24:36,150 --> 00:24:40,140 And this is just the idea behind this is the simplest idea behind it. 249 00:24:40,140 --> 00:24:43,680 You make it bigger than the surface area per unit. Volume is smaller. 250 00:24:43,680 --> 00:24:50,880 You lose heat less quickly. And again, because it is bigger, the middle is for the filler in the meeting really takes longer time for the energy from 251 00:24:50,880 --> 00:24:56,640 the middle to escape and not having a particle in the middle to escape to keep them down. 252 00:24:56,640 --> 00:25:03,270 And so you have this actually happening. Yeah. So it's improving this confinement issue. 253 00:25:03,270 --> 00:25:06,450 But you were saying one of these three main important issues. 254 00:25:06,450 --> 00:25:12,060 So maybe we should briefly talk about what the big challenges for fusion and of where we are right now. 255 00:25:12,060 --> 00:25:16,680 Sure. So we've talked about, you know, we need these insane temperatures to get fusion to happen. 256 00:25:16,680 --> 00:25:21,390 And so it's kind of incredible that this is actually already been achieved. 257 00:25:21,390 --> 00:25:27,930 So in a number of devices around the world, we can routinely create the conditions necessary for fusion. 258 00:25:27,930 --> 00:25:35,880 The problem, however, is in order to heat the fuel to attain these crazy temperatures, we have to use a lot of power. 259 00:25:35,880 --> 00:25:44,400 And so right now, the devices we have to put in a whole lot more power in order to keep the plasma hot than we actually get out in fusion power. 260 00:25:44,400 --> 00:25:46,410 And so this is a problem because, you know, 261 00:25:46,410 --> 00:25:52,860 you can't generate electricity if you have to put in 100 megawatts of heating to get one megawatt a fusion power out. 262 00:25:52,860 --> 00:25:53,130 Right. 263 00:25:53,130 --> 00:26:03,510 And so what ITER is designed to explore is, you know, if if we can create a device that can more efficiently achieve the temperatures that we need. 264 00:26:03,510 --> 00:26:09,400 So if we can get a lot of fusion power out without having to put in as much energy in. 265 00:26:09,400 --> 00:26:12,670 One of the remarkable things about fusion reactions, as I understand it, 266 00:26:12,670 --> 00:26:19,280 from from reading your notes and talking to you earlier, is that it has potential to be self-sustaining further. 267 00:26:19,280 --> 00:26:24,670 And could you explain to us what that means? Self-sustaining means you don't have to put in additional energy. 268 00:26:24,670 --> 00:26:32,320 A candidate running, for example, if you put you know, if you want to have a barbecue, you initially have to heat it up with some of the lighter, 269 00:26:32,320 --> 00:26:39,370 some starters to get the charcoal to a high enough temperature and a charcoal and a high enough to it starts to burn. 270 00:26:39,370 --> 00:26:44,260 Right. And that creates the means. It breaks down and then it breaks down, creates more energy. 271 00:26:44,260 --> 00:26:50,830 And this energy then breaks down further. And you'll have to put InterOil anything more light on it. 272 00:26:50,830 --> 00:26:58,540 And it burns for the rest of your dinner, hopefully. So that's why we seek to achieve fusion that you put in enough energy to start 273 00:26:58,540 --> 00:27:03,490 and then you have a bit of energy left running the Magna's and what you create 274 00:27:03,490 --> 00:27:08,170 enough to flatten everything and just take in more power from the grid that 275 00:27:08,170 --> 00:27:11,470 is self-sustaining in the way there are different regimes are poking about. 276 00:27:11,470 --> 00:27:20,770 You're right. S self-sustaining reaction. It's not a power plant to be self-sustaining and you have to generate more energy into the grid. 277 00:27:20,770 --> 00:27:24,070 So therefore you have to be more self-sustaining. 278 00:27:24,070 --> 00:27:29,230 But self-sustaining fusion reactor is a master and we look at so what are the milestones, what we have here? 279 00:27:29,230 --> 00:27:32,200 So first you have a reaction. 280 00:27:32,200 --> 00:27:39,700 For example, let's consider, you know, the usual deuterium tritium into two different types of hydrogen coming together to give you energy. 281 00:27:39,700 --> 00:27:45,310 OK, so to get them to stick together, you need to put in energy in the form of heating your coils, 282 00:27:45,310 --> 00:27:53,830 the first level of the first milestone's break even, which means you need to produce more energy from the reactions to the amount of energy. 283 00:27:53,830 --> 00:27:59,470 And this is doable in the foreseeable future without much improvement. 284 00:27:59,470 --> 00:28:04,510 We believe, however, not all of this energy created goes back into the plasma. 285 00:28:04,510 --> 00:28:10,720 Some of this is where you have the deuterium, tritium fusion. Most of the energy is releasing the neutron, which leaves the plasma. 286 00:28:10,720 --> 00:28:15,310 So the energy which remains the plasma to continue heating it up is less. 287 00:28:15,310 --> 00:28:24,040 So the next milestone is that you need to be able to generate enough energy, which means the plasma to continue heating it up so it doesn't cool down. 288 00:28:24,040 --> 00:28:29,120 However, you also need energy to run the coils, to run the other things in the power plant. 289 00:28:29,120 --> 00:28:36,790 And this is the next level that you want to be able to have it to generate enough energy, sustainable economic energy from the grid. 290 00:28:36,790 --> 00:28:41,530 And after that, you don't want to create enough energy that you are making your power plants rather than a 291 00:28:41,530 --> 00:28:47,050 scientific experiment so that you can you can generate energy to use for other applications. 292 00:28:47,050 --> 00:28:53,860 And ultimately, we want this energy to be cheap enough to compete to compete with the other sources of energy on the market. 293 00:28:53,860 --> 00:28:59,170 Otherwise, what people won't take it up? So there are these different states. 294 00:28:59,170 --> 00:29:04,510 So the first stage, which we're not quite yet, but you think that we will soon, 295 00:29:04,510 --> 00:29:10,510 is to have more energy released in the reaction when you put then the second stage is to have 296 00:29:10,510 --> 00:29:16,360 more energy remaining in the plasma than you put in because some of the energy is very strong. 297 00:29:16,360 --> 00:29:22,030 And then you have the third stage of having enough energy to run all the calls and all the plants staying in the plasma. 298 00:29:22,030 --> 00:29:28,030 The fourth stage even of that being having surplus energy to then send to the grid and use actually the power plant, 299 00:29:28,030 --> 00:29:33,420 then you have a four and a half stage off stage in time versus being economically viable. 300 00:29:33,420 --> 00:29:37,960 And I should just say that it is probably going to get to the fourth the fourth stage. 301 00:29:37,960 --> 00:29:41,800 Really? Yes, third or fourth at first. 302 00:29:41,800 --> 00:29:52,880 That's how I mean it as an experiment. But that's the goal. OK, you all in various respects, research turbulence in these machines. 303 00:29:52,880 --> 00:29:59,470 Jason, can you tell us a bit about how turbulence comes up in nuclear fusion and why it's 304 00:29:59,470 --> 00:30:02,980 currently a problem for getting these reactions to work as well as we'd like? 305 00:30:02,980 --> 00:30:05,590 Absolutely. It's so turbulent. 306 00:30:05,590 --> 00:30:11,440 So, yeah, turbulence is one of the biggest problems in fusion, and it's actually the reason why we've made our fusion reactors so big. 307 00:30:11,440 --> 00:30:20,530 The problem is, is that turbulence takes a particle that is in the cold fusion and it transports it out rapidly to the edge where it won't fusion. 308 00:30:20,530 --> 00:30:26,980 And this decreases our confinement time, which is Justin says that's one of the components of this triple product. 309 00:30:26,980 --> 00:30:33,220 So you you'd imagine if you know, if you put stuff in the core and it's transported out quickly, you'll get less fusion power. 310 00:30:33,220 --> 00:30:43,060 So specifically in fusion reactors, one of the main drives, if not the main drive for turbulence, is something called the ion temperature gradient. 311 00:30:43,060 --> 00:30:47,800 So basically all that means is when I go from an eye on temperature. 312 00:30:47,800 --> 00:30:51,100 So I remembers the nuclei in my plasma. 313 00:30:51,100 --> 00:30:58,600 If I go from basically room temperature or a couple of thousand degrees to hundreds of million degrees in the core, 314 00:30:58,600 --> 00:31:06,790 and that happens over maybe like one or two metres, I think it is supposed to have a kind of radius of about two metres if that happens. 315 00:31:06,790 --> 00:31:13,000 And two metres, then basically what that. Causes is that causes a lot of eddys, a lot of tonalities to form, 316 00:31:13,000 --> 00:31:17,870 and basically this has been one of the key challenges of fusion over the past 30 years or so. 317 00:31:17,870 --> 00:31:23,140 And people have tried to understand, OK, we have this turbulence, how can we suppress it? 318 00:31:23,140 --> 00:31:29,830 And actually how can we use it to improve the confinement performance of our reactor? 319 00:31:29,830 --> 00:31:37,300 So in a way, this is like if you're in a shop, in a shop, in the middle of winter, it's cold outside, it's hot on the inside. 320 00:31:37,300 --> 00:31:43,930 You have turbulent eddies bringing the hot air from inside the shop into the cold outside in the cold outside. 321 00:31:43,930 --> 00:31:45,880 So these are turbulent eddies. 322 00:31:45,880 --> 00:31:55,570 And the way one of the ways you solve this is not put it all, but also if you put one at all, you have this hot, hot enough air just at the entrance. 323 00:31:55,570 --> 00:32:02,920 And this could not have breaks these turbulent eddies such that you stop having a big ideological from inside the outside, 324 00:32:02,920 --> 00:32:12,310 having a small area inside a small area on the outside. And this is showing a way this and this is one of the ways we try to reduce turbulence. 325 00:32:12,310 --> 00:32:16,110 Go come up. Jason, you were telling us two things that you were saying, 326 00:32:16,110 --> 00:32:22,470 that turbulence is a problem because it can bring this hot water from the centre out to the outside and you lose power. 327 00:32:22,470 --> 00:32:27,480 But then you also mentioned that it could possibly be used to kind of make it more 328 00:32:27,480 --> 00:32:36,180 efficient and think maybe that's related to something that just didn't work. Yeah, so I work I work studying turbulence and tokamak. 329 00:32:36,180 --> 00:32:42,600 And in particular, I'm looking at ways that you can use all of this turbulent activity, 330 00:32:42,600 --> 00:32:46,680 use all this energy and turbulence to actually fight the turbulence itself. 331 00:32:46,680 --> 00:32:57,360 So we've heard that one one way to fight turbulence is to use to use this flow of air in the example of the shop on a good day. 332 00:32:57,360 --> 00:33:03,960 And so similarly, if you use a flow of plasma, then you can shear turbulent eddies and reduce them. 333 00:33:03,960 --> 00:33:15,270 And so I'm looking at a way that you can use the turbulence to create this flow of plasma in order to self-regulating the turbulence. 334 00:33:15,270 --> 00:33:22,440 So you have turbulent eddies that are growing and getting more powerful and they create this plasma flow, 335 00:33:22,440 --> 00:33:27,930 which then acts on the turbulence to stop it from growing. 336 00:33:27,930 --> 00:33:33,090 And the methods that all of you use to study the flow in these plasmids, 337 00:33:33,090 --> 00:33:42,180 how closely might that be related to methods that mathematicians back in the 19th century were using to study ordinary flows of fluids of water? 338 00:33:42,180 --> 00:33:49,950 So depending on what kind of plasma physics you're looking at, you may use an extended version of the Navia Stokes equations, 339 00:33:49,950 --> 00:33:57,330 which basically means you just add an external electro magnetic forces that come from the plasma, just just mathematical. 340 00:33:57,330 --> 00:34:03,180 So the text equations are the classical analytical equations that govern the flow of Newtonian liquids. 341 00:34:03,180 --> 00:34:06,930 So you're saying that some physicists use that, but with a tweak? 342 00:34:06,930 --> 00:34:13,680 Exactly, yeah. And this type of a kind of fluid approach can actually be very fruitful when you're trying to look 343 00:34:13,680 --> 00:34:20,100 at fusion plant design and trying to understand what kind of limits you can have in some cases. 344 00:34:20,100 --> 00:34:30,900 So it is very useful. But there's another approach, which is, I think probably a lot more popular nowadays, which is called the kinetic approach. 345 00:34:30,900 --> 00:34:32,250 So basically in that approach, 346 00:34:32,250 --> 00:34:43,290 we have some kind of mathematical function called a distribution function that looks at the number of particles per unit area per unit velocity area. 347 00:34:43,290 --> 00:34:49,770 And you can manipulate this in all kinds of interesting ways and you can actually derive fluid mechanics from it as well, which is nice. 348 00:34:49,770 --> 00:34:56,670 So that's that's reassuring. But there are also lots of additional subtle effects, like when you add magnetic fields, 349 00:34:56,670 --> 00:35:01,090 how particles orbit around it, for example, that fluid mechanics cannot predict. 350 00:35:01,090 --> 00:35:06,690 I think probably the biggest one of the biggest examples of this is something called Landow dumping, 351 00:35:06,690 --> 00:35:15,690 which is how electromagnetic waves can transfer energy to charge particles and using fluid mechanics like the Navia Stokes equations, 352 00:35:15,690 --> 00:35:21,870 for example, you cannot predict this. You need to go to something called kinetic theory to predict this. 353 00:35:21,870 --> 00:35:26,640 And kinetic theory forms the backbone of lots of the super computer simulations. 354 00:35:26,640 --> 00:35:31,770 We do a lot of the theory we do nowadays because it's a very computationally intensive theory. 355 00:35:31,770 --> 00:35:35,610 Exactly. You can't just run it on like your just desktop computer. 356 00:35:35,610 --> 00:35:38,310 And yeah, it requires, depending on what you're doing, 357 00:35:38,310 --> 00:35:46,140 maybe hundreds or thousands of computing calls to to be able to compute the solutions to your equations. 358 00:35:46,140 --> 00:35:51,420 We've talked a lot about this huge international academic collaborations like with Peter, 359 00:35:51,420 --> 00:35:57,690 all the private sector getting involved for the energy companies who are trying to make nuclear fusion devices. 360 00:35:57,690 --> 00:36:05,640 Yeah. So there's there's a number of private fusion enterprises that have come up in the last maybe 15, 361 00:36:05,640 --> 00:36:10,230 15 or so years with with varying degrees of repeatability. 362 00:36:10,230 --> 00:36:18,390 And some of them really seem, you know, very out of this world, not really connected to reality. 363 00:36:18,390 --> 00:36:23,940 But there are a good number of increasingly scientifically rigorous ones. 364 00:36:23,940 --> 00:36:29,730 So some of the companies have started publishing in peer reviewed journals, which is encouraging. 365 00:36:29,730 --> 00:36:34,380 Most of them choose a scheme that's different than the mainstream scientific community 366 00:36:34,380 --> 00:36:39,210 simply because they don't typically have the resources to compete with devices like ITER, 367 00:36:39,210 --> 00:36:43,470 for instance. And, you know, a lot of these a lot of these configurations, 368 00:36:43,470 --> 00:36:48,840 a lot of these ideas are speculative, but that doesn't mean that they're not worth exploring. 369 00:36:48,840 --> 00:36:58,500 So the private fusion industry has an interesting relationship with the mainstream scientific community, the mainstream academic community, 370 00:36:58,500 --> 00:37:06,360 and that they're generally trying more fringe ideas that the mainstream community has kind of cast off. 371 00:37:06,360 --> 00:37:10,500 But it's really in a lot of cases, it's very difficult to prove that these ideas won't work. 372 00:37:10,500 --> 00:37:13,770 And there still is merit to exploring that. Right. 373 00:37:13,770 --> 00:37:22,320 The main thing that annoys academic researchers about some of these private enterprises is they make they tend to make very grandiose claims. 374 00:37:22,320 --> 00:37:26,190 So the academic community has been working on this for 50 years. 375 00:37:26,190 --> 00:37:33,480 And then some new start up company says they're going to solve the problem in five and don't really give scientific data. 376 00:37:33,480 --> 00:37:37,990 Supporting this claim rubs people the wrong way. Well, I can imagine. 377 00:37:37,990 --> 00:37:42,100 So we're coming to the end of our time here, but it's time to put our chips on the table as it. 378 00:37:42,100 --> 00:37:46,500 So, you know, it is measured away as we can possibly be. 379 00:37:46,500 --> 00:37:56,100 Do you feel that at this stage, any sensible timeline can be put on when a viable, self-sustaining nuclear fusion reactor will be built? 380 00:37:56,100 --> 00:38:01,650 Or do you feel there are still so many difficulties that need to be overcome that that's just not not a good question to ask. 381 00:38:01,650 --> 00:38:05,490 Yeah, I'm telling me to take that. 382 00:38:05,490 --> 00:38:12,120 Yeah. Yeah. So I would say actually getting to a commercially viable fusion reactor, 383 00:38:12,120 --> 00:38:18,000 there is some time dependency in there, but I would actually say a lot of it is funding dependent. 384 00:38:18,000 --> 00:38:22,740 So it's not a timing dependent question. It's a funding dependent question. 385 00:38:22,740 --> 00:38:26,520 Obviously there are some constraints. We can do it tomorrow if we were given 100 trillion dollars. 386 00:38:26,520 --> 00:38:35,820 But I do think that given historic funding levels for fusion have not really lived up to what a lot of people expected and hoped in the field. 387 00:38:35,820 --> 00:38:44,540 I think we've made remarkable progress. I would also add that at current funding levels, kind of 20 50 is, I think, 388 00:38:44,540 --> 00:38:50,850 a fairly reasonable timeline for when people are saying the first economically competitive fusion reactor will come on board. 389 00:38:50,850 --> 00:39:00,660 I think if funding were increased substantially, I think we could probably do it, you know, quite a bit faster. 390 00:39:00,660 --> 00:39:06,160 But I'm not quite I'm not sure if that's going to happen. Well, thank you very much for joining me. 391 00:39:06,160 --> 00:39:10,750 It feels a privilege to feel at the cutting edge of fiscal endeavour. 392 00:39:10,750 --> 00:39:15,338 I hope you've enjoyed listening. And please join us next time on In Our Spare Time.