WEBVTT 1 00:00:00.000 --> 00:00:09.370 Mark Kushner: Welcome to today's the seminar. 2 00:00:09.440 --> 00:00:28.369 Mark Kushner: It's my pleasure to introduce today's seminar speaker, Dr. Gilbert Rick Collins. Dr. Collins is the Tracy Hyde Harris Professor of Mechanical Engineering and Physics and Astronomy, and Associate Director for the Laboratory of Laser Energetics at the University of Rochester. 3 00:00:28.560 --> 00:00:37.989 Mark Kushner: He received his PhD in physics from Ohio State University, and in spite of the fact that Ohio State weren't allowing me to do this seminar. 4 00:00:38.360 --> 00:00:55.590 Mark Kushner: From 1989 to 2016, Rick held positions at Lawrence Livermore National Laboratory, including Rick Leader, Physics Associate Division Leader, Director for the Center for High Energy Density Physics, and with Jewish member of the technical staff. 5 00:00:55.900 --> 00:01:06.129 Mark Kushner: He has filled and worked with several world-recognized groups exploring different aspects of high energy density science and stockpile stewardship. 6 00:01:06.480 --> 00:01:25.329 Mark Kushner: At ALE in the University of Rochester, Rick works with a world-class team of scientists exploring the nature and implications of matter and conditions where external forces overwhelm the quantum fluorescence of the atom and the microphysics leading to polynuclear fusion. 7 00:01:25.750 --> 00:01:31.159 Mark Kushner: He's the director of the NSF Physics Frontier Center for Matter and Atomic Pressures. 8 00:01:31.310 --> 00:01:36.390 Mark Kushner: He holds a visiting professorship at Oxford University and the University of Edinburgh. 9 00:01:36.910 --> 00:01:46.640 Mark Kushner: Rip is the recipient of several awards, including the Richmond Award at the International Association for the Advancement of High Pressure Science and Technology. 10 00:01:46.690 --> 00:02:05.230 Mark Kushner: APS Fellow, AAAS Fellow, he received the APS Award for Excellence in Plastic Physics, the DOE Weapons Recognition of Excellence Award, NNSA Award for Excellence for Stockpile Stewardship, and the NNSA Science and Technology Award. 11 00:02:05.740 --> 00:02:13.480 Mark Kushner: The title of our seminar today is Extreme Matters, Pressure to Explore New Worlds, Exotic Solids, and Star Power. 12 00:02:13.920 --> 00:02:18.190 Mark Kushner: And all of those awards pale in significance to 13 00:02:18.300 --> 00:02:31.240 Mark Kushner: Thank you very much for coming to this seminar, and I hope you will accept this token of our appreciation. Thank you. Well, and get a picture. Oh, yeah. 14 00:02:38.510 --> 00:02:42.410 Mark Kushner: Wow. Well, thank you very much for that introduction. 15 00:02:42.580 --> 00:02:47.169 Mark Kushner: And you guys are really lucky to be here. This is awesome. 16 00:02:47.340 --> 00:02:52.279 Mark Kushner: I've had a great day so far. Hopefully, I don't destroy this, 17 00:02:52.620 --> 00:02:58.230 Mark Kushner: in the next hour. So, it turns out, 18 00:02:58.740 --> 00:03:11.649 Mark Kushner: this field that folks are in, high energy density science, is… is really… it's an amazing field, and everyone's so lucky to be in it. So many things are changing. 19 00:03:11.720 --> 00:03:29.979 Mark Kushner: so many discoveries are being made today. We have the fusion stuff that many of you, I'm sure, have heard about. All these developments at the National Ignition Facility and other places have kick-started, the quest to control fusion, for energy. 20 00:03:30.040 --> 00:03:49.229 Mark Kushner: these startups. We have, right now, we're able to recreate new states of matter that people really hadn't any idea that you could make, in the laboratory before, and I'll say a little bit about that, but this is, as an example, this is like taking a piece of aluminum. 21 00:03:49.370 --> 00:03:59.029 Mark Kushner: And squishing it to a point where it, goes from a good conductor to a transparent insulator and a topological system. 22 00:03:59.130 --> 00:04:10.260 Mark Kushner: And then there's so many astrophysical observations that are being made today. Let me just start with that as an example where we, as a field, can make contributions 23 00:04:10.480 --> 00:04:19.120 Mark Kushner: Though, for example, one of the many astrophysical discoveries being made are just the discovery of various planets. 24 00:04:19.370 --> 00:04:29.010 Mark Kushner: And, so how do we do that? So we take… this is one of our experiments going off. This is the Omega laser. It's a… it's a pretty big laser with, 25 00:04:29.010 --> 00:04:42.710 Mark Kushner: 10 meter, chamber, diameter chamber, and it's got, tens of kilojoules for the laser, and so we take a piece of… a puddle of water, it's just a little, little puddle of water. 26 00:04:42.760 --> 00:04:47.220 Mark Kushner: And we put it into a diamond cell, and then we squish it in a diamond cell. 27 00:04:47.280 --> 00:04:53.570 Mark Kushner: Up to, you know, a few GPAs, so a few, gigapascals. 28 00:04:53.750 --> 00:05:04.109 Mark Kushner: Okay, so number 10 to the 5th pascals is an atmosphere, so I don't know if you guys like SI units, or… so, how could you mute your… 29 00:05:05.680 --> 00:05:07.610 Mark Kushner: Whoa, I thought I didn't. 30 00:05:09.480 --> 00:05:11.610 Mark Kushner: Or maybe the speaker? 31 00:05:11.730 --> 00:05:12.850 Mark Kushner: Okay? 32 00:05:13.580 --> 00:05:31.629 Mark Kushner: Of that. Maybe, okay. Twice. Okay. Twice is… that's great! Okay, so we take this puddle of water, we pre-compress it, and it forms ice 7, so it's a seventh of one of the crystal phases. 33 00:05:31.900 --> 00:05:43.580 Mark Kushner: And then we hit it with tens of kilojoules of laser light, and that squishes the water to a state of matter that had never been seen before on Earth. 34 00:05:43.640 --> 00:05:58.790 Mark Kushner: And it's computer, recreated over here, where you have the oxygen atoms, shown in yellow, and the hydrogen floating like a quantum fluid in between those, that oxygen array, to form what's called the superionic 35 00:05:58.790 --> 00:06:04.760 Mark Kushner: phase of water. And while that had never been seen before on Earth. 36 00:06:04.790 --> 00:06:10.100 Mark Kushner: It's quite likely that it exists in water worlds all throughout the universe. 37 00:06:10.170 --> 00:06:20.469 Mark Kushner: And this would be one of the things that we're trying to help understand. So this is… it allows us to sort of reconstruct various components of planets that are being discovered. 38 00:06:21.480 --> 00:06:24.620 Mark Kushner: Okay, what planets are being scarred? Let's talk about that. 39 00:06:25.220 --> 00:06:32.990 Mark Kushner: So, when you go out tonight, I did see that there was, some blue sky and sunshine. We don't get that much in Rochester. 40 00:06:33.710 --> 00:06:37.450 Mark Kushner: Okay, when you go out, okay, this, this… 41 00:06:37.890 --> 00:06:46.550 Mark Kushner: you're gonna go… see, if I look at this for the, 10th time here, you're gonna see, at night, you'll see all these stars. 42 00:06:46.790 --> 00:06:48.900 Mark Kushner: Okay, the stars are the black dots. 43 00:06:49.240 --> 00:07:07.080 Mark Kushner: So you'll see all the black dots. Now, you notice this is, the full sky, so if you could see through the Earth, you'd see down here at the southern hemisphere, but… and then this is, in times, the standard way of looking across the sky. But you'll recognize a few of these, like the Big Dipper, you guys recognize that, and you see 44 00:07:07.080 --> 00:07:09.569 Mark Kushner: Orion over here? You guys know that? 45 00:07:09.750 --> 00:07:13.730 Mark Kushner: And you got North Star over there. So the… 46 00:07:13.880 --> 00:07:18.490 Mark Kushner: So you'll see those stars, but what you won't see are the colored dots. 47 00:07:19.370 --> 00:07:21.340 Mark Kushner: The colored dots are planets. 48 00:07:21.990 --> 00:07:30.309 Mark Kushner: Number of planets, is growing super fast. Well over 6,000 planets that have been discovered. 49 00:07:30.580 --> 00:07:50.300 Mark Kushner: There are more than a billion plan, stars. We're pretty sure that there's a planet for every solar system, stellar, and that is, that's what gives us pretty good confidence that there are billions of planets throughout the universe. 50 00:07:50.300 --> 00:08:00.149 Mark Kushner: And, we're just now starting to get our arms around that. If you, so you look, you say, well, that's a lot… that's a lot of planets, but, 51 00:08:00.250 --> 00:08:14.570 Mark Kushner: In fact, those are the only ones… only the ones that we've seen. If you look over here, this, little box, this… this box is sort of where Kepler decided, okay, we're going to look a long time. So they just kept staring at this part of the sky. 52 00:08:14.570 --> 00:08:32.510 Mark Kushner: And when Kepler did that, they just kept seeing more and more planets, and, you know, they would… the longer they stared, the more planets there would be, and the colors, the different colors, sort of are where the planets are with relation to their solar host. And so, the green ones are the ones in the habitable zone. 53 00:08:32.740 --> 00:08:45.889 Mark Kushner: ones that are in the sweet spot, the Goldilocks zone, so not too far, so they're cold, not too close, so they're burning up. So those are the ones that are, potentially, hosts for life as we know it. 54 00:08:45.900 --> 00:08:51.069 Mark Kushner: And so, you know, how do they do that? In essence, they take, 55 00:08:51.070 --> 00:09:15.889 Mark Kushner: We have all these observatories that have been launched into space, and also the ones that are on Earth, and every so often, a planet goes between us and their host star, and when we do that, we see an occlusion of light, so that gives us the radius, and it also wiggles the star a little bit, and we can spectroscopically 56 00:09:15.890 --> 00:09:26.039 Mark Kushner: see that wiggling. That allows us to determine the mass, so that way we get the mass and radius of these different planets, and when we do that, we can put it onto a plot. 57 00:09:26.580 --> 00:09:36.179 Mark Kushner: And this sort of shows the plot where you have all of these… we just take all those planets that I just showed you, and we just put them onto a plot of their radius versus mass. 58 00:09:36.510 --> 00:09:41.870 Mark Kushner: And then… and you guys must have done this in, 59 00:09:42.110 --> 00:09:52.789 Mark Kushner: undergraduate school or something, where you take, you just build a planet. So if you have an equation of state, and all of you know what an equation of state is, GV equals NRT, right? That's one equation of state. 60 00:09:53.040 --> 00:09:59.119 Mark Kushner: Some of these other equations of state are a little more complicated, but if you take the equation of state for, like, water. 61 00:09:59.400 --> 00:10:09.030 Mark Kushner: And you… and and you say, okay, I know the equation of state for water, and I can essentially balance gravitational forces with the material pressure. 62 00:10:09.250 --> 00:10:22.139 Mark Kushner: And I can build a planet, and this is what a planet at 10 Earth masses would essentially have about twice the radius of Earth. 63 00:10:22.380 --> 00:10:33.390 Mark Kushner: And so that already, with very little information, just essentially the… how squishy the material is, tells you, about, a bit about the planet. 64 00:10:33.780 --> 00:10:49.690 Mark Kushner: So that's a big part of what we do is, in one case, we are able to help define what materials are in these various planets, and, but it turns out that most of these planets are a little more complex, just like the Earth. 65 00:10:49.840 --> 00:10:54.960 Mark Kushner: It's more complex than a single monolithic, 66 00:10:55.750 --> 00:11:07.100 Mark Kushner: material, and so, like, the Earth has all these different pieces, including the deep interior, the core, which has a solid core, and then surrounding that is an outer core, mostly of iron. 67 00:11:07.330 --> 00:11:17.970 Mark Kushner: And so there are many questions that you can ask, and the one that most people are very interested in is, can that planet host life? So that's a good question to ask. 68 00:11:18.160 --> 00:11:37.400 Mark Kushner: And so, we have a bunch of things that sort of define that. One of them, we think, is, you know, we need to be able to protect a planet from the solar wind of its host star, and one way that Earth does it is through the magnetic field. And so… 69 00:11:37.560 --> 00:11:55.020 Mark Kushner: Our magnetic field is essentially produced by… we have a solid core and a liquid core. The liquid… as we age, the liquid sort of slowly condenses. That drives a thermal gradient across the liquid and drives a convective flow. 70 00:11:55.020 --> 00:12:00.210 Mark Kushner: That drives, that flow, along with the rotation, sort of drives 71 00:12:00.210 --> 00:12:05.429 Mark Kushner: this magnetic field that the Earth has, which is on the order of a Gauss. 72 00:12:05.460 --> 00:12:12.970 Mark Kushner: And that protects us largely from the solar winds, from our atmosphere getting blown off. There are many other things, but all of those things 73 00:12:13.100 --> 00:12:25.049 Mark Kushner: are, you know, like, the iron thermal conductivity, the miscibility, the melt, those are… those, really sort of set whether or not, a planet might have. 74 00:12:25.340 --> 00:12:36.690 Mark Kushner: these qualities, and therefore might be hospitable for life as we know it. So we're looking into these, different microscopic, pieces of… 75 00:12:36.690 --> 00:12:45.680 Mark Kushner: elements of matter at very extreme conditions, and this is sort of how HED conditions can sort of help guide where the next, 76 00:12:45.820 --> 00:12:51.299 Mark Kushner: space missions looking for life, like the Habitable Worlds Project, might… might look. 77 00:12:51.780 --> 00:13:10.700 Mark Kushner: And we use these different facilities. I think maybe everyone knows these. The Omega laser is, of course, the best laser for long pulse lasers at Rochester. We have the National Ignition Facility, which is the highest energy laser, and this doesn't, most of these 78 00:13:10.700 --> 00:13:17.819 Mark Kushner: are long pulse lasers, so most of the experiments that I'll describe are nanosecond-type lasers, which doesn't really, 79 00:13:17.930 --> 00:13:30.300 Mark Kushner: I'll say a little bit about what, we sort of hope some of the short pulse capability, like Zeus, would be able to do to sort of help us understand some of these, HED conditions. 80 00:13:30.780 --> 00:13:31.650 Mark Kushner: Okay. 81 00:13:35.030 --> 00:13:50.199 Mark Kushner: Okay, so there have been a bunch of discoveries which I just wanted to put up. I just mentioned the superionic ice and sort of mixtures with water has helped us understand Neptune and some of the recent revelations of 82 00:13:50.200 --> 00:13:57.750 Mark Kushner: of, Uranus, and that sort of, help, motivating, the next voyage, to Uranus. 83 00:13:57.760 --> 00:14:11.920 Mark Kushner: Early on, there's this discovery of helium and hydrogen demixing that gives rise to a potential heat source in Saturn, and that helped understand 84 00:14:11.920 --> 00:14:22.899 Mark Kushner: Saturn a little bit, and then the melting of a bunch of constituents has helped us understand, really the nature of a lot of these terrestrial planets. So there's a bunch… 85 00:14:22.900 --> 00:14:33.889 Mark Kushner: of different, discoveries that sort of pushed the planetary science along, but if we take all of those, and we just put them onto this phase diagram, I think all of you have seen these things, but what I wanted to just point out 86 00:14:33.890 --> 00:14:45.250 Mark Kushner: So, in this log temperature versus density, high energy density, is everything sort of above this black line, which is the, 87 00:14:45.250 --> 00:14:49.369 Mark Kushner: The line for, 1 million atmospheres. 88 00:14:49.620 --> 00:14:51.760 Mark Kushner: Or 100 gigapascals. 89 00:14:52.070 --> 00:14:59.749 Mark Kushner: And so that is the… those are the conditions where the external forces overwhelm the chemical pressures. 90 00:14:59.770 --> 00:15:17.800 Mark Kushner: the chemical forces of nature. So above that, that's where chemistry is dramatically changed. At atomic pressures, that's above about 300 million atmospheres, that's where the external forces overwhelm the quantum forces of an atom. The atoms themselves change. 91 00:15:18.180 --> 00:15:32.239 Mark Kushner: And then, and then if you keep going, you get to about 300 billion atmospheres. That's where this incipient stage of thermonuclear, reactions start to… start to take hold. So that sort of describes 92 00:15:32.240 --> 00:15:39.979 Mark Kushner: The pressure, space and some of these astrophysical objects where they belong. 93 00:15:40.230 --> 00:15:45.170 Mark Kushner: But I guess the main point is she didn't take away anything. 94 00:15:46.160 --> 00:15:47.070 Mark Kushner: Okay. 95 00:15:47.710 --> 00:15:55.950 Mark Kushner: When you reach these conditions, many of the fundamental physics laws that you learned for 96 00:15:56.060 --> 00:15:59.620 Mark Kushner: Standard conditions, you know, the laws should be… 97 00:16:00.150 --> 00:16:03.630 Mark Kushner: Global, they begin to change. 98 00:16:03.800 --> 00:16:06.119 Mark Kushner: Okay, and I hope… I hope you… 99 00:16:06.240 --> 00:16:15.649 Mark Kushner: see those examples as we go through here. I show a couple of simple examples here, but we'll talk to that in a little bit. 100 00:16:15.810 --> 00:16:27.060 Mark Kushner: Now, so how do we do that? We walk through this phase diagram, using a bunch of different compression techniques. One is we can launch a shock wave, so we just turn on a laser. 101 00:16:27.260 --> 00:16:46.960 Mark Kushner: And if it's sort of the right intensity, it heats up your material, so you launch a… you hit your target with a laser, heats it up, blows off, some ablation, that launches a reaction force, and that launches a compression wave. That compression wave is moving faster than the speed of sound. 102 00:16:46.990 --> 00:17:04.150 Mark Kushner: Pretty easy to do for most things. You get a shock wave, and that gives… so we can explore things that are pretty hot. If you, turn on the intensity slowly, so that is, you, turn on the compression slowly enough. 103 00:17:04.650 --> 00:17:13.259 Mark Kushner: So that you don't form a shot. So, to do that, you have to launch compression waves that move at or below the sound speed. 104 00:17:14.050 --> 00:17:19.300 Mark Kushner: Okay, now, it's a bit tricky, but if you, if you just, ping the table here. 105 00:17:19.430 --> 00:17:26.279 Mark Kushner: I'm launching a sound wave into the table, and that slightly compresses the material. 106 00:17:26.730 --> 00:17:30.099 Mark Kushner: And as I do that, the sound speed goes up. 107 00:17:30.470 --> 00:17:33.510 Mark Kushner: So I can, click it a little bit harder. 108 00:17:34.100 --> 00:17:42.719 Mark Kushner: So the density gets a little bit higher, and sound speed goes up, so I can keep pushing faster and faster and faster. And that allows us to 109 00:17:43.020 --> 00:17:51.800 Mark Kushner: roughly isentropically compressed. Intrinsic properties keep it from being perfectly isentropic, but allows you to ramp compressed materials. 110 00:17:52.170 --> 00:17:56.379 Mark Kushner: Okay, now, it turns out, and I don't have a sheet of paper, but if… 111 00:17:56.380 --> 00:18:17.010 Mark Kushner: We always show these projections of equations of state, because it's easier to think about, but, really an equation of state is this three-dimensional contour, and so most of the… most of the ways that I, will project this is in pressure, temperature. I was just showing in temperature density, so usually we're looking at these projections. 112 00:18:17.010 --> 00:18:20.600 Mark Kushner: But, this is sort of how, 113 00:18:20.600 --> 00:18:36.659 Mark Kushner: a sequence of different shocks of different intensities would follow across this phase diagram. So these… these are… the equation of state is a three-dimensional contour, and when we have phase transitions, there's kinks in there, but… so we map these out with these different, compression, techniques. 114 00:18:37.710 --> 00:18:41.340 Mark Kushner: Okay, so, here we go. 115 00:18:42.200 --> 00:18:46.700 Mark Kushner: We're gonna start with squishing matter slowly. 116 00:18:46.930 --> 00:18:59.329 Mark Kushner: And it's like everything in science. You have an idea, and you think you're gonna go into the lab and do it, and 10 years later. 117 00:18:59.330 --> 00:19:08.689 Mark Kushner: You did it, but it wasn't quite as fast as you thought. So, so how do you ramp compressed stuff? It turns out… 118 00:19:08.850 --> 00:19:23.119 Mark Kushner: before you can ramp compressed stuff, you actually have to know how squishy it is. You have to know what the equation of state is to get it just right. And so, the first work really was done, this beautiful work done at Sandia. 119 00:19:23.120 --> 00:19:42.520 Mark Kushner: Clint Hall, Jim Assay, who's the person that really recognized this, Mark Knutson, and David Riesman, and many others, they sort of came up… they showed that you can do this, at the Z facility, and then… and then there were a number of ways that, people came up with, for doing it on lasers. 120 00:19:42.720 --> 00:19:51.030 Mark Kushner: And this plot shows sort of one of the early examples of doing it in a laser, where a bunch of laser beams, those are the purple things. 121 00:19:51.080 --> 00:20:07.739 Mark Kushner: They went into what's called a hole run, it's like a gold can, so you put this… all these laser beams into a gold can that converts the light into X-rays, and the X-rays do exactly what I was describing earlier, where it ablates off a material and launches a compression wave. 122 00:20:07.740 --> 00:20:11.969 Mark Kushner: And so, in essence, we learned how to turn the laser power on 123 00:20:11.970 --> 00:20:30.120 Mark Kushner: very slowly, and then the radiation temperature in the whole ROM came up very slowly, and that allowed us to generate a pressure profile that compressed the material, just right. 124 00:20:30.660 --> 00:20:39.009 Mark Kushner: Okay, so let's see. This, this is sort of like an experiment that goes on, 125 00:20:39.420 --> 00:20:44.419 Mark Kushner: In essence, this is a target in the center of the NIF target chamber. 126 00:20:44.740 --> 00:21:02.000 Mark Kushner: That is a piece of diamond that's sitting on the side of this whole ROM wall. We have a bunch of laser beams that come into the Hol-ROM. That essentially creates an X-ray oven, which drives the target. 127 00:21:02.000 --> 00:21:06.930 Mark Kushner: The targets are sort of 100 micron scale, although there's, some… 128 00:21:06.970 --> 00:21:26.970 Mark Kushner: Problem, but anyway, 100 micron scale. And then, you get this ablation, which drives this compression wave, which is shown in blue, and then the material starts to accelerate. We have a visor diagnostic, which is just sending in, red light, and it bounces off the back side of the package. 129 00:21:27.020 --> 00:21:44.820 Mark Kushner: When that light is reflected, it… it turns out it Doppler shifted. That… the visor actually is a Doppler shifting interferometer, so it measures that Doppler shift. That gives us what the velocity is of the material. We map that velocity as a function of time for different steps. 130 00:21:44.940 --> 00:22:03.709 Mark Kushner: And so this is the output… the direct output of, the VISAR diagnostic, so these are the… these fringes are, direct mapping of the Doppler shift, and… and this allows us to get the… the free enter… the, the free surface velocity, and from that, we get the stress versus density. 131 00:22:03.710 --> 00:22:09.829 Mark Kushner: using a Lagrangian analysis, which is just a simple hydrodynamic relationship, and when we do that. 132 00:22:09.830 --> 00:22:23.979 Mark Kushner: we're able to get this, pressure versus density. It should be stress versus density. And so this blue line is really the first measurement. The iron, at these very high pressures, 133 00:22:23.980 --> 00:22:42.469 Mark Kushner: showing that, for the first time, you can constrain how squishy iron… the iron core is in these, terrestrial planets, and that helps, really, for the first time, constrain, models of these, terrestrial planets. We've done that for a number of materials, but that, 134 00:22:42.800 --> 00:22:46.969 Mark Kushner: That was the first time we had done this for… for iron. 135 00:22:46.970 --> 00:23:03.790 Mark Kushner: I think one of the things, even today, there's a lot of progress underway trying to develop new analysis techniques. I think I mentioned to several of you, the Bayesian framework for analyzing these is starting to allow us to 136 00:23:03.790 --> 00:23:12.070 Mark Kushner: Take into account the equation of state, as well as the internal strength of the material, to, 137 00:23:12.160 --> 00:23:18.919 Mark Kushner: To, get good estimates of both of those intrinsic, material properties. 138 00:23:19.700 --> 00:23:30.680 Mark Kushner: And then we have an army of people that are really going after different diagnostics. So if you have this… if you have this new ability to make these materials, now you want to try and understand it, and 139 00:23:30.680 --> 00:23:42.919 Mark Kushner: All of the, there weren't really new capabilities for how you would make, material measurements at these, on, on a billionth of a second time scale. So we have a bunch of folks. 140 00:23:42.920 --> 00:23:53.649 Mark Kushner: Developing, diffraction, spectroscopy, inelastic and elastic spectroscopy, terahertz, various radiography, spectroscopy. 141 00:23:53.980 --> 00:23:58.510 Mark Kushner: And I don't have… you know, so I'm not going to talk about all these, I'm just going to talk about one. 142 00:23:58.560 --> 00:24:04.999 Mark Kushner: And that's diffraction. I'll talk about a couple of others along the way, but just to… just to show… 143 00:24:05.000 --> 00:24:19.099 Mark Kushner: Like, the diffraction's taken a long time. It started with Johnson years ago on the gas gun doing dynamic diffraction. Of course, diffraction, static diffraction was done many years before this, but, 144 00:24:19.100 --> 00:24:33.719 Mark Kushner: Then, when lasers were starting to be used to compress matter, Justin Work started, doing, diffraction at, the Vulcan laser, and then the Janus laser, and then Dan Callantar, many others. 145 00:24:33.720 --> 00:24:42.989 Mark Kushner: And now we're able to do, very, very fast diffraction, and what this does is it allows you to see the ion positions 146 00:24:43.100 --> 00:24:56.890 Mark Kushner: under the dynamic compression, and that really helps understand the electronic configuration, as well as just the phase of the material. Is it solid? Is it liquid? What type of lattice structure does it have? 147 00:24:57.830 --> 00:25:00.409 Mark Kushner: Okay. 148 00:25:02.870 --> 00:25:13.580 Mark Kushner: Now, all of you… I've taken freshman physics and… Early chemistry, In all of those courses. 149 00:25:14.060 --> 00:25:22.399 Mark Kushner: You learned, you may not remember that, you learned that when you squish stuff to these crazy pressures, things get easy. 150 00:25:23.390 --> 00:25:29.070 Mark Kushner: Okay, and that was given to us mostly by Fermi. 151 00:25:29.230 --> 00:25:37.850 Mark Kushner: And Fermi was brilliant. I mean, he set the course for so many of our fields, but when you come up to, part of 152 00:25:38.120 --> 00:25:45.310 Mark Kushner: Science that doesn't have any data, you usually assume this… you make simple assumptions. 153 00:25:45.600 --> 00:26:01.610 Mark Kushner: And one of the simple assumptions was, as you squish atoms closer to… close together, essentially what happens is the electrons start to move from valence or core levels, and they get promoted to the Fermi C. 154 00:26:01.850 --> 00:26:04.740 Mark Kushner: So, in the Fermi electrons, those are the electrons… 155 00:26:04.850 --> 00:26:12.310 Mark Kushner: The conduction electrons, that really determine the mechanical properties of the system. 156 00:26:12.360 --> 00:26:32.329 Mark Kushner: And so you just, as you squish it further, the electrons get promoted, and then you're left with these ion cores, and like in a white dwarf, the ion cores would lock into a simple structure, and you have the Fermi C sort of dominating much of behavior. 157 00:26:32.770 --> 00:26:39.440 Mark Kushner: Okay, and that, that's the way we think about most of the planets and stars, and that's, that, 158 00:26:39.700 --> 00:26:49.790 Mark Kushner: That, that works pretty well. But it turns out, we've started to squish stuff to very, very high compression. 159 00:26:49.940 --> 00:27:02.889 Mark Kushner: And, instead of the material going from a simple system and staying, you know, becoming simpler, and always becoming… everything becoming a metal, and that drives sort of a simple melt curve. 160 00:27:04.420 --> 00:27:15.590 Mark Kushner: the one case I'll show, although now we're… we have… we have several, but sodium is, like, the best case, because sodium is… Everyone… it's an alkali metal, it's, like, the simplest things. It's on the… it's… 161 00:27:15.830 --> 00:27:17.740 Mark Kushner: It's a light alkali metal. 162 00:27:18.390 --> 00:27:22.819 Mark Kushner: So we squished sodium, because we thought that would be the best place to start. 163 00:27:22.940 --> 00:27:25.530 Mark Kushner: And, in fact, what happens… 164 00:27:25.700 --> 00:27:30.639 Mark Kushner: Is, instead of the melt curve, the melt curve was predicted to just, you know, go… 165 00:27:30.670 --> 00:27:47.980 Mark Kushner: go up, and the crystal structure would be simple. But essentially, the more we compress it, we still, even all the way up to, I'll show you in a minute, 12 billion atmospheres. The structure turns out to be very complicated. 166 00:27:48.080 --> 00:27:55.400 Mark Kushner: And instead of, and we follow this compression path, along this compression path. 167 00:27:55.550 --> 00:28:14.600 Mark Kushner: The material, goes from being a very good conductor to something that is semiconducting and then wants to be transparent, an insulator. And computational tools are showing that it is a topological insulator, much like what I described earlier. 168 00:28:14.650 --> 00:28:29.000 Mark Kushner: If you were able to recover this, which people are now starting to do, this would be a great topological insulator, much like the bismuth telluride system that's used in quantum computing today. 169 00:28:29.210 --> 00:28:37.150 Mark Kushner: I don't know how to use this at this stage right now, but but it has that, type of electronic structure. 170 00:28:37.460 --> 00:28:49.300 Mark Kushner: So, in essence, that's for the case of sodium, but in fact, it's predicted also to be in aluminum. We've seen some of those structural transitions. 171 00:28:49.300 --> 00:29:03.660 Mark Kushner: magnesium, I showed you Gorman's, beautiful work, and many other systems. We're now in the process of seeing this similar stuff in potassium and lithium. And moreover, it's not just 172 00:29:03.980 --> 00:29:18.969 Mark Kushner: these solids, but it's predicted to occur in the plasma phase, and in the sodium, and this is something I'd love for people to help us think through. Even in sodium, when it's in the fluid phase, the 173 00:29:19.200 --> 00:29:34.230 Mark Kushner: the reflectance has this precipitous drop, and so somehow these electrons are coming out of their Fermi C, and being locked into some bubble state. 174 00:29:35.340 --> 00:29:50.110 Mark Kushner: Okay, so what's happening, so what this is showing is, the typical picture that I just described to you, that we expected as sodium would be squished, you'd end up with this sea of electrons and locked into a simple crystal structure. 175 00:29:50.110 --> 00:30:00.360 Mark Kushner: But what we're finding is these electrons are getting sucked into these interstitial spaces, and that occurs right when the compression of the inner atomic spacing is comparable to these. 176 00:30:00.360 --> 00:30:17.449 Mark Kushner: core orbitals, and I don't… and essentially, the ions are taking up so much of the room that the electrons can't preserve their… the symmetry of the wave functions and the Pauli exclusion principle, and still stay around in these Fermi, states. 177 00:30:17.570 --> 00:30:36.359 Mark Kushner: And so we're trying to understand the endpoint of this. Does it… when would it become a Thomas Fermi picture? And so computational efforts lead the way, all the way up to 20 terapascals, so that's 200 million atmospheres. 178 00:30:36.490 --> 00:30:46.139 Mark Kushner: And someone can check me in, because remember, I'm jet-lagged, so sooner or later, I'm going to get one of these conversions wrong. But anyway, you know, we don't have, 179 00:30:46.800 --> 00:31:01.959 Mark Kushner: We don't see anything close to what is, people expected from a Thomas Fermi, but nevertheless, we're trying to benchmark these types of computations. We have the first set of experiments at the National Ignition Facility. 180 00:31:01.970 --> 00:31:13.079 Mark Kushner: Where we're taking it up to 1.2 terapascal, so 12 megabar, 12 million atmospheres. And, in essence, we have some beautiful diffraction. 181 00:31:13.120 --> 00:31:30.969 Mark Kushner: But, even with the diffraction that we've seen so far, these, these are complicated structures. These, these are not, BCC structures. These are complicated structures, but we need a better light source to go further. 182 00:31:30.970 --> 00:31:37.350 Mark Kushner: So we're in the process of exploring all… really, a whole new generation of materials. 183 00:31:37.710 --> 00:31:46.859 Mark Kushner: But as materials get harder, the fraction that I showed is harder. It turns out to be more challenging. And we need, 184 00:31:46.990 --> 00:31:52.730 Mark Kushner: We need a better light source. Let me just go back to this. This is how we do diffraction. 185 00:31:53.060 --> 00:32:11.980 Mark Kushner: So, this shows the compression that I showed earlier, where we compress, and this is the velocity of the function of time. That allows us to get the thermodynamic state. And then, once we reach a certain state, we take a bunch of laser beams, we hit a foil. 186 00:32:12.260 --> 00:32:17.390 Mark Kushner: The foil heats up, and we tune the intensity so that it heats up just right. 187 00:32:17.470 --> 00:32:26.640 Mark Kushner: It produces helium alpha, in this case it's a germanium foil, and that, produces, you know, near 10 kilovolt X-rays. 188 00:32:26.640 --> 00:32:42.719 Mark Kushner: This is the compression… these are the compression beams. Our target, is… is right here, and so these x-rays go through and then produce these diffraction, lines on the… on film that is around the chamber. 189 00:32:42.820 --> 00:32:59.359 Mark Kushner: But the problem is, the photon energy is sort of limited to maybe 12 kilovolts. We just can't get past that, so that means we can't really shield, the system. So what we really need is something that is higher fluence and 190 00:32:59.450 --> 00:33:04.140 Mark Kushner: Somewhere between 20 and 50 kilovolts of the x-rays. 191 00:33:04.840 --> 00:33:07.830 Mark Kushner: So we have this effort to try and develop… 192 00:33:08.080 --> 00:33:19.240 Mark Kushner: a simple X-ray source, and this is where I'm hoping maybe one of these days we come to Zeus to try and figure out how to do this better. 193 00:33:19.260 --> 00:33:29.599 Mark Kushner: But what we're doing, at least at the… in this… in the simple sense, we're working with Los Alamos. They just use a simple accelerator, so a simple photoejector, to generate 194 00:33:29.600 --> 00:33:48.830 Mark Kushner: the electrons and put it through a simple chicane, and then once the beam's prepared, we scatter off with another laser, it's on the order of a couple hundred joules, and that'll produce about 10 to the 10 photons at 50 kilovolts, so that's the first design that we have. So that's one of the directions that we're headed. 195 00:33:49.510 --> 00:33:57.920 Mark Kushner: And so, what we're trying to do is emulate some of these X-ray sources that, you guys have heard of LCLS? 196 00:33:58.870 --> 00:34:16.729 Mark Kushner: LCLS and European XFL. So we go there all the time, we use those X-ray facilities, they're awesome. They have really wimpy lasers, okay? So they have great diagnostic, wimpy lasers. We have… 197 00:34:16.730 --> 00:34:24.259 Mark Kushner: you know, great lasers, but honestly, the diagnostics are pretty wimpy. So we're trying to figure out some way to pull in the two. 198 00:34:24.820 --> 00:34:35.100 Mark Kushner: But even though they have pretty wimpy compression capability, I mean, they're working on that. You know, there have been a lot of discoveries, both in terms of the liquid structure. 199 00:34:35.100 --> 00:34:45.060 Mark Kushner: of carbon, and the ability to sort of measure temperature from diffraction using the, diffuse scattering. So there's been a bunch of, 200 00:34:45.060 --> 00:34:55.250 Mark Kushner: developments, using, these, advanced X-ray sources that hopefully one day we'll be able to bring to the, major compression facilities. 201 00:34:55.750 --> 00:35:00.560 Mark Kushner: Okay, let me see. What time… what time do I… what time am I supposed to stop here? 202 00:35:00.780 --> 00:35:06.059 Mark Kushner: A little bit after 4. A little bit after 4. Okay, so we're, 203 00:35:06.180 --> 00:35:08.779 Mark Kushner: I'm gonna take… I'm gonna take that, 204 00:35:08.910 --> 00:35:12.590 Mark Kushner: Generally, a little after form. Okay, so, 205 00:35:15.150 --> 00:35:19.309 Mark Kushner: I've already mentioned it a bunch of times. So what is a quantum material? 206 00:35:20.070 --> 00:35:21.440 Mark Kushner: We'll look at the feed graph. 207 00:35:22.180 --> 00:35:23.639 Mark Kushner: What is a quantum interior? 208 00:35:23.820 --> 00:35:24.670 Mark Kushner: What do you think? 209 00:35:34.080 --> 00:35:34.940 Mark Kushner: Yes. 210 00:35:35.190 --> 00:35:49.700 Mark Kushner: material that behaves non-classically? Oh, that's very good, very good. Okay, so… and, if, material behaves non-classically, so, it behaves, quantum mechanically, a lot of times what we mean is 211 00:35:49.700 --> 00:36:01.360 Mark Kushner: the ions, are also starting to behave quantum mechanically. Usually, we don't think that way. Usually, folks, assume the ions are classical, and the electrons are… 212 00:36:01.470 --> 00:36:06.560 Mark Kushner: Quantum mechanical. But in the case where the ions are also quantum mechanical. 213 00:36:06.610 --> 00:36:14.960 Mark Kushner: That you have a different type of, quantum material. And, one way to think about, 214 00:36:14.960 --> 00:36:30.140 Mark Kushner: that quantum scale is the de Broglie wavelength, so that's lambda dB. I don't like to think… the de Broglie wavelength sounds pretty, standoffish, but you think about that as the quantum blurring distance, so that's sort of the distance where you just don't… 215 00:36:30.300 --> 00:36:46.999 Mark Kushner: have information. It's a, you know, you don't have, the traditional classical information, so it's quantum blurring distance. And that's a Planck's constant, which is a very small number, divided by the square root of T and M, so the mass and the temperature. 216 00:36:47.290 --> 00:37:00.330 Mark Kushner: And so people have, for almost 100 years, more than 100 years, noticed this temperature dependence, and they say, okay, we're just going to take temperature to zero, near zero. 217 00:37:00.330 --> 00:37:09.830 Mark Kushner: And that's going to swell this quantum blurring distance, and it's going to just swell it so that it is greater than the inner particle distance. 218 00:37:09.830 --> 00:37:26.540 Mark Kushner: And then we get a new quantum behavior, and that's the case of helium. So helium, you squish… you cool it down to 2 degrees Kelvin. That gives you a de Braille wavelength of about 9 angstroms, which is the inner particle spacing, and it undergoes a superfluid transition. 219 00:37:27.320 --> 00:37:30.130 Mark Kushner: In HED, we don't have to do that. 220 00:37:30.800 --> 00:37:32.720 Mark Kushner: Right? We squish stuff. 221 00:37:33.090 --> 00:37:52.990 Mark Kushner: And so, we essentially take any material, and we can squish the atoms close enough together so that it still satisfies us, so that you have the, inner part… this quantum blurring distance gets to be greater than the inner particle spacing. So, even at sort of modest temperatures. 222 00:37:53.060 --> 00:38:01.540 Mark Kushner: If you take hydrogen at 2 terra pascal, 20 million atmospheres, at 1,000 degrees. 223 00:38:01.940 --> 00:38:04.500 Mark Kushner: We should have the same type of thing. 224 00:38:04.680 --> 00:38:13.249 Mark Kushner: same type of quantum transition. Only in the case of hydrogen, It becomes superconducting and superfluid. 225 00:38:13.900 --> 00:38:21.969 Mark Kushner: Now, someone has to ask a question before we're done how hydrogen can do that, but we're gonna move on. So this is a phase diagram of hydrogen. 226 00:38:22.470 --> 00:38:31.560 Mark Kushner: And don't be fooled, this is a double, double, double lock, okay? Shouldn't… you should never, never use those, okay, because it really is… 227 00:38:31.950 --> 00:38:34.740 Mark Kushner: It's almost disturbing, but, 228 00:38:34.940 --> 00:38:51.529 Mark Kushner: Nevertheless, this is, this is pressure and GPA on this double log, scale, where we have, the solid range of hydrogen and, in, and then you have the fluid phase, and then your, warm dense matter phase. 229 00:38:51.530 --> 00:38:57.240 Mark Kushner: And this is this, this is this quantum blurred, system, which is… 230 00:38:57.280 --> 00:39:00.729 Mark Kushner: Which is one of the directions that we're really trying to get to. 231 00:39:00.870 --> 00:39:05.169 Mark Kushner: And so we have these, efforts to compress 232 00:39:05.320 --> 00:39:15.600 Mark Kushner: The hydrogen under these ramp-compressed experiments, and we're trying to just squish it so that it, kisses this new region. 233 00:39:16.060 --> 00:39:34.350 Mark Kushner: And a key part of that is us we've been trying to develop compression paths so that we can tune the entropy just so, so that we enter into that, into that new realm. This is an experiment where it sort of shows the state of the art of a few years ago. 234 00:39:34.410 --> 00:39:48.650 Mark Kushner: Those compression paths that I just showed, are… these are real experimental compression paths for different experiments that just start off on different entropies, and then… so these are just different isentropes. 235 00:39:48.650 --> 00:40:03.709 Mark Kushner: As we compress the material, it undergoes one transition where it goes from molecular insulating and transparent to opaque. You'd think that's like a semiconductor, but maybe that's the way we think about it. And then it becomes conducting 236 00:40:03.970 --> 00:40:21.030 Mark Kushner: And fully metallic. And so, you have this, region where it's transparent to opaque, and then, this metal insulator-like transition. And what we've… we've made a lot of progress since then, so that's up to 300 GPA. 237 00:40:21.120 --> 00:40:45.859 Mark Kushner: We've made progress where we're now able to drop the entropy even lower than what I showed, and we're able to get up to about 750 to 800 GPA, and this is just to show that we've collected data in there. But in all of these cases, the reflectance sort of saturates out at this 50%. If it were to become a superconducting superfluid, it'd be well 238 00:40:45.860 --> 00:40:47.550 Mark Kushner: low for median percent. 239 00:40:47.640 --> 00:40:50.280 Mark Kushner: Okay, so that's one of the things we're looking for. 240 00:40:50.710 --> 00:40:55.750 Mark Kushner: Okay, so, so what we've done is we have, new data. 241 00:40:56.230 --> 00:41:11.640 Mark Kushner: that, show, the same deuterium points, shown in blue, also, extended out to higher pressure. So these are the same, transitions. It goes from insulating to opaque, opaque to conducting. 242 00:41:11.750 --> 00:41:36.000 Mark Kushner: And, the red are for hydrogen, the blue is for deuterium, and so there's some transition that is, looks like it has an isotope dependence. If you just look at the energy difference between these two curves, it turns out that energy difference is comparable to the energy difference of the molecular bond between hydrogen and deuterium, which is essentially the difference in the zero-point energy. 243 00:41:36.670 --> 00:41:45.960 Mark Kushner: And, and, so that's one thing, so that's suggested that this transition is driven by the dissociation, so that's a new, 244 00:41:45.980 --> 00:42:04.789 Mark Kushner: And then the second thing is, as we go to higher pressure, all these curves seem to be coasting along the melt curve, which means we haven't seen anything conducting in the solid phase. And I'll just say that we do have one experiment where we've compressed stuff 245 00:42:04.790 --> 00:42:16.980 Mark Kushner: In the solid phase, and we haven't really seen it become conducting to, very high pressures, something that we didn't really expect, but we're repeating those experiments, 246 00:42:17.230 --> 00:42:18.680 Mark Kushner: As we speak. 247 00:42:19.500 --> 00:42:24.200 Mark Kushner: Okay, so how would we know… I want to ask… 248 00:42:25.850 --> 00:42:29.930 Mark Kushner: How would you… let's say… let's say we make this material. 249 00:42:30.120 --> 00:42:31.280 Mark Kushner: Ta-da! 250 00:42:31.690 --> 00:42:32.610 Mark Kushner: How do you know? 251 00:42:35.650 --> 00:42:38.730 Mark Kushner: You made superconducting superfluid hydrogen. 252 00:42:40.070 --> 00:42:41.090 Mark Kushner: How do you know it? 253 00:42:44.520 --> 00:43:00.089 Mark Kushner: Yeah, we're struggling with that too, so don't worry about it. Yeah, go ahead. You could try to measure its reflectivity. Oh, the reflectivity's good, so that's one thing that we can do, and so we would measure the reflectance and see if it jumps up to this 98%, 254 00:43:00.090 --> 00:43:06.459 Mark Kushner: So that's… so that's one. It turns out if it's superfluid, it turns… the superfluid 255 00:43:06.460 --> 00:43:20.860 Mark Kushner: has an interesting process that, it's always a two-fluid… even in, helium-4, it's not a… all the atoms don't both condense. You have a two-fluid system, and what that drives is vortices. 256 00:43:20.860 --> 00:43:36.900 Mark Kushner: And these vortices, show up as defects in the refractive index, and so that's… that allows you to see it. And so one of the things that we are setting up to do is set up to measure these vortices 257 00:43:36.900 --> 00:43:45.100 Mark Kushner: that, occur if it were to become superfluid. And so these are the type of things that have been done in helium 258 00:43:45.100 --> 00:43:55.389 Mark Kushner: at LCLS using diffractive imaging techniques, and so we're setting up diffractive imaging-like techniques to measure these types of vortices as we compress the hydrogen. 259 00:43:55.860 --> 00:43:58.559 Mark Kushner: Okay, now, it turns out, 260 00:43:58.730 --> 00:44:02.159 Mark Kushner: There's a ton of other stuff as we go to higher and higher temperatures. 261 00:44:02.910 --> 00:44:07.859 Mark Kushner: Most of what we've talked about is at lower temperatures so far down here. 262 00:44:07.960 --> 00:44:24.990 Mark Kushner: if instead of doing these ramp compressions, we launch shock waves to get into this more warm, dense regime. There have been a number of recent discoveries on that. Let me just show you one on hydrogen. Oh yeah, so this is 263 00:44:24.990 --> 00:44:33.630 Mark Kushner: This is a terrible slide. This is, maybe you've all seen this, the warm, dense matter. This is, like, the terrible slide. Never show one of these. 264 00:44:34.480 --> 00:44:36.030 Mark Kushner: There's never… 265 00:44:36.110 --> 00:44:54.019 Mark Kushner: But I'm going to show you. Here's temperature versus density, and the point is, this is, this is a line for temperature equals the Fermi energy, this is a line for temperature equals the plasmon frequency, plasma energy. This is when the, the thermal energy equals the Coulomb energy. 266 00:44:54.020 --> 00:44:59.849 Mark Kushner: And so, right in the regime where all of those coalesce. 267 00:44:59.940 --> 00:45:04.370 Mark Kushner: We made measurements on the equation of state for hydrogen. 268 00:45:04.410 --> 00:45:09.990 Mark Kushner: And it turns out, so Malia did these measurements, they're beautiful measurements. 269 00:45:09.990 --> 00:45:30.319 Mark Kushner: The original paper, showed that, this is pressure versus density. This is for a shockwave moving through hydrogen, and you're measuring the thermodynamic state. And this… these are, all these different colored curves are theoretical predictions, and then these are all data… 270 00:45:30.320 --> 00:45:39.989 Mark Kushner: Of various quality, and these are the… so Amalia's data with the highest pressure, up to about 600, GPA, 6 megabyt. 271 00:45:39.990 --> 00:45:51.560 Mark Kushner: And it was offset from all of the new models. We didn't really understand that, and then… so there was a big effort to say… there was a big effort to understand 272 00:45:51.560 --> 00:46:06.270 Mark Kushner: These experiments were done with a reference material, so it was compared to a reference material, so everyone said, well, the reference material might not be well understood, so there was, like, two and a half years spent to understand the reference material. 273 00:46:06.270 --> 00:46:16.119 Mark Kushner: I think we understand it better. What that did was that pushed the red… the red data points out to the green data points, which made it even worse. And so now we're, like, two sigma away. 274 00:46:16.230 --> 00:46:25.439 Mark Kushner: And honestly, I… We couldn't really figure out what the heck was going on. 275 00:46:25.770 --> 00:46:30.150 Mark Kushner: It… it turns out Ryan came up with this notion 276 00:46:30.670 --> 00:46:40.730 Mark Kushner: That if you, construct the electron plasma waves, and just calculate the heat capacity of that, that gives you about the right energy deficit for… 277 00:46:40.730 --> 00:46:56.000 Mark Kushner: what's missing here. And so you can ask, well, why wouldn't the ab initio calculations get that? And we think maybe it's because the size of the box of the ab initio calculations are just too small, and you can't really capture these long wave… 278 00:46:56.130 --> 00:46:59.780 Mark Kushner: excitations. 279 00:47:00.120 --> 00:47:11.519 Mark Kushner: Maybe that's right. So, but I… I think the real message here is, as anytime you sort of move things to a new regime, you learn something new. 280 00:47:12.450 --> 00:47:30.069 Mark Kushner: Okay, let me go to the next step. So, we looked at things at low temperature, then we went to slightly higher temperature, and we used shock waves to get up to, say, 10 million atmospheres. 281 00:47:30.270 --> 00:47:36.739 Mark Kushner: But let's say we want to understand, what's going on at hundreds of millions of atmospheres. 282 00:47:37.410 --> 00:47:46.310 Mark Kushner: The only way we can really do that, it turns out, is if we hit a material with too much intensity. 283 00:47:46.350 --> 00:48:04.279 Mark Kushner: It's… we don't really get this nice ablation and then compression wave. We essentially preheat the material, and it makes it really hard to do thermodynamic measurements. Although, we have to figure out how to do this. You know, I think you might have done these polarization-dependent measurements early on. 284 00:48:04.280 --> 00:48:13.209 Mark Kushner: But, you know, there might be ways of us inhibiting, hot electrons getting into the material. We have the intensities there, but, 285 00:48:13.280 --> 00:48:28.180 Mark Kushner: Right now, we don't know really how to use higher intensities without these plasma wave effects heating up the material. So what we do to get the pressures above about 100 million atmospheres is we use convergent techniques. 286 00:48:28.220 --> 00:48:45.380 Mark Kushner: It's the same technique that's used in ICF, inertial confinement fusion, where, you know, they use a shell, and they compress, deuterium tritium, and they can get it up to hundreds of billions of atmospheres. 287 00:48:45.380 --> 00:48:55.630 Mark Kushner: You can also use, like, a solid ball. So you can use a solid ball, and that compresses, you launch a shockwave, shockwave runs into the center and bounces off it, and you can get to very, very high pressures. 288 00:48:55.630 --> 00:48:57.639 Mark Kushner: But it turns out not very high density. 289 00:48:58.260 --> 00:49:02.019 Mark Kushner: The few, can sort of generalize this. 290 00:49:02.650 --> 00:49:08.620 Mark Kushner: We're using… we're trying to understand how to use all of these different spherical targets. 291 00:49:08.870 --> 00:49:29.319 Mark Kushner: And it turns out, if you use a solid ball, it's largely controlled by hydrodynamic effects. As you increase the gap in the center, the void in the center, it's dominated by conduction processes. If you get to thinner shells, it's conducted… it's dominated by radiation processes. 292 00:49:29.320 --> 00:49:33.210 Mark Kushner: So we're trying just to understand where we can go in phase-based 293 00:49:33.210 --> 00:49:37.170 Mark Kushner: With these different, target geometries. 294 00:49:37.170 --> 00:49:51.760 Mark Kushner: And if… if we just, plot out their pressure versus density for different, for these different systems, this NIF-Critcher experiment is essentially this, solid ball, so that's launching a solid single shot. 295 00:49:52.060 --> 00:50:03.670 Mark Kushner: And the problem is you can't really get to very high densities, you can get to very high pressures, but not very high densities. If you go to thinner shells, you can get to, 296 00:50:03.700 --> 00:50:12.969 Mark Kushner: Higher densities and higher, pressures, and it doesn't require quite as much, energy to do that. 297 00:50:13.160 --> 00:50:21.240 Mark Kushner: But, so that's essentially what we're trying to do, and so we use these convergent techniques to get into this billion of the atmosphere regime. 298 00:50:21.570 --> 00:50:37.670 Mark Kushner: And this shows a simple example. It's a little bit complicated to try and understand these, the hydrodynamics of these things, but you start off with a shell, sort of like this. You fill it with deuterium or whatever. You fill this plastic ball shell with the gas. 299 00:50:37.670 --> 00:50:53.369 Mark Kushner: And then you illuminate that shell, and it, again, ablates off, drives a compression wave. In this case, now the compression, the shell, compresses, and there's a shock wave in the gas that, bounces off. 300 00:50:53.370 --> 00:51:08.719 Mark Kushner: the center and recompresses to bring the shell up to very, very high compression, and then it explodes. And that's sort of shown here, where you have this converging shock, it goes in in the gas, it bounces off the center, and then recompresses 301 00:51:08.790 --> 00:51:10.220 Mark Kushner: the… 302 00:51:10.540 --> 00:51:20.100 Mark Kushner: the shell. And so then, it's at that point that we start to look at the state of the material of the shell in this particular case. 303 00:51:20.220 --> 00:51:40.080 Mark Kushner: So this is… this is a case where we've started to use these Bayesian inference techniques to map the radius as a function of time, which we've used to get pressure. We use spectroscopy and just the Bremsstrauling emission to get temperature and density, and so this is allowing us to sort of map 304 00:51:40.080 --> 00:51:47.540 Mark Kushner: How well, the material, looks, what the pressure is, the function of mechanical pressure. 305 00:51:47.690 --> 00:51:59.079 Mark Kushner: If it sits… so this dashed line is the ideal gas, everything… our data are shown in the different dots. If it's below, that means you have more coupling. 306 00:51:59.190 --> 00:52:15.890 Mark Kushner: Than in an ideal gas, an ideal situation. And you would expect that by the time you get to, you know, a tenth or close to a billion atmospheres, that, it would be ideal gas. But, you know, it at least seems that even at a billion atmospheres, we're not quite there yet. 307 00:52:15.920 --> 00:52:25.339 Mark Kushner: Sort of surprising to me, and it definitely is different than a lot of the basic physics models that are all assuming ideal gas at this stage. 308 00:52:26.120 --> 00:52:32.349 Mark Kushner: Okay, now let's say we take one of those balls and we put a little piece of stuff inside the shell. 309 00:52:32.590 --> 00:52:37.450 Mark Kushner: And we're going to use chromium for a particular reason, but we put a little chromium layer 310 00:52:37.750 --> 00:52:47.049 Mark Kushner: And then, we do the same thing. We squish the shell, it gets recompressed by the return shock of the gas. 311 00:52:47.280 --> 00:52:59.720 Mark Kushner: And when that shock goes off from the gas, it backlights the shell. So in essence, you have this hotspot of the gas that's generating X-rays that go through the shell. 312 00:53:00.030 --> 00:53:19.539 Mark Kushner: That allows us to either photopump, that would create an absorption event, or an emission event from the 1S to 2P, which is one of… these are just the atomic states of the chromium. And what we are able to do is see this simple transition for several different ionization states. 313 00:53:19.540 --> 00:53:26.440 Mark Kushner: So we're able to map, essentially what the ionization evolution is, is a function of density. 314 00:53:27.370 --> 00:53:29.200 Mark Kushner: Okay, so just keep that in your head. 315 00:53:29.320 --> 00:53:42.260 Mark Kushner: what is the ionization state as a function of density for a given temperature and density? Because now we… I hopefully convinced you we sort of have an estimate of what's going on with the thermodynamic states. 316 00:53:42.500 --> 00:53:43.380 Mark Kushner: Boom. 317 00:53:44.270 --> 00:53:56.549 Mark Kushner: So, what's going on here is, essentially, we're getting this shift in these different transitions as a function of density. In this case. 318 00:53:56.550 --> 00:54:06.899 Mark Kushner: It's, releasing. And the reason for this massive shift is because we have, because there's a change in the screening. 319 00:54:06.900 --> 00:54:23.439 Mark Kushner: of those core orbitals of the atom, the chromium atom, which is changing as a function of density. So the screening is changing as a function of density. A lot of people call that plasma polarization shift, it's related to the, 320 00:54:23.610 --> 00:54:29.199 Mark Kushner: Why you're getting some of this, change in the ionization. 321 00:54:29.430 --> 00:54:37.780 Mark Kushner: But, I like to just think about it as screening. And, and this is the picture I want you to have in your head. 322 00:54:38.330 --> 00:54:46.750 Mark Kushner: So this is… this is an isolated atom. You have your beautiful Bohr orbits. All of you can calculate a Bohr, orbit, 323 00:54:47.000 --> 00:54:53.419 Mark Kushner: Now, I… I squish this material To a billion atmospheres. 324 00:54:53.820 --> 00:55:00.870 Mark Kushner: The electrons that you thought were in this plasma, or dense plasma, or ferment plasma, whatever. 325 00:55:01.010 --> 00:55:06.860 Mark Kushner: Are getting squished in to the deep interior core orbits. 326 00:55:07.420 --> 00:55:16.449 Mark Kushner: And that screening creates a change that screens the Coulomb charge of the ion for these electron orbits. 327 00:55:17.020 --> 00:55:21.079 Mark Kushner: And, we're now able to start to map 328 00:55:21.300 --> 00:55:27.620 Mark Kushner: How much… what fraction of the electrons of these outside electrons 329 00:55:27.740 --> 00:55:33.570 Mark Kushner: Are being sucked into the… into these, the interior states of the atom. 330 00:55:33.880 --> 00:55:45.939 Mark Kushner: And so, just by measuring, you measure a shift of about 10 eV, and it sort of suggests that, you know, we have, for n equals 2 level, we're sort of at, 331 00:55:45.940 --> 00:55:59.289 Mark Kushner: 0.1 electron that's being shoved into that N equals 2 level, and about, you know, 0.02 electrons being shoved into, the N equals 1 level. 332 00:55:59.630 --> 00:56:03.339 Mark Kushner: If you just try and extrapolate that further. 333 00:56:03.630 --> 00:56:23.589 Mark Kushner: What we're trying to do is build a picture of how the atomic orbitals change as a function of density, and, just from this simple screening. So you have, going from this simple Bohr picture, which you would calculate with Schrodinger-type picture. 334 00:56:23.590 --> 00:56:30.429 Mark Kushner: Out to this, highly screened, system. So that's, 335 00:56:30.430 --> 00:56:47.629 Mark Kushner: That's where atoms are no longer atoms that we, knew and loved at standard conditions. Of course, it takes even more pressure to get to the point where you're squishing stuff, so the nuclei are starting to be, 336 00:56:47.690 --> 00:57:03.309 Mark Kushner: undergoing thermonuclear processes, and that's sort of on the hundreds of billions of atmospheres. And many of you, I'm sure, have already read a couple of times the beautiful 337 00:57:03.370 --> 00:57:17.719 Mark Kushner: results of, the ignition campaign. I just want to make one very important point here. So, I worked on the ignition campaign all throughout here, and right after I left, they started making a lot of progress. 338 00:57:18.270 --> 00:57:24.459 Mark Kushner: And… I'm sure that was unrelated. But… 339 00:57:24.610 --> 00:57:44.299 Mark Kushner: Nevertheless, there's this tremendous progress in controlling and understanding thermonuclear ignition at the National Ignition Facility. For us, what that allows us to do 340 00:57:44.710 --> 00:57:48.570 Mark Kushner: Is now we have convergent systems to get to… 341 00:57:48.640 --> 00:58:01.300 Mark Kushner: Tens of billions of atmospheres, and if we can start to exploit these interior states of thermonuclear capsules. 342 00:58:01.300 --> 00:58:09.900 Mark Kushner: We should be able to get to hundreds of billions of atmospheres, and that's one of the directions we're starting to move towards. 343 00:58:09.990 --> 00:58:15.529 Mark Kushner: And that's sort of the end of our journey, and thank you very much. I went a little bit over time. 344 00:58:22.770 --> 00:58:25.550 Mark Kushner: Thank you very much. Are there questions? 345 00:58:30.410 --> 00:58:37.779 Mark Kushner: Is that not quite easy for the pilot? 346 00:58:37.900 --> 00:58:47.190 Mark Kushner: Yeah, that would be the first case that we would use, is using the optical light 347 00:58:47.190 --> 00:59:00.530 Mark Kushner: of the visor, and measure the intensity of the reflectivity of reflective… reflectance. Do you expect the soup fluid conditions to… to come right to the back surface of the… 348 00:59:00.530 --> 00:59:15.790 Mark Kushner: the target then, or you don't think it might be happening inside, but… Oh, very good, very good. That's really a good… that's a good question. So, right now, we don't have… 349 00:59:15.890 --> 00:59:21.500 Mark Kushner: The best access, optical access, Deeper into the interior. 350 00:59:21.620 --> 00:59:32.319 Mark Kushner: The calculations show that it should work all the way up to that interface, which is a lithium fluoride interface with, hydrogen. 351 00:59:32.440 --> 00:59:49.649 Mark Kushner: We're not… it could be that the dynamics of the compression are just so that heat transport at that interface mucks it up a little bit. That isn't the way our, initial calculations suggest, but 352 00:59:49.880 --> 01:00:03.809 Mark Kushner: That's the interface that we have access to. We are looking at, trying to understand how X-ray Thompson scattering, signatures, would evolve at, under these types of conditions. 353 01:00:03.990 --> 01:00:11.570 Mark Kushner: And so we're working to calculate what that scattering profile looks like. 354 01:00:11.760 --> 01:00:18.969 Mark Kushner: It's been a little bit of a challenge, but I think there's a unique signature there, also. 355 01:00:19.940 --> 01:00:39.699 Mark Kushner: The, I think all of the x-ray measurements, especially if we're able to do the, diffractive imaging, you know, LCLS or something like that, that would be… that would look at the bulk, yeah. Yeah. No, good, good point. I guess the other thing that we're working towards is to look at the Meissner effect. 356 01:00:39.890 --> 01:00:53.749 Mark Kushner: And in that case, we would be trying to pass magnetic field flux through the sample, and essentially we'd lock in a magnetic field flux. And if, 357 01:00:54.190 --> 01:00:58.549 Mark Kushner: If… if the material is… is super fluid. 358 01:00:58.600 --> 01:01:14.710 Mark Kushner: the magnetic field flux wouldn't get through the sample, and there'd be some penetration depth. But in essence, if a field doesn't get through, we have a design for an optoelectric material to look at how 359 01:01:14.840 --> 01:01:28.800 Mark Kushner: how much flux does get through the sample. So, that's another technique that would be more bulk measurement, but in terms of the reflectance, yeah, we would be, limited to that window interface. 360 01:01:30.030 --> 01:01:40.520 Mark Kushner: Yeah. This might be a naive question, but, you talked about breaching these Fermi-like states at high pressures and going through states, but 361 01:01:40.720 --> 01:01:47.259 Mark Kushner: to reach that, wouldn't you need to be… have temperature high compared… large compared to the Fermi energy? 362 01:01:49.050 --> 01:01:58.090 Mark Kushner: So you're gonna have to ask that slightly differently. So usually, so, 363 01:01:59.030 --> 01:02:06.990 Mark Kushner: To be in this plasma phase, so we've gone to, 364 01:02:07.490 --> 01:02:14.469 Mark Kushner: in the… in the very high temperature plasma phase, you have this 365 01:02:14.720 --> 01:02:28.439 Mark Kushner: you would have a Thomas-Fermi-like picture, which is in this plasma, but you have a very similar behavior in the solid, and it's driven mostly by the Fermi interaction. 366 01:02:28.700 --> 01:02:41.769 Mark Kushner: Yeah, yeah. So it, I like, I like where you're headed with that, because a lot of people that live in the high temperature realm are only used to thinking about it there. 367 01:02:41.770 --> 01:02:49.430 Mark Kushner: It turns out it translates in both, it's just that the velocity of the electrons is dominated by different things. 368 01:02:51.540 --> 01:02:53.099 Mark Kushner: No thanks, that's good. 369 01:02:55.090 --> 01:03:08.910 Mark Kushner: Yes, go ahead. Could you explain a little bit more about the disagreement between the Eugonio predictions and measurements that you said the explanation had to do with the electron plasma wave excitation? 370 01:03:08.980 --> 01:03:16.080 Mark Kushner: Maybe. Okay, so, in essence, the, 371 01:03:17.000 --> 01:03:22.050 Mark Kushner: So, we… we launch a shockwave through the deuterium. 372 01:03:22.820 --> 01:03:28.780 Mark Kushner: And we measure its, what's called a Hugonio state. 373 01:03:28.950 --> 01:03:33.040 Mark Kushner: We do that by measuring a shock velocity. 374 01:03:33.150 --> 01:03:50.039 Mark Kushner: in quarts, and then the quartz unloads into the hydrogen, and then we measure the velocity in the hydrogen. And then we use the velocity in the quarts, and the velocity in the hydrogen, in an imped… what's called impedance matching. 375 01:03:50.320 --> 01:03:58.869 Mark Kushner: And, what that does is it uses conservation of mass and momentum right at that interface. 376 01:03:59.060 --> 01:04:05.429 Mark Kushner: And if you know the equation of state of SiO2, 377 01:04:05.680 --> 01:04:07.790 Mark Kushner: And you have to know pretty well. 378 01:04:08.110 --> 01:04:19.539 Mark Kushner: That gives you… you're able to calculate what the particle velocity is in the Hugonio state of the hydrogen, and then you measure the shock velocity state in the hydrogen. 379 01:04:20.360 --> 01:04:31.210 Mark Kushner: Those two velocities, essentially, are what are required to close the Rankin-Higonia relations, which are the conservation relations for shock waves. 380 01:04:31.770 --> 01:04:36.990 Mark Kushner: So we make those… we make those measurements with fairly good fidelity. 381 01:04:37.120 --> 01:04:44.570 Mark Kushner: And we end up with a measurement that has 382 01:04:44.710 --> 01:04:48.170 Mark Kushner: Compressibility, which is quite a bit higher than what 383 01:04:48.370 --> 01:04:55.629 Mark Kushner: People had expected, with these ab initio calculations, so density functional theory. 384 01:04:55.810 --> 01:04:59.810 Mark Kushner: Using a variety of different, potentials. 385 01:05:01.050 --> 01:05:05.769 Mark Kushner: And I think I showed every one that's been calculated at this stage. 386 01:05:07.180 --> 01:05:15.139 Mark Kushner: And so, what Ryan did… Was, essentially, 387 01:05:15.800 --> 01:05:30.009 Mark Kushner: said, well, you know, what… what physics could be missing out of these ab initio calculations? And one of the things that was, suggested, and this came from discussions between me and Peter and 388 01:05:30.730 --> 01:05:45.850 Mark Kushner: was these plasma waves are starting to be excited right around the time where you see the deviation in compression. And the plasma waves have a real energy, right? It's a real excitation. It's just a… it's another electron plasma 389 01:05:45.990 --> 01:05:52.220 Mark Kushner: degree of freedom. And in essence, the DFT should have it in there. 390 01:05:52.380 --> 01:06:08.280 Mark Kushner: Right? If… if you did density functional… if you had a large enough cell size, you should be able to do that. That's sort of, I think, the number that, I might get this wrong, but I think if you had 512… 391 01:06:08.740 --> 01:06:13.959 Mark Kushner: particles in a box. Maybe it's a little bit larger than that, but I think that was the right scale. 392 01:06:14.330 --> 01:06:26.650 Mark Kushner: If you had that, you'd get most of that electron energy, plasmon energy. But because most of these calculations are with 32 or 64 particles in a box, you miss it. 393 01:06:27.230 --> 01:06:31.289 Mark Kushner: That's the art… that's, you know, that's sort of the… 394 01:06:31.640 --> 01:06:33.520 Mark Kushner: Does that answer your question? Thanks. 395 01:06:34.510 --> 01:06:40.760 Mark Kushner: I'm getting a little bit short on time, so let's take a few from the chat. Oh, we have the chat. 396 01:06:43.510 --> 01:06:45.579 Mark Kushner: I don't mind listening to that. 397 01:06:45.970 --> 01:06:50.099 Mark Kushner: So, Michael has asked several times, still wondering what is better. 398 01:06:51.240 --> 01:06:53.470 Mark Kushner: Maybe that's unanswerable at the moment. 399 01:06:54.270 --> 01:06:56.799 Mark Kushner: What is matter? 400 01:06:59.130 --> 01:07:02.879 Mark Kushner: I'm glad someone didn't ask that when I was interviewed. 401 01:07:03.080 --> 01:07:10.890 Mark Kushner: So, matter is perhaps the condensed phase of energy. 402 01:07:11.160 --> 01:07:20.610 Mark Kushner: That, we're… we're able to see. How's that? 403 01:07:20.720 --> 01:07:26.880 Mark Kushner: Maybe that's a start for an answer? 404 01:07:30.330 --> 01:07:40.699 Mark Kushner: And then, from Daniel Peters, have any experiments left any part of the compressed sample with a stable compressed state that can be handled and examined? 405 01:07:41.570 --> 01:07:45.079 Mark Kushner: It has to last longer than a nanosecond? 406 01:07:45.260 --> 01:07:53.369 Mark Kushner: So, we've worked pretty hard at, recovering materials, and we've been successful in some cases. 407 01:07:53.630 --> 01:08:00.810 Mark Kushner: I, I would say, 408 01:08:01.820 --> 01:08:18.619 Mark Kushner: We sort of stopped doing that a while back, because it… it was… the preponderance of energy that you were putting into just trying to recover stuff that you weren't sure. There was a lot… it was a lot of work, because you… we usually used, 409 01:08:18.770 --> 01:08:31.299 Mark Kushner: Something like foam or something to slow the material down, so you… whatever you compress the material up with, you could design a way of decompressing it along a 410 01:08:31.620 --> 01:08:39.550 Mark Kushner: the correct pressure history, so that it would be… could be stable if you locked it in. 411 01:08:39.790 --> 01:08:46.150 Mark Kushner: But we don't have a lot of examples. I would say Mark Myers is the person that has put the most energy into that. 412 01:08:46.430 --> 01:08:57.959 Mark Kushner: energy, most effort into trying to stabilize these different states. We have stabilized, there have been a lot of materials that have been, recovered. 413 01:08:59.810 --> 01:09:09.630 Mark Kushner: That aren't, maybe compressed to, tens of millions of atmospheres, so, things that go way above their yield strength. 414 01:09:09.800 --> 01:09:20.240 Mark Kushner: But are still materials, even things that have melted and refroze. We've definitely done that, but we've not been able to recover something like these topological insulators at this stage. 415 01:09:20.870 --> 01:09:26.859 Mark Kushner: That's probably a good place to end the seminar. So, thank you very much for that, Dr. Consider.