Expert Interview: Cameron Geddes

[00:00:06] Lauren Biron: Hello everyone. I’m Lauren Biron, a science writer at Lawrence Berkeley National Laboratory, and I’m here today with Cameron Geddes, who’s the head of the Accelerator Technology and Applied Physics Division at Berkeley Lab. Cameron, thank you for being here to talk about what’s happening in fusion energy research.

[00:00:25] Cameron Geddes: Thank you for having me here.

[00:00:27] Lauren Biron: So let’s go ahead and start with the big picture. What is fusion and why is it so exciting?

[00:00:33] Cameron Geddes: Thank you. Yes. So fusion is the energy that powers the stars. It’s the combination or the fusing of light nuclei, such as hydrogen and in doing so, it would release energy. That’s exciting because it offers essentially unlimited power using abundant fuels and with minimal long-lived wastes, radioactive or otherwise. And such abundant clean energy offers solutions to problems in energy security, cost, and pollution, and really could be transformative for society.

[00:01:02] Lauren Biron: Berkeley Lab doesn’t have a fusion facility, so how are our scientists able to contribute to this research?

[00:01:09] Cameron Geddes: Berkeley Lab’s capabilities as a multi-program laboratory are really essential to fusion in a number of different ways. Those include our leadership in high field superconducting magnets, where we lead the magnet development program for high-energy particle physics that’s developing a new generation of magnets that have the possibility of making magnetic fusion systems smaller by enabling higher fields.

We also lead exascale simulation efforts where we pioneer simulations of the largest scales in electromagnetic systems that can be really important to the microphysics of fusion.

That goes together with our facilities like NERSC and ESnet, and pioneering concepts towards so-called “super facilities” or “Integrated Research Infrastructures” that combine the data from experiments and simulations to really powerfully advance broad science. Also incorporating artificial intelligence and machine learning methods to combine experimental and simulation data and to scale across understanding of all of the systems that are required in fusion. Those are really starting to be impactful in our modeling of the fundamental physics at the smallest scales that go into the whole facility modeling of fusion reactors.

We also operate laser facilities. Those aren’t at the scale to make fusion themselves, but they test important physics relevant for fusion, and we do that as part of LaserNetUS that enables broad user bases across the nation to access laser facilities and do science for fusion and related physics.

[00:02:35] Lauren Biron: I know one area where Berkeley Lab really shines is in magnet science. So I wonder if you can tell us about some of the challenges with superconducting magnets that our researchers are working on solving.

[00:02:47] Cameron Geddes: Superconducting magnets are so important because they’re used to confine plasmas for fusion.

So there are two approaches to fusion. One uses high field magnets to control and confine a plasma to make it burn. And to do that, the field that’s generated by the magnets is really the key factor that tells us how big the system will be. And that’s a major determinant, obviously, of its cost and of how practical it is.

So there’s really a nascent revolution happening that has a lot of potential to really improve fusion systems and the size of fusion devices, which is so-called “high-temperature” superconductors. So, as their name implies, these kinds of materials have the ability to be superconducting at higher temperatures, but equally importantly, they have the potential to double the available magnetic field, strongly reducing the size of fusion devices.

LBL leads a US magnet development program for high energy particle physics that has really pioneered the methods for employing these types of superconductors and magnets. So we’re now poised to really leverage these types of magnets for fusion, and have been working both with private companies and with the Department of Energy Fusion Energy Sciences to start a high temperature superconductor program for fusion.

There are really some challenges for such a program to address in controlling these types of superconductors for fusion. For example, how do you control the magnet when it exits the superconducting state, so-called quenching? That’s a big challenge for these types of magnets because it can actually destroy them due to the amount of energy that’s released in the small volume. And so LBNL and our partners are pioneering the diagnostics that can detect precursors of those types of quench events and the controls that can allow us to control that process and make it safe.

[00:04:26] Lauren Biron: Another specialty of the lab I know is laser plasma accelerators. Could you give folks a quick overview of what those are and how they are useful for fusion?

[00:04:36] Cameron Geddes: So, plasma based accelerators are really notable for their ability to generate very high energy beams of subatomic particles in very short distances. That has a number of potential roles in fusion.

So we operate our laser plasma accelerator facilities to do what are called mid-scale experiments. So these are not experiments that achieve fusion conditions themselves, but they probe physics aspects that are important to making a fusion system work, and they can access a level of precision and a repetition rate that allows a richness of data that wouldn’t be possible at fusion facilities that can only fire on the order of once a day. We fire about once a second, which allows us to get precision data on the fundamental physics processes and to build things like AI and ML models to get precision understanding of processes relevant for fusion.

So for example, in a collaboration that was executed by the University of Michigan as part of LaserNetUS, they collected exquisite data at the micron scale on the evolution of instabilities in hydrodynamics that are important to how a fusion target would come together and create fusion in an inertial confinement fusion system. And in such a system we use lasers or particle beams to compress a target and that compression generates fusion. To make such a target compress, we have to delicately control what are referred to as hydrodynamic instabilities. That is instabilities that occur during compression. And understanding those instabilities in detail is the place where midscale experiments come in.

So in addition, these systems can create fast moving beams of ions, and those beams can be used in multiple ways in fusion. They’re already being used in fusion experiments to probe the fields that are present in targets. By having an ion beam go past an assembled fusion target, you can get an image of the fields that exist in it and how those fields evolve over time. And as we better understand the ion acceleration process and how we can put energy into that ion beam efficiently, there’s even the possibility that you would couple that ion beam to a target and use it to deposit energy into that fusion target, thereby reducing the energy of the driver that would be required and increasing the performance of the fusion system.

So that’s one of the possibilities that’s being explored to take us from where we are now, where initial ignition has been demonstrated to a system that could really operate at gain sufficient to support power generation.

[00:07:00] Lauren Biron: So that reminds me of the old joke that fusion is always about 30 years away. How are you feeling about progress in the future?

[00:07:10] Cameron Geddes: So I’ve been in the field for about that long and the last few years have seen tremendous progress. In fact, the community has now demonstrated ignition and target gain in inertial fusion experiments on the National Ignition Facility at Lawrence Livermore National Laboratory.

And we’ve demonstrated record temperatures and confinements on magnetic devices like the Joint European Torus. We’re now at the point of being able to engineer gain rather than speculate on whether it’s possible. And that’s really translated into a tremendous surge in private investment with several billion dollars invested by an array of private companies, uh, some of whom are actually building fusion machines right now.

So I think that timescale has actually accelerated tremendously just in the last few years.

[00:07:51] Lauren Biron: Looking ahead, what are you most excited about and where do you see the lab making the biggest impact?

[00:07:59] Cameron Geddes: So looking ahead, I’m really excited about that transition that I just talked about from doing basic plasma physics to understanding whether we could possibly get ignition to now understanding how we could get high gain and potentially building fusion systems.

I think that really plays into the strengths of Berkeley Lab as a multidisciplinary, multi-office national laboratory. We have at the lab everything from leading computing capabilities to nuclear science, to accelerator and plasma science to facilities like the Advanced Light Source that allow us to test materials. All of these things are going to have to go into our building an actual fusion system, and so I see it as a tremendously exciting time and one for which the lab is very well positioned.

[00:08:40] Lauren Biron: It’s clearly an exciting time for the field and an exciting time for the lab. So, Cameron, thank you for walking us through this and I can’t wait to see what comes next.

To learn more about how Berkeley Lab is advancing fusion energy research, visit lbl.gov.