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Carolyn Kuranz: Started

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Carolyn Kuranz: Alright, so we're all being recorded. Great. So I am very excited to be introducing Professor Steffi dam.

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Carolyn Kuranz: Today we're going to hear about her experimental plasma physics for fusion energy development so

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Carolyn Kuranz: Stuffing as well here today, a stuffy works on magnetically confined plasma which is an area of expertise that we don't have in Michigan. So I think it's really

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Carolyn Kuranz: Going to be really great to hear about something that we don't do but related to some of our work here. So,

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Carolyn Kuranz: Stephen currently has experiments at the Pegasus three at University of Wisconsin Madison. So we'll be hearing about that.

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Carolyn Kuranz: And she received her PhD in plasma physics from Princeton University where she worked on the national spirit Mac national spherical Tomek experiment which I believe is called an X and sex at Princeton plasma physics lab.

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Carolyn Kuranz: And she received her BS in nuclear engineering and Engineering Physics from

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Carolyn Kuranz: University of Wisconsin where she is now an assistant professor and Steffi were very pleased to present you are to honor you with the renowned Mitzi mugs and I, you have to hold it up and you may even take a sip out of it. And I think did Mark already take a screenshot with you. Okay.

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Carolyn Kuranz: Yes, excellent. I got it. We got our pictures so

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Carolyn Kuranz: I'm so welcome, we'll be hearing from from Stephanie. I'm looking really really looking forward to this. And here is Professor Diem

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STEPHANIE J DIEM: Thank you so much. Okay, I'm going to attempt to share my screen correctly.

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STEPHANIE J DIEM: Okay.

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STEPHANIE J DIEM: Then

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Carolyn Kuranz: Yes.

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STEPHANIE J DIEM: That work you are seeing it correctly. Okay, great.

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STEPHANIE J DIEM: Well, thank you so much for the invitation to come and I love the mug.

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STEPHANIE J DIEM: I always look forward to hearing who's been at Mitzi by seeing who posts a picture of the monks and now I'm excited. I have one.

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STEPHANIE J DIEM: So I am, thank you so much for the invitation. Today I'll be presenting on my talks called exploring transformative startup solutions for magnetically confined fusion plasmas.

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STEPHANIE J DIEM: So I'll be talking specifically about the Pegasus three experiment at the University of Wisconsin Madison in the department of Engineering Physics.

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STEPHANIE J DIEM: And so I'd like to thank our whole team. This is really fusion is a team effort here. So it's myself and then emeritus professor a funk and then we have five scientific staff for engineers. And this is all supporting

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STEPHANIE J DIEM: 10 graduate students who really drive the research that we do here and today I'll be talking more about the exciting upgrade that we're going through right now and plans for the future.

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STEPHANIE J DIEM: So before I go into the details of my talk. I like to give just to how I got here. I always thought people knew exactly what they wanted to be when they were scientists when they were young.

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STEPHANIE J DIEM: I was not the case. So in high school I really loved art and I liked math and physics. I was really leaning towards art for undergrad and then I had a

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STEPHANIE J DIEM: Teacher who said, You know, you're good at math, physics, why don't you think about engineering. So I, I just kind of jumped in with it. I really didn't know what an engineer did. So I went to UW Madison, because I'm from Wisconsin.

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STEPHANIE J DIEM: And I picked noodle engineering on the sole basis that it looks like it was the one that was more physics involved involved for the new for engineering degrees. I didn't really know what it meant.

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STEPHANIE J DIEM: To be a nuclear engineer and what they actually did. So looking for not only what an engineer did but also a way to pay for college because I didn't have a way to pay for it.

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STEPHANIE J DIEM: Showed up on campus. Day one went to my department chair asked who was hiring and so he gave me a list of faculty members. And so I just decided to start at the top of the list and work down

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STEPHANIE J DIEM: Looking for a job. So the first person I went to worked on fusion energy. And so that's how I found out what fusion energy was and he described it as this.

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STEPHANIE J DIEM: Confining plasmas of magnetic fields as it's almost analogous to using rubber bands to confine jelly. And so I found that a really complex challenging problem and also with the application of

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STEPHANIE J DIEM: You know, helping the environment. I was hooked. From there on, so I worked on fusion energy research as an undergrad I did. I learned how to run a token Mac. I also designed a soft X Ray, Ray. So looking at soft x ray mission from a plasma to tell you about the

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STEPHANIE J DIEM: instabilities in the plasma. Then I went to grad school at Princeton, and I worked on sex.

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STEPHANIE J DIEM: It's a spherical token max. So I'll talk more with a spherical show chromatic is later on and they are. I looked at microwave, a mission from the plasma.

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STEPHANIE J DIEM: And then I was hired by Oak Ridge National Laboratory. I worked on not only using microwaves to heat plasmas. This is you may be familiar with Ampex so I worked on the

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STEPHANIE J DIEM: Prototype to impacts working on the, the electron heating for that. And then I also was on long term assignments at General Atomics

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STEPHANIE J DIEM: Working on the D 3D fusion facility I modeled. I do a lot of modeling, as well as experimental work. So there I modeled we use frozen deuterium pellets you shoot it into the plasma to kind of mitigate

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STEPHANIE J DIEM: Build up of energy at the edge of the plasma. So I worked on that. And then I did a little bit of microwave research on the side and then

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STEPHANIE J DIEM: Earlier this year, I joined the faculty at the University of Wisconsin Madison in the Engineering Physics Department

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STEPHANIE J DIEM: Where I work on Pegasus three now and I do microwave heating for that. And I also threw in a picture my cute dog, which you might hear during this time because we're all working from home.

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STEPHANIE J DIEM: So as a kind of what I'm going to be talking about today. So we're focusing on this talk for startup. A for took a Mac. So why investigate startup for Tokyo max.

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STEPHANIE J DIEM: And I'll go through these topics. So the most efficient use of the main magnetic field by account most efficient use of the magnetic field is by a compact turtle geometry.

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STEPHANIE J DIEM: And the reason is, so I'll go into more why we do this, and specifically looking at the spherical tokamak geometry to study this this compact operational space where we're looking at low aspect ratio.

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STEPHANIE J DIEM: When you're going to these compact geometries. This really reduces the central induction capacity for the machine so

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STEPHANIE J DIEM: In all Tokyo max. The main startup technique is using what's called an omega solenoid and that's where you drive current in the solo mode at the center of the the token Mac and then it induces the plasma current

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STEPHANIE J DIEM: And so we'll talk about that first. Then I'll talk about lighting measure fusion. So this is looking at the new Pegasus three experiment to study innovations in plasma startup techniques.

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STEPHANIE J DIEM: So we'll be with the experiments focused on techniques to help reduce, reduce the cost and also the complexity of future fusion reactors and

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STEPHANIE J DIEM: So when I talk about startup. I guess I say lighting a match, you can really think of it kind of like lighting a pilot plant a pilot light.

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STEPHANIE J DIEM: So startup means in this case to initiate a plasma from a vacuum that can be sustained non inductive Lee so

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STEPHANIE J DIEM: A non inductive sustainment technique is something like neutral beans or radio frequency waves and then

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STEPHANIE J DIEM: The last part of this talk, I'll focus on radio frequency waves, which is what I specialize in and how we can use them to heat and drive current and spiritual Tucker, Max, and how will apply this in pegs three and also looking at synergistically enhancing other non so nodal startup techniques.

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STEPHANIE J DIEM: And here on the right hand side of the slide.

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STEPHANIE J DIEM: This is our experimental team. So as I mentioned, they all do a fabulous job. And right now, we're all working really, really hard on the upgrade. So this is the, what you see now is the previous version of the experiment and it'll look fundamentally different when we're done with the upgrade.

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STEPHANIE J DIEM: So first I will talk about

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STEPHANIE J DIEM: Basically an introduction to magnetic confinement and why we would look at spherical tokamak geometry.

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STEPHANIE J DIEM: So took him back plasmas require current drive and heating to achieve fusion. So the fusion power is proportional to the triple products. So this is the density

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STEPHANIE J DIEM: Or n times temperature that capital T times tally which is the confinement time. So we need external heating is required to reach temperatures for that ignition.

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STEPHANIE J DIEM: And after ignition, the self heating then sustains the plasma. So here shown on the right hand side is the token max geometry. So, it's, it looks more like a doughnut shaped we have

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STEPHANIE J DIEM: To confining magnetic fields. The turtle field and that goes around this way and then the political field that goes around the short by and so it makes a helical magnetic confining field.

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STEPHANIE J DIEM: And there's several ways to

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STEPHANIE J DIEM: To heat and Dr. Current externally in the plasma. So the first is the OMA kidding, that's when we have that central solenoid drive current in that in induces the plasma current

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STEPHANIE J DIEM: And then there's also neutral being heating. So this is when you inject high energy neutral particles to impart energy and drive current in the plasma and then the other method, which is what I've highlighted here.

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STEPHANIE J DIEM: Which is right using radio frequency waves, and in particular electron cyclotron or EC resonance is in the micro range of frequencies of for these devices.

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STEPHANIE J DIEM: And I'll talk more at the end about how we encounter conditions and spherical Topamax where you have high densities. And this means that injected microwaves can be reflected. So we require alternative methods of coupling microwave power.

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STEPHANIE J DIEM: So I mentioned the three RF omega neutral beam. There's another thing that we're another method that we're using. That's not traditionally used in Tokyo max.

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STEPHANIE J DIEM: To drive current and to initiate those plasmas. And that's through felicity injection techniques that can initiate and drive took Mac plasmas.

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STEPHANIE J DIEM: So magnetic polyphony or this this k is it's Lincoln this of magnetic flux and a volume. So let's shown here in the schematic illustrating the flux linkage into royal took Math, Geometry.

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STEPHANIE J DIEM: So when a token back of the plasma felicity results from linking of these turmoil and playful Fluxus you can increase the plasma his listening.

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STEPHANIE J DIEM: By increasing the plasma listening, you can increase the turtle plasma current. So in so holistic means listening injection means driving a current parallel to the magnetic field. And this is required for all took max. So holistic is proportional to this plasma current

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STEPHANIE J DIEM: So anytime you have a turtle plasma current you essentially have publicity and that's this this two methods of adding listening so

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STEPHANIE J DIEM: This is AC listening injection. This is increasing the flux via magnetic induction within a target volume. So traditionally through that only solenoid or DC listening injection. This is when you have a potential upon along open field lines that penetrates the magnetic boundary

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STEPHANIE J DIEM: So what we've done on Pegasus in the past is look at adding DC felicity injection to start up plasmas. And so going forward. What I'll give you an overview of what we're going the direction we're taking the program and that's focusing on DC felicity techniques.

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STEPHANIE J DIEM: And then also radio frequency waves.

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STEPHANIE J DIEM: So first just the basics of what a spherical Tomek is it's a low aspect ratio took a Mac.

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STEPHANIE J DIEM: So here is showing the cross section, you'll see the circular donut like is a token Mac and then inside of it is what a spherical took Mac geometry looks like. So essentially,

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STEPHANIE J DIEM: If you shrink down the central hole of a took a Mac that donut shape.

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STEPHANIE J DIEM: You get more of a cord out Apple shape. And so this is a low aspect ratio where we define the aspect ratio. A as the quantity of are the major radius.

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STEPHANIE J DIEM: Divided by the minor radius. And this has this quantity is less than two for you to call something needs to be less than two to call it a spherical token Mac so

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STEPHANIE J DIEM: You'll also notice that spiritual token max have unnaturally long enough natural elongation so that it's more shaped so it's

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STEPHANIE J DIEM: This is the kappa factor which is the be that the halfpipe divided by the minor radius and you get that without active shaping coil. So it's naturally elongated plasmas. You also have strong toward this city. So this means your turtle field very significantly across the plasma volume.

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STEPHANIE J DIEM: And one of the benefits for spherical token might consider figuration is that you will efficiently utilize the Troy field.

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STEPHANIE J DIEM: So the average field line curvature. The other thing is that the average field line curvature optimize for Magneto hydrogen and stability.

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STEPHANIE J DIEM: For a given Troy field. So you'll see the particles direct trajectory shown here in this black line and and what this means is that the particles will spend the least amount of time in the low field side. So the, the lower

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STEPHANIE J DIEM: Magnetic field region and they'll, they'll wind back down the center column. So they'll spend more of their time in that high magnetic field location where you. We call that the good curvature region where it's better confined

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STEPHANIE J DIEM: And this

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STEPHANIE J DIEM: This efficiency then leads to high beta royal and beta turtle is basically a figure of merit is is given by the

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STEPHANIE J DIEM: Met the plasma pressure divided by the magnetic pressure. So it's basically how efficiently. Are you using your magnetic field to confine the plasma. And so that's one of the benefits of spiritual token max.

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STEPHANIE J DIEM: However, with these benefits saying we have an engineering trade off when you go to this low aspect ratio so low aspect ratio means you have a smaller Central Column.

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STEPHANIE J DIEM: This means you have little to no space needed for your needed turtle field coils. A diagnostics that you may need any cooling for the terminal field.

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STEPHANIE J DIEM: Also, you have limited oh make both seconds seconds or just the magnetic flux, you can use the available magnetic flux to drive that plasma current

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STEPHANIE J DIEM: Because you have this small so new to it. So knowing area, so you can't really have that much space to drive that much current and so Pegasus says I've very small radius, the radius and Sony's only three centimeters.

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STEPHANIE J DIEM: The also feasibility of reactor Central Column for neutron shielding. So ultimately, what reason why I got into

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STEPHANIE J DIEM: You know, plasma physics and fusion energy is to help solve real world problems. So bringing clean abundant energy sources to people. And so if you're going to look at scaling up

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STEPHANIE J DIEM: The small Central Column that you have in a spherical tokamak means you have less space to put something like neutron shielding in there so we we can use copper coils for a tornado fields because we have such a we take such good advantage of the compact geometry.

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STEPHANIE J DIEM: So because we have, we need to scale any room for shielding and other things we have to start looking for non so I know it'll start up is preferred. If you want to scale this up.

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STEPHANIE J DIEM: And so you can look at this is identified as nonlinear little startup is a critical challenge for the spherical tokamak

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STEPHANIE J DIEM: So future st designs called for solenoid free operation and nuclear spherical token max generally minimize that all make solenoid to shielding and costs.

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STEPHANIE J DIEM: However, if you can go this route of completely removing the only excellent solenoid. This really simplifies tokamak design. So not only benefits for spherical took max. You can also benefit.

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STEPHANIE J DIEM: Advanced token max as well. And you can you can also pretended potential advantages of removing that only solenoid means

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STEPHANIE J DIEM: cost reduction, you have more space for in board shielding also Blanket Material you reduce the portal field system requirements and lower the electromechanical stresses for the device.

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STEPHANIE J DIEM: And so here on the right hand side of this slide is a an example pilot from a pilot plant study by john Menard that showing the know or small only solenoid that

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STEPHANIE J DIEM: Device, you can use you can design with a high temperature superconducting magnets. So the solenoid for your startup techniques may also offer tools for modifying the current profile for something like stability concerns.

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STEPHANIE J DIEM: So now that we've gone over you know really why we care about.

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STEPHANIE J DIEM: Investigating startups for spherical Tucker max and took max. In general, I'll go into the Pegasus program. And this is where we're

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STEPHANIE J DIEM: Going to this new direction. It's just Pegasus three to study innovations in plasma startup techniques.

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STEPHANIE J DIEM: And we're focused on really the techniques that can help reduce costs and complexity of feature fusion reactors. So this is looking at the engineering concerns to if you're going to go ahead and build this

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STEPHANIE J DIEM: And as I mentioned, the elimination of the soul nine greatly, greatly simplifies these for automatic design and requires none inductive startup pathway. So the

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STEPHANIE J DIEM: Pegasus three mission is that we're solving this little known for you start up for sts and advanced Topamax by looking at the following methods. So first we'll have advanced local felicity injection

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STEPHANIE J DIEM: Will have also coaxial holistic injection and I'll go through those techniques and what how we can drive current with those

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STEPHANIE J DIEM: Next also radio frequency wave assist sustain mint and start up and then we're going to look at developing scenarios that are combative compatible down the line with neutral beam heating and current tribe.

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STEPHANIE J DIEM: And I'm really excited about this path because we've decided to go all in. And we're actually completely removing the solenoid.

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STEPHANIE J DIEM: The central solenoid. So we'll have no backup plans we really have to make sure that we can find a way to get these techniques to work successfully and we'll be able to compare and contrast these with all in one device.

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STEPHANIE J DIEM: So the research program will provide a predictive understanding of the solenoid free techniques and then we'll be able to extrapolate. Eventually the techniques to next field next step devices.

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STEPHANIE J DIEM: So the main features of Pegasus three and again no only solenoid. We are also have advanced control of our plasma we're expanding our diagnostic sweet.

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STEPHANIE J DIEM: And we're significantly increasing our turtle fields. Our total magnetic field by a factor of four. So here I've shown on the left hand side.

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STEPHANIE J DIEM: What Pegasus previously used to look like. You can see the. It's a two meter wide vessel by two meters tall essentially

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STEPHANIE J DIEM: The red coils are the oilfield coils and the small blue coils. You can see those are the turtle field conductor links and that

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STEPHANIE J DIEM: Is contrasted to Pegasus three which is shown on the right hand side. So here you can see it looks a lot bigger. In this picture, but actually the vacuum vessel is the exact same size.

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STEPHANIE J DIEM: The major thing that stands out is that we have beefed up our total field conductor line because these are these red links right here.

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STEPHANIE J DIEM: And we have. So we'll have an increase in the total field previously we had a field on access of point one five Tesla we're increasing this to nearly point six Tesla.

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STEPHANIE J DIEM: We're also increasing the pole flank and on this is all achieved while maintaining a very ultra low aspect ratio. So I mentioned earlier spiritual Tokyo max are aspect ratio is less than two were at the ultra low regime. So we're at 1.2 ish

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STEPHANIE J DIEM: And you can see

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STEPHANIE J DIEM: In addition to these return legs. They have a notch in them the notch allows the TF see the TF return leg conductor to flex germy during thermal expansion of that Central Column while we're running

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STEPHANIE J DIEM: And there's also torque plates on the top and bottom. And this is the counter. The barber pole stresses when we run the machine.

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STEPHANIE J DIEM: So here's. I just wanted to show this this evolution of our total field coils, because it was pretty amazing when we took them out and we compare them all on the bench.

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STEPHANIE J DIEM: So phase one. It was probably half as much as, as previously. So you can see we had flexible return legs and this was a solid copper bar and then surrounding are those are multiple bars that are packed together surrounding that.

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STEPHANIE J DIEM: That coil was the only solenoid. Then we moved on to phase two, where the central portal field was point one five Tesla, and then again surrounding that magnet was our own make solenoid coil which was very large, if you were to include put the solenoid. On top of that, phase two.

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STEPHANIE J DIEM: Turtle field coil it would actually be the same radius as the Pegasus phase three turtle field coil which is shown at the top of the middle fig figure. So this allows us to get up 2.6 Tesla with our current

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STEPHANIE J DIEM: Our current power supply set

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STEPHANIE J DIEM: And the current cooling requirements to

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STEPHANIE J DIEM: So now I'm going to go through the different nonsteroidal startup techniques different systems will have access to. So the first is local felicity injection

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STEPHANIE J DIEM: So I'll local soliciting injection provides a discrete non XE symmetric approach to holistic injection. So the this relies on localized plasma sources that are local that are

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STEPHANIE J DIEM: Located in the edge region. You can see them pointed out here in the figure. And what you do is you

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STEPHANIE J DIEM: Place a bias with respect to some electrode which can be the vacuum vessel vessel and then current is extracted

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STEPHANIE J DIEM: From this injector. It follows the magnetic field lines. So you can see them in this figure kind of the red lines are wrapping around that. That's to simulate what those current streams from the guns look like

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STEPHANIE J DIEM: And then it follows the magnetic field lines if the cell field from the current can overwhelm the vacuum portal field, then this can relax into a token Mac like configuration.

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STEPHANIE J DIEM: And I'm just going to show you this video here. This is one of our local felicity injector plasmas. So you can see these bright flashes in the beginning, that's the the injectors that are lighting up. This is a high school speed movie of the plasma discharge with the LA chai on

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STEPHANIE J DIEM: And you can see this initially when you start out, you saw discrete streams and bounces relaxing to a total Mac like state. So it was routinely used for startup on Pegasus. In the previous run

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STEPHANIE J DIEM: And now we're going to be focusing on projecting this technique to high performance facilities and this requires tests at increasing to royal field.

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STEPHANIE J DIEM: So the critical physics issues that will be able to look at is looking at confinement tests. So this is if we inject power will it be confined in the plasma or do we have open field lines the powers, just a goes out of the plasma. We can also look at

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STEPHANIE J DIEM: How the method of current Dr for local who listening injection. So this looking at turbulence driven dynamo current drive mechanisms.

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STEPHANIE J DIEM: And we can also look at what limits the plasma. Plasma current were able to drive. So this is looking at the Taylor limit that sets the maximum achievable current that can be driven

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STEPHANIE J DIEM: So in this this current limit shown right here. This side capital size, the total magnetic flux and the small size, the, the little the injected flux

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STEPHANIE J DIEM: So here in the upper right hand side figure is shown a plot of this is a real possibility that was running the previous version of Pegasus current versus

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STEPHANIE J DIEM: Elapsed time during the discharge and with only injecting eight kilograms of current, they were able to drive a 200 kilogram plasma with this local felicity injection method. So we're going to be looking at how does this current drive scale with increasing tornado field.

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STEPHANIE J DIEM: And so we we have access to two injector configurations. So we'll have two arrays of two by four centimeters squared circular injectors and that's similar to what was shown on the previous slide.

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STEPHANIE J DIEM: And then we'll also have advanced non circular injector. So this is called. We call it the comment injector. And it's port mounted so it's looking at

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STEPHANIE J DIEM: Forward thinking towards if you're going to apply this in a reactor setting you want something that's kind of like plug and play. It'll be there to start up the plasma. So, put it on a port you when you install it.

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STEPHANIE J DIEM: Put it on the port, turn it on and then something that you would not going to have for the rest of the the run is just for startup.

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STEPHANIE J DIEM: And so our goal for experiments is routine experiments at 0.3 mega amps and our projections using power balance for Pegasus three operations suggests that with both of these will be able to easily hit that goal of 300 killing amps.

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STEPHANIE J DIEM: So next coaxial felicity injection

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STEPHANIE J DIEM: And so coaxial holistic injection provides a comparison to an XE symmetric policy injection approach that we had with the the injectors that I showed for LA chai.

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STEPHANIE J DIEM: And for coaxial listening injection. This is when you

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STEPHANIE J DIEM: So you have. Basically it works by you apply a potential difference between two coaxial to royal and electrodes

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STEPHANIE J DIEM: And then the field lines that connects these electrodes and felicity felicity that policy, transport into the vessel.

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STEPHANIE J DIEM: So their stages of coaxial felicity injection. So first, what you do is you inject a current in the dirty region. So that's shown here in that left hand figure

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STEPHANIE J DIEM: As you inject a current between these two electrodes and then Jay Crosby forces expand the subjected current sheet in this ploy plane filling out the vessel.

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STEPHANIE J DIEM: And then the total current of fills in that polio volume. So basically it's a bubble of plasma that you're evolving into the main vessel.

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STEPHANIE J DIEM: And so this bubble the bubble burst condition requires the threshold of j cross be stress across the current layer to overcome that field line tension.

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STEPHANIE J DIEM: So you have to drive sufficient current along these open field lines to overcome that field line tension and then allow that injected little flex to expand into that vessel volume.

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STEPHANIE J DIEM: So we'll have to techniques transit CH AI and also that's just an abrupt start for CH AI and then you'll have also sustained CGI. So this is kind of like the LA try approach where you're just slowly evolving it for sustained CH I as well.

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STEPHANIE J DIEM: And so, this hasn't been done previously on Pegasus. We'll, we'll be adding this as a new capability to Pegasus three, it has in the transit form been done on an sex.

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STEPHANIE J DIEM: So any Pegasus three experiment will have comparison comparative studies of holistic injection techniques that a little bit explore that these increased fields we have

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STEPHANIE J DIEM: Will have access to novel a flexible coaxial Holocene injection system in a dedicated experiment.

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STEPHANIE J DIEM: It's novel, because we have floating plates instead of what's previously been done, which was a break in the vacuum vessel and this allows flexibility when you have just floating plates as opposed to a vacuum vessel break we're, we're in the coils are being installed.

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STEPHANIE J DIEM: In our diverted region to support this system are two to three times more powerful than a standard inverter and this provides enough political flex for the coaxial eliciting injection system.

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STEPHANIE J DIEM: And so we'll be able to look at a few few different critical physics topics. So this is exploring flux can conversion efficiency. How do you efficiently evolve. These plasma is also the role of the footprint and that means basically this you can see this hot pink line is the footprint.

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STEPHANIE J DIEM: How spreading out that flux can change the efficiency in the current were able to drive in the plasma. And then also, because we have these techniques, all in one machine. We can do a really great and thorough comparison and look at other synergies with other methods.

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STEPHANIE J DIEM: And then we'll also be able to validate projection to a one mega camp startup system. And so the other thing I wanted to point out is that

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STEPHANIE J DIEM: While it's great, it's starting up plasmas without a solenoid CGI results in really cold plasmids. So it requires auxiliary heating to raise the electron temperature in that plasma. If you want to sustain the reaction for longer never sustain the plasma for longer.

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STEPHANIE J DIEM: And so that leads to the, the last portion of this talk.

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STEPHANIE J DIEM: Which is what I'm mostly involved in, and that is using radio frequency waves to heat and drive current and Institute with Tokyo max and also looking at how that system can enhance non the other non zone little techniques that we have on hand.

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STEPHANIE J DIEM: So that's we're talking about specifically I'll be getting into

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STEPHANIE J DIEM: certain type of wave. It's called the electronic Bernstein wave or Eb W for short.

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STEPHANIE J DIEM: And so all magnetic and make it RF waves can resonate with the natural frequencies in the plasma and provide heating and current drive. So if you apply a magnetic field to a plasma.

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STEPHANIE J DIEM: There alert Laurens force has makes means that there's a force on the particles that has them resonate around a magnetic field line and that frequency that they resonate around the magnetic field line is called the cyclotron frequency. So we take advantage of that frequency

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STEPHANIE J DIEM: So we can use launched microwaves that can be absorbed near these resonance, the cyclotron resonance locations in the plasma.

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STEPHANIE J DIEM: So here is shown just kind of a portal cross section of a plasma. So this vertical teal line is the center line or the center column. You can think of it in in a spherical tokamak

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STEPHANIE J DIEM: And the magnetic field will then fall off as one over are the total magnetic field. So you can plot the electron cyclotron frequency. And you can either

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STEPHANIE J DIEM: As a function of radius here. And so you can tune their microwave source frequency to either the electron or Island. I am cyclotron motion and then you can pick your RF source frequency

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STEPHANIE J DIEM: To be absorbed at a very precise location and this can be this can be used to provide healing or current drive at that location. And so there's a couple of waves. You can you can inject

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STEPHANIE J DIEM: It's either the ordinary mode which is in launched obliquely to the surface or we call oh mode for short. This is the electric field is perpendicular is parallel to the magnetic field.

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STEPHANIE J DIEM: Or the extra ordinary mode or X mode for short. And this is with the electric field perpendicular to the magnetic field.

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STEPHANIE J DIEM: So for plasmas with. So now let me know how that works for you know in general for token max for microwave absorption at a precise location.

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STEPHANIE J DIEM: We can look at what happens in something like a spherical token map.

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STEPHANIE J DIEM: So that's when electrons like electrons wave injection provides plasma heating and current drive in certain conditions.

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STEPHANIE J DIEM: So for plasmas with relatively low total magnetic field and high density, which is what you see in compact.

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STEPHANIE J DIEM: Sprinkle Tucker, Max. The OH mode and the X mode are reflected near the plasma edge. And so when this happens, we call these plasmas over dense and so you can see this, it's shown in this diagram right here.

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STEPHANIE J DIEM: Here in the center of our plasma would be the normal absorption location if you're tuning to the cyclotron resonance at the location.

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STEPHANIE J DIEM: But this surface occurs where the plasma is actually too dense and so the microbes are reflected out. So this means we have to explore alternative healing methods.

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STEPHANIE J DIEM: And this happens in certain I want to emphasize in certain conditions and spirit Gattaca max. So this happens for lower frequencies that you inject or if you're looking at fundamental absorption to

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STEPHANIE J DIEM: So if we can't use the or the X mode, we have to search for another wave that we can couple to so plasmas are like black bodies. They can host a sea of waves. And so one of them is the electron Bernstein wave

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STEPHANIE J DIEM: And they can propagate in over dense plasmas. So, electron Bernstein waves or Eb W for short or hot plasma waves, they pop. They are propagate perpendicular to the magnetic field.

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STEPHANIE J DIEM: They do not experience any density class in the plasma and their longitudinal electrostatic waves. So it's, I have this diagram here to give to show kind of what the motion.

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STEPHANIE J DIEM: Of electron Bernstein wave looks like. So it's basically coherent motion of the electrons. So you'll get as the electrons go around.

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STEPHANIE J DIEM: The field, you'll get an alternating electric field when they bunched together and then you'll get propagation of the wave to the right here.

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STEPHANIE J DIEM: I like to think of this in terms of if you're going to a football game.

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STEPHANIE J DIEM: We do this a lot at CAMP RANDALL here Bucky badger will start the wave around the stadium.

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STEPHANIE J DIEM: And you'll see a wave propagating around the stadium. But if you actually look at the individual people. They're just going up and down. So I like to bring sea legs are kind of like that in that the sense they're coherent motion of single particles.

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STEPHANIE J DIEM: And this means they can't propagate in a vacuum. They have to have the plasma there to actually move and I've also shown here. The electronic Brinson wave dispersion relation. So this just tells us how the plasma moves into medium.

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STEPHANIE J DIEM: And really what matters in the dispersion relation, if you're looking at first glance you care about is where can you see a resonance

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STEPHANIE J DIEM: Resonance in this equation. And so if you look here as the wave frequency approaches the electron cyclotron harmonic, which is equal to, you know, the frequency and clear frequency is equal to n.

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STEPHANIE J DIEM: And it's just the harmonic number times the electron cyclotron frequency, the wave is strongly absorbed.

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STEPHANIE J DIEM: And so we can take advantage of this with the electron Princeton wave. So we can tune. Pick a source frequency that can also heat and drive current at the electron cyclotron resonance frequency with the electron Brinson wave

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STEPHANIE J DIEM: So I'm going to show this, then we have two great we found a wave that can propagate in these heightened states plasmas. It can absorb

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STEPHANIE J DIEM: At locations at the cyclotron frequency. Now, how do we actually get power to that wave to propagate into the plasma from the back end region.

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STEPHANIE J DIEM: And so that's when we look at wave coupling.

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STEPHANIE J DIEM: So here I kind of show. This is a picture of one of the Pegasus plasmas. And if we were going to zoom in to the edge of this plasma and just look at on one the slab, you can kind of look at how the waves different waves will propagate in different regions in the plasma so

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STEPHANIE J DIEM: For these plasmids. We're looking at over dense plasmas high density. If you were to plot how the OMO launch from the outer region would respond to the plasma. As I mentioned before, it's reflected out for these high density plasma seats over an inch plasma.

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STEPHANIE J DIEM: So then we can look at what elder waves are in these plasmas. There's also the slow X mode can propagate to great we found to two waves. They're kind of close together.

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STEPHANIE J DIEM: Which means you can start taking advantage of tunneling power coupling power from one wave into another. So we call this mode coupling or wave coupling.

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STEPHANIE J DIEM: And so for electronic Brinson waves we take advantage of coupling from the OH mode to the X mode here. And so you want to put those two solutions to those two waves as close together to get

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STEPHANIE J DIEM: The power to couple between them and the way that you can do that is, it depends on the density gradient and the edge of the plasma. So how steep. If you have a really steep.

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STEPHANIE J DIEM: Edge density gradient, you can actually move those two waves solutions together and get powered a couple also the magnetic field pitch. So that's

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STEPHANIE J DIEM: Basically, where you launch that oh mode in relation to the magnetic field, you want it. Oh, please, to the magnetic field and that kind of helps you with that way of coupling to that tells you where to point your launcher to get this this wave coupling to happen.

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STEPHANIE J DIEM: And so once you couple from the slow X mode to the electronic burns anyway. Once a couple to from the OMO to the slow X mode you can get the absorption is just the

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STEPHANIE J DIEM: Full absorption from the X mode to the electronic currency wave happens near the end of the plasma.

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STEPHANIE J DIEM: Just because the solutions of those two waves happens right on top of each other at that location.

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STEPHANIE J DIEM: So what we can do is if you launch from outside the vacuum vessel and Oman. You can couple to the X mode to the electron brainwave and that's called oh XP coupling.

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STEPHANIE J DIEM: You can also and this is the window, basically, that you look for is is when we talk about the electron Bernstein wave coupling efficiency. So this is going from

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STEPHANIE J DIEM: We that one D picture of mode coupling to now a 2D picture.

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STEPHANIE J DIEM: So it's basically happens in a bull's eye here. So you have to point it at a specific location. So that depends on the magnetic field pitch.

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STEPHANIE J DIEM: That tells you the center of this Bullseye where you can get the most power coupled between those branches and then the density gradient

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STEPHANIE J DIEM: Make tells you how wide of a bull's eye how wide of a coupling window you can get so so you really kind of use this as a guiding of when you're designing a system, you want to take advantage of optimizing that coupling between those two those those three waves.

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STEPHANIE J DIEM: So the other way, if you just want to bypass the mode you can launch from the high failed side if you can put an antenna down below or on the board side.

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STEPHANIE J DIEM: And you can just directly launch it in the slow X mode and it will couple fully to the BW so we'll be able to look at both kind of mode coupling techniques in Pegasus three

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STEPHANIE J DIEM: So this is just a broad overview of the radio frequency wave heating and current drive that will be explored as a component of the nonlinear nodal startup.

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STEPHANIE J DIEM: Program for Pegasus three. So, we will look at several long term scientific campaigns studying the synergistic effects for improving eliciting injection and RF current drive efficiency.

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STEPHANIE J DIEM: This is if you actually increase the electron temperature while you're in, in doing holistic injection, you can actually improve the current drive through from that's occurring from holistic injection

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STEPHANIE J DIEM: Also comparative tests of most major non Sonia little startup techniques.

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STEPHANIE J DIEM: So we can really study in one device which is better between the three techniques that we have and how do they opt, how can we optimize it by using these processes together.

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STEPHANIE J DIEM: We can also look at current profile tailoring so because we can pick this specific radius that we get absorption, we can actually drive current to that specific location to

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STEPHANIE J DIEM: And then we can look at scenarios of handing off from these nonsteroidal startup techniques.

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STEPHANIE J DIEM: To non inductive sustainment using reactor relevant non inductive sustainment tools. So this is something like you can add another RF heating system Michael repeating system or neutral beam injection

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STEPHANIE J DIEM: And the initial campaign experimental campaigns will focus on really understanding that coupling between the vacuum region and the plasma to these in these over dense classmates.

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STEPHANIE J DIEM: And will be using a BW heating capabilities and studying how they may sit synergistically enhance this local who listening injection induced plasma current by lowering the receptivity of those plasmas. And then a long term, we can look at RF only startup.

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STEPHANIE J DIEM: So the initial LBW programs seeks to explore these synergies that I've mentioned

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STEPHANIE J DIEM: The relative low magnetic total magnetic field and the high density of our plasmas really drives us at these

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STEPHANIE J DIEM: These field levels to use electronic currency waves.

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STEPHANIE J DIEM: So will be implementing a 500 kilowatt LBW system will be using eight gigahertz source frequency. This is a collaboration between Oak Ridge National Lab.

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STEPHANIE J DIEM: NEA for Scotty and Italy and also UW Madison. So for Scotty has a wonderful eight gigahertz kleist Ron based system that they'll that we are working on getting through loan and then we're developing a

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STEPHANIE J DIEM: Resident power supply to drive these clients John's and shown on the right hand side is a political cross section of the plasma.

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STEPHANIE J DIEM: Along with the fundamental electron cyclotron resonance locations for a variety of turtle fields that we will have access to early on in our campaigns.

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STEPHANIE J DIEM: So you can see that spanning we can span our total field from 0.3 all the way up to 0.4 or five Tesla, and that will result in fundamental absorption at the electron cyclotron frequency range for these plasmas.

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STEPHANIE J DIEM: And then we'll be able to will will be focusing on a demonstration of electron electron Bernstein, we have current drive for feature sustainment studies.

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STEPHANIE J DIEM: So this will be able to first first phase will be looking at coupling and synergistically improving policy injection. The next phase will be looking at

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STEPHANIE J DIEM: Can we drive current in specific locations in the plasma. And so this is a simulation. I did looking at a we're going to put a little launcher about 30 degrees above the mid plane.

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STEPHANIE J DIEM: And the modeling shows here you can see we. These are these little raise that are injecting these are the VW propagating in the little cross section of the plasma.

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STEPHANIE J DIEM: And the modeling shows current Dr can be picked off access in this case. So this is, this is the results from the

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STEPHANIE J DIEM: calculations of the driven current with the Fokker plunk code called CQ well 3D and you can see the absorbed power occurs around a row of 0.3 and a simulation show that we can drive around 30 killing amps.

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STEPHANIE J DIEM: Current with this method with injecting 400 kilowatts of power and this current is actually comparable to the central current from local holistic injection. So it'll be a great way to demonstrate. We can do current profile tailoring

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STEPHANIE J DIEM: And then we can also very the total field to change the absorption location. So this is all focused on the eight gigahertz system that

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STEPHANIE J DIEM: Will be doing with electronic Bernstein wave heating

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STEPHANIE J DIEM: And this is good is valid up to 0.4 or five Tesla. So the second phase of RF and this is just all proposed right now. The BW portion has been funded for eight gigahertz.

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STEPHANIE J DIEM: This is more forward thinking at the second phase of RF so this is adding electron cyclotron heating and electron cyclotron current drive for felicity injection synergies and also a path to direct startup. So if we increase our tutorial field to something like five Tesla.

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STEPHANIE J DIEM: Then we actually enter a regime where we're not over dense and we can go to a higher frequency, so we can just couple these

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STEPHANIE J DIEM: The or the X mode to directly to the plasma. And so this can be looking at heating after the coaxial whole holistic injection system has turned off.

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STEPHANIE J DIEM: And so this is we can look at significantly increasing the electronic temperature here for something like a sustainment phase, we can also look at local holistic injection exploring

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STEPHANIE J DIEM: Electron heating during la vie for increased current drive efficiency and also we can explore pure RF startup scenarios.

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STEPHANIE J DIEM: And this is just initiating the plasma solely with RF. So this way we can compare, which is more efficient starting it with just our up starting with just CH AI or starting with La chai. And then looking at sustaining to

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STEPHANIE J DIEM: So for this system, we can exploit the second harmonic electron cyclotron resonance frequency. If we go with the source frequency of 28 gigahertz and

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STEPHANIE J DIEM: Significant absorption can occur. The second harmonic that's shown here in the portal cross section this dashed line here is two times the

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STEPHANIE J DIEM: The electron cyclotron harmonics. So this is where a significant absorption will occur and the density cut off is low enough so that we can actually couple these plasmas during the startup.

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STEPHANIE J DIEM: And so this is some modeling for that system. It shows the path to high absorption during local homeless. The injection

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STEPHANIE J DIEM: The LA. Try to produce targets are accessible to these higher frequency of electron cyclotron injection and we have a wide range of densities for these plasmids. So we're targeting on developing a

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STEPHANIE J DIEM: Target plasma that that's the lowest density possible so we don't have to worry about cut offs. And so I've done some modeling to look at

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STEPHANIE J DIEM: Where we would aim, an injector to actually couple the most power and get absorption to these cold plasmas. So the this is showing the upper left hand side.

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STEPHANIE J DIEM: If we're looking at the total angle of the launcher and then how much power is getting first pass absorption just means how much power is getting absorbed.

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STEPHANIE J DIEM: Right on first injection into the plasma without worrying about inject absorption after it bounces around. So the peak, we expect to see 15% absorption at these really low CH I plasma temperatures of 15 EV

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STEPHANIE J DIEM: And this is what we expect for CH I plasmas. And then the lower hand side. So once we've identified where to launch it, we can look at how does the absorption of the microwaves change.

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STEPHANIE J DIEM: As a function of the electron temperature. So just naturally electron cyclotron absorption increases as you heat up the plasma.

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STEPHANIE J DIEM: So a lower right hand side we we plot the first pass absorption as a function of temperature. And so as I mentioned, it starts around 15% and then once we heat up the plasmas to 300 dB. We get about 70% absorption

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STEPHANIE J DIEM: And so the initial EC H modeling shows. This is probably a promising capabilities for this feature for the system.

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STEPHANIE J DIEM: And then this just shows a where we expect the absorption to actually occur within the plasma radius. So the, the, here's shown a portable the portal cross section and a total cross section here.

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STEPHANIE J DIEM: And this is showing central absorption is possible at this 28 gigahertz frequency for a for these plasmids. And for this case I've looked at an intermediate case. So this is an electron temperature of 150 EV, and we're going to expect to get 42% absorption

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STEPHANIE J DIEM: And then finally, we can look at running these systems together.

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STEPHANIE J DIEM: Looking for simultaneously for scenario development. So this is looking at optimizing both the startup phase and then looking at hand off or sustainment so we can look at using the

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STEPHANIE J DIEM: Higher frequency system during active holistic drive to significantly increase the electron temperature and thereby, it will, in turn, increase the electron Bernstein wave convert current drive efficiency.

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STEPHANIE J DIEM: And so for this case I've shown on the left hand side is the EC H says during the early time of startup. So using that to improve publicity injection with heating with the microwave system and then

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STEPHANIE J DIEM: Tune towards the second harmonic here and then handing off to electronic Bernstein wave current drive where you also have a fundamental resonance here.

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STEPHANIE J DIEM: And so for this.

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STEPHANIE J DIEM: I can just show you how you can improve current drive so assuming that the electron psychos try and heating during policy injection provide significant increases in the electron temperature. So this is heating something to like one ke VI.

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STEPHANIE J DIEM: The BW current Dr can increase by a factor of two. So instead of previously where I showed simulations were predicting of 30 kilograms of current drive now we're driving 50 to 60 kilo amps of current drive just by preheating with that. The, the higher frequency system.

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STEPHANIE J DIEM: So there's going to be several diagnostics required to verify RF heating and current Dr. I won't go into too much detail, but one methods you can do is you can

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STEPHANIE J DIEM: Have a soft x ray imaging diagnostic to look for characteristics of electron Bernstein droid stripe high energy tails so you can look at that, through the soft x ray spectrum.

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STEPHANIE J DIEM: So you can use simulations to get a sense of what the the signatures from the south extra camera would be like. And so this one shows on the right hand side. This figure shows these. It looks like Batman peaks.

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STEPHANIE J DIEM: On on different channels of the stuff of a simulated sub x ray detector that just means those are signatures, we would expect if we're getting significant current drives. So that's something we can look forward to

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STEPHANIE J DIEM: When we're implementing a diagnostic like this. And so in summary, the long term plans for RF seek to enhance non social tools on Pegasus three experiments.

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STEPHANIE J DIEM: And this will provide a bold tests of nonsteroidal startup a spherical tokamak startup.

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STEPHANIE J DIEM: Using reactor relevant techniques. So I went through several techniques will have on Pegasus three which is the new direction of the program.

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STEPHANIE J DIEM: A local holistic injection coaxial holistically injection and also electron brains to wave assist and sustainment and then the future we're looking at adding electrons cyclotron heating and current drive

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STEPHANIE J DIEM: So the RF auxiliary heating and current drive system will enable long term scientific campaigns. So we'll be looking at synergistic effects.

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STEPHANIE J DIEM: For improving holistic injection and our current drive efficiency this sub will also provide comparative tests of most major non-seasonal startup techniques.

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STEPHANIE J DIEM: And will also be able to start demonstrating looking at current profile tailoring and

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STEPHANIE J DIEM: More towards stability and also handoff from these non colonial startup techniques to on non inductive sustainment using these really reactor relevant non inductive sustainment tools and all of this allows us to

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STEPHANIE J DIEM: It allows unique studies at this near ultra low aspect ratio device.

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STEPHANIE J DIEM: So I'll just end with some pictures for our upgrade so Pegasus three is now under construction. We actually

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STEPHANIE J DIEM: It's been ongoing during the pandemic. So we've been able to accomplish a lot with just a few people in the lab. So Pegasus is decommission, you can see that picture in the middle so

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STEPHANIE J DIEM: The top plate. The is gone. And basically, that was all of the current of the leads for the tornado field coils and the only solenoid, that's all gone.

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STEPHANIE J DIEM: It's actually not even a token back anymore because we just ripped off the all of the turtle field coils last week.

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STEPHANIE J DIEM: We've completed the electrical, mechanical design and analysis of that turtle field system to give us a robust device. We have the new chortle field center rod is

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STEPHANIE J DIEM: At the lab, it's been qualified. We also have the conductors and return structures are delivered shortly. I expect that will be pulling out that old

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STEPHANIE J DIEM: center stack which has the old solenoid in it, and the old total field coil, so we can put in our new

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STEPHANIE J DIEM: Turtle field coil. Next, we also have all new power supplies that we've built that is to drive the higher performance magnetic oils that we have and also adding in the power supplies for our new local holistic injection and our coaxial holistic injection systems.

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STEPHANIE J DIEM: So thank you so much for inviting me.

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Carolyn Christine Kuranz: Thank you. Stefan. I'm sure everyone's at home, clapping for you.

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Carolyn Christine Kuranz: Yeah. Wow.

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Carolyn Christine Kuranz: And so now we have some time for some questions, so people want to pop them in the chat or just unmute themselves.

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Carolyn Christine Kuranz: I will go ahead and I'll take the first question while people are are preparing or writing. And so, well, first of all, thank you for your Bucky. The Badger analogy. That was excellent. I might steal it. But I'll replace it obviously

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Carolyn Christine Kuranz: But so

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Carolyn Christine Kuranz: Like with laser experiments. It's sometimes the case that you can do something at

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Carolyn Christine Kuranz: With a kind of lower energy laser or smaller laser and then like ramp it up to larger systems and then doing something on if, for example, is that something here where this could ramp up to, you know, D 3D or even either or to a fusion pilot plant like

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Carolyn Christine Kuranz: How does this more broadly fit into that.

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STEPHANIE J DIEM: Okay. That is a great question, and that one. I should have emphasized. Because really we're looking at. I love this question.

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STEPHANIE J DIEM: We're looking at specifically, how can we design these systems and scale them up for something on

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STEPHANIE J DIEM: NS Tsu. So that's the more immediate one. So ultimately, we'd like to especially looking at the local holistic and just injection system because it's it's that monolithic port, you can just plug in

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STEPHANIE J DIEM: That is something you can imagine. And we're planning on this.

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STEPHANIE J DIEM: Designing it and making it more efficient and understanding how it projects. So we can go ahead and implement that on sex you

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STEPHANIE J DIEM: And then further using that information to look forward even further to something like an STD based power of fusion plan or or even at because this works for helping out advanced took them x two.

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Carolyn Christine Kuranz: Okay, cool. That's really cool.

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Carolyn Christine Kuranz: I said, additional

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Carolyn Christine Kuranz: Questions. Okay, go ahead. Right.

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Ryan David McBride: Great talk, Stuffy

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Ryan David McBride: About the DC current drive and these injectors and putting them in the plasma and contact with the plasma. Do you are there like sheets to developed is there. Does it affect the plasma. Anyway, like, cool it or introduce mix into the plasma.

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STEPHANIE J DIEM: Contaminate. Yes. That is a great question. So that's one of the things we're really

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STEPHANIE J DIEM: Looking into is how impurity injection. Right. You don't want to, you want to minimize any kind of impurities. You also want it to make it out of materials that a robust

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STEPHANIE J DIEM: To the plasma contacts it. So that's a one of the drivers for the next version of the injectors that we have. So we're looking at

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STEPHANIE J DIEM: Installing an optical system that looks at if there's any arcs that are forming on the the cathodes

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STEPHANIE J DIEM: Of of the injectors and understanding that and maybe if there's a way you can tied into your power supply. If you see an arc forming you kind of turn off your power supply to clear the arc

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STEPHANIE J DIEM: Very, very small amount of time and then keep it going. Because one of the things we found is, it takes a lot of time to condition these guns. And so if you're going to install this on a larger device.

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STEPHANIE J DIEM: You want to understand the engineering that goes into minimizing any kind of conditioning constraints that you have

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STEPHANIE J DIEM: And and the impurity injections. So that's driving some of our dissertation projects, one of the students is looking at engineering design of the guns will. Another one is looking at understanding where the impurities are coming and how they affect the overall radiated power of the plasma.

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Ryan David McBride: Great, thanks.

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jefoster: So, um,

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jefoster: Yeah, I have a question can hear me okay yeah yeah okay so so I was wondering about, is it possible to get that Eb who type coupling just by

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jefoster: Launching say like an extraordinary away from Highfield side across felines did they were the reason why I asked is, because in some plasma and some of that.

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jefoster: Michael a platinum sources that I work with. We are injection is was primarily extraordinary wave and we get

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jefoster: Absorption that can't be explained by the dispersion relation and we just hand wave and say it as it's converting two different modes.

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jefoster: But in a large system can't those waves scatter around so that the way that you're injecting from Highfield side can interfere with something that is scattered off of the wall on the low side and maybe they can interact. Is that possible.

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STEPHANIE J DIEM: Yes. Yeah, that's definitely. Yeah, that's definitely possible. So, especially when you're launching from the low field side.

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STEPHANIE J DIEM: You don't expect all that power to couple so you expect some of it to scatter off and it can just like redirect and and get coupled back into the plasma. So that's something we can look at and installing little probes around the machine to look for stray radiation.

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STEPHANIE J DIEM: And also modeling helps understand this, you can you can kind of predict how much you expect to get absorbed and you can predict where it's going to get absorbed. The other thing that we're going to look at doing is, and I'm going to

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STEPHANIE J DIEM: Go back. One of these is an electric field probe. And so this looks at local spectroscopic measurements of the RF electric field vector in the vicinity of the RF launchers.

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STEPHANIE J DIEM: So you can use this to follow the mode conversion process between oh annex mode. So it gives you the magnitude and direction electric field. So you can

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STEPHANIE J DIEM: Compare that to like a full way of code that has that expected electric field that's occurring through that conversion process and compare that to those measurements.

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STEPHANIE J DIEM: That's something we can look at doing. Yeah, I see, I see.

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jefoster: And so just to follow up since you have this up as yourself x ray camera there. Is it so that that's looking at brimstone them, then that's how you get the temperature of electron

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STEPHANIE J DIEM: Here that's looking at just you can you can put a filter on to look at. I think for this. Um, when I simulated it, it's probably a brilliant filter that's looking at, like, maybe up to 50 K GV, something like that. Oh, yeah.

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STEPHANIE J DIEM: There's also cameras to CCD cameras that Louise still gotta appreciate at ppl he has a really nice sub x ray camera that we were looking at maybe doing a collaboration with that to

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Carolyn Christine Kuranz: Me follow up questions.

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Carolyn Christine Kuranz: Go ahead. Mark Yeah, good. Oh.

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Carolyn Christine Kuranz: OK.

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jefoster: John sorry so so so so yeah so I have to ask, so I may have missed it, because I was

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jefoster: Amazed have seen all the beginning of your talk, but I thought so. Most. How does the plasma GUNS WORK. And I know Ryan asked a question about, oh,

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STEPHANIE J DIEM: Okay, yeah, yeah. So for those basically we start it's you have a bias between the electrodes of the gun and something like the top plate of the device. And so you play that bias and you can extract the current from the gun that way. And so then it just naturally

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STEPHANIE J DIEM: Goes around your magnetic field.

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STEPHANIE J DIEM: Ultra magnetic field lines. Yeah.

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STEPHANIE J DIEM: And then it has. And then we have holistic conserving

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STEPHANIE J DIEM: I'm forgetting the word here mechanisms to kind of drive current and relax to have the token Mac like state.

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jefoster: Oh, so so that that gun can be a source of evaporated.

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STEPHANIE J DIEM: Material. Yep. Okay. Yeah, yeah. Cool.

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Carolyn Christine Kuranz: Okay, so I think that's, that's all the questions we have for you, Stephanie. Thank you so much. It was this was a really interesting talk. And hopefully you can come visit IN PERSON SOMEDAY. And, well, I applaud you again.

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STEPHANIE J DIEM: Thank you for

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Carolyn Christine Kuranz: And actually, you and I are gonna stay on.

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Carolyn Christine Kuranz: Yeah. Yes. Thank you very much. Yeah.

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STEPHANIE J DIEM: Thank you all so very much to