WEBVTT 1 00:00:05.980 --> 00:00:25.149 Mark Kushner: Welcome everyone today. It's my great honor to introduce to you our speaker, Dr. Breena Geppert Kleinth, from Los Alamos National Laboratory. Dr. Geppert Kleinreth is the Deputy Group leader of the p. 1. Dynamic Imaging and Radiography group in the Physics Division or P division at Laml. 2 00:00:25.270 --> 00:00:36.219 Mark Kushner: In this role she manages over 60 scientists, engineers, postdocs, students, technologists and technicians. Her work focuses on the development of nuclear imaging techniques for inertial confinement, fusion or Icf 3 00:00:36.360 --> 00:00:43.339 Mark Kushner: in fact, she and her team have developed the 3D. Neutron and gamma imaging diagnostics used on the national ignition facility or M 4 00:00:44.013 --> 00:00:57.340 Mark Kushner: these nuclear imaging diagnostics, in particular have delivered key performance metrics for high Yield Icf employees on the Nif and ultimately helped lead to the 1st successful nif ignition shots that we just heard about in the past couple years. 5 00:00:57.530 --> 00:01:13.270 Mark Kushner: Dr. Geppard Heirath is also very excited about the prospects of inertial fusion, energy, or Ifb, which is distinctly different from Icf, and that's what she's going to be talking to you about today, but especially now with the nif ignition results and with all the activity going on in private fusion industry. 6 00:01:13.280 --> 00:01:40.230 Mark Kushner: She's authored or co-authored over 60 publications and accumulated over 2,500 citations. Her success in Icf diagnostics development has led to her receiving the DOE Secretary's honors award 3 times, as well as the American Fiscal Society's John Dawson award for excellence in Plasma Physics research. She also serves as the vice chair for the American Physical Society's 4 Corners section, and she's been at Lnl. Since 2012 when she started there as a graduate student. 7 00:01:40.460 --> 00:02:02.750 Mark Kushner: She holds a Phd. In nuclear physics from Vienna University of Technology, and originally held from Austria. And I'll also add that Verena serves on our the mock center that we have, that we run here at the University of Michigan. She serves on our Center Science Advisory Committee or Csac. We're very lucky to have her and get her expertise for steering the shift of our center. 8 00:02:02.830 --> 00:02:12.099 Mark Kushner: She also is the lab mentor for our very own Landon Tafoya, who's many of you know, is a Phd. Student here working, and also a Mipsi fellow. 9 00:02:12.661 --> 00:02:25.908 Mark Kushner: In fact, Landon is how Brina and I got to know each other through when she recruited Landon here to University of Michigan. He's already working with Brina. Got to know Brina, so it was very fortunate. So now we have her here with us today. So 10 00:02:26.190 --> 00:02:43.120 Mark Kushner: again. So she's going to be talking to us about the synergies and research or synergies between research and inertial fusion, energy or Ife and inertial combinement. Fusion or Icf, again, are 2 very distinctly different things. But before she tells us about that, we want to present her with the most prized 11 00:02:43.420 --> 00:02:53.319 Mark Kushner: prize. Thank you so much. Thank you. Thank you. 12 00:02:54.820 --> 00:03:04.009 Mark Kushner: Do you need an acceptance speech? Or oh, yeah, sure. Let's welcome our speaker again. Okay, thank you so much. 13 00:03:06.560 --> 00:03:32.410 Mark Kushner: All right, 1st of all. Thank you so much, Ryan, for the very generous introduction. So, and thank you all for coming this afternoon to my seminar. And, as Ryan said, I'm a Deputy group leader at the lab, but I also recently have accepted a new role as the liaison between our Scf program and our Ife program, which is the fusion energy Sciences program through the DOE office of science. 14 00:03:32.560 --> 00:03:59.950 Mark Kushner: And I only recently started working on this. So naturally, what I did 1st is, I want to look at these synergies through the lens of what I know, which is diagnostics. So you'll hear a lot about diagnostics today. And this talk has many contributions from the nuclear imaging science team and also the Gamma reaction history team. And of course our Lawrence Livermore National lab and the lab for Laser Energetics collaborators. 15 00:04:01.920 --> 00:04:26.880 Mark Kushner: All right. But before I get technical I want to give you a pitch for a while like working at the Los Alamos National Laboratory and hopefully recruit some of you so and introduce myself a little bit more. I have a degree in nuclear physics. So I'm in now in a field that isn't my Phd. Field. I wanted to highlight that. I am a Deputy Group leader. So I'm responsible for 65 to 80 people depending on summer students. 16 00:04:26.880 --> 00:04:39.120 Mark Kushner: which is really fun connecting with many people and learning about all of the research. We do everything from neutrino list, double beta decay to exploding plutonium and subcritical experiments out in Nevada. 17 00:04:39.120 --> 00:05:08.939 Mark Kushner: I'm a mom of 2 young kids that keeps me very busy or 2 and 5, and I'm also an immigrant originally from Austria, and now hold a green card. Hope to become a citizen one day here, and I'm an outdoor enthusiast, and of course, my pitch for working at Lana is that we have doing world class science. And there's amazing people there to do really great work. But also this picture is of me fly fishing 15 min from my house in a national park. So just saying. 18 00:05:10.020 --> 00:05:10.990 Mark Kushner: alright. 19 00:05:11.080 --> 00:05:22.810 Mark Kushner: let's look at what we're talking about when we say, ife so, our current inertial confinement, fusion, facility, like the national ignition facility, has a rip rate of about, we shoot once a week. 20 00:05:22.830 --> 00:05:50.870 Mark Kushner: and we have an energy gain of typically much less than one. We have recently reached ignition and energy gain, and we're up to about 2 point something. Now, this plasma is highly diagnosed. There is lots of diagnostics. So someone has counted them one. I think there's like over 100. But it is unclear. How many there even are, because they often change. And we really study plasma instabilities in these implosions. 21 00:05:51.050 --> 00:06:06.470 Mark Kushner: When we talk about the next steps, we're thinking about a scientific demonstration facility that would reach that ignition regime consistently. So, energy gain higher than one, and we would want to learn how to accustom 22 00:06:06.470 --> 00:06:27.389 Mark Kushner: higher rep rates up to like tens a day, so that we can get more and more data to learn more. And then a pilot plant would be something that actually produces electricity. But then we would have had to figure out the fuel cycle. We want an energy gain of depending on. If your inertial confinement comes from pulse power or lasers of at least 10, maybe 100, 23 00:06:27.390 --> 00:06:55.419 Mark Kushner: and our rep rates should be at about 10 hertz, and then a power plant would do the exactly the same as a pilot plant, but just is designed for ongoing power production, and our nutrients per shot, as you see at the bottom, would have to probably go up about 3 orders of magnitude from where we now. But I do want to say that 10 years ago, when we started Nif, we had a thousandthth of the yield that we have now. So this progress is feasible. 24 00:06:56.340 --> 00:07:21.220 Mark Kushner: And then here's a graph from Ricardo, Betty at Lolly. That is nice, because it puts magnetic fusion and inertial confinement, fusion on one graph pressure versus temperature. All I want to say here is, we've studied all these devices, all these facilities over the last decades. But where we really want to go is the top right hand corner, the ignition regime nif has now moved further to the top right? 25 00:07:21.220 --> 00:07:27.550 Mark Kushner: But when we want to have a fusion, energy, facility, we really want to be in the top right of that plot. 26 00:07:27.760 --> 00:07:55.419 Mark Kushner: Let's look at what we have now, our facilities for inertial confinement. Fusion in the Us. Are Omega at Ali Nif at Lawrence Livermore, and see it's a national lab. We have shot rates that are the highest at one, about an hour at Omega, but about a week at Nif our nutrient yields go from like 10 to the 14 to about 10 to the 18, which are the highest, yields on the Nif. Right now 27 00:07:55.420 --> 00:08:06.670 Mark Kushner: our energy per shot goes from about one Kilojoule to 5 megajoule, and our burn durations are from tens of picoseconds to a few nanoseconds on something like the C machine 28 00:08:06.670 --> 00:08:23.509 Mark Kushner: for a fusion power plant. We need to be in a slightly different regime at a shot cycle of about 10 hertz. Much higher nitrogen yield of up to 10 to the 21, and we want to reach high gain. So at least 50 to 5,000 megajoules. And then 29 00:08:23.620 --> 00:08:41.449 Mark Kushner: that spectrum of burn durations is just a sign of that. There's different mechanism for laser fusion versus pulse, power, fusion in laser fusion. We would probably expect to go down to 40 picoseconds. Oh, this is time. So I better hurry up. This advances by itself. 30 00:08:41.450 --> 00:08:49.490 Mark Kushner: Okay, so let's brief introductions for inertial confinement, fusion for those of you who don't work in inertial confinement. Fusion. 31 00:08:49.490 --> 00:09:12.080 Mark Kushner: deuterium and tritium is the most likely to be used for energy production, because it has a high cross section, and those are materials that produce a lot of energy per reaction, we produce an alpha particle and a neutron. So you already see that the neutron comes directly from the fusion reaction. So it's a good thing to diagnose the plasma. 32 00:09:12.140 --> 00:09:13.250 Mark Kushner: and 33 00:09:13.280 --> 00:09:35.820 Mark Kushner: ignition means a self-sustaining reaction now, so increasing self-heating removes the need for external heating. That's the loss in criterion. And what happens is that the center of the fusion reaction here the fusion implosion at Nif serves kind of like a spark plug. So we produce conditions there for fusion, and then the alpha particles 34 00:09:35.820 --> 00:09:57.669 Mark Kushner: get stuck with stopping power that is very short in the surrounding cold fuel that hasn't burned yet, and heat that the conditions where that burns as well, so that alpha heating is the key to ignitions and ignition was achieved in 2021, and energy gain greater than one and a half was then achieved at the end of 2022, 35 00:09:59.660 --> 00:10:19.209 Mark Kushner: so the Nif itself is a large facility, 260 meters long, or a few football fields, as they always say, there's 192 beams. It's the largest laser in the world, 2 megatroules of energy, a 10 meter diameter, target chamber, and we shoot a 1 carbon capsule filled with deuterium and tritium. 36 00:10:19.280 --> 00:10:30.539 Mark Kushner: What happens is we use this laser drive to illuminate this middle capsule here at the top right, that's called the whole RAM that translates the laser drive into an X-ray bath. 37 00:10:30.540 --> 00:10:52.050 Mark Kushner: which then ablates the capsule or a rocket drive is what it's called, as the outside of the capsule burns off, and then compresses that capsule and the compression and heating and shock then creates the conditions necessary for fusion, and if we also have alpha heating, then we have ignition. We have a sustained burn or burning plasma. 38 00:10:54.530 --> 00:11:21.880 Mark Kushner: All right, a little bit more about the history. We had our 1st implosion in 2011, so it took about a decade to reach ignition. At 1st we learned more about the laser pulse shape. It was from a square pulse. It became a complex shape that was ideal for multiple shocks, and that improved the stability. And then, in 2015, we changed the ablator from plastic to diamond. That gave us better implosion. Symmetry. 39 00:11:21.880 --> 00:11:49.360 Mark Kushner: In 2018 we increased the capsule size, reduced the whole RAM size. So you have more energy coupling. Get more energy into the target. And then in 2021, we had a smaller laser entrance hole. On the whole RAM more laser energy and much better target quality, and that gave us better energy coupling and fewer perturbations. Then. Now, since then we have reached the ignition regime regularly whenever they have attempted these high yield shots. 40 00:11:49.420 --> 00:12:18.580 Mark Kushner: and on the right here you see a 3D neutron image of that burning hotspot of the 1st ignition shot in 2 1 0 8 0 8. And what I want to see here before we dive into it is that Lionel diagnostics have been crucial in diagnosing ignition, and they provide data even in challenging conditions. Because when this 1st ignition shot happened, all the lights went out in the facility and lots of diagnostics shut down. So our diagnostics actually produce data. 41 00:12:20.340 --> 00:12:47.140 Mark Kushner: All right. So this plot is a little bit difficult because it's tiny. But let me show you. So this is the Hybrid E campaign. That's that high Yield campaign on the Nif. Those are just shop numbers so kind of like linear in time, how we developed. And then you can see that over the time from you know, we started this campaign in 2019, we have 1st reached burning plasma. And then we reached energy gain later. 42 00:12:47.290 --> 00:13:17.180 Mark Kushner: And what we did in this campaign is we tune the shape of the implosions to become more symmetric, and that's what you see here. The p. 2 over the P. 0 is just a measure of how squished or elongated the implosion is, and so that you can see that typically these really high energy shots tend to be very round, although the dynamics are a little bit more complicated. So we'll talk about that in a minute. 43 00:13:18.200 --> 00:13:37.900 Mark Kushner: And then we clearly see ignition markers in these really high yield shots. With our lanyl diagnostics, the nuclear diagnostics. The 1st one here is a measure of the burn volume, so that is also from the neutron image the 3D neutron image, where we see that the burn volume becomes larger because the burn volume extends during ignition. 44 00:13:37.920 --> 00:13:58.509 Mark Kushner: and then on the right hand side. That is the reaction history. So the fusion rate over time becomes the burn with where we actually see thermonuclear conditions becomes shorter and shorter. So up here in the top left are kind of these high yield ignition shots very short burn time. 45 00:14:00.020 --> 00:14:27.240 Mark Kushner: All right. I want to emphasize that lentil has over 80 years of diagnostic experience for single shots. A few examples here, neutron time of flight detectors. This is one that has been deployed on sea gas. Cherenkov detectors are the ones that provide this reaction history. So this is a pulse shape of a reaction history. The peak width. Oh, that's a little bit shifted. But the peak with this here is about 90 picoseconds. So that's a typical shot 46 00:14:27.240 --> 00:14:38.880 Mark Kushner: on Nif, and then on the right, you see a 3D neutron image. We also measured the fuel density with downscattered neutrons, and we also measured the remaining ablator shape with carbon gamma rays. 47 00:14:39.260 --> 00:14:51.680 Mark Kushner: And the Us. Really leads the world in nuclear detector technologies for fast diagnostics. So we have the tools to help. Ife use this diagnostic expertise. 48 00:14:52.680 --> 00:14:59.030 Mark Kushner: All right, I want to talk a little bit about nuclear imaging before we jump into the next topic. 49 00:14:59.330 --> 00:15:26.529 Mark Kushner: So if you imagine this burning plasma here in the center, this hotspot, we have a surrounding colder fuel that we want to heat with alpha heating. We have characteristic neutrons that are at 14.1 Mev. Emitted directly from the burning Hotspots. We can measure those. Some of them scatter in the surrounding cold fuel, lose some of their energy arrive at our detector later. Those are the down scattered neutrons. They tell us something about where the cold fuel is. 50 00:15:26.540 --> 00:15:36.999 Mark Kushner: and then we can also measure Gammas because they arrive at our detector, first, st because they travel at the speed of light. And so there's fusion. Gammas, at a small cross section 51 00:15:37.150 --> 00:16:03.899 Mark Kushner: that actually reaches directly. And there's gammas from neutron carbon interaction, where the neutron hits one of the carbon atoms in the remaining ablator, and produces a gamma as well, and this is about 100 micron across or so. That's roughly that compressed volume in an if impulsion. And, as I said, the neutron coming directly from the fusion. Reaction, of course, is a good diagnoser for the burn volume. 52 00:16:06.520 --> 00:16:22.019 Mark Kushner: All right. We have 3 of these instruments in the Nif. So the left. Here is a CAD model of the Nif. The small gray ball in the middle is the 10 meter target chamber that we talked about, and our detectors then sit at about 30 meters. 53 00:16:22.120 --> 00:16:23.899 Mark Kushner: Those are our cameras. 54 00:16:23.970 --> 00:16:43.630 Mark Kushner: about 30 cm from the target. We have an aperture, so we do pinhole imaging very similar to a camera obscura, with the difference that our aperture has a shape, and it is extended. The aperture needs to be long, because the interaction length of the neutrons of the 14 Mev. Neutrons 55 00:16:43.630 --> 00:16:57.150 Mark Kushner: with any material is long. In this case we use a high Z material, so we use gold, and it's 20 cm long. And so that makes that aperture shape quite complicated. It's also triangular and tapered. 56 00:16:57.150 --> 00:17:15.119 Mark Kushner: We use the triangular shape because we use a scribe to pull out slowly along the length of those 20 cm to produce our pinholes. Here, at the bottom, you can see the front of the pinhole, and these are tens of microns, pinholes, and they go down to just a few microns at the end. 57 00:17:15.589 --> 00:17:18.520 Mark Kushner: And then the image, the resulting image you get 58 00:17:18.619 --> 00:17:39.109 Mark Kushner: doesn't look anything like your source. It looks like this like your aperture, these triangles. So this is an inverse problem where this image is a convolution of your aperture, shape with your source shape. But we want to know the source shape. So this uses a Bayesian interference technique for reconstruction. There's many variables. 59 00:17:39.110 --> 00:17:51.100 Mark Kushner: One of the biggest uncertainties is that you cannot really measure these apertures very well. You can characterize the front and the back, but you can't really see through them, because they're so small. 60 00:17:51.100 --> 00:18:10.179 Mark Kushner: and there is no highly energetic neutron source in the world where you could actually image that aperture to characterize it other than nif. So we characterize it over the course of about a year of having it deployed on the Nif. So our reconstruction gets better and better and better the longer we have it on the Nif. 61 00:18:13.740 --> 00:18:24.010 Mark Kushner: All right. We have. We have energy, integrated detection. That's image plates. These are plastic sheets interleaved with image plates. 62 00:18:24.010 --> 00:18:50.440 Mark Kushner: So the neutrons get stopped there, and then produce images that are time integrated. So all of the primary and scattered neutrons are all measured there, so that because the primary signal is the largest kind of gives you a primary image on those image plates, and also gives you extra images from the bermstrawling from the hotspot, and then you can see here the timing spectrum on the bottom left 63 00:18:50.440 --> 00:19:15.689 Mark Kushner: the Gammas arrive at our detector first, st then the primary neutrons, and then the downscaired neutrons, and the way we measure them is, we have a dual line of sight, and then we have different simulators and different cameras, and the cameras are intensified with micro channel plates, but also gated with the microchannel plates. So then, we can gate on those peaks here to measure these 3 different things 64 00:19:18.760 --> 00:19:37.110 Mark Kushner: because we have 3 systems in total on the Nif, we can do limited view tomography that allows us a visualization of that burning hotspot. And compared to what we saw earlier how our Hotspot looks now when there's ignition. This is what it typically used to look like, a lot more perturbed. 65 00:19:37.140 --> 00:19:59.320 Mark Kushner: This is an old image from a few years ago, where we also did X-ray Imaging and the X-ray imaging here highlights, high sea material. And so you see, this is the fill tube being jetted into the capsule during the implosion, and when you put them together, you see that it fits very well. So in that region you don't actually have fusion reactions. 66 00:19:59.490 --> 00:20:08.799 Mark Kushner: This was the 1st visualization of that fill tube defect that then led to making the fill tubes a lot smaller, unfollowing high yield shots. 67 00:20:11.300 --> 00:20:40.399 Mark Kushner: And then these gated images. As I said, the downscattered image, provide information about the density you have to assume that the neutron scattered only once, and then you need to know the angular Cross section and the angular cross section gives you this illumination function. So when you look at it from only one line of sight. You only see this like front part of the capsule. So we actually have a second detector like that deployed on the other line of sight on the equator 68 00:20:40.698 --> 00:20:46.659 Mark Kushner: not on the pole, but on the equator. So we could make this more. 3D. That's work that's ongoing. 69 00:20:49.820 --> 00:21:01.419 Mark Kushner: all right. And then Gamma imaging is our newest edition. It's a little bit more complicated to interpret. So what we need to do is we need to actually do model based interpretation. 70 00:21:01.420 --> 00:21:29.100 Mark Kushner: and again based on interference with a model that tells you how much carbon is in the Hotspot, how much carbon is remaining and didn't burn. And what is a good model for the shape of that carbon? Because when you look only along one line of sight, you don't really know where that carbon is that gave you that signal, and you need to also take into account the fusion, Gammas, because we cannot separate them. They all arrive at our detector at the same time. 71 00:21:30.430 --> 00:21:35.610 Mark Kushner: But then we can get a model for the carbon density probability in the impulsion. 72 00:21:36.600 --> 00:21:39.560 Mark Kushner: All right. So here. 73 00:21:40.360 --> 00:22:01.690 Mark Kushner: Oh, that's cut off. I wanted to show you. You know what you saw earlier in those dots on those plots. We've been tuning the shape for optimal symmetry because some repeats of the 21 0, 8 were very obliged, like the shot on the left here, which degraded the performance, and we didn't get as much yield. 74 00:22:01.800 --> 00:22:10.599 Mark Kushner: So we tune the lasers to, then become more round again, and here you see higher and higher yields, which show less asymmetry. 75 00:22:10.830 --> 00:22:23.289 Mark Kushner: and then even higher yields where we get into the energy gain region, we suddenly see a new prolate asymmetry that are allocated in in the C axis. 76 00:22:23.290 --> 00:22:43.199 Mark Kushner: and that doesn't seem to impede performance. So these thick caps seem very robust. And we're thinking that the P. 2 could actually be from change dynamics, because we're now seeing the capsule during the disassembly process versus the assembly process is a guess from the reaction history. So I'll show you that in a minute 77 00:22:43.520 --> 00:22:49.110 Mark Kushner: and gain over one and a half has now been reached 5 times the last times, a few weeks ago. 78 00:22:50.430 --> 00:23:07.659 Mark Kushner: All right. How do we measure fusion, burn history? I've mentioned it now. So when you look at the reaction. What I didn't show you earlier is that there's actually a small branching ratio where you have an excited helium that produces a gamma ray, and then later a neutron and an alpha. 79 00:23:07.720 --> 00:23:34.150 Mark Kushner: and the neutron signal is broadened by the Doppler effect. So neutron time of flight, where you do time. Resolution of these neutrons gives you the ion temperature measurement and the alpha particles get stuck in the fuel right? They deposit their energy there and do the alpha heating so the particle that is most unperturbed for a time. History is that characteristic gap. So they're ideal for measuring reaction history. 80 00:23:34.470 --> 00:23:40.119 Mark Kushner: And this is what that would look like. You would see the laser power here, and then the reaction start up. 81 00:23:40.250 --> 00:23:53.979 Mark Kushner: and that you see the burn width there, and what you can get out of that reaction. History measurement is the bang time that tells you something about the energy absorbed in the capsule. You can get the burn width 82 00:23:53.980 --> 00:24:14.970 Mark Kushner: which tells you the duration of thermonuclear conditions, and tells you about the assembly and disassembly process. And then the shape of this reaction. History gives really good boundaries for simulations. But we've also recently, in these ignition shots seen, they can tell us something about the robustness of the implosion. So I'll get to that in a few minutes. 83 00:24:15.470 --> 00:24:37.490 Mark Kushner: And so here we can distinguish these energies between the fusion neutrons and those n carbon gamma neutron gammas, because in a gas Taurenkev detector, which is what the Grh instrument is. You can actually set a measurement threshold with your gas pressure, so we can only measure the fusion. Gammas. 84 00:24:37.510 --> 00:25:00.000 Mark Kushner: the Cherenkov process is actually really fast under 10 picoseconds. The way it works. You have gamma radiation coming to a gamma electron converter. That's just a puck of material, we produce a constant electron which then in the pressurized gas, produces Cherenkov radiation, and that light is then brought through a Casagranian optic to a photomultiplier too 85 00:25:01.060 --> 00:25:02.170 Mark Kushner: significant. 86 00:25:07.360 --> 00:25:10.370 Mark Kushner: No, that doesn't let me do anything. 87 00:25:12.400 --> 00:25:13.400 Mark Kushner: Yeah. 88 00:25:15.870 --> 00:25:39.849 Mark Kushner: anyway. So normal. That process itself is very, very fast, whereas Pmts are not that fast. They usually have a resolution of about 100 picoseconds. Now, we have new technology, pulse, dilation, photomultiplier to hoops that was developed specifically for the nif where we now get down to 10 picoseconds, which is very important because our burn durations are getting shorter and shorter. Now. 89 00:25:41.440 --> 00:25:48.838 Mark Kushner: all right. And this is the dynamics that are changed, that I kind of talked about when we looked at those prolate shapes. 90 00:25:49.270 --> 00:26:18.410 Mark Kushner: These are simulations by Brian Haynes. That's another capability we have at the national labs is radiation hydrodynamic modeling. So this is X-ray simulations, and what we see when we look at very low gains or low yields, we see this curve here in the bottom below the cliff. So most of the fusion reactions actually happen before peak compression. So while we assemble the implosion. 91 00:26:18.650 --> 00:26:32.910 Mark Kushner: and then, when we're above that so-called Ignition Cliff, a lot of the reaction rate is actually, during the explosion phase. So we think that the hotspot actually swings from oblate to prolate during the implosion phase. 92 00:26:33.100 --> 00:26:49.429 Mark Kushner: And we call that a cliff, because what we've seen now is that very small changes make huge variations. So we're actually now studying the gam reaction history diffusion rates in the logarithmic space. I will talk about that in a little bit. 93 00:26:49.500 --> 00:27:09.870 Mark Kushner: Okay, so let's go back back to this plot. Where are we now? I optimistically place this just before a scientific demonstration facility, because I'm hoping that we can build something next when we reach that ignition machine constantly that we understand it enough now that we can build that. 94 00:27:10.140 --> 00:27:12.100 Mark Kushner: And then we need to go further. 95 00:27:13.240 --> 00:27:28.459 Mark Kushner: And so one of the things that we need to do. This is from a basic research needs. Workshop report is, I think, that right now we maximize the diagnostics to maximize, the understanding of the plasma and the ignition regime. 96 00:27:28.460 --> 00:27:49.209 Mark Kushner: And so we still need to develop diagnostics to learn more about how to achieve high gain variables that we haven't been measuring yet, because we haven't had high enough yields. Then we need to develop plant infrastructure diagnostics and get to rep rated and rat hard detectors to operate at the level of a pilot plant. 97 00:27:50.580 --> 00:28:00.160 Mark Kushner: and then you would minimize diagnostics to maximize power output because you don't have a lot of real estate around your target to insert diagnostics in a power plant. 98 00:28:01.740 --> 00:28:12.269 Mark Kushner: This is from a proposal that we recently wrote that Brian was also on where we said, what do we need for diagnostics if we were to do some work right now? 99 00:28:12.290 --> 00:28:36.910 Mark Kushner: What do we want to? Where do we want to go? How can we change our current diagnostic to go towards fusion energy, we think we need to eventually determine a minimum diagnostic suite for a pilot plant. It needs to be reliable. So we need to really understand the high radiation environments in a demonstration plant. And so we need to develop and test rad heart components. 100 00:28:36.950 --> 00:29:04.110 Mark Kushner: We think they need to be rep rated. So we need to develop machine learning supported high rep rate analysis codes. They should ideally be universal. So we can develop driver agnostic detector designs, whether it's lasers or pulse power. And we want to start testing concepts and parts in relevant facilities facilities that have hybrid grade like lasernet us, and facilities that have high gains like the nif. 101 00:29:04.980 --> 00:29:32.439 Mark Kushner: So how can our diagnostics evolve? This is a project that a student collaborator did at lab for laser energetics at Omega, which is very cool. She used machine learning a convolutional neural network, for in this case X-ray imaging data to build a 3D. Reconstruction of hotspot morphology, using a simulation database from a rad hydrocode 102 00:29:32.440 --> 00:29:48.720 Mark Kushner: as training data to then on the spot, change their laser tuning. So what they did, an experiment on Omega, where they built an asymmetric capsule. So if you illuminated it symmetrically, it would give you an asymmetric implosion, and then 103 00:29:48.720 --> 00:30:05.430 Mark Kushner: based on these reconstruction. They precisely tuned the laser drive to get this implosion to be symmetric with this asymmetric target. And it's a cool demonstration of how you could use imaging, or maybe neutron imaging to use plant control, right 104 00:30:05.880 --> 00:30:07.609 Mark Kushner: use for plant control. 105 00:30:08.860 --> 00:30:36.729 Mark Kushner: Another evolving diagnostic that we can work on is the 1st ever spatially resolved ion temperature measurement. This is a project we worked on a few years ago. What we want to do here is, as I already said, the nutrients are doppler broadened. So this is the 14.1 Mev. Nutrient peak in timescale at 30 meters, and what happens is it gets broader and broader as the temperature increases because of doppler broadening. 106 00:30:37.020 --> 00:30:40.989 Mark Kushner: And so you can use that fact to measure ion temperature. 107 00:30:40.990 --> 00:31:03.499 Mark Kushner: And in this case this is the 1st spatial, resolved ion temperature measurement. We have spatial information because we have a slit aperture and so on a stack of scinilators. We position information on the Y-axis, and then we connected that to a street camera where you have timing information. So you now have time information on the x-axis and the picture there in the bottom in the middle 108 00:31:03.500 --> 00:31:24.049 Mark Kushner: is the 1st spatially resolved Ion temperature measurement, and from that we reconstruct the temperature profile across the c-axis of the source and the picture in the bottom left, as you might recognize. Those are 2 students holding the aperture, one of them Landon de Foia, back when he was still an undergrad 109 00:31:24.460 --> 00:31:25.900 Mark Kushner: working with us. 110 00:31:26.510 --> 00:31:47.090 Mark Kushner: and Landon is also the one that is working to bring this technology to 2D. Tomography to the Nif. Now, when we have consistently higher yields for the 1st time. This is feasible to measure ion temperature. Spatial. Resolved, that's a direct plasma variable. So that will be really important to understanding that ignition regime. 111 00:31:47.390 --> 00:31:55.750 Mark Kushner: We have a ring aperture in a ring aperture. The information is along the radius 112 00:31:55.930 --> 00:32:19.949 Mark Kushner: of this circle here in that shadowy region. So then we would have scintillating fiber petals, or around where along each of the scinilator sticks stacks, we would get the position information, and we would do a tomography trick to get a 2D image. And then we could use multiplexing instead of a street camera to put that into Pmts. 113 00:32:20.260 --> 00:32:26.769 Mark Kushner: Because we would have so many simulators, we would need so many street cameras which would make that experiment not affordable. 114 00:32:26.990 --> 00:32:49.240 Mark Kushner: And Landon, recently published on this multiplexing technique that he developed where we showed that we can recover these signals even with very long optical fiber delays. And that could also be this multiplexing technology, a way of rad hardening detectors, right? Because we're now bringing our Pmts very far away from our radiation sources. 115 00:32:51.120 --> 00:32:52.386 Mark Kushner: And then, 116 00:32:53.220 --> 00:33:06.130 Mark Kushner: as a last diagnostic thing, I wanted to say that Dr. H. Diagnostic is actually ideally suited for Ife applications already it's a radiation heart has a very high repetition rate, and what we're looking at now 117 00:33:06.380 --> 00:33:21.919 Mark Kushner: is, the team is looking at something called the alpha, which is the logarithmic derivative of the reaction history, and that tells you quite a bit about the thermonuclear conditions, the assembly process, the burn. 118 00:33:21.920 --> 00:33:36.749 Mark Kushner: but the maximum value of that is here is plotted on the right versus the robustness of the implosion, and that's the yield that you measure versus a clean one. D. Yield that you can simulate, and you see there's a sort of threshold 119 00:33:37.190 --> 00:33:45.320 Mark Kushner: at a certain point where all of these higher yields than are proportional to ignition shots. 120 00:33:45.560 --> 00:33:52.389 Mark Kushner: And so the reaction history can be used to gauge the robustness of each shot in Laser Iv in real time. 121 00:33:54.180 --> 00:34:04.049 Mark Kushner: And then beyond diagnostics. My other wheelhouse is the nuclear data, because that's where I did my Phd, so I looked at that a little bit as well. 122 00:34:04.360 --> 00:34:29.240 Mark Kushner: And Leonel House is one of the most important nuclear data evaluation catalogs the in-depth. The evaluated nuclear data file is used by physicists everywhere. So I'm sure you have had some touch points with it. The data relevant to fusion is very sparse. What do I mean? What's relevant to fusion. It's incident, neutron energy of about one to 15 Mv, because that's kind of the energy range where we are 123 00:34:29.239 --> 00:34:44.250 Mark Kushner: in the fusion reactions and then mostly light elements like lithium would be used for breeding tritium. So that would be the tritium fuel cycle. We would bombard a lithium blanket with neutrons to produce tritium 124 00:34:44.510 --> 00:35:12.239 Mark Kushner: and also heavier elements in the plant infrastructure. We also need to study how their health is affected by nutrient bombardment. What you see here is one of the lithium cross sections, and what you can see there's 2 measurements only, and the lower one is not captured by the theory at all. The fit here. So this is not very well evaluated. This is what the evaluators would not like. So we need a lot more data points here to understand this. 125 00:35:12.410 --> 00:35:37.099 Mark Kushner: and I would say that the Icf community has the experimental opportunities to fill these gaps. So what you see at the top, right here is another picture by a collaborator at Loe, Chad Forrest, who proposes to have a Mini lithium blanket in the Omega chamber, running parasitically for a whole year, where you could collect a lot of data over the course of the time 126 00:35:37.100 --> 00:35:48.869 Mark Kushner: parasitically and study those cross sections. Also, we could measure the cross sections directly with the nuclear reaction vessel and then a detector away from that detector to measure the total cross section. 127 00:35:49.270 --> 00:36:18.470 Mark Kushner: Another opportunity could be a measurement similar to what a collaborator Alan recently did in a Hayes just measured the fission cost fiction of uranium, putting depleted uranium foils on the whole realm. Here you see these little pieces of uranium that are glued to the whole realm, and we use the Icf implosion as a neutron source, 14 Mev. Neutron source, and one could imagine the same for fusion, relevant energy, relevant materials. 128 00:36:18.720 --> 00:36:27.609 Mark Kushner: On the bottom left is the energy spectrum of the Los Alamos Neutron Science Center. That's the facility. I work at a large accelerator. 129 00:36:27.760 --> 00:36:44.230 Mark Kushner: a proton accelerator that impinges on a tungsten target and then produces neutrons usable from 100 kv. Up to a few 100 Mev. So we have a neutron spectrum available at Leonol to measure these fusion relevant cross sections. 130 00:36:45.420 --> 00:36:58.480 Mark Kushner: All right. I've talked a lot about how we can evolve in the Icf program to go towards Ife. But I also think that that drive will really benefit the existing Icf program. 131 00:36:58.730 --> 00:37:20.179 Mark Kushner: The Icf program at the National Labs is paid for by the Nnsa stockpile stewardship program. So that reduces the need for nuclear testing. It helps us understand our nuclear weapons. And these applications of ignition need a robust ignition platform. So a next generation facility would benefit the Nnsa as well. 132 00:37:20.190 --> 00:37:28.860 Mark Kushner: We will make advances, advances in data analysis, and also incorporate machine learning and AI methods that will help the programs. 133 00:37:28.920 --> 00:37:53.020 Mark Kushner: We will make advances in detector materials for high yields red, hard, reparatable. And the really most important part is, I think, that a lot of young people but you should correct me if I'm wrong, want to work on fusion energy. So I think we want to benefit from that energized workforce, and all together make progress in the field. So I think the Icf community has the experience and the tools. 134 00:37:53.020 --> 00:38:07.780 Mark Kushner: especially at the national labs, but also in Academia to take on the Ife challenge. So I think we should. And those are just my credits for both those Trh team and this team. And then my program managers. So thank you. 135 00:38:16.160 --> 00:38:17.450 Mark Kushner: That's for 136 00:38:21.590 --> 00:38:22.090 Mark Kushner: yeah. 137 00:38:24.120 --> 00:38:31.880 Mark Kushner: Thank you for the call and for the detectors that you mentioned what signals measuring? 138 00:38:33.030 --> 00:38:40.759 Mark Kushner: What signal is the the the Turk of light? Directly that we're measuring? What's the frequency? If it's 139 00:38:40.970 --> 00:38:45.050 Mark Kushner: okay to say, what's the frequency of the transfer of light. 140 00:38:45.790 --> 00:38:46.590 Mark Kushner: I 141 00:38:46.790 --> 00:39:00.780 Mark Kushner: that's a that's a tough question. I don't actually know, because I'm not an expert in that detector, so I'm sorry I can't answer it. But I'll get back to you. Yeah, because we are using lasers to the ignition. So I monitor whether that will interfere with the 142 00:39:00.970 --> 00:39:04.400 Mark Kushner: drink of light, and it's reduced from the 143 00:39:04.640 --> 00:39:14.189 Mark Kushner: no, that does not interfere with that. But it's also contained in a in a diagnostic, you know. Detector. Let's see, let's look at the picture again. 144 00:39:15.870 --> 00:39:34.839 Mark Kushner: So here this is all contained in stainless steel. So what? The only thing at the front is the window that's usually beryllium or something that converts that gamma radiation to electrons. And it's highly directional pointed at the target. So it's also at a very different time. As the laser is turned on. Okay. 145 00:39:35.110 --> 00:39:36.080 Mark Kushner: yeah, thank you. 146 00:39:37.290 --> 00:39:39.130 Mark Kushner: I think it's visible light at the end. 147 00:39:39.700 --> 00:39:43.420 Mark Kushner: I think so because it's just optics. Yes. 148 00:39:47.700 --> 00:39:52.220 Mark Kushner: so can I ask for the specialization of the one D detector with 149 00:39:54.450 --> 00:39:59.050 Mark Kushner: the neutron imaging in general. This is about 10 microns. 150 00:39:59.290 --> 00:40:05.749 Mark Kushner: because I also want to try. I try to design, some for our experiments. But 151 00:40:06.760 --> 00:40:25.230 Mark Kushner: and it's not so successful. What I have to say is, we're cheating in the sense that we have a magnification of 100, because our aperture is only 30 cm from the source, and our detector is at 30 meters. So the resolution at the detector is much lower than the resolution at the source. 152 00:40:26.190 --> 00:40:36.670 Mark Kushner: So I'm sorry we asked the talking about this one or about the but I'm talking about the neutron imaging. This detector has no spatial resolution, just the line of sight. 153 00:40:43.500 --> 00:40:53.689 Mark Kushner: And I saw the uranium completed experiments just published recently this week, or something. Yes, and I'm just curious. What? What was the nuclear physics question? 154 00:40:54.650 --> 00:41:00.120 Mark Kushner: I think the nuclear physics question was just the Fission Cross section at 14 Mv. 155 00:41:00.680 --> 00:41:03.000 Mark Kushner: Brilliant? Yes, interesting. 156 00:41:04.790 --> 00:41:12.009 Mark Kushner: And that's about all they said in the paper. So there might be some applications that that is relevant for. Okay? 157 00:41:13.935 --> 00:41:17.360 Mark Kushner: Alright any other questions. 158 00:41:20.340 --> 00:41:24.589 Mark Kushner: Okay? If not, let's thank our speaker again. Thank you so much. 159 00:41:24.960 --> 00:41:26.060 Mark Kushner: We can see. 160 00:41:28.990 --> 00:41:33.171 Mark Kushner: And I think there's still some leftover food. So usually there is. 161 00:41:34.760 --> 00:41:35.490 Mark Kushner: Okay. 162 00:41:38.773 --> 00:41:41.426 Mark Kushner: Thank you so much.