WEBVTT 1 00:00:01.020 --> 00:00:11.230 Mark Kushner: We're ready to start so folks could take their seats. 2 00:00:22.030 --> 00:00:32.939 Mark Kushner: Welcome to the 15th Annual Mipsi Graduate Symposium, Mipsi, Michigan Institute for Plasma Science and engineering. 3 00:00:33.590 --> 00:00:34.849 Mark Kushner: Oh, folks! 4 00:00:36.620 --> 00:00:38.529 Mark Kushner: Oh, microphone is not on. 5 00:00:47.100 --> 00:00:59.079 Mark Kushner: Welcome to the 15th Annual Mipsi Graduate Symposium. My name is Mark Kushner, and I'm the director of Mipsi, Michigan Institute for plasma, science, and Engineering. 6 00:00:59.290 --> 00:01:21.330 Mark Kushner: This is an annual gathering where graduate students, undergraduates can have an opportunity to display their research, to network with their colleagues to learn about the research of other folks at the Universities in Michigan and to compete for the best presentation award 7 00:01:22.070 --> 00:01:30.649 Mark Kushner: in today's program. We'll have some introductory remarks by Professor Godzinkuglau. I'm sorry 8 00:01:31.130 --> 00:01:37.590 Mark Kushner: from Wayne State University, who is the chair of the Avs. Michigan chapter. 9 00:01:38.360 --> 00:01:47.209 Mark Kushner: and I'll have a few comments to say, and I'll introduce Professor Brueggeman, who is today's featured presentation. 10 00:01:47.360 --> 00:01:50.435 Mark Kushner: So, Gandhi, would you like to begin? 11 00:02:03.100 --> 00:02:03.980 Mark Kushner: Perfect? 12 00:02:04.180 --> 00:02:29.070 Mark Kushner: Yeah. Good afternoon. Everyone. Thank you for including us in the like Mipsi Graduate Symposium. We are glad to join every year. My name is Gyoza Tutinjolo. I'm an assistant professor of the Ec. Department at Wayne State University, and I'm also this year's chapter Chair of American Vacuum Society, Michigan Chapter. I'm sure you have heard about American 13 00:02:29.070 --> 00:02:36.219 Mark Kushner: society and Abs. But this is just a like short slide. Talking about the mission of the Abs 14 00:02:36.220 --> 00:02:39.140 Mark Kushner: to promote research and communicate knowledge 15 00:02:39.140 --> 00:03:03.100 Mark Kushner: in the areas of surface interface vacuum and thin film science and technology Avs has specialized journals, and it also holds every year and a big international symposium. This year it was in Tampa, and in addition to that, there are local chapters and focus conferences and symposiums taking place every year. 16 00:03:03.100 --> 00:03:12.409 Mark Kushner: And we represented here in the Michigan we have different focus areas, quantum sciences led by 17 00:03:12.837 --> 00:03:40.190 Mark Kushner: Dr. Shannon nicely, and tin films led by me. Vacuum power and space electronics is led by Dr. From Msu. And this is our leadership structure. I serve as the chair this year, and next year Shannon will take the role, and she will also be our symposium chair, and we also have roles in like vice, chair treasurer, and public relations. 18 00:03:40.190 --> 00:04:03.719 Mark Kushner: Maybe a small announcement. Currently we are looking for volunteers to take the positions of treasurer and secretary from Pilar, which will be a difficult role to fill in. But we are a very supportive collaborative organization. So if you are interested in volunteering, we would be happy to welcome you in the Avs. Michigan. 19 00:04:05.000 --> 00:04:11.659 Mark Kushner: Our main activities is actually our spring symposium that takes place every year in June. 20 00:04:11.660 --> 00:04:36.629 Mark Kushner: Last year we held it at Wayne State University, and our focus was the materials, processes, and devices for novel computing hardware. We also collaborate with Mipsi every year for their graduate symposium, and we have additional meetings. And we also have a science educators workshop program. We are sponsoring the participation of a high school 21 00:04:36.630 --> 00:04:38.459 Mark Kushner: teacher every year to the 22 00:04:38.460 --> 00:04:47.940 Mark Kushner: Avs Symposium, which is another outreach event that we are very passionate about. This is an kind of save save the 23 00:04:47.940 --> 00:05:12.829 Mark Kushner: date node for the 2025 symposium. It will take place at Michigan, State, chaired by Shannon, and this year's team will be materials for quantum applications, and it will take place in June 2025, most likely. But we are still working on establishing the final date. If you are interested in this 24 00:05:12.830 --> 00:05:20.630 Mark Kushner: symposium, you can reach out to us. When we have the flyers and the schedule available, we will be also sharing it 25 00:05:20.650 --> 00:05:27.880 Mark Kushner: at the local universities in Michigan. We will also have a student poster presentation session. 26 00:05:28.400 --> 00:05:34.320 Mark Kushner: Yeah. And we are all always welcoming new members. Yeah, I forgot, I included in multiple slides. 27 00:05:34.370 --> 00:06:01.910 Mark Kushner: And lastly, Kimberly, here is working very hard to establish the student Champ chapter of Southeast Michigan of Avs. I think now they are like filling out the paperwork so almost like they are ready to be officially recognized by Avs and Avs is a great organization. And I think student Chapter is a great way to join this community. 28 00:06:01.910 --> 00:06:26.899 Mark Kushner: There are like multiple networking opportunities and professional development opportunities. And there is a form here available from the QR link. If you are interested, you can join like you can scan the code and fill out the form. Kimberly's email is here, and I think she's also attending the symposium. So I saw flyers out there. If you. If students are interested 29 00:06:26.900 --> 00:06:36.469 Mark Kushner: in joining this like chapters, we also would like to see it flourish. This is not only like limited to a 1 University 30 00:06:36.854 --> 00:07:01.449 Mark Kushner: University of Michigan, Michigan State, or many State Universities can all participate in this student chapter. And yeah, this concludes, I like, lastly, and we also have our like. We we are also happy to sponsor the like poster award for Avs, like Avs. Michigan chapter today. And yeah, like, we will also be awarding a poster like poster award 31 00:07:01.450 --> 00:07:09.029 Mark Kushner: the end of the poster session, and thanks again for like welcoming us in the graduate symposium. Thank you. 32 00:07:28.740 --> 00:07:30.430 Mark Kushner: Oh, thank you, Kati. 33 00:07:30.820 --> 00:07:40.969 Mark Kushner: Just a quick overview of this afternoon, after the introductory remarks. We'll have the presentation by Professor Brueggeman. 34 00:07:41.020 --> 00:08:00.009 Mark Kushner: and directly afterwards everybody should go to the Ecs atrium. There'll be plenty of people here to guide you there if you happen not to be from and please post your presenters. Put up your posters as soon as you get there, so that they're available for all the poster sessions. 35 00:08:00.170 --> 00:08:06.029 Mark Kushner: Then we'll start at 3 15 for poster session, one followed by post of session. 2 and 3. 36 00:08:06.140 --> 00:08:11.220 Mark Kushner: Take down your posters, then we'll have the best presentation awards ceremony. 37 00:08:12.390 --> 00:08:23.820 Mark Kushner: Oh, there is a competition for the best presentations. We have 4 judges this year, who, I think, are in the audience, Dr. Heath, Lefere. 38 00:08:23.980 --> 00:08:30.469 Mark Kushner: Dr. Diego Diaz, Dr. Luis Jose, and Professor Shannon nicely. 39 00:08:30.560 --> 00:08:33.940 Mark Kushner: and there are 2 competitions going on. 40 00:08:34.190 --> 00:08:40.800 Mark Kushner: This is for the Mipsi best presentation as well as the Avs. Best presentation. 41 00:08:42.530 --> 00:09:07.360 Mark Kushner: So is there life after the Mipsi Graduate Symposium. I'd like to point out that. Yes, there is that there will be a great success in your careers after the Symposium, and here is an excellent example of that success. 2 prior award winners of the best presentation at the Mipsi Symposium are now professors here and 42 00:09:07.430 --> 00:09:10.250 Mark Kushner: at the University of Michigan, and at Michigan State. 43 00:09:10.260 --> 00:09:22.559 Mark Kushner: Professor Peng Zhang, in 2011, won the best presentation award. And he, I think it's public knowledge, is on the process of moving from Michigan State to University of Michigan. 44 00:09:22.800 --> 00:09:25.660 Mark Kushner: and Professor Shannon nicely, who is 45 00:09:25.720 --> 00:09:32.249 Mark Kushner: here in the audience, also won the 2,011 best presentation award 46 00:09:33.010 --> 00:09:44.430 Mark Kushner: had a distinguished career at Oxford University, and is now on the faculty at Michigan State. So there is life after the Symposium. 47 00:09:45.990 --> 00:09:51.479 Mark Kushner: Now, I'd like to start with the introduction to our seminar speaker. Today 48 00:09:51.720 --> 00:10:01.290 Mark Kushner: Professor Prita Bergerman is distinguished. Mcknight University Professor and the Ernst Eckert, Professor of Mechanical Engineering at the University of Minnesota. 49 00:10:01.650 --> 00:10:21.100 Mark Kushner: Peter received his Bs. Ms. And Ph. Degrees in Physics, engineering and applied physics at Ghent User University, in Belgium. He was then a professor at the Eindhoven University of Technology in the Netherlands before joining the faculty of the University of Minnesota in 2013, 50 00:10:21.460 --> 00:10:29.130 Mark Kushner: his research is focused on low temperature, plasma, science, and engineering with applications to health and sustainability. 51 00:10:29.370 --> 00:10:51.779 Mark Kushner: Peter has many roles. He serves as a director of graduate studies in mechanical engineering. He's a director of the high Temperature plasma Laboratory at the University of Minnesota. He serves on several editorial boards. He served on the National Academy's decadal study for plasma science in charge of the low temperature plasma effort 52 00:10:51.990 --> 00:10:57.430 Mark Kushner: is plasma editors for the Iop Journal Iop Journal Physics D. 53 00:10:57.530 --> 00:11:01.740 Mark Kushner: Has organized countless symposium workshops and review papers. 54 00:11:01.940 --> 00:11:12.219 Mark Kushner: co-edited the 2,017 and 2,022 plaza roadmaps that are the footprint for the field of low temperature plasmas. 55 00:11:12.530 --> 00:11:24.040 Mark Kushner: He's received several awards, including the Avs. Peter Mark Memorial award. The Iu Pac. Young scientist, award the Nora Hershkowitz early career award. 56 00:11:24.160 --> 00:11:29.680 Mark Kushner: and the Taylor Award for its distinguished research at the University of Minnesota. 57 00:11:30.050 --> 00:11:36.249 Mark Kushner: and he is also recipient of the Inaugural University of Michigan plasma prize. 58 00:11:36.430 --> 00:11:46.010 Mark Kushner: and that takes a little bit of explanation. We here at the University of Michigan, established the Plasma prize last year 59 00:11:46.100 --> 00:11:58.780 Mark Kushner: to acknowledge not only excellence in plasma, science, and engineering, in fact, any field of plasma, science, and engineering, but also advances in science that will lead to societal benefit. 60 00:11:59.770 --> 00:12:10.170 Mark Kushner: and the 1st call for nominations. We had a selection committee that was independent of Mipsi. So this was very much a very objective process. 61 00:12:10.240 --> 00:12:18.430 Mark Kushner: and the choice of for the 1st Inaugural University of Michigan Plaza Prize with Professor Peter Brookeman. 62 00:12:19.110 --> 00:12:28.090 Mark Kushner: The citation is for contributions to the understanding of non-thermal plasma, interactions with solids, liquids and living matter. 63 00:12:28.280 --> 00:12:41.170 Mark Kushner: scientific leadership and advancement of plaza-based technologies, enable applications in plaza biology chemical conversion, and water treatment, and that, I think, sums up 64 00:12:41.480 --> 00:12:47.059 Mark Kushner: a career goal and a career direction that we would all be proud of if it was our own. 65 00:12:47.460 --> 00:12:55.860 Mark Kushner: Peter. There is one award that's not on your list that is most revered, and 66 00:12:56.400 --> 00:12:59.259 Mark Kushner: perhaps is more unique than any of these. 67 00:12:59.600 --> 00:13:07.760 Mark Kushner: and that is the mipsy mug. So, Peter, if you could come forward and accept the mipsy mug. 68 00:13:08.410 --> 00:13:11.993 Mark Kushner: Thank you very much. Mark 69 00:13:19.700 --> 00:13:28.130 Mark Kushner: the title of Peter's Seminar. Today is low temperature plasma, science to advance human health and enable a sustainable future 70 00:13:46.270 --> 00:13:50.529 Mark Kushner: check. I have a double, and you can. I think you'll just grab the share. 71 00:13:50.860 --> 00:13:55.750 Mark Kushner: Yeah, it was a double. It's going to give me trouble, I know. Okay. 72 00:14:15.670 --> 00:14:21.510 Mark Kushner: okay, thank thank you so much for the kind invitation and and the too kind introduction 73 00:14:21.610 --> 00:14:37.299 Mark Kushner: you. You really raised the bar now for the expectations of my presentation, which I hope I can meet. So you know, Mark mentioned some some of the work I'm doing in in very multidisciplinary fields. So I want to kind of stress that 74 00:14:37.410 --> 00:14:57.570 Mark Kushner: at least half of that work is done by collaborators from another field. I would never be able to make on my own contributions to human health without the work I've done with colleagues, microbiologists, virologists, and also in sustainable future applications. I work a lot with colleagues from 75 00:14:57.570 --> 00:15:07.469 Mark Kushner: electrical engine you know, electrical engineer as well, but chemical engineering and chemistry. You know where I learn a lot from every day. And this kind of what we keeps driving. So when I, 76 00:15:07.470 --> 00:15:16.759 Mark Kushner: when I, you know, was asked to to give this presentation, I was thinking, Okay, should I talk about plasma, science? Or or should I talk more about the impact? And so I kind of 77 00:15:17.350 --> 00:15:44.560 Mark Kushner: going to try to combine both? And one of the points there is that you won't see any measurement of an electron density or an electron temperature. And so they're kind of all in the same order. So think about 10 to 14, electron density and electron temperature, probably between 2 to 3, 4 Ev, and so it's maybe a little bit boring, I think, for the plasmas we do. But I think the richness comes from the chemistry that these plasmas 78 00:15:44.790 --> 00:16:01.690 Mark Kushner: are producing. And so a lot of the work we've been focusing on is diagnostics. But I won't be talking a lot about diagnostic. But kind of okay, what can we conclude from these diagnostics and increase our understanding for applications that can contribute to human health or a sustainable future. 79 00:16:01.810 --> 00:16:06.594 Mark Kushner: And so that work was supported by by several agencies. 80 00:16:07.280 --> 00:16:27.259 Mark Kushner: you know the usual plasma funding agencies like Department of Energy and National Science Foundation. But you know, we also are funded by the electrochemistry program from Army Research office, and also, you see also, you know, Department of Agriculture presented some of our work on. So I want to kind of make these links with the other fields. And 81 00:16:27.300 --> 00:16:33.899 Mark Kushner: and you know, hopefully, I can share some of the excitement I have about connecting with with some of these fields. 82 00:16:34.990 --> 00:16:35.730 Mark Kushner: So 83 00:16:36.620 --> 00:16:45.209 Mark Kushner: you know, in our field and low temperature plasma. So most of the the work I will be talking about will be clearly, you know, atmospheric pressure. 84 00:16:45.520 --> 00:16:46.840 Mark Kushner: That's good. Okay? 85 00:16:47.450 --> 00:16:48.320 Mark Kushner: And 86 00:16:49.510 --> 00:17:05.190 Mark Kushner: you know, we, we see a lot that. Okay, you, you generate a plasma with electric field. So you basically, it's an approach to convert electrical energy into chemical energy, or really kind of aligns quite well with division of power to X that's driven. 87 00:17:05.587 --> 00:17:09.970 Mark Kushner: And so the idea is, you know, you have a feedstock can be 88 00:17:10.200 --> 00:17:22.739 Mark Kushner: yeah, natural feedstock, or can be material. You want to improve the material, or you want to convert the feed stock in a more valuable feedstock. And the idea is using a plasma to be able to to achieve that. 89 00:17:22.760 --> 00:17:28.689 Mark Kushner: So there is a lot of, you know, exciting areas that people are working on. And I think Mark mentioned 90 00:17:29.130 --> 00:17:47.480 Mark Kushner: the decadal study a couple of years ago identified a couple of these areas, and I'm sure you work in Michigan in all of these areas. But again, where I want to talk a little bit about is an example of health and decontamination, and then talk a little bit about the idea of 91 00:17:47.530 --> 00:18:08.559 Mark Kushner: using plasmas to drive chemical reactions. And then, if you want to drive chemical reactions, you want to do this selectively, you don't want to make 100 different species. So, you know, is there ideas and trying to discuss some of these ideas, but also an example, maybe, of material synthesis. How can we potentially make that a greener, you know, and also controlled 92 00:18:09.000 --> 00:18:10.030 Mark Kushner: process? 93 00:18:10.554 --> 00:18:20.935 Mark Kushner: If if we really think about this, and and if you. If I need to summarize my my research on one slide, I think that would be probably this slide that 94 00:18:21.840 --> 00:18:32.429 Mark Kushner: plasmas are sometimes seen as something that's expensive. So how can we make it? Energy efficient is often as an engineer, important, not always. If you can do something unique, that doesn't matter. 95 00:18:32.520 --> 00:18:45.009 Mark Kushner: But the other thing with plasmas is we can do many, many things with plasmas. The only thing is that it's not always selective meaning. We don't always have a single product, or it's not always as controllable as we want. 96 00:18:45.210 --> 00:18:56.960 Mark Kushner: And I think if you think about selectivity, I think there a lot of science questions come in. Because if you do understand the fundamental processes, you can kind of try to control or drive them in a certain direction 97 00:18:57.000 --> 00:19:07.208 Mark Kushner: and then hopefully have a science based approach to make a device or or a process that can be adapted in the future and industry. So so that is kind of the area that I've 98 00:19:08.288 --> 00:19:14.060 Mark Kushner: you know. Try to explore in the in the last few few years with with colleagues in in different fields. 99 00:19:16.750 --> 00:19:32.959 Mark Kushner: Okay? And so you know, I know this is a very broad and diverse group. And so I thought, Okay, I can give a very general talk, or I can give a few examples, and and I think at the end I go for the example. So I want to show an example for virus 100 00:19:33.120 --> 00:19:38.120 Mark Kushner: decontamination that we've worked on for about 10 years with with colleagues and 101 00:19:38.499 --> 00:19:54.730 Mark Kushner: you know, it's kind of interesting. It was very applied initially, it became highly fundamental. And some of these fundamental insights we gained made another new kind of area of applied work. And so I want to kind of show what we did in that area and how that motivated some of our work, these insights. 102 00:19:54.730 --> 00:20:16.639 Mark Kushner: and then the other is selectivity. I think you know chemical selectivity. If you think about selectivity as converting one species into another species. How can you do this selectively? You know, plasmas can make many reactions. So you couple this with catalyst. And so I want to talk a little bit about the challenges and the opportunities in that area based on an example. 103 00:20:16.990 --> 00:20:40.220 Mark Kushner: And the other area I would like to. Highlight is, if you use plasmas as an electrode interfacing with the liquid, you can see this as an electrolysis process, and of course there are quite a few differences than just having a metal electrode injecting electrons in the liquid. And so what can we do this and what I will? Highlight? There is kind of an example of 104 00:20:40.220 --> 00:20:51.920 Mark Kushner: material synthesis in such systems. And and how we can try to understand the differences between this potentially non-conventional electrolysis approach and and conventional electrolysis. 105 00:20:52.560 --> 00:20:59.640 Mark Kushner: Yeah. And so I hope that you know, giving this broad 3 examples, that there is something at least for everybody in in this room. 106 00:21:01.030 --> 00:21:03.346 Mark Kushner: So for for human health. 107 00:21:04.060 --> 00:21:27.520 Mark Kushner: you know, we have certainly a broader interest. But you know, I think there are 2, maybe 3 big areas. So people think about decontamination. So there's also the effect of wound healing or infection particular Mrsa, for example, so multidrug resistant bacteria. There's a big interest in using plasmas to try to inactivate, for example, biofilms in these wounds. 108 00:21:27.520 --> 00:21:46.949 Mark Kushner: And then there is the aspect of, for example, cancer treatment that is explored. So we kind of, you know, we didn't really kind of go too much in the medical area, you know, sometimes touched upon. But we kind of looked more to decontamination. And you know, initially, virus is something we you know. 109 00:21:46.950 --> 00:21:59.460 Mark Kushner: I actually had this collaboration a couple of months before I joined University of Minnesota. There was a wheel drive from a virologist to try this out so very applied. Can you kill virus? At the time there was very little work in this area. 110 00:21:59.460 --> 00:22:18.009 Mark Kushner: and the key idea at the time was, you know, this is 2012, I think. You know, if you look to foodborne illnesses. And this is, you know, if you look to the website of the Center of Disease Control. We have outbreaks every year. You know, about half of these outbreaks are virus 111 00:22:18.690 --> 00:22:29.329 Mark Kushner: and a lot of them, norovirus. So that was kind of the motivation. And if you look to decontamination approaches of food, most of these approaches have been developed for bacteria. 112 00:22:29.400 --> 00:22:36.270 Mark Kushner: and actually some of these approaches not even clear how effective they are against fire. So that was kind of the context where we looked at this. 113 00:22:36.340 --> 00:22:52.249 Mark Kushner: And so we look to make a plasma source. And and this may be a key result of that work that you know summarized that. Okay, we want to have something simple. You know, food can be very inhomogeneous. So we want something remote. We produced a DVD. And this is kind of a picture heads on. 114 00:22:52.310 --> 00:23:08.119 Mark Kushner: and there are small holes. They're about 600 micro where the air flows through. So you treat air and you blow it on the food sample. So ultimately, you know the shape of the food doesn't matter. And can we, in this remote configuration, inactivate relatively long the species, a combination of 115 00:23:08.290 --> 00:23:25.389 Mark Kushner: reactive nitrogen and oxygen species, think about ozone, and and then more, maybe some more complicated nox and nitrogen species. And and you can see here, you know, there are many, many viruses. I don't. I don't think I mean there are different like envelope, non-envelope, so we can inactivate them 116 00:23:25.450 --> 00:23:39.489 Mark Kushner: on time. Scales of minutes seems to be working well, and the nice thing seems that the plasma is not particularly, you know, specific, related to the kind of virus or even bacteria, so that seems to communicate a good all around. Disinfectant. 117 00:23:41.200 --> 00:23:58.889 Mark Kushner: Now, the problem, of course, plasma is an oxidizer, so some foods, won't, you know, respond very well to the oxidation they might change color. Or there are other things. Okay. So no. But interesting is the time scale. And so we started looking at the time into treating plasma droplets. So very fundamental study. 118 00:23:59.280 --> 00:24:06.429 Mark Kushner: And we saw that we could actually make chemical change on on the order of tens of milliseconds. 119 00:24:06.680 --> 00:24:27.820 Mark Kushner: And so the question became, okay. You know what are conditions that can drive or enhance this kind of inactivation on much smaller time scales. And the motivation obviously is, if it's airborne, and you want to have, you know, treatment of virus. For example, in an Hvac system or your ventilation system. The residence time of the gas is not minutes to treat. You need to treat on tens of milliseconds. 120 00:24:27.940 --> 00:24:47.150 Mark Kushner: and you know you need some. You know, effectivity. So we compare that. And we can kind of show based on some very small lab scale experiments that we can do similar efficiency. If we kind of optimize the system very well, we can get similar efficiency. 121 00:24:47.150 --> 00:25:00.340 Mark Kushner: As, for example, Uvc, so it looks like efficiency wise, it would be fine. The question is, can you do this on a very short time scale, and the reason, you know, why we wanted to look at this at the time this was before the Covid outbreak 122 00:25:00.340 --> 00:25:02.656 Mark Kushner: was a 1st fighter, so 123 00:25:03.700 --> 00:25:24.399 Mark Kushner: So porcine, respiratory, and reproductive, syndrome virus. You know Minnesota has many pigs, I was told, and turkeys, and there is a lot of outbreaks, a huge amount of loss. So that was the idea. If you can get it in Hvac systems, can you do this? And this was based on, you know, very fundamental data. And so the reason why 124 00:25:24.440 --> 00:25:28.799 Mark Kushner: we looked at this and this is kind of studies from our collaborator 125 00:25:29.330 --> 00:25:32.620 Mark Kushner: who works on on pig fighters a lot. 126 00:25:32.730 --> 00:25:58.240 Mark Kushner: you know. They started to realize problems, and they started to put, you know, filters in their ventilation systems of their barns, so to try to avoid barn, to Bow barn transmission, and you could see that kind of the transmission may be reduced by a factor of 2 over 10 years, but you know, even barn to barn transition was very difficult to contain. And so that was kind of the idea. Okay, can we use virus? 127 00:25:58.330 --> 00:26:11.299 Mark Kushner: And the motivation was there. Okay, if you have short lived pieces, you know. This could actually, you know, work on a much shorter time scale than we have. You know the example I showed you in air. 128 00:26:11.310 --> 00:26:16.059 Mark Kushner: And one of these pieces. And this is something where kind of the fundamental work comes back 129 00:26:16.080 --> 00:26:16.955 Mark Kushner: is sing 130 00:26:18.030 --> 00:26:38.230 Mark Kushner: singlet oxygen. So this is maybe one of the very few examples in literature where we track species from the gas phase into the liquid phase where the biological medium is up to the biological molecules like the proteins. And you know the capset of the virus. 131 00:26:38.230 --> 00:27:01.230 Mark Kushner: And we showed actually that if you can bring your virus in contact with these short lived pieces, you actually have a lot of oxidation by short-lived species on the virus capsid up to a point that you actually do no longer have the virus have the proteins, and the receptors have no longer the ability actually to connect to the cell. So you're not 132 00:27:01.310 --> 00:27:08.289 Mark Kushner: killing the virus. You're not breaking them up. You're actually changing the functionality of their approach to infect the cell. 133 00:27:08.380 --> 00:27:29.209 Mark Kushner: And you see a lot of oxidation of some of these molecules. So it was kind of really nice. This is like 5, 6 years of work from students, you know, tracking, seeing that oxygen, measuring it in the liquid and then correlating, and that seems to go to conditions where, indeed, you can have very fast reduction if you have these pieces, and they're actually reaching your virus. 134 00:27:29.230 --> 00:27:44.270 Mark Kushner: And so we build and tested this in a wind tunnel at the end, you know, based on this fundamental insight, where you have the irisalized particles, you know, going through a plasma in the wind tunnel. This is about 15 ms. So a very fast flow rate. So this is more than. 135 00:27:44.470 --> 00:27:52.900 Mark Kushner: oh, yeah. Okay, more than 100 liters per minute. I believe in a DVD plasma and what you can see there. Indeed, if you look to 136 00:27:53.470 --> 00:28:22.460 Mark Kushner: Pcr, for example, you look to the genetic material. You know the virus are still there after the treatment. So your plasma doesn't behave like a filter. It does behave like, you know. You do chemical change of the virus. But if you collect the virus before the control or after the plasma, you see that you know the control, the Tcd, this is actually checking how many viruses are still able to infect a cell. Yeah, you see that this is going quite down. 137 00:28:22.510 --> 00:28:27.620 Mark Kushner: and the efficiency of that reduction is very similar to hipaa filters efficiency. 138 00:28:27.720 --> 00:28:44.400 Mark Kushner: So that brings the idea that you know, based on some of this knowledge of these short lived pieces and actually getting through the plasma. The short lived pieces typically don't survive too long in an afterglow. You can actually get very, very quick reduction and kind of 139 00:28:45.225 --> 00:28:51.710 Mark Kushner: you know, inactivate these these virus particle in flight. For example, in an Hvac system. 140 00:28:51.910 --> 00:29:10.839 Mark Kushner: you know, why might this be better? You could say, well, okay, you need to produce electricity for sure. But filters have a very high pressure drop while a plasma ultimately is an open system. So the pressure drop can be significantly less which could hopefully overcome some of the energy needs that you need to to drive the plasma. 141 00:29:11.440 --> 00:29:16.269 Mark Kushner: Yeah. So that's kind of one example, that that I wanted to highlight in in 142 00:29:16.730 --> 00:29:41.440 Mark Kushner: okay, the biological or the health area where we worked on. And I think you know what really helped us. There is, you know, great collaboration with virologists trying to, you know, really understand? Also, you know, the biological side of the project combining this with insights of the plasma, you know, allowing us to kind of define the project ultimately to to go to these 10 ms inactivation times. 143 00:29:41.840 --> 00:29:42.520 Mark Kushner: Oh. 144 00:29:42.830 --> 00:29:51.810 Mark Kushner: yeah. And then Covid happened actually, after that experiment. But I think it was too early, maybe a couple of more years. Maybe we could have made a contribution there. 145 00:29:52.956 --> 00:29:55.870 Mark Kushner: So the second topic is, you know. 146 00:29:55.960 --> 00:30:06.479 Mark Kushner: this maybe, was not selectivity. No, but it was certain. Using certain species to to you know, create a desired goal for your inactivation of of the virus. 147 00:30:06.490 --> 00:30:09.201 Mark Kushner: The second topic I want to highlight is 148 00:30:10.370 --> 00:30:36.279 Mark Kushner: plasma catalysis. And so this is really related to selectivity. So the original work was, for example, in ammonia synthesis. But I will show another example. That, I think, is maybe easier and more clear where your plasma activates a molecule that's very difficult to dissociate. No, so you have enough energy. But then, what you're doing with the Radicals, and how can you tune these radicals to drive towards a chemical 149 00:30:36.280 --> 00:30:50.880 Mark Kushner: reactions that are selective and going to ammonia and maybe not going back to and to where you started from. So that's kind of the entire idea. You wouldn't be heating your catalytic reactors anymore. Now, you have electrical energy. So you could get away from 150 00:30:50.880 --> 00:31:17.230 Mark Kushner: thermal processes that might be based on combustion and produce. For example, Co. 2, this is really the idea now of Co 2 reduction. And if you think about this, I mean any major industry. Really, you know, manufacturing or chemical industry produces a lot of Co 2. And so ultimately, that's kind of, can we do this with a process that is equally efficient. 151 00:31:17.360 --> 00:31:22.979 Mark Kushner: you know, equally selective and you know, does not produce ultimately the Co 2 152 00:31:23.877 --> 00:31:32.700 Mark Kushner: and there are 2 areas. And I want to briefly, highlight. I don't. I don't not going to talk too much about the 1st one but you can do this thermally so 153 00:31:33.116 --> 00:31:37.879 Mark Kushner: and that's maybe the most intuitive and and most easy to understand. 154 00:31:37.900 --> 00:31:46.550 Mark Kushner: So ultimately, you know, if you drive the power up of the plasma, you get significant gas heating so you can just use plasma as a gas heating source 155 00:31:46.560 --> 00:32:06.340 Mark Kushner: and drive thermalchemistry for some reactions like methane. You know, from the moment you are at like 13 to 1,500. Kelvin, you dissociate methane, you can form carbon, you can form hydrogen. And so there's an example from a company monolith, and we do also some work in that area where you basically go from methane 156 00:32:06.430 --> 00:32:34.579 Mark Kushner: and produce hydrogen and solid carbon. Also, you can then use the hydrogen instead of the methane, and then the carbon gets in solid products. So it doesn't go in the atmosphere. If, for example, there is an oxidation process and another area where we recently started working on in collaboration with my colleague, Kors. Hagen is iron ore reduction. And this is something surprising that to make steel, it's about 9% of the Global Co. 2 emissions are due to iron ore reduction and steel making in general. 157 00:32:34.910 --> 00:32:45.819 Mark Kushner: And so they use coke. No, so an oxidation. You remove the oxygen forming Co. 2. So you produce huge amount of Co 2, for you know the iron you make. 158 00:32:46.040 --> 00:33:13.039 Mark Kushner: And and so, like I mentioned in collaboration, we, you know, produced a process where, in principle, we can use plasma as a heating source, we have hydrogen for removing the oxygen from the iron oxide forming iron. But this is in principally all I mean. You can have a non-thermal equivalent that close to room temperature, but in principle the processes that are more industrial kind of looked at right now are quite thermal. So 159 00:33:13.250 --> 00:33:16.809 Mark Kushner: plasma as a heating source is a pretty good 1st approximation. 160 00:33:16.840 --> 00:33:43.600 Mark Kushner: But that's basically thermodynamic outcome. So your product is determined by thermodynamics. You're not driving that away. So the question is, now, can we use a plasma to do things selectively, and then a non-thermal plasma may be close to room temperature. And the key challenge, of course, is that your electron temperatures are several. Ev, so you have a lot of electrons above the dissociation threshold of molecule. You do a lot of ionization. Even so, the selectivity 161 00:33:43.630 --> 00:33:55.979 Mark Kushner: is not really there to break a very selective bond. No. So you will break many bonds, typically maybe some bonds quicker than others. But there will be. There's a distribution of electron energies. You will break many bonds. 162 00:33:56.070 --> 00:34:09.339 Mark Kushner: and that is ultimately kind of the reason why, you know, initial applications, like polymerization or decomposition, have been quite successful, translated to industry. But you know this kind of making certain chemical molecules 163 00:34:09.350 --> 00:34:23.499 Mark Kushner: has been challenges, and this entire idea of combining a catalyst that is very well known to make, for example, just one species, you know, has been, you know, resonating with the community for quite some time. So the idea is. 164 00:34:23.560 --> 00:34:50.900 Mark Kushner: you know, a catalyst in the catalysis community would dissociate a molecule, have a selective reaction on the surface, and that needs to disort. And then you get a molecule back in the gas phase. Here we use the plasma to activate a molecule. So dissociation energy is not so much of a trouble. But you still need your surface reactions to have the radical, for example, recombine in the way that they make specifically one species. So that's kind of the idea behind 165 00:34:51.425 --> 00:34:56.794 Mark Kushner: behind this. And I want to show this with an example I will talk about. I know. 166 00:34:57.630 --> 00:35:03.909 Mark Kushner: The reason is, you know, maybe it has impact. It's a it's a nitrogen fixation process. 167 00:35:04.010 --> 00:35:12.519 Mark Kushner: you know, and I think you're all familiar with Haber Bosch. And about 100 years ago we had an order process that was based on plasmas with Knox 168 00:35:12.590 --> 00:35:34.990 Mark Kushner: high temperature. No, so high temperature produce a lot of no, but that became too expensive. And then everything was replaced by harbor bos. And so basically now to make Hno 3. Like the fertilizer, we sustain our world population agriculture with. You know, everything goes to basically harbor bos and then moves from ammonia back to the oxidized state. 169 00:35:35.100 --> 00:35:38.269 Mark Kushner: And so the idea is, can we have a plasma process 170 00:35:38.430 --> 00:35:51.989 Mark Kushner: at low temperature selectively making? And can we do this? You know, by using a catalyst, because if you would just use a plasma, you might be making many oxides. You might be making ozone. So the question is, can you drive selective reactions. 171 00:35:52.550 --> 00:35:55.790 Mark Kushner: And so ultimately, you have 172 00:35:55.840 --> 00:36:06.209 Mark Kushner: gas phase reactions now, for sure. And we know them very well. That's also one of the reasons why we picked the system, and they are competing with surface reactions that might make. 173 00:36:06.220 --> 00:36:09.609 Mark Kushner: And 2 or also, you know, certain oxides. 174 00:36:09.640 --> 00:36:17.749 Mark Kushner: And so the question we kind of asking is okay. If you combine the plasma with this catalyst? Are there conditions where surface reactions dominate? 175 00:36:17.770 --> 00:36:22.480 Mark Kushner: What are these conditions? And can these reactions actually lead to higher selectivity. 176 00:36:22.820 --> 00:36:34.289 Mark Kushner: And what are the timescales of these reactions? And so we, we set up a, you know, quite a specific experiment for that. That's certainly not something you would translate to industry, because kind of the applied research 177 00:36:34.340 --> 00:36:48.620 Mark Kushner: is that you have many, many pack beds now. So I mean, I'm sure you've seen some catalytic reactor. And if not, this is just basically a glass tube. If you go to these labs filled with beads. And then many people, if you want to put a plasma, put a plasma. Plasma is highly inhomogeneous. 178 00:36:48.640 --> 00:37:00.580 Mark Kushner: and you have kind of all kind of gradients. So fundamentally, it's almost impossible to understand or even to probe, what's going on. And so we kind of the approach we had is that we generate a plasma that we can 179 00:37:00.640 --> 00:37:12.060 Mark Kushner: very well characterized, you know, in the case of N. 2, we don't want to make too much Nox, so we inject the plasma, the oxygen in the afterglow after the plasma. And then we put a catalyst here. 180 00:37:12.470 --> 00:37:15.888 Mark Kushner: And this is a very fast flowing reaction reactor. So 181 00:37:16.610 --> 00:37:37.089 Mark Kushner: residence times can. I think, you know, for some conditions, even go to tens of microseconds. So we are operating on conditions where radicals survive to go to the catalyst. We don't combine them with the plasma, because then we cannot decouple the plasma and the catalyst effect. But we are operating on residence time where short lived species do survive 182 00:37:37.090 --> 00:38:04.990 Mark Kushner: when they enter the catalytic bed. And the nice thing here is, it's kind of a transmission function. So we do molecular beam measurements. So we can measure radicals and neutral species. We can do this at a certain position, you know, without a catalyst with the catalyst, and then you can see how much of these pieces are consumed and directly relate surface reactions to species produced in the plasma and correlate which species are responsible for which process. 183 00:38:05.160 --> 00:38:30.110 Mark Kushner: And so the the way this is done is not just a surface. We actually use wires wool that works very well. We can high surface area when we'll show some conditions where you can tune the amount of surface area and can actually see that in some cases you don't see any catalytic reactions, while in other cases they dominate. And so we have this tune ability and also the full decoupling. So they don't 184 00:38:30.340 --> 00:38:33.240 Mark Kushner: interfere with each other when doing the analysis. 185 00:38:34.020 --> 00:38:48.909 Mark Kushner: So this is a typical situation. So you produce a plasma, and of course the plasma produces some nox, even if you inject oxygen. But this kind of your baseline. So you see that if you measure about 5 186 00:38:49.500 --> 00:39:02.460 Mark Kushner: 5 you know, after the the nozzle where you have some mixing already. You know that you have certain amount of atomic nitrogen still present, and some oxides and ozone being formed. 187 00:39:02.995 --> 00:39:18.189 Mark Kushner: You know. And if you measure a little bit further, you see that the n reduces even? No, because the residence, certain residence time here, and but ultimately you don't have further formation. So the idea is now, if you put a catalyst there. 188 00:39:18.656 --> 00:39:38.730 Mark Kushner: You know what is the change, and then you can see that ultimately, when you have the catalyst. No, there is no more. And leaving the catalytic bed. So all the atomic nitrogen is collected on the catalytic surface somehow. And you see this huge increase in no formation. So a very strong correlation with having surface reaction. 189 00:39:38.970 --> 00:39:41.569 Mark Kushner: And and somehow this increase. 190 00:39:41.700 --> 00:39:53.639 Mark Kushner: And so we were really happy with this. But then, you know, we wanted to kind of make that quantitatively. Can you say something? I mean, you know, if you want to design a reactor like this, you do need quantitative over transport timescales. No 191 00:39:54.615 --> 00:39:55.479 Mark Kushner: and 192 00:39:56.301 --> 00:40:19.419 Mark Kushner: you know she had an excellent student working on that, together with my colleague, Aditya Ban. And so he did many, many studies. Okay? And I show a few highlights here. So it was interesting that you could actually make that a selective process. So what you see here is we change the amount of oxygen going in the reactor, and for higher oxygen 193 00:40:19.420 --> 00:40:27.230 Mark Kushner: you have more n consumption. But you see that the amount of N consumption 194 00:40:27.320 --> 00:40:35.119 Mark Kushner: and the amount of I know, generation becomes actually the same. So there seems to be a 1 and one correlation at some point. 195 00:40:35.200 --> 00:40:57.459 Mark Kushner: Yeah, that every n you lose in your catalytic bed seems to well, indirectly suggest leading to an animal being formed explaining this increase. And so the question is, now, okay, how do these conditions change? And what is now the driving force between? You know where you have like full selectivity, I would say, and then, in the cases for lower oxygen, where this is not the case. 196 00:40:57.920 --> 00:41:10.159 Mark Kushner: And so, you know, we did many measurements. And again, some example. Here, if you just look to the gas phase, you see that the N is reducing, but it doesn't really lead to any. No formation. 197 00:41:10.310 --> 00:41:14.260 Mark Kushner: So in the gas phase, what happens is N can react with oxygen. 198 00:41:14.570 --> 00:41:25.759 Mark Kushner: And then you would say, that's selective. But the inverse reaction also occur and can then react back with your product. And so you have no selectivity. Most of these reactions. Just go back to where you started. 199 00:41:26.870 --> 00:41:28.509 Mark Kushner: and then when you 200 00:41:28.620 --> 00:41:50.989 Mark Kushner: drive with a catalyst, you see that you know for every situation you you completely consume your N radicals, and you have this consistent increase in the amount of no being formed. So it seems that when you have surface reactions they can be selected, at least in this case here. And yeah, maybe I didn't say that. It's on a silver catalyst. 201 00:41:51.220 --> 00:42:11.559 Mark Kushner: And so you know, now you can make this quantitative. So we know the kind of reactions we expect in the gas phase. We know the kind of reactions we expect on the surface. Well, maybe we don't know the details that would need some computation, but we know that every N. Probably will end up being in. No. We can then change the ratio between the gas phase 202 00:42:11.830 --> 00:42:40.829 Mark Kushner: and the surface reactions by changing the amount of catalytic surface per volume we have here. And you see significant differences. We can fit this with a model. The model is exceedingly simple. You consider 2 reactions. No, the back and forward reaction for a no destruction and formation, a surface reaction that represent a loss in the plug flow reactor. And then we kind of assume that that surface reaction lead to a no formation. 203 00:42:40.830 --> 00:42:58.839 Mark Kushner: And then, of course, you have also DNA formation for the same reactions. So in principle, we have all the data. We have the concentrations. No, so we don't have the rate coefficients. We have the gas phase rate coefficient. But we can basically fit this with all our experimental data and get reasonably well fits. 204 00:42:59.160 --> 00:43:26.799 Mark Kushner: And then, if you look to the situation. Or if you say, Okay, the experimental density and the fitted density, you know, under the entire range, you know, which is more than an order of magnitude corresponds quite well, and you can actually fit both the surface reaction rate and the gas phase gas phase. We know you can see your fitting rate, maybe factor 2 to 3 off. But I think this is pretty reasonable, but I think what is really interesting is that we have a value which is relatively accurate for the surface 205 00:43:26.870 --> 00:43:28.200 Mark Kushner: reaction rate. 206 00:43:28.540 --> 00:43:31.069 Mark Kushner: And then that's kind of interesting, because 207 00:43:31.110 --> 00:43:39.520 Mark Kushner: you know, and needs to move through a boundary layer to the catalytic surface. No. And so this is kind of unique. If you have a catalytic reaction 208 00:43:39.610 --> 00:43:48.519 Mark Kushner: in in catalysis, everything happens on the surface, they'd have no reactions in the gas phase, but with the plasma. We have many quick reactions in the gas phase. 209 00:43:48.730 --> 00:44:00.659 Mark Kushner: And so, you know, you have a boundary layer, a flow boundary or concentration boundary layer. There are many correlations for wires, and you can estimate that the sorry that the that the mass transfer rate 210 00:44:02.377 --> 00:44:20.279 Mark Kushner: you know, for you know the time it takes especially the rate of, you know. Transfer from the bulk. Sorry from the bulk to the catalyst, you know, is on the order of the rate that we experimentally observed. So it seems that this is not limited by reaction rates on the surface. 211 00:44:20.320 --> 00:44:31.110 Mark Kushner: This reaction for our experimental conditions is limited with the time it takes of N going through this boundary layer and reaching the surface. And then something quick happens on a much faster time scale. 212 00:44:31.800 --> 00:44:32.630 Mark Kushner: you know. 213 00:44:33.060 --> 00:44:53.669 Mark Kushner: And and so, okay, how can we? Then, you know, interpret. So for which conditions then do we get, you know, selective reactions, and which not well, we know that the gas reactions are not selective. So if you compare the rate of the gasoline reaction where you destroy the no, no, which is the loss, and make back n. 2. 214 00:44:53.670 --> 00:45:03.350 Mark Kushner: With the rate on the surface, you can actually calculate a time scale. And then what you see is that actually, you cannot have more than 250 ppm. Of no. 215 00:45:03.560 --> 00:45:06.599 Mark Kushner: because otherwise the back reaction becomes dominant. 216 00:45:06.850 --> 00:45:11.769 Mark Kushner: and that kind of explains because people had been looking for many years. You know their 217 00:45:11.830 --> 00:45:21.859 Mark Kushner: a lot of catalytic work on other molecules where you could find very nicely, you know, results where catalysis is doing something, and for I know that was one of these molecules. 218 00:45:22.120 --> 00:45:38.310 Mark Kushner: or it didn't work. Now, is this good thing? Probably not. No, because it really limits your conversion. That's the reason. If your system is too good, you will not see any catalytic reaction, because you consume everything. The active species don't reach your catalyst anymore. 219 00:45:38.480 --> 00:45:49.570 Mark Kushner: Yeah. And so that kind of allows us to to quantify this and and really answer the questions, you know. And and we we've done it also with with ammonia. And and what we've seen, you know 220 00:45:49.800 --> 00:45:53.679 Mark Kushner: generally, is that the plasma 221 00:45:53.790 --> 00:46:03.089 Mark Kushner: impact is really radical driven. So you make radicals in the gas phase, they need to reach the surface to actually get catalytic reactions. 222 00:46:03.455 --> 00:46:09.680 Mark Kushner: And then these timescales are really important. No. So in certain cases, okay, your diffusion times should be 223 00:46:10.060 --> 00:46:32.550 Mark Kushner: shorter than, or certainly slower than, the reaction on the surface. That seems to be going much quicker. But then you have 2 conditions. No, when the no is too high, you won't see the catalytic effect because your gas reactions dominate when the No is too low, your surface reactions can dominate. So you really need to tune. And I think this kind of 224 00:46:32.680 --> 00:46:38.850 Mark Kushner: okay, very fundamental. I'm not going to claim that this is anything near something that practically can be used. 225 00:46:38.950 --> 00:46:41.290 Mark Kushner: But you know this kind of studies, I hope. 226 00:46:41.360 --> 00:46:57.739 Mark Kushner: gives you an idea that they might be important because they might give us time scales, length, scales of reactions, ideas of transport, and how some of these findings can help us build better reactors, ultimately to drive selective chemistry moving forward 227 00:47:00.437 --> 00:47:05.800 Mark Kushner: and the last example. And it's something I've maybe worked on 228 00:47:06.470 --> 00:47:13.232 Mark Kushner: quite for a long time. Is plasma liquid? Actually, my Phd was was on this topic already. 229 00:47:13.650 --> 00:47:21.269 Mark Kushner: and you know this is kind of a similar situation. So you interface gas phase plasmas with a liquid interface. 230 00:47:21.410 --> 00:47:30.459 Mark Kushner: You know you have a complicated gas phase chemistry going on. Some of these pieces are injected in the liquid and can drive reactions in the liquid phase. 231 00:47:31.090 --> 00:47:49.439 Mark Kushner: And the example I want to show. Here is some work done by some of my students and postdocs, and in collaboration with Chatz, where we looked at material synthesis. But maybe you know before that I, you know, broaden a little bit. So the idea there is that 232 00:47:50.300 --> 00:48:01.000 Mark Kushner: plasmas are complicated. You have many, many species, you know, some of the models also what Marcus can have hundreds of species or more than 100 of species. So ultimately, you know, anything can really happen. 233 00:48:01.250 --> 00:48:08.910 Mark Kushner: And so the idea is, you know, can we kind of simplify that? And in a certain context, that that might, you know, be the case? 234 00:48:09.472 --> 00:48:23.219 Mark Kushner: And so the idea here is. So we have a simple plasma, typically just helium. No, we produce electrons. We inject electrons. Electrons are reducing species, as you probably remember, from your chemistry class, and 235 00:48:23.770 --> 00:48:29.410 Mark Kushner: we always have some evaporation, so there will always be some dissociation of water or some photolysis 236 00:48:29.610 --> 00:48:32.459 Mark Kushner: that the plasma also will produce oh, radicals! 237 00:48:32.560 --> 00:48:40.370 Mark Kushner: And so in principle that allows you to drive redox reactions in either way, oxidation or reduction in in the liquid phase. 238 00:48:40.630 --> 00:48:50.190 Mark Kushner: Why can this be important? Well, you know, many reductions that are driven in the liquid phase are very nasty chemicals 239 00:48:50.310 --> 00:49:00.799 Mark Kushner: toxic, you know, environmental impact, and so on. Take forever if it wants to be controlled. So there is kind of an opportunity there potentially for plasma to make to make a difference. 240 00:49:01.647 --> 00:49:09.162 Mark Kushner: And we worked. Actually, that's in collaboration with Professor Lineage, who is also from this university and 241 00:49:10.110 --> 00:49:17.319 Mark Kushner: you know, we looked at this with very simple molecules, and and you know it is possible, at least with this simple molecule to kind of 242 00:49:17.390 --> 00:49:37.560 Mark Kushner: predict the conversion in this system. So we have very ferro cyanide. It's kind of a typical indicator. No. So they change color when they go in the oxidized or the reduced state, and based on the knowledge of our oh flux and electron flux. We can explain more or less. So I mean, you know, here is this is modeling 243 00:49:37.760 --> 00:49:55.889 Mark Kushner: and experiment together, and you kind of well, maybe it's a little bit higher. But you see that you know, this is within the same order. So this basic idea of electron and oh, driven reactions can can actually be used to predict some at least simple chemistry, at least. 244 00:49:56.570 --> 00:50:01.449 Mark Kushner: And now the idea is okay. Redox reactions. If you look to reduction. 245 00:50:01.490 --> 00:50:08.730 Mark Kushner: you know, and you use metal ions. You can actually make metal atoms, they can nucleate. And you can start making materials. 246 00:50:08.900 --> 00:50:29.940 Mark Kushner: You don't make these materials at a metal interface. If you have electrolysis, the material would probably be deposited on the liquid. But here your electrode is gas phase. So you have kind of a free. You can make 3D materials in print. I mean, you know, you could make whatever they're not sticking to your electrode. So this is kind of the idea, and many people show this over the years. 247 00:50:29.940 --> 00:50:47.409 Mark Kushner: you know, interesting nanoparticles, metals. And this is an example from lineage group here on bimetallic. So mixtures some control on that. So there's many. But it was not really understood. So this entire idea was, okay. We inject some electrons. We have reduction. We make these particles. In some case you have a very wide 248 00:50:47.967 --> 00:51:03.439 Mark Kushner: size distribution. In some cases they're very narrow. I mean, control was not clear. And you know, this was kind of a really, I think, influential paper for my work from Mcguire and team in in the Uk. 249 00:51:04.450 --> 00:51:18.410 Mark Kushner: That always struck me like plasma is kind of the best in this graph. Okay? So it's kind of a dose for a moderate dose. We have 2 orders of magnitude, more reduction. And I kind of never understood like, how is this possible? Okay? So 250 00:51:18.450 --> 00:51:26.600 Mark Kushner: you know, plasma is not 100% efficient normally. So so how is this possible? And so we kind of push that and and try to understand. 251 00:51:27.029 --> 00:51:53.230 Mark Kushner: You know, how do we reduce these gold particles? What's the mechanism, and can actually make a very simple one d model? I give it to you many, many assumptions. But can we get a model to get the idea, you know, to get some? You know growth mechanism out of this, what you think happened. And and there we go back to these droplets that I briefly mentioned for the virus we have a very, you know, this isn't the ideas 252 00:51:53.230 --> 00:51:58.770 Mark Kushner: from Mcguire's group. Actually, we have droplets for a very short time, and the plasma very controlled. 253 00:51:58.810 --> 00:52:01.350 Mark Kushner: We know the fluxes. We can measure them. 254 00:52:01.410 --> 00:52:18.500 Mark Kushner: We make nanoparticles. You can see here relatively small size distribution of the particle. You know. How is this working? We have no surfactants. No, that's another thing. Normally, you need all kinds of chemicals to, you know. Make sure they're not agglomerating. How might this work? 255 00:52:19.660 --> 00:52:31.290 Mark Kushner: And you know a couple of interesting things to say you. You can, even without plasma, make nanoparticles and droplets through this work. But what we see in plasma that there is really a threshold effect, and it turns out 256 00:52:31.470 --> 00:52:35.960 Mark Kushner: the exact plasma. Conditions don't matter as long as you're above the threshold 257 00:52:35.990 --> 00:52:54.739 Mark Kushner: or power, you know, whatever you vary, you need to be above a certain threshold of electron flux or UV flux to generate significant particles. And you see you can get it on the threshold. And all of a sudden, you get a narrower and narrower size distribution. So you need a certain short lift. Typically short lived 258 00:52:54.790 --> 00:52:58.959 Mark Kushner: radical flux to your interface to to do reduction ultimately. 259 00:52:59.830 --> 00:53:11.699 Mark Kushner: and that really drives on a very simple, you know, classical nucleation theory. Now, that's kind of the idea. Okay, so let's assume that this threshold effect is represented by classical nucleation theory. 260 00:53:12.090 --> 00:53:38.730 Mark Kushner: And if you think a little bit about okay, which pieces are now here responsible? No. And this is this idea, plasma is 100 times more efficient than most other techniques that are electron based. I forgot to mention that earlier, you know, then, is this really all due to electrons. So if we can characterize a plasma. And so here, this is a low density plasma, so well atmospheric pressure. But electron density is relatively low. 10 to 1710 to 18 per cubic meter. 261 00:53:38.730 --> 00:53:46.880 Mark Kushner: And so with Bremstrahlung we can actually measure that. And we can also measure the conversion of the ions and the droplet. 262 00:53:47.030 --> 00:53:51.279 Mark Kushner: And if you can compare this, and even looking to the conversion. 263 00:53:51.762 --> 00:53:57.120 Mark Kushner: so 10 ms in the plasma, we convert 70% of the ions. 264 00:53:57.410 --> 00:54:01.610 Mark Kushner: You know their diffusion time to the interface. The droplets are about 40. Micron 265 00:54:01.730 --> 00:54:06.189 Mark Kushner: would only allow about 30% of these ions reaching even the interface. 266 00:54:06.320 --> 00:54:23.829 Mark Kushner: so there is no way that anything happening on the interface is just explaining all this reduction we observe. And we can even, you know, estimate the electron flux know. So based on bremsstrahlung, we measure the electron densities here. You can actually estimate the number of electrons. And and 267 00:54:23.840 --> 00:54:41.179 Mark Kushner: Professor Kushner has also done models that give, I think, very similar values for electrons. And you see that these electrons are. I mean, I'm not saying this is perfectly accurate estimate, but they are at least 2 orders of magnitude lower, and you need at least 3 electrons to reduce one 268 00:54:41.320 --> 00:54:47.420 Mark Kushner: ion. So so they are significantly lower. And here you see back this factor 250. 269 00:54:47.710 --> 00:54:57.830 Mark Kushner: So you've seen that you have an efficiency of making or reducing gold that is about 250 times higher than just having electrons going in into the liquid. 270 00:55:00.290 --> 00:55:16.760 Mark Kushner: And you know we played around with it, and so we assume certain flux to the interface fast reduction at the interface. By short lived species electrons could be photons. We don't specify them. Then you have a nucleation model 271 00:55:16.780 --> 00:55:42.130 Mark Kushner: that you form these nuclei. These nuclei are diffusing in the end, you know, around the droplet. And then we postulate growth process that has been by colleagues looked at by, you know, similar conditions with hydrogen peroxide, that you have something called autocalotalytic reduction. So hydrogen peroxide would typically not reduce gold on its own, the ion. But when it's on a surface. Somehow, surface enhanced 272 00:55:42.130 --> 00:55:51.739 Mark Kushner: reduction process seems to be possible, and there has been some experimental measurements of that. So when we, when we include that hydrogen peroxide is made by the plasma. 273 00:55:52.055 --> 00:56:13.160 Mark Kushner: You know, and I'm not going to the details here. You know what we come out here in this model. We can predict the size roughly, of the particles that come out of the process. It is a two-step process. You have very fast reduction, and then very slow growth of the particles that are separated in time. And this actually allows you to control size distribution. 274 00:56:13.190 --> 00:56:26.649 Mark Kushner: because in one process you control the number of nuclei and the other process you grow. How much gold is responsible for for the growth and what you can see here, you know, initially, shortless pieces can be as low as 2%. 275 00:56:27.100 --> 00:56:51.330 Mark Kushner: You know of the reduction for the nuclei. And then the majority of the ions that are reduced are actually coming from this autocatalytic row, and it seemed that these 2 processes, both initiated by plasma, enabling that control and so understanding and controlling that might kind of open potentially even further opportunities. And so we were really excited. I mean, there is a lot of work 276 00:56:52.276 --> 00:56:54.863 Mark Kushner: ongoing on, you know, 277 00:56:55.940 --> 00:57:14.770 Mark Kushner: pfas, and and you know, and you know, other chemicals and decomposition and a lot of models. But you know, we were really also interested in seeing, can we kind of in a very simple way. Maybe it's kind of a more complicated growth process, you know, at least in 1st approximation. Understand some of these processes, and then observing this kind of 278 00:57:14.990 --> 00:57:20.309 Mark Kushner: a reasonably good correspondence between the 2. But the nice thing here is, you know. 279 00:57:20.340 --> 00:57:37.119 Mark Kushner: and I don't know. We need to be careful with Faraday efficiency. But no. So we have about 250 times more reactions than we inject with the electrons. So even if they cost more to produce, that might still be a process that is viable compared to other situations. 280 00:57:39.062 --> 00:57:44.170 Mark Kushner: Yeah. And with this I maybe conclude so. I'm you know I'm 281 00:57:44.750 --> 00:58:01.470 Mark Kushner: you know I do, Thompson, scattering. Okay, I do. Laser induced fluorescence. So many of the results here, you know, are based on a lot of diagnostics which I enjoy. But I'm really kind of an enjoying to explore opportunities for for plasma related, you know, to health, certainly, and sustainability. 282 00:58:01.963 --> 00:58:20.959 Mark Kushner: You know I showed you some results on the virus and electrification over. I still think that plasma catalysis can make a significant contribution if we can control and build our insights in new reactors that are being studied and developed. 283 00:58:21.561 --> 00:58:24.610 Mark Kushner: And and you know, more and more. I 284 00:58:24.640 --> 00:58:47.959 Mark Kushner: I haven't been in materials for for a long time. I came from from liquids, and so on, but more and more, you know, I think, you know, widening the perspectives of plasmas from semiconductor industry to other material processing opportunities, I think, might be also for the future a great opportunity, and I showed you here an example in liquid. But there might be many other one. 285 00:58:48.450 --> 00:58:53.559 Mark Kushner: and if if it's allowed just one slight of publicity, I 286 00:58:53.620 --> 00:59:02.154 Mark Kushner: you know I've the honor with my colleagues to host the international symposium on plasma chemistry. So if if some of these topics 287 00:59:02.640 --> 00:59:10.149 Mark Kushner: you know we discussed, and and you know in general plasma chemistry that are of interest for you, so next summer. Please consider. 288 00:59:10.430 --> 00:59:13.290 Mark Kushner: you know, visiting us in in Minnesota 289 00:59:13.500 --> 00:59:18.650 Mark Kushner: for for this conference. So I think it's about 10 years ago that meeting was in the us. So 290 00:59:19.305 --> 00:59:24.630 Mark Kushner: you know, this is an opportunity without an international flight, to actually attend this meeting. 291 00:59:25.290 --> 00:59:31.730 Mark Kushner: Okay, with this. Thank you so much again, for, you know, inviting me, and happy to answer any questions you might have. 292 00:59:39.110 --> 00:59:41.489 Mark Kushner: Thank you, Peter. Are there questions? 293 00:59:42.950 --> 01:00:06.450 Mark Kushner: Yes, yeah. Once or twice you use the term or stress. The term gas phase plasma. Just kind of interesting to me is that in opposition to like a liquid phase, plasma, or like, what? Why do you use that terminology? Yeah, I think I was influenced by my colleagues from astrophysics and fusion. So when when we you know, I think it was the 1st time when we were writing this decadal report. 294 01:00:06.510 --> 01:00:19.199 Mark Kushner: one of the initial titles was Interactions of plasmas with gases, liquids, and materials, and I found this at the time. Strange that you know, some plasma physicists think that we interact. I mean. 295 01:00:19.280 --> 01:00:27.700 Mark Kushner: no, plasma is not a gas. It interacts with the gas. And so yeah, I kind of maybe went there with gas phase. Plasma. So yeah, what I mean is really. 296 01:00:28.140 --> 01:00:28.910 Mark Kushner: you know. 297 01:00:29.080 --> 01:00:37.640 Mark Kushner: could well not vacuum. No, but you have some base pressure of gas. Yeah. And and maybe I contrast it with liquid here in this case. Yeah. 298 01:00:37.720 --> 01:00:42.719 Mark Kushner: I know that many plasmas produced in liquid are not necessarily liquid phase plasmas. 299 01:00:42.830 --> 01:00:47.130 Mark Kushner: That's another discussion. But yeah, that's the contrast I'm making here. Yeah. 300 01:00:47.980 --> 01:01:14.799 Mark Kushner: So I think it's quite interesting. What you're doing with that air purification is there any risk of producing, let's say, unhealthy species like carbon monoxide or ozone or ammonia in the process? Yes, I think well, if you have, I mean, okay, depending on what's in in the air, of course. But but air you will mainly produce ozone is probably one of the most important ones. 301 01:01:15.097 --> 01:01:21.940 Mark Kushner: You know. But there are systems where plasmas are used, and and ozone is relatively, for example, easy to remove by active carbon. 302 01:01:22.070 --> 01:01:24.510 Mark Kushner: So these systems will never be there. 303 01:01:25.035 --> 01:01:31.680 Mark Kushner: Without a combination of some catalytic material that can inactivate the ozone. For example. Yeah, yeah. 304 01:01:34.720 --> 01:01:36.519 Mark Kushner: any other questions. 305 01:01:38.600 --> 01:01:56.860 Mark Kushner: Last question for me. So, Peter, as you know, when you walk into a place like Arpa E. The reaction you get is well, that's wonderful. What is the path to gigatons per year of protection. So can you comment a bit on 306 01:01:56.940 --> 01:02:00.739 Mark Kushner: what is necessary to scale these processes? Yeah. 307 01:02:01.180 --> 01:02:09.190 Mark Kushner: yeah, I don't. I don't know if your your question is triggered, but we recently got an Arpay grant. So so I had to answer that question. 308 01:02:10.830 --> 01:02:15.090 Mark Kushner: And I mean at the time, I must admit I was not fully convinced myself. 309 01:02:15.250 --> 01:02:19.090 Mark Kushner: so I did a we did a calculation for the iron ore. 310 01:02:19.270 --> 01:02:24.890 Mark Kushner: No, and so an iron is a huge industry. The blast furnace is enormous. I don't have the exact numbers, but 311 01:02:24.980 --> 01:02:26.220 Mark Kushner: if you would. 312 01:02:26.410 --> 01:02:40.530 Mark Kushner: you know, with a certain energy efficiency assumed to replace a blast furnace, and we have about 10 or 20 in this country. I believe you need a nuclear power plant to deliver the energy to replace a blast furnace roughly. 313 01:02:40.960 --> 01:02:47.229 Mark Kushner: And I thought, like, Okay, how will this work? I mean, you know, apart from the scaling, it's the energy needs. So 314 01:02:47.640 --> 01:02:55.150 Mark Kushner: you know, I was kind of greedy apart from the scaling the energy. Need. I was quite skeptical. But then their answer was, Yeah, but 315 01:02:55.310 --> 01:03:09.290 Mark Kushner: a lot of green processes use electricity. So you are not the only one struggling with this question that you need huge energy. So that's kind of off the table, which I think is for me a huge relief. And so the remaining question is, then, okay, what's scaling? 316 01:03:11.540 --> 01:03:20.159 Mark Kushner: I think the answer there is that we will likely not replace blast furnaces. We probably have distributed 317 01:03:20.450 --> 01:03:25.750 Mark Kushner: system and and thinking more about a circular economy 318 01:03:26.030 --> 01:03:31.669 Mark Kushner: were, you know, based streams that are produced locally that are not that huge 319 01:03:31.790 --> 01:03:40.790 Mark Kushner: can be used in a smaller scale plasma to locally produce the kind of materials or or the kind of chemicals that you need. And I think 320 01:03:40.860 --> 01:03:45.609 Mark Kushner: this makes sense, like, you know, I think, yeah, the 321 01:03:45.660 --> 01:04:06.599 Mark Kushner: the huge scale. I think it's almost impossible. I mean you. You need. I mean, you need parallelization. I mean, you could, you could make a huge yeah, I think we did the number. I don't want to kind of give huge numbers, because I think I might be off so on the back of on the top of my head. But you know ultimately, for, like microwave, it's about. 322 01:04:06.990 --> 01:04:11.960 Mark Kushner: you know, 100 kilowatts per reactor. Maybe that's now commercially, that you could do. 323 01:04:12.410 --> 01:04:14.859 Mark Kushner: But you might need hundreds of these. 324 01:04:15.100 --> 01:04:20.779 Mark Kushner: you know, to kind of replace some of. So it becomes parallelization of processes. 325 01:04:20.920 --> 01:04:28.610 Mark Kushner: Now, there are already processes, like, you know, electrolysis based processes that are like that. I think aluminum making, for example. 326 01:04:28.660 --> 01:04:33.200 Mark Kushner: is a series of these processes. So it's it's not that this is not out there. 327 01:04:33.250 --> 01:04:39.170 Mark Kushner: but I don't think it's out there yet at the scale of the huge iron cement or kind of. 328 01:04:39.770 --> 01:04:45.749 Mark Kushner: So I think it's a circular economy and and kind of having local way streams 329 01:04:45.990 --> 01:04:52.849 Mark Kushner: converting it back to usable or value added materials is probably the way to pitch it, in my opinion. 330 01:04:54.160 --> 01:04:59.530 Mark Kushner: Thank you, Peter, and if there are no more questions, I thank our speaker again. 331 01:05:06.610 --> 01:05:19.610 Mark Kushner: So for our poster presenters. If we could meander over to the Ecs atrium, the 1st poster session will begin at 3 15, and hopefully all the posters will be up by then. Thank you. 332 01:05:27.426 --> 01:05:29.680 Mark Kushner: Thank you.