WEBVTT 1 00:00:00.000 --> 00:00:12.410 Mark Kushner: He's caused by the fire drill. Not any of ours full. So and I'd like to welcome today. Denise Hinkle, from Lawrenceville National Lab. 2 00:00:12.972 --> 00:00:30.749 Mark Kushner: She got her Phd. From Ucla and plasma theory and then went to little more. And is now the Associate division leader for energy density and Icf in the design physics theory. 3 00:00:31.256 --> 00:00:55.230 Mark Kushner: She's also a Fellow of the Aps, and also has recently was the chair of the Aps the past past chair before Carl. So I'm the past chair. She's the past pass. She's ha very happy to be the past past chair, I can assure you. Real reason. She traveled all the way from California mug. 4 00:00:55.828 --> 00:01:01.220 Mark Kushner: Oh, thank you. Thank you very much. Okay. 5 00:01:01.796 --> 00:01:02.833 Mark Kushner: there you go. 6 00:01:03.430 --> 00:01:06.542 Mark Kushner: Thank you. Absolutely. 7 00:01:08.100 --> 00:01:18.359 Mark Kushner: Yeah. So thank you. It's exciting times I'd like to share with you some of the excitement around the results we've had at the National Admission Facility. At Libermore. 8 00:01:18.740 --> 00:01:24.689 Mark Kushner: So we didn't just get to admission. We've gotten beyond. And we're we're continuing. So 9 00:01:26.330 --> 00:01:27.410 Mark Kushner: so 10 00:01:27.580 --> 00:01:50.979 Mark Kushner: it took us a while to get there. You can date things back to actually the fifties when John Knuckles first talk, thought about a concept of Icf, it wasn't for the concept that we're gonna discuss today. That's gotten us to ignition. It was directly driven laser fusion, but that was nicely coupled with the invention of the laser 11 00:01:51.632 --> 00:01:53.229 Mark Kushner: in 1960. 12 00:01:53.240 --> 00:01:58.270 Mark Kushner: And so he got to thinking about how we could use lasers to drive fusion. 13 00:01:58.450 --> 00:02:21.060 Mark Kushner: And with that came a series of developments in laser technology. We had some. We had multiple laser facilities at the Livermore laboratory, the first being the Argus laser, which you can see was one Kilojoule, and then Shiva, which was 10 kilojoules. These were one Omega lasers. So they were infrared, and they generated 14 00:02:21.290 --> 00:02:46.269 Mark Kushner: a massive amounts of hot electrons. And didn't they? They made progress and diagnostics and understanding and and learned about actually the field of high energy density physics using these lasers. But it they didn't operate the way that they wanted to. And so the field sort of skipped through from one Omega to passing through 2 omega, 527 nanometers and sort of landed on 350, 15 00:02:46.270 --> 00:02:57.820 Mark Kushner: one nanometers of ultraviolet light to drive laser driven implosions. And that's what was brought up at Nova. That's what, said Omega. And that's what was decided for now. 16 00:02:57.820 --> 00:02:59.170 Mark Kushner: and Nova 17 00:02:59.170 --> 00:03:22.749 Mark Kushner: as at a 30 kilo dual laser, was very instrumental in making the case for Nif. There was a technical contract on Nova through the late 19 nineties that identified there were key things that were identified by multiple review committees that we had to sort out before we could bring Nif online and the know. The technical contract was very instrumental in doing that. And the key decision for Nif to bring it online happened in the nineties. 18 00:03:22.750 --> 00:03:33.860 Mark Kushner: It took a long time to build the laser. Nova was shut down in about 1998, so that all of the Livermore employees would focus their attention on doing a nif online. 19 00:03:33.970 --> 00:03:51.879 Mark Kushner: and the project was completed in July of 2,009, and we started our first experiments. Then we did our first cryogenic experiments, trying to get fusion yield, and about the 2,011 timeframe, and we ran the National Admission campaign through 2,012. 20 00:03:52.240 --> 00:04:15.799 Mark Kushner: After that we started to change things around, not focus on one thing. And we got to Alpha heating, using a high foot design that actually, I was the designer. For in 2,013, and by Alpha heating we mean that more fusion yield came out of actually Alpha heating the hotspot of the fuel. Then came from Pdv. Work of compression on that fuel. Blob. 21 00:04:16.817 --> 00:04:40.629 Mark Kushner: I think that we made it well, I don't think I know. We made a series of changes then between 2,013 to try to make our whole ROM the way that we indirectly drive the capsule implosion to make it more efficient to make the capsule itself more efficient, and to reduce any type of energy that wasn't causing radial inward motion of the capsule, we did our best to reduce that. 22 00:04:40.730 --> 00:05:09.360 Mark Kushner: and that culminated in a shot on August 8. That's N. 210808. That's how we identify our shots. And for Nef. And then the year of the month and the date. We achieved 1.3 mega joules of fusion yield on that shot. That was a a target gain of about point 7. If you calculate the lesson criterion for that, you'll find that by that criterion we actually achieved ignition. We did this 23 00:05:09.680 --> 00:05:21.865 Mark Kushner: here sheriff. I skipped over this, but Niff was designed to be a laser to Jen to operate at 500 terawatts and 1.8 mega tools. It is the world's most powerful sorry, not powerful, energetic laser 24 00:05:22.230 --> 00:05:47.460 Mark Kushner: and what we did here was we. We pushed the laser energy up to 1.9 megajoules, and then, on December fifth of 2,022 and the subsequent shot last July we actually use 2.0 5 megajoules of laser energy. The laser facility will work very hard to make sure that we could get that amount of laser energy. And then this fiscal year our fiscal year starts on October first 25 00:05:48.023 --> 00:06:01.469 Mark Kushner: we started feeling once a quarter laser shots at 2.2 megajoules. The facility made some upgrades and sustainment to get us to 2.2 mega tools. We can do that once a quarter. 26 00:06:01.720 --> 00:06:13.749 Mark Kushner: and going to 2.2 mega joules, enables you to go to a larger capsule thicker up later provides more protection. So the hotspot on its interior, and we actually got 5.2 mega joules of Yield out 27 00:06:13.920 --> 00:06:34.729 Mark Kushner: our goal over the course of the next couple of years is to try to push to 10 mega tools of yield, and we'll talk a little bit more about some follow-ons that we would do after that. That's what we're calling the Nif enhance yield capability, or at Livermore, because we're very well known for having way too many acronyms. We call that Eic. Okay? 28 00:06:34.730 --> 00:06:59.040 Mark Kushner: So next week, actually, Sunday or Monday, depending upon how Fielding the target goes, we're gonna take our next shot at 2.2. Major joules. The goal is to again try to mitigate all aspects of the implosion, to make it more radial and more compressed. Coupling as much energy to the hotspot as we can. So I will say it's been an amazing journey and haven't stopped yet. 29 00:07:02.990 --> 00:07:03.880 Mark Kushner: Oops. 30 00:07:04.110 --> 00:07:31.319 Mark Kushner: Okay? So, as I said earlier, we've achieved and exceeded all definitions of ignition, and by admission what we mean is more energy out than laser energy delivered to the target and more energy out in fusion energy. So you look at the amount of laser energy that's delivered. So the laser entrance hole of the target, and if we get more energy out of the fusion yield than that. Then we've achieved gain of whatever that fraction in that ratio is. 31 00:07:31.320 --> 00:07:46.650 Mark Kushner: And, as I told you on December first we got target gain of one here just last. What is it? 6 weeks ago we got greater than 5 megajoules. We demonstrated target gain of unity several times. Now at Nif. 32 00:07:46.690 --> 00:08:07.636 Mark Kushner: We use the indirect drive approach that we've talked about. And this sort of this plot of fusion energy versus campaign kind of shows you how we've walked up when we started. We didn't get a lot of yield here when we did the when we got to Alpha heating fuel gain, we mitigated ablation front instabilities to get here. 33 00:08:07.980 --> 00:08:19.580 Mark Kushner: And then we made the whole ROM and the capsule more efficient to get to this. And we've been sort of using these hybrid platforms to push up to where we are today. 34 00:08:21.720 --> 00:08:33.969 Mark Kushner: Okay, so I thought we'd start at the beginning. If this is too elementary. I apologize. But I wanted to make sure that we are all on the same page. That fusion occurs when 2 light nuclei combine, and if you look at the left here. 35 00:08:33.970 --> 00:08:55.108 Mark Kushner: you can take a hydrogen nucleus protein. It's just a proton, and if you add a neutron to it, you get a deuterium neutr nucleus, and if you take deuterium and you add a neutron to that, you get tritium. If you can take a deuterium nucleus and a tritium nucleus and you can get them close enough to one another, get them to overcome the potential barrier between them. 36 00:08:55.731 --> 00:09:14.710 Mark Kushner: That means compressing it, getting it dense enough, and if you can get it hot enough that the cross section for reaction between the 2 will occur. Then what will happen is you'll produce a helium nucleus which we call an alpha particle, and you'll produce a very energetic neutron. And this is what we call the fusion yield. 37 00:09:17.480 --> 00:09:46.330 Mark Kushner: and if you measure the mass of the products before and after the fusion process, you'll find that the deuterium and trutium nucleus have more mass than the fused helium nucleus and the neutron, and that additional energy, that additional mass, was converted to energy. And it's in the amount of 17.6 Mev. The neutron comes out at 14.1 Mev, and that particle comes off with 3.5. 38 00:09:50.610 --> 00:10:15.580 Mark Kushner: So in order to get the fusion process to happen, you have to pressurize it to high temperature and density, and in the sun it's gravitational confinement that sustains fusion. When you do inertial confinement, fusion. What you're doing is you take something. It's not the size of a basketball, but if you took a nif capsule and you scaled it up to the size of a basketball, the amount that you have to compress it is taking the basketball 39 00:10:15.580 --> 00:10:25.229 Mark Kushner: and compressing it down to the size of a p. And that's how much we're compressing the capsule inside our target, which is basically the size of a PA pea 40 00:10:25.476 --> 00:10:50.130 Mark Kushner: and what you're achieving when you do that is a temperature that is greater than 5 times the temperature at the center of the sun a pressure that is 2 times greater than that at the center of the sun. But it's not sustained. It's it's for a very short amount of time. So you do this. And if you were thinking about doing this for inertial fusion, energy, what you would need to do is to have a high rep rate razor that could do this several times a second. And you would have to be able to throw 41 00:10:50.130 --> 00:11:01.570 Mark Kushner: basically literally throw a capsule in front of the laser in order to do that. And that's what we, those are the kinds of schemes that people are looking at for future inertial fusion, energy, capabilities. 42 00:11:04.650 --> 00:11:08.630 Mark Kushner: So if you think about just going back to ignition now. 43 00:11:08.890 --> 00:11:16.759 Mark Kushner: what you have to do is take the fusion, fuel, fuel and heat it and compress it to the point where Alpha helium will start to occur. 44 00:11:16.920 --> 00:11:35.479 Mark Kushner: And here is a a a plot of the cross section of different fusion reactions versus ion temperature. And if you look at the deuterium tritium, a reaction which we just talked about on the previous page, you can see that it has the highest cross section, which is why we're using deuterium and tritium. 45 00:11:35.760 --> 00:11:57.300 Mark Kushner: And what we mean by Alpha heating is that you have assembled this blob of Dt fuel in the middle of your experiment, and you want to get it dense enough. Okay? And you want to get it confined enough that those alpha particles will deposit their energy within that hotspot of Dt. 46 00:11:57.320 --> 00:12:24.109 Mark Kushner: And if they deposit their energy in the hotspot, because this is a function of of temperature, the temperature increases, and so the cross section increases. So the likelihood, the probability of more reactions occurring. Goes up. And then, as you heat more you work your way up to scale. So the ratchet rate increases, you get more reactions and you get more heating. It's basically a thermal instability that you're driving at the center of your experiment. 47 00:12:27.780 --> 00:12:35.430 Mark Kushner: So what are what is it that you have to overcome? All right. So we're doing 2 things to get this 48 00:12:35.950 --> 00:12:52.210 Mark Kushner: blob of Dt fuel into a state where fusion can occur. The first thing is we're compressing it, and we're doing that by a blading material off the outside of it so that it will implode via conservation of momentum. That's Pdb work. 49 00:12:52.210 --> 00:13:08.955 Mark Kushner: And we're doing alpha heating as we just described you. Wanna get this central hotspot, surrounded by a dense enough shell that all alpha particles are stopped, or a large portion of them are within that fuel, and heated up versus the the mechanism that we just talked about. 50 00:13:09.290 --> 00:13:30.129 Mark Kushner: But you have to think about the losses that occur as well, and first off you can radiatively cool the Hotspot via radiative losses, such as Bremsstrahlung. So that's an energy loss. And you can also radiatively cool via thermal conduction that cools the fuel. As well, so what happens is you come in. 51 00:13:30.410 --> 00:13:48.919 Mark Kushner: You have an implosion. So that means that this thing is getting smaller and smaller and smaller to the point where the internal pressure is too high and it starts to explode. You wanna get you'll kind of want to have the process happen throughout this whole course of the implosion and the explosion. 52 00:13:49.350 --> 00:14:16.539 Mark Kushner: So if you look at heat balance, you can say that the time rate of the change of the temperature okay, occurs. As a function of the alpha heating that goes on. That's increasing the temperature. And when you're imploding, this increases it, the temperature, but it decreases it on explosion because you're getting larger volume, and then you have your loss terms, radiative losses and conduction losses. 53 00:14:16.540 --> 00:14:43.649 Mark Kushner: So if you balance these 2 terms, then you see that the iron temperature scales like T to the 3.6, and if you draw a slope on that cross section that looks sort of like T to the third T to the fourth that fits. And if you balance these 2 terms, Alpha heating versus radiative losses, you find that you need a minimum, 10 temperature of 4.3 kev in the Hotspot to get ignition to happen. So that's sort of like the minimum 54 00:14:43.780 --> 00:15:05.159 Mark Kushner: entrance that you need in order to get fusion to start in order to get 4.3. Kev, you need a pretty fast implosion you need about this is 320 kilometers per second. Typically our implosion velocities inward are more like 380 kilometers per second. They can be as high as 420, but 380 seems to work really well. 55 00:15:07.350 --> 00:15:14.390 Mark Kushner: So here's a picture of Nif. I think you kind of got the message that we use nif the world's most energetic laser to drive this process. 56 00:15:15.582 --> 00:15:18.199 Mark Kushner: It's and 57 00:15:18.600 --> 00:15:21.810 Mark Kushner: it's about the size of 3 football fields. 58 00:15:22.270 --> 00:15:32.840 Mark Kushner: So it's a large laser. You have to remember that it's built on 1980 S. Laser technology. It was designed in the nineties. So here, what you're seeing here are capacitor banks 59 00:15:32.840 --> 00:15:57.829 Mark Kushner: that charge the amplifiers this main section here. You can't see the master oscillator room. It's underneath, but these are the main amplifiers that amplify the laser light they come into a switch yard. Here you have 2 bays, Bay one and Bay 2. They come into the switch yard, and everything's taken from sort of a horizontal orientation into a spherical orientation. That's why you see, all these funny laser being 60 00:15:57.830 --> 00:16:00.330 Mark Kushner: lines and they enter the target chamber. 61 00:16:00.400 --> 00:16:12.040 Mark Kushner: I get asked this question a lot on laser wall plug. If you look at the amount of energy it takes to drive an experiment like this, it's about 300 megajoules of electrical energy. 62 00:16:12.686 --> 00:16:36.590 Mark Kushner: And we're not comparing to this. What we're comparing our numbers to is the amount of laser energy that has been generated and enter as a target, and the reason for that is that Nif was designed to be a proof of principle, capability for achieving fusion, ignition in the laboratory. It wasn't meant to be an efficient laser. There's lots of ways that you can make this laser more efficient. 63 00:16:36.620 --> 00:16:45.559 Mark Kushner: But what we are here to show is that we can achieve ignition. And that is our measure of that metric. What's fascinating about this is 64 00:16:45.680 --> 00:17:12.670 Mark Kushner: here we have something that's the size of 3 football fields. All of these laser beams come into this target chamber. The target chamber is about 10 meters in diameter, and inside the target chamber is you're looking at a whole ROM. It has the capsule inside, and that's typically about a centimeter long and about a half a centimeter in diameter, and the pellet of fusion fuel is 2 65 00:17:13.013 --> 00:17:33.600 Mark Kushner: in diameter, and when you find, look at your final central hotspot that you create, it's about 25 microns, 20 to 30 microns. It's the size of a human hair. So we're going from something the size of football fields down to the size of a human hair in this process. So when you think about that from a computational 66 00:17:33.720 --> 00:17:41.620 Mark Kushner: capability perspective, that's a lot of spatial and temporal time scales that you want to describe in your simulation. 67 00:17:45.480 --> 00:17:54.500 Mark Kushner: So our approach, as I said earlier, is indirectly driven laser fusion. And what you do is you use laser 68 00:17:54.780 --> 00:18:09.440 Mark Kushner: to create X-rays. Those X-rays make a radiation oven that drive the capsule. So this is a cutaway of what a whole realm looks like. You have 96 laser beams that enter from the top, and 96 from the bottom. 69 00:18:09.640 --> 00:18:33.169 Mark Kushner: I always marvel at the feet of engineering here because we call the again. I tell you Livermore loves their acronyms, and Leah is a laser entrance hole, and there's a laser entrance hole in this end, cap and one in this end, cap. They're about 3 and a half millimeters in diameter, and we're fitting 96 laser beams into them and pointing and getting the energy through that laser entrance hole into this cavity. 70 00:18:33.210 --> 00:18:56.940 Mark Kushner: So the first thing is to get the laser beams in. Okay, once you get the laser beams in, they strike the interior of this wall, which is typically either gold or depleted uranium covered with gold, and that excites atomic transitions in the gold and those atomic transitions then reradiate back to the ground state, and they fill this cavity with X-rays. And that's what you're seeing here. 71 00:18:56.990 --> 00:19:07.959 Mark Kushner: So you've made radiation oven. Now for this capsule. Okay, that's composed of Dt fuel on the inside, and it has an ablator on the outside. The ablator is made to a blade. 72 00:19:08.700 --> 00:19:22.050 Mark Kushner: and what happens is as this oven heats up, it ablates off the outside of the capsule into the whole ron that makes things challenging for the laser beams, but you keep them keep them going, and the capsule implodes. 73 00:19:22.210 --> 00:19:28.930 Mark Kushner: because by conservation of momentum. If I've blown something off outward, the rest of the capsule will accelerate inward. 74 00:19:29.310 --> 00:19:39.670 Mark Kushner: The fuel core reaches about 500 billion atmospheres, and if we're lucky we'll ignite, and then a burn wave will start to propagate outward from that central hotspots. 75 00:19:42.240 --> 00:20:01.129 Mark Kushner: And, as I said, Nif was originally designed. At 1.8. We can now go up to 2.2 megajoules of laser energy to, in fact, to to drive the inertially confined implosions. Here's a zoom in of what I just showed you. Of the 96 laser beams entering through the top and bottom. They do so in 4 cones. 76 00:20:01.957 --> 00:20:24.170 Mark Kushner: If you look up here you can see there's red lines that come down over the capsule. Those are what we call the intercomes, and they're according to the whole ROM axis at an angle of 23 and 30 degrees, and then the outer cones strike closer to the laser entrance hole. You can kind of see these faint red lines here, and they're at an angle of 44, and 50 degrees. With respect to the whole arm axis. 77 00:20:24.591 --> 00:20:52.979 Mark Kushner: And so what happens is they have to propagate through this whole ROM. It's filled with gas, the capsule of blades into this whole ROM. And so you've got a lot of plasma there now that the laser beams have to travel through. So one of the first things that you need to overcome is, will will there be laser plasma interactions? Will they backscatter the light? How much hot, how many hot electrons will they create? And how energetic are those hot electrons? Because that can preheat my fuel if I'm not careful 78 00:20:52.980 --> 00:20:54.859 Mark Kushner: and make it difficult to compress. 79 00:20:54.860 --> 00:21:13.260 Mark Kushner: So you don't want a lot of hot electrons, and you don't want them to be energetic. And since we're limited in energy, we can only go up to 2.2. Mega Joules, you wanna make sure that as much energy as you put out. There's laser puts out. You wanna get as much as that as you can into the target. So we worry about laser plasma interactions. That's the first step. 80 00:21:16.640 --> 00:21:17.270 Mark Kushner: Okay? 81 00:21:17.990 --> 00:21:19.350 Mark Kushner: And so 82 00:21:19.390 --> 00:21:48.359 Mark Kushner: what is the job of the whole ROM. I already told you it makes a radiation oven. You should sort of think about it as being a convective radiation oven, not in the sense that it's convective, but in the sense that it's symmetric that you want, the radiation that the capsule sees to be symmetric as symmetric as possible all the way around it. So it's 2 jobs are to get the radiation hot enough and to get it round enough and the hot enough can be limited by laser plasma interactions. 83 00:21:48.360 --> 00:22:16.190 Mark Kushner: The round has been our challenge. Okay, we've gotten over for the most part, being susceptible to laser plasma interactions that limit the amount of laser energy we can provide. But to this day we work very hard to get the the implosion to be round ideally. You want the implosion to remain round from the moment that the radiation turns on till the moment when it ignites, and that's a very challenging endeavor. 84 00:22:16.340 --> 00:22:28.689 Mark Kushner: However, even though laser plasma interactions have been challenging to getting that the drive that we need, they can actually help us here. And that's a very interesting story. 85 00:22:30.140 --> 00:22:52.710 Mark Kushner: But before I tell you about that, what what do I mean by round? I have a little thing up here, and what I mean by round is, you need to look at the low mode, radiation asymmetries that the capsule feels. So here again is my cartoon of Nif. I have outer beam striking near the laser, entrance hole and inner beam striking over the capsule. If I have too much energy on these inner beams 86 00:22:52.810 --> 00:23:21.369 Mark Kushner: compared to the outer beams. Then I'll push too hard like this, and I won't get around implosion. If only that happened at noon. Okay, we would be happy. However, if you have too much energy on the outer beams, you press too hard on this side of the implosion, and you get what we call an oblate implosion in nerf terminology. Prolate is we call a sausage. We're very invested in breakfast. And O blade is a pancake. Okay. 87 00:23:21.390 --> 00:23:37.950 Mark Kushner: so typically, what happens? You design an experiment for nif it looks like you're gonna get it symmetric in the simulation you shoot it on if and it turns out to be. Oh, blade. You're not. You don't get enough. Drive over the waste your waist, star with respect to laser Drive. 88 00:23:40.730 --> 00:23:57.820 Mark Kushner: But okay, so we already talked about. So I'll come back to that in a minute, I should have put these in a different order. So the laser plasma interactions that I'm talking about that limit us to being hot enough is basically back, scatter and back. Scatter occurs in 2 flavors. 89 00:23:57.820 --> 00:24:11.040 Mark Kushner: One is stimulated, brilliant scatter, and the other is stimulated. Ramon, scatter Brill on occurs when your incident laser scatters off of the normal mode, an iron acoustic wave in the plasma. 90 00:24:11.040 --> 00:24:31.319 Mark Kushner: and it's a feedback instability. So if if you can drive up very large ion acoustic waves and back, scatter because of the feedback instability, and if it's if your laser light scatters off of a lang, me or an electron plasma wave. Then you get stimulated Roman scatter, and that wave can then land our damp and give you hot electrons. 91 00:24:32.304 --> 00:24:57.139 Mark Kushner: What has been our friend actually is cross beam, energy transfer, which is basically a form of roll on forward scatter. So you're not back scattering the light. But what happens is you can have 2 forward going beams, and they overlap, and you can transfer one you can transfer energy power from one beam to another through a shared ion acoustic wave. It's basically forward, roll on, scatter. 92 00:24:57.640 --> 00:25:00.100 Mark Kushner: When we designed nif 93 00:25:00.900 --> 00:25:25.609 Mark Kushner: we were worried about, we we thought our designs were gonna be perfect. And we realized that this could happen. And we were worried. That costume energy transfer was gonna mess up our symmetry. So we purposefully nif was purposefully designed with a wavelength separation between the inner and outer beams, so that you could detune this and not have it happen. When we turned on nif. 94 00:25:25.810 --> 00:25:50.710 Mark Kushner: What happened was, we got an extremely oblate implosion, and we ended up using cross beam energy transfer for a brilliant scouter where the beams overlap basically in the laser entrance hole to transfer power from the outer beams to the inner beam so that we could get around implosion. So it's actually been our friend. It's the one thing good thing that laser plasma interactions has done for us. And this has been actually our most powerful tool for getting 95 00:25:50.710 --> 00:25:57.590 Mark Kushner: symmetry. Now we've actually expanded. So we have not just 2 color. We call this 2 color 96 00:25:57.800 --> 00:26:10.359 Mark Kushner: transferring energy from the hour to the inners. But we also have 3 color where we can transfer energy between the 2 sets, the 2 intercomes at 23 and 30 degrees. And between the 2 outer cones. That's for color. 97 00:26:12.320 --> 00:26:16.390 Mark Kushner: Okay, so this is just showing you the same thing. Basically. 98 00:26:16.770 --> 00:26:38.219 Mark Kushner: the the point here was that we use Crossmom energy transfer in our first, we use it in all of our shots. But in 221204 was the first shot where we got target gain of unity. And this is a neutron image that has been put together, and you can see that the image is very round. So 99 00:26:38.590 --> 00:26:50.810 Mark Kushner: We had to work our way up to getting there the first time we tried this out of the box we didn't get it round. That was in September of that year, but by the second try we did get the the the image to be round. 100 00:26:54.139 --> 00:26:54.859 Mark Kushner: So 101 00:26:55.720 --> 00:27:00.189 Mark Kushner: you can also look at how we've walked up in in a 102 00:27:00.420 --> 00:27:23.219 Mark Kushner: a space that we like to look at, which is hotspot pressure versus hotspot energy, and you'll notice that these axes say Alpha off. So what you do in the simulations is you don't allow the alpha particles to deposit their heating into the fusion fuel, and you can then just look at the hydrodynamics of the implosion, and what's going on without the complication of Alpha heating. 103 00:27:23.330 --> 00:27:28.169 Mark Kushner: And this is the ignition boundary right here, somewhere in the shady region. 104 00:27:28.190 --> 00:27:49.409 Mark Kushner: And you can see that we this was the National Admission campaign where we started. We moved our way up like this, and then we came down and we moved up like this, and then finally we went over the border of ignition boundary and beyond with 210808, and then with the subsequent experiments when we did this 105 00:27:49.410 --> 00:28:00.799 Mark Kushner: first experiment of 21 8 to 8. We tried several repeat experiments, and we never did as well the the target for for that 21 8 to 8 shot 106 00:28:00.800 --> 00:28:18.700 Mark Kushner: was the best target that we had ever fielded capsule at Nif. It was just fortuitous. We'd also made some design changes to that experiment. But what we found by doing the repeats is, you want a certain amount of robustness to both your laser delivery? 107 00:28:18.740 --> 00:28:39.719 Mark Kushner: If doesn't deliver exactly what you want it, it gets close. It tries very hard, and it has, you know, error bars that it shoots for, but sometimes it doesn't. And so you want your target to be robust enough to those laser deliveries that might not quite meet requests that you can still get ignition and burn. 108 00:28:39.770 --> 00:29:07.620 Mark Kushner: and you also, if our targets aren't perfect, even with our best targets, they're not perfect. The outside of our capsules are smoother than any other surface that we know of, and yet it still has enough roughness that it can generate hydrodynamic instabilities that can kill your capsule in terms of mixing high z material into your hotspot. So we needed something that would take us to a more robust place. 109 00:29:07.620 --> 00:29:15.870 Mark Kushner: And so what we've decided was, well, if we could make the ablator thicker, we could win in a lot of different ways. 110 00:29:15.870 --> 00:29:25.949 Mark Kushner: First of all, it increases confinement. Okay, if you have more fuel, aerial density outside of this hotspot, then you can hold the fuel together for a longer amount of time. 111 00:29:25.950 --> 00:29:47.549 Mark Kushner: Secondly, it's better for stability. What happens is, if you have hydrodynamic mix, it's that's working its way in. It has to travel longer from the outside. It has to travel a longer path through the ablator, and so you're less likely to get as much into the the fuel that you're trying to it get to ignite. And this makes the fuel more clean. 112 00:29:47.550 --> 00:30:02.409 Mark Kushner: This work from 21 8 to 8 up through our most recent shots has been designed work done by Annie Criter. Annie Criter, was an undergraduate here at the University of Michigan, and then she went on to Berkeley, and then to Livermore Lab. 113 00:30:06.080 --> 00:30:09.040 Mark Kushner: So you can ask yourself, or I can ask myself 114 00:30:09.110 --> 00:30:13.259 Mark Kushner: so why did it take so long to achieve ignition. You know 115 00:30:13.470 --> 00:30:15.239 Mark Kushner: a lot of 116 00:30:15.903 --> 00:30:30.260 Mark Kushner: not me. It wasn't me, but our management promised ignition in 3 years, and you know, thought, well, we'll just get it right out of the box. So why, it takes so long. And I think that there's 3 key aspects to this. 117 00:30:30.480 --> 00:30:42.439 Mark Kushner: The first is, and I. I alluded to this earlier that when you study high energy, density, physics and Icf is a branch of high energy density, physics. You have multiple, spatial and temporal scales. 118 00:30:42.970 --> 00:30:44.300 Mark Kushner: And 119 00:30:44.400 --> 00:30:56.930 Mark Kushner: because of that, because we're going from something that's on a very small, spatial and temporal scale to something that's on a very large spatial and temporal scale. You cannot computationally, directly, numerically, simulate all of that physics. 120 00:30:57.130 --> 00:31:04.440 Mark Kushner: It's not computationally tracked. But we don't have the computational power. And even if we did, you'd never get it done in time to prepare for an experiment. 121 00:31:04.780 --> 00:31:28.870 Mark Kushner: So what you do is you use reduced model descriptions of what you call subgrid physics physics that's not occurring on the hybrid dynamic S length and time scales, and that subgrid physics might be tested in certain areas of parameter space, but certainly not in all areas of parameter space, and certainly not at the frontier where you're crossing over into new areas where we've never been before. 122 00:31:29.540 --> 00:31:30.690 Mark Kushner: And so 123 00:31:31.323 --> 00:31:44.520 Mark Kushner: that makes it challenging. I think that most of the time we get into the right parameter regime we get close. But you actually need to have feedback from the experiments in order to close the loop on getting to where you want to be. 124 00:31:45.070 --> 00:31:53.360 Mark Kushner: Now, over the last several decades. Many of these reduced models of subdigrant physics have improved and they will continue to improve. 125 00:31:53.710 --> 00:32:15.509 Mark Kushner: They're still not accurate enough, and we know that many of them are not accurate enough. And actually, it's a priority of our program to define and execute focus experiments at Nif. We don't just do experiments on making yield. We do experiments to try to improve our code capabilities, to drive us even further, and that is a priority to improve our predictive capability. 126 00:32:15.770 --> 00:32:22.229 Mark Kushner: So in the meantime, while we wait for these predictive capability improvements to come along. 127 00:32:22.800 --> 00:32:47.319 Mark Kushner: What we do is we do simulation work that are calibrated to our experimental observables. So that means reducing the amount of power or changing a key aspect of the physics to make it look like what it does from the experimental observables. Once you've calibrated that design, then you can perturb around it, and you can still use that design to be predictive. 128 00:32:48.155 --> 00:32:48.800 Mark Kushner: But 129 00:32:48.930 --> 00:32:54.290 Mark Kushner: you don't want to perturb it so much that you walk far away from where your calibration exists. 130 00:32:54.380 --> 00:33:07.390 Mark Kushner: and finally, new and improved diagnostics coming online have helped the in this feedback loop, showing us things that we didn't know before about our simulations, where we weren't computing things properly. 131 00:33:08.930 --> 00:33:28.040 Mark Kushner: So that's our design challenge. It's to incorporate the correct physics at all relevant, spatial and temporal scales. Not all of the physics, but the physics that you, as the person that's designing the experiment, as the physicist knows, feels your tuition tells you is important to the physics models. 132 00:33:28.040 --> 00:33:40.449 Mark Kushner: and you could break this up into thinking about things at the macro mezzo and micro scale. And here at the macro scale. We have our whole one. You can see the lasers coming in, and the cap. This is not the size of the capsule, that's the capsule blading. 133 00:33:40.740 --> 00:33:54.489 Mark Kushner: And so the gross hydro dynamic like, and time scales are set by the target size, which I told you is about a centimeter in length, and also the laser pulse link. Our typical laser pulse link these days is about 134 00:33:54.590 --> 00:34:19.110 Mark Kushner: 1010 nanoseconds, roughly speaking, that environment inside the whole ROM sets the plasma parameters and the scale length for the plasma parameters. So that's gonna impact things like laser plasma interactions, hydrodynamic instabilities, heat transport atomic physics, all of the things all of the subgrid physics that we don't, that we need to continue to improve. 135 00:34:19.350 --> 00:34:28.750 Mark Kushner: If you look the mesoscale, here's 2 examples. There's others as I just mentioned. One is the beam. The beam is composed of many speckles that are microns 136 00:34:29.054 --> 00:34:52.839 Mark Kushner: wide, like 8 microns wide, and and they're about 175 microns in length, and these, as they interact with the plasma. As the beams travel through the target, they evolve on micro micron and length scales and picosecond time scales. And the same is true. If you look at this is, see, this is supposed to be a blow up of this little laser beam that's going in here. That's what these arrows mean. 137 00:34:52.840 --> 00:35:06.969 Mark Kushner: And you see here you have a capsule, and this is supposed to be a blow up image of the capsule, and you can see hydrodynamic growth of features of imperfections in the capsule that are growing up. And that impacts implosion stability. 138 00:35:07.010 --> 00:35:32.050 Mark Kushner: And then, finally, you have a micro scale where detailed processes of beam propagation occurs on the light time scales and the light spatial scales. If you think about wave particle and wave wave interactions. Those are important. And then also within the capsule, you have engineering features like the fill tube, there's a tent. There's a membrane that holds the capsule in place inside the whole room. 139 00:35:32.050 --> 00:35:48.686 Mark Kushner: You have to worry about the impact of that on the capsule, and how that because it creates a shadow and can cause hydrodynamic instabilities. The ablator that we use now is high density carbon. It's crystalline. So we need to make sure that when we first? 140 00:35:49.680 --> 00:36:13.719 Mark Kushner: I don't wanna say pound it, but when we want we want to strike it hard enough with radiation at the beginning that you get it to melt, which means you need to have 12 MB of pressure hitting the capsule initially. And all of these have to be done in detailed simulations with reduced models that are developed and then fed into the larger hydrodynamic simulations. 141 00:36:16.610 --> 00:36:32.109 Mark Kushner: So I mentioned also that diagnostics are a very important aspect of the work that we do, and when you take your simulation and you incorporate into it the observables that you see. And here's an example of many of them that we see. 142 00:36:32.110 --> 00:36:56.699 Mark Kushner: These are basically mostly either. X-ray images, neutron images. Some gamma stuff from gamma rays as in burn within bang time. And also you can look at shock speeds and shock timing because you wanna get that right when you design your target. All of these are important to spectroscopy has helped us and identify impurities in the Hotspots. 143 00:36:56.700 --> 00:37:05.659 Mark Kushner: and also has helped us to understand a little bit about our plasma condition. But all of these have been really significant in driving forward our understanding. 144 00:37:07.930 --> 00:37:12.819 Mark Kushner: So I told you a little bit about where we are and how we got there. 145 00:37:12.910 --> 00:37:19.150 Mark Kushner: But where are we going? And right now we're in the process of developing a proposal to upgrade myth. 146 00:37:19.300 --> 00:37:39.270 Mark Kushner: And we turn. We have called out the enhanced yield capability. Ec. And here's a little blow up of a part of Nif. You have a power amplifier, and you have a main amplifier here. You can see that the main amplifier has 11 slabs of glass. These are the flash lamps that are powered by the capacitors. 147 00:37:39.270 --> 00:37:57.970 Mark Kushner: Okay, right here down here. But in the power amplifier we have 1, 2, 3, 4, 5 slabs of glass, and there's 2 unoccupied locations. And so the proposal is to put these slabs of glass in the power amplifiers, and that should increase the a available energy by 40%. 148 00:37:57.970 --> 00:38:06.589 Mark Kushner: We can use existing vendor base, the one that we have and proven technologies. We don't need to to do any technological advancement there. 149 00:38:07.309 --> 00:38:36.500 Mark Kushner: Once you do it for one beam line, you can do it for other beam lines, and they say that it's not gonna require facility downtime. So we're constantly now, we're now working with our oversight National Nuclear Security Administration to see if we can bring this to fruition. The hope is that we can get up to 2.6 to 3 megajoules of input laser energy with just modest modifications. Now, normally, how this works is, we go back to the design. 150 00:38:36.500 --> 00:38:51.390 Mark Kushner: You design a target at 2.6 to 3 Mega rules, which is what we're doing now and then that drives the requirements for the facility which then they say, now we can't do that. Yeah, that's good. And then you may have maybe have to modify or design or not. 151 00:38:51.760 --> 00:38:55.609 Mark Kushner: But we've been working on the design aspect of that as well. 152 00:38:56.173 --> 00:39:16.526 Mark Kushner: And we've identified design options that generate yields between 20 to 40 mega rules at 3 mega rules of input laser energy. So here we you start with a one d scaling. So you do things in one d. Because and nothing will ever be better than what you do in one d. 2D. And 3D. Effects will always degrade what you're doing. 153 00:39:16.920 --> 00:39:45.519 Mark Kushner: And so if you look at a one d model, this is this is what it looks like, and these are current nif shots that we have down here, and we believe that by going up to somewhere between 2.6 to 3 Mega Joules, we should be able to hit this regime right here. Actually, these look a lot better. We've gotten something in the 2.6 to 3 mega drill limit up actually, up around the one d model. We'll have to see if that still pans out or not, but we think that we can substantially 154 00:39:45.520 --> 00:39:57.930 Mark Kushner: enhance the amount of yield we get it now yield depends on several things. It's not just one quantity. You wanna make sure that your implosion is compressible. So you don't want it to have a lot of entropy. 155 00:39:58.080 --> 00:40:11.879 Mark Kushner: You don't want it to get preheated. You want to maintain it on what we call as low and 80 about as possible. But also what we need to do is to look at how to improve the efficiency of our whole Roms which we're doing now 156 00:40:11.980 --> 00:40:28.899 Mark Kushner: we're we've started talking about higher efficiency ablators. You can see thoughts about switching back to churn ablator from high density carbon, basically because there's not as much energy tied up and ionizing the ablator material with Ch as compared to Hdc. 157 00:40:28.940 --> 00:40:45.550 Mark Kushner: and maybe we'll start with, we're gonna start with 80 about implosions that are around the amount of entropy that we currently have. But the idea would be to reduce that because that makes the implosion more compressible and it should generate more yield. 158 00:40:45.620 --> 00:40:46.810 Mark Kushner: So 159 00:40:46.850 --> 00:40:52.200 Mark Kushner: that's sort of the plan that we've laid out. And again, we're trying to bring that to fruition. 160 00:40:55.520 --> 00:41:04.959 Mark Kushner: So we're not just laying out the plan. We're doing as much as we can to test the physics now in preparation for making the case for this. 161 00:41:05.100 --> 00:41:30.059 Mark Kushner: and our main risks are laser plasma instabilities and symmetry control, and then, above and beyond that, if you're driving something at 3, Mega Joules, and suppose you want to put a package of material on the side or something like that. And you wanna see how it in what the impact of neutrons are on it, or high levels of radiation, you may have to pull some laser quads off 162 00:41:30.060 --> 00:41:49.310 Mark Kushner: to backlight that, or to to blow it down a little bit, something similar to maybe what you do at Zeus, and if I take those quads out. Then can I really still get the implosion to go the way we want? And so we have to think about those. How do I? How do. I fold this into my thinking about future applications. 163 00:41:49.310 --> 00:41:58.799 Mark Kushner: But the first thing on our list is laser plasma instabilities. And the reason is that we're going to scale the target up. You can see here. 164 00:41:59.570 --> 00:42:24.140 Mark Kushner: we're gonna take our current whole ROM, and we're gonna take our current capsule and we're gonna scale it up by a factor of 1.0 9. We actually have these experiments starting next month. That's what we call hydro scaling. You scale everything in an oil area and manner. But what we're not scaling is we're not scaling laser spots. So the intensity will go up. We're gonna put more power through the same spot size, and the reason for that is 165 00:42:24.460 --> 00:42:28.649 Mark Kushner: smaller spots will give us more agility to move. 166 00:42:28.710 --> 00:42:40.829 Mark Kushner: If if your spot is filling this laser entrance hole. It's really hard to move it around on the wall and kind of smear out the radiation along here as much as you can, so it gives you more agility, and where you can point the beams. 167 00:42:41.650 --> 00:43:06.620 Mark Kushner: But right now, what we see in our current shots is that we typically get about 97 and 98% of energy coupled into the target. But the where it doesn't couple is on the rise to peak power. And so here you have the foot of the pulse. You have. This launches one shock into the cap. So this launches the second, and then this launches the last shock on this rise to peak power we typically get 168 00:43:06.620 --> 00:43:21.789 Mark Kushner: but a little bit of stimulated brill scatter. It's not energetically significant, but it's happening at a time in the laser pulse when the capsule is very sensitive. It's coming in starting to move very quickly. So it's a not a great time for it to happen, and 169 00:43:21.940 --> 00:43:29.729 Mark Kushner: it can impact as symmetry, because that may be happening on one side of beams and not on another. And so you're ruining the symmetry that you plan for. 170 00:43:30.720 --> 00:43:46.170 Mark Kushner: Also, when Tom Chapman, who is our Lpi team lead, looks at this. He thinks that we're close to threshold to really taking off with a lot of back scatter. So we're going to do some initial laser plasma. Interaction tests. So here, if you look at what the black 171 00:43:46.200 --> 00:44:10.590 Mark Kushner: curve is, that is what our current laser pulse looks like for scaling up by a factor of one pound 1 point O 9. This is what your pulse would look like, and so we can actually run a pulse up to about this region. But we wouldn't get this last bit. So right now, we're gonna walk up very carefully doing a back scatter assessment. We're gonna have to maybe just walk up to here to start with and then add energy bit by bit. 172 00:44:10.590 --> 00:44:31.740 Mark Kushner: to get to the 2.2 mega tool level to see what the back scatter looks like. And once we get that information, if there's a lot of back scatter, then we're gonna have to modify the design. If there's not, then what we're gonna do the following year is try to make some emulator targets of what this back end of the laser pulse what the conditions look like, and see what kind of back scatter we get. 173 00:44:32.590 --> 00:44:36.430 Mark Kushner: So that's kind of what the plan is for the time being. 174 00:44:38.110 --> 00:44:40.440 Mark Kushner: So we've got a long way to go. 175 00:44:40.580 --> 00:44:47.359 Mark Kushner: But we have taken a very important step forward, and the questions are, how large of a gain can we achieve? And if 176 00:44:47.640 --> 00:45:02.000 Mark Kushner: we are developing higher gain designs, we are making a case to increase the amount of energy that nif is capable of delivering. And we are working on improving our predictive capability, informed by focused experiments. 177 00:45:02.040 --> 00:45:12.780 Mark Kushner: And we have a a saying at Littlemore. There used to be this big banner hanging outside the director's office. That says making the impossible possible. But basically, that's what we did. 178 00:45:12.900 --> 00:45:18.719 Mark Kushner: And it wasn't just powered by Nif. But it was a very important international collaboration that got us there. 179 00:45:18.880 --> 00:45:30.110 Mark Kushner: So I have. If ever everybody is willing. I do have a 5 min video to show you how nif works. If people are interested in seeing that otherwise we can end here. You wanna see that 180 00:45:44.580 --> 00:45:45.470 Mark Kushner: sables 181 00:45:51.430 --> 00:45:52.210 Mark Kushner: easier. 182 00:45:56.070 --> 00:45:57.530 Mark Kushner: Think it's good 183 00:46:30.400 --> 00:46:31.410 Mark Kushner: that looks like. 184 00:46:31.960 --> 00:46:32.670 Mark Kushner: yeah 185 00:46:34.503 --> 00:46:37.186 Mark Kushner: should be able to go first screen 186 00:46:38.890 --> 00:46:40.439 Mark Kushner: just how many minutes 187 00:46:56.980 --> 00:47:01.215 Mark Kushner: we could just play without sound. I can try and say. 188 00:47:05.930 --> 00:47:06.640 Mark Kushner: sort. 189 00:47:17.670 --> 00:47:18.670 Mark Kushner: Cli. 190 00:47:21.530 --> 00:47:24.089 Mark Kushner: hey? Let's not worry about the sound. Let's just see 191 00:47:26.600 --> 00:47:43.029 Mark Kushner: the universe, for billions of years has been lit by the fire of countless stars. In these stellar cauldrons hydrogen nuclei are fused together to form helium nuclei, releasing energy that lights the heavens. 192 00:47:43.200 --> 00:47:47.959 Mark Kushner: Can we build the technology to harness this awesome energy on Earth 193 00:47:48.100 --> 00:47:52.669 Mark Kushner: as we approach our planet? That is exactly what's happening today. 194 00:47:55.760 --> 00:48:05.169 Mark Kushner: Far beneath these clouds lies the National ignition facility located at Lawrence Livermore National Laboratory in Livermore, California. 195 00:48:05.270 --> 00:48:14.059 Mark Kushner: This facility has been built to bring star power to earth. It is the world's largest and highest energy laser system 196 00:48:14.500 --> 00:48:21.180 Mark Kushner: containing a hundred, 92 laser beams. Nif will explore controlled nuclear fusion 197 00:48:21.190 --> 00:48:47.929 Mark Kushner: to ensure global security enable sustainable clean energy and advance our understanding of the universe 85 feet tall. The laser and target area buildings inside are 2 parallel laser bays, each containing 96 E. 9 real time. 198 00:48:57.940 --> 00:49:07.170 Mark Kushner: We will follow the process for creating a miniature star in the target chamber by riding along with some of the laser beams. The process. 199 00:49:07.280 --> 00:49:08.650 Mark Kushner: the universe. 200 00:49:20.040 --> 00:49:26.000 Mark Kushner: the universe for billions of years has been lit by the fire of countless stars 201 00:49:26.280 --> 00:49:32.850 Mark Kushner: in these stellar cauldrons, hydrogen nuclei are fused together to form helium nuclei. 202 00:49:32.940 --> 00:49:36.069 Mark Kushner: releasing energy that lights the heavens. 203 00:49:36.220 --> 00:49:41.000 Mark Kushner: Can we build the technology to harness this awesome energy on earth 204 00:49:41.130 --> 00:49:45.719 Mark Kushner: as we approach our planet. That is exactly what's happening today. 205 00:49:48.770 --> 00:49:57.760 Mark Kushner: Far beneath these clouds lies the National Ignition facility located at Lawrence Livermore National Laboratory in Livermore, California. 206 00:49:58.300 --> 00:50:02.649 Mark Kushner: This facility has been built to bring star power to earth. 207 00:50:03.090 --> 00:50:07.040 Mark Kushner: It is the world's largest and highest energy laser system. 208 00:50:07.540 --> 00:50:29.210 Mark Kushner: containing 192 laser beams. Nif will explore controlled nuclear fusion to ensure global security enable sustainable, clean energy and advance our understanding of the universe 85 feet tall, the laser and target area building is the size of 3 football fields. 209 00:50:29.480 --> 00:50:36.030 Mark Kushner: Inside are 2 parallel laser bays, each containing 96 beam lines. 210 00:50:36.110 --> 00:50:46.190 Mark Kushner: In this animation, which is millions of times slower than real time. We will follow the process for creating a miniature star in the target chamber 211 00:50:46.200 --> 00:51:06.579 Mark Kushner: by riding along with some of the laser beams. The process starts by first energizing the laser amplifiers in the 2 laser bays by dumping electrical energy stored in capacitors into flash lamps. They convert the energy to light that is absorbed by the laser glass in the amplifiers. 212 00:51:06.640 --> 00:51:15.279 Mark Kushner: Later, when the laser pulses pass through the glass, they will extract this energy, thereby increasing the laser beam energy. 213 00:51:15.440 --> 00:51:20.370 Mark Kushner: Our trip with the laser beams begins in the master oscillator room. 214 00:51:20.460 --> 00:51:29.019 Mark Kushner: where a very low energy laser pulse is created. This pulse is only 20 billionths of a second long in duration. 215 00:51:29.240 --> 00:51:36.989 Mark Kushner: which is a beam of light about 20 feet long. It's amplified and then split into 48 laser pulses. 216 00:51:37.310 --> 00:51:46.469 Mark Kushner: which are carried over to the 2 laser bays, using fiber optic cables. Here the 48 pulses are amplified in a preamplifier 217 00:51:46.580 --> 00:51:49.160 Mark Kushner: by a factor of about 10 billion. 218 00:51:49.620 --> 00:52:05.929 Mark Kushner: Then they're split into 192 pulses and sent into the main laser system. As we track 8 of these beams. Through the facility you can see the path of the beams highlighted in red. The first amplification occurs in the power amplifier. 219 00:52:06.200 --> 00:52:11.350 Mark Kushner: It has 5 blast slabs that were energized by the powerful flashlands. 220 00:52:13.020 --> 00:52:25.319 Mark Kushner: Then they travel to the main laser cavity that directs the laser light back and forth 4 times through 11 sets of laser amplifier glass in the main amplifier system. 221 00:52:25.710 --> 00:52:29.010 Mark Kushner: This gives the laser beams another boost of energy. 222 00:52:29.600 --> 00:52:39.530 Mark Kushner: During this time optical components ensure that the beams maintain their required pulse, shape, quality, and spatial uniformity. 223 00:52:39.660 --> 00:52:45.039 Mark Kushner: On the final pass through the optical system the laser light is allowed to exit 224 00:52:47.760 --> 00:52:58.200 Mark Kushner: and travel back through the beam lines and up to the power amplifier once more to pick up even more energy before heading down the long stretch to the switch yard 225 00:52:59.560 --> 00:53:14.210 Mark Kushner: in total, the energy of the laser beams is increased a quadrillion times as they travel more than 1,500 meters from the master oscillator room to the target chamber. In the switch yard. 226 00:53:14.320 --> 00:53:19.430 Mark Kushner: Parallel bundles of beams are rearranged into a conical configuration 227 00:53:19.590 --> 00:53:25.000 Mark Kushner: that's so they can be focused into the center of the target chamber and onto the target assembly. 228 00:53:25.450 --> 00:53:35.010 Mark Kushner: The assembly holds the spherical fuel pellet containing hydrogen. Here you see the 8 beams split into 2 groups of 4 beams, each 229 00:53:35.230 --> 00:53:35.960 Mark Kushner: one group 230 00:53:36.330 --> 00:53:37.010 Mark Kushner: up 231 00:53:37.350 --> 00:53:38.310 Mark Kushner: other travel. 232 00:53:39.740 --> 00:53:42.889 Mark Kushner: equidistant entry ports on the target chain. 233 00:53:43.200 --> 00:53:52.100 Mark Kushner: Finally, the beans pass through the final optics assemblies which convert the original infrared laser light to ultraviolet. 234 00:54:00.230 --> 00:54:08.289 Mark Kushner: The beams then converge on the 10 target assembly called the hole rod, generating a bath of X-rays. 235 00:54:09.270 --> 00:54:16.920 Mark Kushner: This causes the tiny target sphere to implode and ignite in a controlled, self-sustaining fusion, reaction. 236 00:54:19.670 --> 00:54:30.090 Mark Kushner: the same process that powers the stars. This will be the start of a new journey that will bring not only discovery and innovation. 237 00:54:50.292 --> 00:54:51.457 Mark Kushner: Yes, yes. 238 00:54:52.590 --> 00:54:53.520 Mark Kushner: please. Host 239 00:54:54.120 --> 00:54:54.910 Mark Kushner: 99 240 00:54:57.026 --> 00:55:25.189 Mark Kushner: you mentioned to to go to enhanced yields bring another piece of glass into the power amplifier. Was it? Is it? Just what's there now? Empty support structure for a piece of slab class? You saw that they said here that there's 5 slabs in the power amplifier. There's actually it was designed to hold 7 slabs of glass. So there's just 2 that aren't holding anything. So why? Why, just now doing this same 241 00:55:25.250 --> 00:55:33.479 Mark Kushner: that I don't know the answer to, except we could get to the energies that we needed without putting those additional slaps of glass in. So I guess we didn't. 242 00:55:33.780 --> 00:55:36.419 Mark Kushner: So I that no. 243 00:55:36.430 --> 00:55:40.340 Mark Kushner: it's it's mind boggling, that it's so simple. Right? So. 244 00:55:43.120 --> 00:55:46.569 Mark Kushner: thanks for the great talk. You mentioned how 245 00:55:46.690 --> 00:55:49.480 Mark Kushner: important factor that you want to control is 246 00:55:49.530 --> 00:55:52.870 Mark Kushner: like avoiding a sausage or a pancake compression. 247 00:55:53.010 --> 00:55:55.270 Mark Kushner: Has it been investigated? 248 00:55:55.530 --> 00:55:57.910 Mark Kushner: The curvature of the hallram. 249 00:55:58.080 --> 00:56:00.839 Mark Kushner: because I imagine you could maybe like 250 00:56:01.140 --> 00:56:05.560 Mark Kushner: control what kind of incident angles the laser have. And also, maybe 251 00:56:05.600 --> 00:56:10.070 Mark Kushner: what like the mode structure is cause you want to avoid like asymmetric codes. 252 00:56:10.170 --> 00:56:19.150 Mark Kushner: So thank you for that question. That's a good one. So for those that you didn't hear. I don't know if you heard in the back or online? The question was, Have we looked at different 253 00:56:19.610 --> 00:56:28.010 Mark Kushner: curvature shapes of whole Roms, and an attempt to control low mode asymmetries that the capsule sees with the radiation that's 254 00:56:28.530 --> 00:56:29.730 Mark Kushner: generated 255 00:56:29.870 --> 00:56:46.870 Mark Kushner: by the whole ROM wall. And the answer to that is, we do have so back around 2,01314. We had a joint endeavor with Ca, who's, you may know, is building Lmj. Laser mega jewel. So they're interested in this as well, and we shot Rugby Holrams 256 00:56:47.020 --> 00:56:49.689 Mark Kushner: and Rugby is 257 00:56:49.910 --> 00:57:01.970 Mark Kushner: shaped like a Rugby, actually a Rugby football and that wasn't a very successful campaign. We and I don't necessarily think it's because of the shape it. I think it was because of other factors. 258 00:57:02.130 --> 00:57:21.020 Mark Kushner: But then we had an internal R&D project. Looking at, what could we do in terms of whole room shape to improve the efficiency? Because most of our wall loss is a function of surface area. So if you can reduce the surface area of the whole ROM, then you can generate a more efficient whole realm. 259 00:57:21.410 --> 00:57:28.370 Mark Kushner: And so one thing that we came up with was the fresh from. And the fresh ROM is basically 2 cones 260 00:57:28.420 --> 00:57:53.079 Mark Kushner: that come together, and they're very wide over the waste. So they're wide over the waste, and they're narrow where the laser entrance hole is for and it it so it's kind of angled like this. And we currently have a campaign at Nif. That's looking at. What can we do if we, if we try to generate an implosion very similar to the hybrid implosions that we're doing? Can we do it with less laser energy? 261 00:57:53.080 --> 00:57:58.599 Mark Kushner: First of all, because then that means that then you could scale that up. So that's the first thing that we're looking at. 262 00:57:58.900 --> 00:58:12.590 Mark Kushner: It's very challenging this. Actually, it's we've we've only shot cylinders. It's very challenging to actually change the shape of the whole room. And to really understand how to control that. But it is something that we're working on. 263 00:58:12.910 --> 00:58:13.610 Mark Kushner: Thank you. 264 00:58:16.570 --> 00:58:27.760 Mark Kushner: Maybe your main simulation answer this. But what's the if everything is perfectly manufactured. It works perfectly. What's the like? Predicted maximum yield you could get from the current laser. 265 00:58:29.480 --> 00:58:51.620 Mark Kushner: Well, in our original designs. I'm remembering a license plate that somebody had that was very instrumental in the Icf program that said, go for 30 Mj. Geo. For 30 mj, so the original point designs that were generated by Neph using 1.8 mega rules of energy were thought they would thought that they would achieve 30 Mega rules. 266 00:58:51.620 --> 00:59:01.049 Mark Kushner: We're very happy to get to 5. I think that right now our goal is looking at trying to get to 10. And can we make things more efficient and get there 267 00:59:01.600 --> 00:59:20.599 Mark Kushner: in in recent design simulations that Annie Criter has done for Yc, going up to 2.6 megajals. She's getting 40 megajals, and we're actually then taking her designs and trying to optimize them with machine learning, auto tuning techniques that have been developed, not optimizing. 268 00:59:20.780 --> 00:59:32.289 Mark Kushner: trying to optimize on the physics like understanding what aspects of the capsule we would need to change, to further enhance that. And what is the trade off? So we 269 00:59:32.370 --> 00:59:50.480 Mark Kushner: right now, I I think our thinking is that we should be able to get to something in the high 30 Mega joules. Maybe we need to divide that by a factor of 2. But we'd like to think that if we're increasing things by a factor of 1.0 9 in size, and we're getting to 10 megajoules that may be getting to 30 or 40. Isn't that much of a stretch 270 00:59:53.060 --> 01:00:09.830 Mark Kushner: following the same line? What fraction of the fusible material actually contributes to the fusion in the 5 megajoule shot or in the 30 mega. Okay? So I think what you're asking is out of the fuel. We're probably at something like 5 or 6% of the fuel is burnt up. 271 01:00:10.540 --> 01:00:13.170 Mark Kushner: The most that you could probably achieve is 272 01:00:13.200 --> 01:00:32.229 Mark Kushner: realistically 25%. That is the maximum achievable. Burn up fraction. And so that's one of the things that we're really looking to do when we go to these thicker ablators. And we're confining things better. We're doing it for that very reason, so that we can in improve the burn up fraction of the fuel. 273 01:00:36.560 --> 01:00:47.700 Mark Kushner: Most power plant designs use direct drive. Is there any? There have been plans in design? Are there any plans for doing direct drive on there? 274 01:00:48.486 --> 01:00:54.410 Mark Kushner: So are you asking in general to study the science, or are you asking about an if kind of question? 275 01:00:55.258 --> 01:01:09.781 Mark Kushner: So we we do have. We do have direct drive experiments that happen on this as part of our regular proposal process. So they are ongoing. 276 01:01:11.630 --> 01:01:14.120 Mark Kushner: I think that it 277 01:01:14.380 --> 01:01:39.190 Mark Kushner: no, not yet. They're still working on understanding the impact of cross beam energy transfer on Nif, because for them cross beam. If you do direct, drive laser fusion. What happens is that incoming laser light is taken by outgoing laser light. And so you actually extract energy from the implosion with cross beam energy transfer for something that's directly driven by lasers. But for us it's helpful for symmetry. 278 01:01:39.290 --> 01:01:47.895 Mark Kushner: But along the lines of where you first started the question. There are startups that are looking at indirectly driven ife type of 279 01:01:48.993 --> 01:01:54.689 Mark Kushner: schemes for power plans. One such company is Longview 280 01:01:54.700 --> 01:02:09.189 Mark Kushner: and long view. The CEO of long view is at Moses, so he is trying to pee back on the results at Nef and use those to extrapolate to what you would need to do for an ife type of situation. 281 01:02:09.420 --> 01:02:31.510 Mark Kushner: So there is work going on going in that the the direct drive work at Nif is very low. We've always talked about having 2 target chambers which we've never had, where one could be dedicated to direct drive and one to indirect drive, because the way that you come in you have to use special kinds of targets to direct the laser beams where you want for direct drive, because that's not how it was designed 282 01:02:33.040 --> 01:02:34.090 Mark Kushner: laser 283 01:02:34.540 --> 01:02:40.200 Mark Kushner: other plans to mitigate the impact of some of the instabilities that occur during the implosion 284 01:02:40.470 --> 01:02:42.969 Mark Kushner: by using magnetic fields. For example. 285 01:02:43.500 --> 01:03:06.469 Mark Kushner: Okay, so we've also had campaigns at Nif, where, thank you. What we're doing is using magnetic fields to magnetize the target. So you basically, it's similar to what you do at Omega. You wrap a coil around the outside of the target. You have to use a special way to position it. You can't use the standard way. The goal is not to get to a region 286 01:03:06.981 --> 01:03:32.469 Mark Kushner: where you're dominated by magnetic energy. The goal is to confine the off particles longer in the implosion, because they are traversing around magnetic field lines. They spend longer in the fusion fuel, and we'll dump more energy, therefore, into that region. It is something that we always talk about doing, but the facility isn't quite ready to do. Cryogenic implosions 287 01:03:32.470 --> 01:03:41.390 Mark Kushner: that ha are have external magnetic fields. But it is something that we've actually looked at and developed and have in our back pockets that we can pull out. 288 01:03:43.470 --> 01:03:51.335 Mark Kushner: Okay, well, let's thank you again for 289 01:03:52.350 --> 01:03:53.050 Mark Kushner: something. 290 01:03:54.140 --> 01:03:59.419 Mark Kushner: and please, the food showed up late. So on your way out, please take food. 291 01:04:02.435 --> 01:04:08.384 Mark Kushner: Save us.