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Tammy Ma

Tammy Ma

Lead, Inertial Fusion Energy Initiative, Lawrence Livermore National Laboratory

By David Zierler, Director of the Caltech Heritage Project
June 16, 2023

DAVID ZIERLER: This is David Zierler, Director of the Caltech Heritage Project. It is Friday, June 16th, 2023. I am delighted to be here with Dr. Tammy Ma. Tammy, it is wonderful to be with you. Thank you so much for joining me today.

TAMMY MA: Thank you so much for having me.

ZIERLER: To start, tell me please your title and institutional affiliation.

MA: Sure. My current title—I actually have many, but one of them is the Lead for the Inertial Fusion Energy Initiative here at Lawrence Livermore National Laboratory.

ZIERLER: The Lead means what? What are some of the scientific and administrative responsibilities you have in that role?

MA: What it means right now is we are trying to grow a new program to apply the fusion research that we do towards the application of energy. We'll probably go into it a little more during this talk, the different applications and why we are where we are right now. My role right now is to bring our Laboratory together, develop a science and technology roadmap for where we want to go, and then also work with the community externally as well to help grow a national program in inertial fusion energy.

ZIERLER: Tammy, of course Lawrence Livermore National Laboratory is a big place. Can you describe where this Initiative sits organizationally both within the National Ignition Facility and the overall lab?

MA: Absolutely. Right now, why we're calling it an initiative is it sits directly with the Director. The Director has chosen a couple of areas of potential growth for the Laboratory, areas that get to leverage a lot of the different capabilities that we have across the Laboratory, that we actually see as a future path for the Lab. Because we are a national security laboratory, all the work that we do is meant to be in the good of the nation. "Science on a mission" is actually I think our motto. We see inertial fusion energy as something that would be great for the country if we can make it happen. But it does require leadership. It requires focused effort to grow what that program should look like. That's why this initiative sits directly with the director, and then if we can grow it and actually bring in funding to do S&T research, bring in funding to do other things, then we will figure out where it fits best within the overall structure of Lawrence Livermore.

ZIERLER: Given the National Ignition Facility's leadership in stockpile stewardship and nuclear weapons safety, obviously without getting into any sensitive details, does the quest for nuclear fusion have a national security component to it as well? Or is this more a basic and applied science kind of environment?

MA: It's very much both. The National Ignition Facility is the world's largest, most energetic laser, and what we can do with it is actually generate conditions that you cannot generate elsewhere on Earth right now. We can create plasmas of very high temperatures, densities, pressures, in some cases similar to what you have inside nuclear weapons. That's why we can study those conditions at typically a very micro scale and then use that science to validate our simulation codes. These are the same codes that we may actually run to ensure the safety, security, and reliability of the nuclear stockpile. Because since 1992 in the Comprehensive Test Ban Treaty, we have not done any underground nuclear testing in the U.S., or anywhere in the world, actually. Because of that, we still have nuclear weapons in our arsenal, and so we need to ensure that they are safe, they are secure, if heaven forbid we ever had to use them they would work the first time. That is the deterrence. We use science to make sure that the stockpile is effective in the absence of nuclear testing. That's partially what the NIF is used for. We also do a bunch of fundamental science on the NIF. We actually open it up to academics around the world. It's a typical proposal review process; you come up with an idea, and you apply. What we can do is actually generate astrophysical phenomena in the laboratory and observe that, instead of waiting for something to actually happen in the universe. So, all kinds of very cool science. We just explore plasmas in all kinds of different ways. Then it just turns out that the same fusion process that we generate for the stockpile stewardship mission are the exact same plasmas that form the basis of a clean energy source. It's a dual-use technology, basically, which the national labs have a ton of expertise in, and this is another example.

ZIERLER: A question about collaboration. It's a worldwide effort, of course, to create nuclear fusion. That involves academia, national governments, private enterprise. Is Lawrence Livermore's purview that it has capabilities where the creation of viable nuclear fusion energy can be an in-house proposition entirely? Or does Lawrence Livermore need those collaborations? Are there capabilities elsewhere that Livermore doesn't have?

MA: Absolutely. It is a collaboration now, and it will definitely be a collaboration going forward. The overall challenge of realizing fusion energy, turning it into a viable, economical energy source, turning it into power plants, is such a monumental challenge. There's so much development that needs to be done, both in the fundamental science and all types of engineering. We know we cannot do it alone. We absolutely need help from all different sectors, all different industries, national labs, universities, private industry, all that coming together. But our role right now is, we achieved ignition on the NIF; we have a lot of the expertise that is needed to help lay the groundwork and to find what a roadmap might look like. That's where the majority of our effort resides right now in terms of the fusion energy sphere.

ZIERLER: As a matter of that collaboration, what does Livermore offer? What are its capabilities that make it unique in this worldwide effort?

MA: First and foremost, we have the National Ignition Facility. It is the only laboratory on Earth right now where we can achieve burning plasma, and the only one that has achieved fusion ignition—so, target gains greater than one. So, we absolutely need to continue to use the NIF to develop the science and learn more. Besides that, we also have phenomenal expertise in lasers. The old joke goes that our acronym is LLNL, which stands for Lasers, Lasers, Nothing but Lasers.

ZIERLER: [laughs]

MA: In terms of very high energy, big, big lasers, that's where Livermore specializes. We continue to push forward the forefront in different laser architectures, figuring out the technology behind lasers, but a bunch of other stuff, too. I'm a high-energy density physicist. We have great expertise there in both generating these high-energy density plasmas, diagnosing them, learning from them, and also the simulation codes to go along with them, trying to understand what is actually happening. The development of those codes, a lot of that is done here, so the codes are Livermore codes, per se. We have the design physicists that can model those plasmas. Besides that, we have great computational scientists. We have one of the fastest supercomputers in the world, and are always constantly upgrading, to try to push the forefront there. We have great machine learning, artificial intelligence scientists that are developing new techniques for AI applied specifically to science problems. What that means is, there's all kinds of new requirements that come out of new science that is being done, that is more than just, "Generate me a picture of a cat playing a guitar." It's actually, how can we use AI and machine learning to actually do scientific discovery, or accelerate science? We have additive manufacturing, advanced manufacturing, great capabilities here, to push the boundaries there of new techniques, new materials that you can additively manufacture. Higher resolution, new techniques there. We work with industry very closely in that arena. We have new diagnostics that we build, many of them in-house. For example, the instrumentation that we use on the NIF you don't get to buy off the shelf in many cases, because nobody else has use for it, so we built a lot of that in-house, which also means for that instrumentation, building entirely new detectors, new materials that can detect better, or with higher resolution. Different types of cameras, different types of materials—a lot of work there. Then also expertise just running these very big science facilities. That is an art in its own, in order to operate something super complex efficiently and safely.

I think the figure of merit typically is, whatever the capital cost was to build that machine, the operating cost for one year is about 10% of that original capital cost. That just gives an idea of, okay, so you've built something; that's great. How do you keep it running? Then with all of these machines, they took a lot of investment. They took a lot of work. You always want to make them better all the time, too. It should already be a piece of machinery that is unique, forefront in the world, but you want to keep pushing that. That means advancing that technology as well. For example, with the NIF, our next big challenge is certainly sustainment, because it's 20 years old. Imagine your 20-year-old refrigerator; things are going to start just kind of wearing down because it's running 24/7. But beyond that, pushing up to greater energy, greater powers; that means improving the technology somehow. In our case it means optics that can be more hardened, can run at higher energies. Upgrading the computer system that actually runs the laser. All of these little things are going in require a lot of investment, a lot of R&D in all of these different areas.

ZIERLER: Of course the creation of viable nuclear fusion will have profound implications for energy use and climate change mitigation. Is Lawrence Livermore operating under some kind of a sustainability mandate either from the DOE or the White House, where one of the main thrusts of achieving this is really as a solution to wean ourselves of fossil fuels?

MA: As far as I know, no, there isn't that kind of mandate that we're working with. Some of our Climate Group is certainly trying to contribute to net-zero goals that the Biden administration put out, for example, but in terms of fusion, not necessarily. In fact, one of the big reasons that we're going after fusion energy, though, is actually energy security as much as climate security. Because fusion is meant to be this clean, we say limitless, super abundant energy source, and if we can manage to do that, that completely changes the paradigm of how we use energy, and it frees the U.S. from a lot of the inter-relationships that we have with other countries to ensure that we have a steady energy source. Ideally, it is an energy source not just for the U.S. but every country in the world to have its own energy sovereignty, to have control over its energy sources. From that perspective, we're a national security lab; energy is a big component of that national security. That's a good fraction of the reason why we're so interested in fusion energy.

ZIERLER: The creation of limitless or abundant energy has profound business implications as well. There's many private enterprises that are involved in this, and because it's private enterprise, to some degree they're involved in a race to who can get there first. How does Lawrence Livermore position itself so that it is assisting private enterprise without necessarily perhaps playing favorites? How does that work?

MA: You did a lot of research there! Yeah, that is exactly the job of a national lab. What we're trying to do is help develop some of the foundational technologies to grow potentially a fusion energy industry, an entirely new energy industry. It is our job as a national lab to develop technologies generally for the first time. We do not mass produce. We do not manufacture something, more than once or twice, after we develop it. We typically do technology transfer out to private industry. We very often sign agreements to them to hand over the technology to a private company so they can manufacture whatever it is and then it can be bought. And sometimes we buy it back from them, in fact, if we need to use that technology. Right now, you're right; in this fusion ecosystem, lots of private companies popping up. Many of them do come to us to leverage some of the expertise we have here, whether it's in simulation codes or laser development or executing experiments themselves. What we have to make sure is that we treat all the companies fairly, unbiasedly.

With inertial fusion energy, what we did was set up a collaboratory, and I can send you the link to this collaboratory, if you're interested. What we did was bring together many of the national labs from across the U.S., and in some cases university labs as well, that are currently doing work that is related to inertial fusion. Now, keep in mind, inertial fusion energy hasn't been funded in the U.S. in the past ten years, so it was like inertial confinement fusion work that was related. We brought them all together so that we could all talk to each other and figure out who was getting approached by private companies and work out some of these issues. On the website that we have, we actually list out our capabilities at each of these national labs where we might be interested in partnering. We held an industry day, similar to what DARPA often does. The private companies responded to say, "Oh, this is what we might be interested in. This is what we need help with." Then as a collaboratory, we could all see that information and then try to figure out who amongst us might be best suited to help these private companies and figure out where the alignment was. Because it's also not our job to just help whoever comes to ask for help; there needs to be some mutual benefit as well. Certainly it's super exciting to have these private companies that we can now interact with, and maybe try out different ideas, work in a paradigm where they're more agile, maybe more flexible than we are. They're sometimes interested in building new infrastructure that we can benefit from. So, it's a very dynamic place to be right now.

ZIERLER: As companies are racing or competing to achieve viable nuclear fusion energy, is there only one way to skin a cat, or are there different approaches to nuclear fusion and Livermore is responsive to many, or it does things in a particular way and it's only responsive to one particular way of getting there? How does that work?

MA: There's many different ways to skin this cat. Right now, we don't know actually which way has the highest potential or might be the best one in the long run. Certainly there is magnetic fusion, where with magnetic fusion you're using gigantic magnets to hold your plasma long enough that it can fuse. This is typically tokamaks or stellarators. The ITER project in the south of France is a gigantic tokamak. Then with inertial fusion, that is using lasers, sometimes pulse power or heavy ions, to actually basically compress your plasma and use the inertia of the compression to actually hold your plasma in place long enough to give it time to fuse. Even within inertial fusion, there's all kinds of different approaches. There is direct drive, where you can shine lasers directly on a fuel pellet to compress it. What we do on the NIF is indirect drive, so the lasers come in and they hit a cavity, a little cylinder, with two holes on either end, and the lasers actually hit the inside wall of that cylinder to create x-rays. We use those x-rays to compress the fuel pellet. There's other designs where you separate the heating and compression stages, something called fast ignition, so you would still compress your capsule up to decent densities, and then you bring in a short pulse very high intensity laser to generate a beam of energetic particles that then deposit their energy and heat that way. There's other designs called shock ignition. There's magneto-inertial, where you combine magnets and inertial fusion. Many, many different approaches now.

There's also some approaches that even use different fuel for their fusion reaction. Most of our experiments have centered around DT, deuterium-tritium, isotopes of hydrogen which have the highest cross-section, probably for fusion, in the temperatures that we can achieve on Earth, in a lab. But there's other fuels that you can fuse—D-helium-3, deuterium and helium-3; or p-boron, a proton with a boron atom. All of them have pros and cons. There's many different potential ideas right now. I think one of the limitations of the field is actually that we don't have enough facilities, because you need a certain scale, a certain size of facility, to test a lot of these things in order to see if they are viable.

ZIERLER: Let's now move onto the physics of nuclear fusion. You've already conveyed wonderfully just how difficult and complex this quest to achieve nuclear fusion is. In so many areas of physics, the challenge, the really hard part, is getting at the interplay of theory and experiment. "Will we ever see experimental validation of string theory?" "Why hasn't CERN seen something beyond the Higgs?" Things like that. For nuclear fusion, is the theoretical framework perfectly established, or are there missing items in the theory itself that are giving the experimentalists difficulty?

MA: I think any scientist that says the theory is fully established in any field would not be telling the truth, because there's always more to learn. Certainly what we do here at Livermore, I guess in the U.S., for nuclear fusion, is very much this interplay, interexchange, between theory and simulations, and then experimental validation, finding out your experiment was wrong but taking what you learned there to improve the code, the modeling, all over again. There are certainly still a lot of unknowns in our simulations. Certainly the NIF is the ninth in a series of bigger and bigger lasers that we have built here at Livermore; almost all of them, we thought we could achieve ignition with. Every time, we found out that we did not have enough laser energy, until we got to the NIF. Even on the NIF, when we built the NIF, due to constraints of time and budget, we knew that the two-megajoule laser was just on the hairy edge of achieving ignition. Even the codes said, "This is just on the hairy edge."

I think the last 10 years of experimentation have taught us a lot about how incomplete some of our understanding was of the physics. Each time we got a little bit closer, each time we increased the performance on the NIF, we found out something new about the implosion that we had not accounted for in the simulations. For example, early on, we saw that our performance was nowhere—we expected like right after we turned on the NIF that we would get ignition. Of course, obviously we didn't. What we found out early on was that we had perturbations from how the capsule is actually held in the hohlraum. What we do is we build the hohlraum in two halves, you put a very thin membrane across the two sides, and clamp the capsule, right in the middle. For us, a symmetrical implosion, meaning staying spherical, as spherical as possible as we do that compression, is super important. Because what we're doing is taking the kinetic energy of implosion and turning that into heat. If you deviate from round in any way, you're basically wasting your kinetic energy. And all of that energy is so precious. So, early on, we would do all these shots, and we would take x-ray images of the hotspot, and it was never very round. It would be oblate or prolate, or we would see streaks across the hotspot that we didn't understand. It turns out that those membranes that we were using to hold the capsule in the middle caused serious perturbations to the implosion like right as we were at the beginning, and they just grew as we did the compression. Our codes initially did not model that correctly, and it took quite a while to figure that out.

Okay, so we solved that; great. Then later on we found—each time you solve one problem, it gives you a window to a better implosion, but that reveals other things that perturb. I think it has been a really great example, though, of how having the codes and that experimental validation really has to work hand in hand. When I give NIF tours, I actually always stop when we get to the windows and point at the supercomputer, halfway across the Lab, which is also in a pretty large building, so you can see it. The point is that neither of these facilities would exist without each other. In order to justify building the supercomputer, we needed this really gnarly physics problem that only a supercomputer could solve. Likewise, you can't do these experiments without guidance from the codes, because there are 10,000 different physics parameters to change on every shot, and you absolutely have to rely on the simulation codes to guide you.

ZIERLER: Just a fun thought experiment, to give a sense of all of the technological leaps and bounds that make all of this possible, let's say we had a time machine and you could give Enrico Fermi a tour of the lab. What would be understand—

MA: I would want to tour his lab first!

ZIERLER: [laughs] What would he understand immediately? Where would he see a perfect continuation of his project to build controlled nuclear energy? And what would he look at and it would be incomprehensible to him?

MA: Oh my gosh. I think the scale and the complexity would be incomprehensible. Fission, by comparison, is easy. All you have to do is have a critical mass, of your uranium or plutonium, and it will go. On the NIF, you have to have so much precision at every level. We know the length of every single electrical cable inside NIF in order to sync up all the instruments with when the shot actually happens. I would think it's something that is very, very difficult to conceive. Even for me, thinking ahead to what the next-generation facility would look like, it is evolutionary, not something that looks totally different. To be able to imagine such a big difference from 60 years ago, I can't imagine.

ZIERLER: Of course the joke I'm sure you know—that nuclear fusion has been around the corner for 40 years. To go back to December of 2022, when this announcement was made, even before it was made, the Department of Energy, Lab leadership, there was a tremendous buildup. It was almost like the DOE version of a major album drop.

MA: [laughs]

ZIERLER: There was so much anticipation—"What is the Secretary going to say?" The joke about being 40 years around the corner, the joke there is that there has been a lot of hype in this field over the years.

MA: Oh, yes.

ZIERLER: Obviously the DOE lab leadership is aware of this. What made this different? Why did the administration, the Department of Energy, why did it—I don't want to use the word "hype" here, but why did it make the announcement feel as big as it was? What was different this time around?

MA: I think hype is something that is, by definition, part of our fusion field. I think people need so much optimism to even work in the field, because it is so incredibly difficult. I think everybody has to imagine that—previously it was that we would get ignition during your lifetime, during your career. Then I think it's, okay, I think we absolutely have to be able to make fusion power plants within 20, 30 years—people are saying five to ten years now, but whatever—in order to keep themselves going. But more to the point of your question, I think it was a super big deal for the Department of Energy, because it is an example of a win, from sustained investment and sustained support over decades. In order to achieve nuclear fusion, it wasn't just put your head down and work really hard; it was something that is incredibly interdisciplinary, and you have to pull in expertise from across the complex. In fact, those types of needs are what spurred a lot of the competencies that we have within DOE now. We already talked about the supercomputers.

A lot of the drive behind bringing in supercomputers, developing those supercomputers, was actually to help solve plasma physics problems. Likewise, the laser development over time has been pushed by the fusion needs that we have had. Then each of these areas has grown into its own big thing. That's why the DOE has continued to go after fusion, because there are so many amazing spinoffs, spinouts, that come from fusion, a lot of them making technology possible today. For example, plasma TVs, a lot of the underlying plasma physics at work there to make that technology happen came through funding this type of research. Also I think just the potential, the idea of what fusion can do for humankind. After all, we are called the Department of Energy. Fusion is the last energy source that we have not really been able to tame. That alone, for those of us that are curious and believe in what humans can actually do, that alone makes you want to go after it.

ZIERLER: To go back to this dichotomy that you established, which I love—the revolutionary and evolutionary—the announcement and the research behind it, what aspects do you see as evolutionary, that this is another brick in the wall of this 40-year endeavor, and what of it is really like a quantum leap, that it got us way beyond the incremental development over the years, that gets us much closer to ultimately where this is headed?

MA: I think for the most part—and I think this is true for science—there isn't a lot of science news coming out in the media, so very often it seems like somebody had a eureka moment, and there was something totally revolutionary that made something happen. But for the most part, for those of us that do research, we know that most of it is evolutionary. We are building on the knowledge base that was there before. I think that is actually true for how we got to ignition, for where we are today. But there are huge leaps that make this possible. For example, a lot of the technologies we actually needed to complete construction of the NIF did not actually exist at the time when DOE signed off to say, "Yeah, let's start this construction project." That is just incredibly forward-leaning and is a huge example of how government itself actually takes really big risks. We have this reputation that government is slow, isn't willing to try new things, but it's actually not true. Government is the one that said, "Let's go for it, even though we don't have all the solutions yet, and we will find those solutions." And we did. So, there are some examples for how we were able to actually have new optics manufacturing techniques, to be able to fill the NIF with these thousands of gigantic optics that we needed for these lasers that did not exist before. I wouldn't call that necessarily revolutionary in itself, because again, you're taking the knowledge that you have, you're adding huge amount of innovation, but those are just some of the examples of the creativity that can happen when you push it, when something actually has to happen. We had a timeline, we had requirements, and only because of those stringent requirements are you pushed to think so creatively to actually make something happen. In many cases, I think we often need those boundaries, we often need those timelines, in order to spur the creativity for something to happen. Right now, the government has put out this bold decadal vision for fusion commercialization. It sounds crazy, because there's so much development that needs to be done, but that is the kind of thing that can really put momentum into the system, put pressure into the system for people to think creatively and really innovate and to make something happen.

ZIERLER: Since this announcement and your amazing ability to communicate the science, and really to be the public face of this breakthrough in so many ways—

MA: One of many, one of many. [laughs]

ZIERLER: —one of many, yes—How has your day to day changed, both administratively, both in terms of the public outreach, and in terms of the science itself?

MA: There has been a lot of media interest, and it has changed my job structure quite a lot. Because of the excitement that is around fusion right now, we absolutely want to take advantage of it. We really want to capitalize on it. Because it's not so often that the public is really interested in science of any type. I do a couple of media events probably every week—podcasts, interviews. I've been traveling a lot to give talks as well, both talking about our ignition result and how we achieved that—and certainly we want Livermore to take credit for that, and then give credit to all the thousands of people that worked on this project over the decades—but then also to lay the foundations for the next step, because we will also need a huge amount of support to realize fusion energy. I mentioned earlier, we don't have a national—well, okay, we just started a national program in inertial fusion energy. It's not a lot of money right now, so that's going to have to grow significantly if we're serious about it. We need support for that, but we also need to change the public perception of nuclear energy. We see that it is imperative that we go out and communicate in order to—and it's certainly not enough—but try to make strides in spreading the message, the potential of fusion, but then also hearing the concerns from communities and see what they care about. Because in the end, it's great to do science and have some fundamental increased understanding of the universe, but if you don't apply it to something useful, to humanity, and if you don't communicate it, then how do you know that science was done?

ZIERLER: Let's go back now and establish some personal history. How many generations back do you have a relationship in your family? Did you know your great grandparents, your grandparents?

MA: No. I didn't know my great grandparents. My grandparents and parents immigrated on my dad's side of the family to the U.S. and my mom's side of the family to Canada. I only know my grandparents. I don't know farther back from that.

ZIERLER: Where did both your mom and dad's parents come from, or their families came from?

MA: They came from Guangdong, Canton, in South China. Both of my parents immigrated to Hong Kong first before coming over to Canada and the U.S.

ZIERLER: What years did they immigrate?

MA: They were both children. I think my mom was 13 or 14 when she went to Canada, and similarly my dad was 13 when he came to California. My dad was 1969, and then I think my mom was—well, she was born in 1954, so 1978ish.

ZIERLER: Did they have memories from their parents about World War II and the Japanese occupation?

MA: They did. Very much so.

ZIERLER: What stories have you heard?

MA: Initially, when I was very young, when I was a kid, my parents had said to me, "You can marry whoever you want, but you are not allowed to marry Japanese."

ZIERLER: Oh, wow.

MA: So, that was residual. They've changed, quite a lot, and now they don't care, at all, but at the time that was true. Yeah, they do have stories. My uncles on my dad's side have stories about hearing the planes going overhead and then having to run and hide because they were enemy planes. My mom was carried on her grandmother's back, going from China over to Hong Kong. I also have uncles that had to swim across the bay from—I don't know if "bay" is the right word, actually—from China to Hong Kong, and many people did not make it, but they did. My father's side of the family—oh, maybe you can help me with this—supposedly they came to the U.S. as refugees under Kennedy's Refugee Act. I've tried to do research and haven't found much information about it, but apparently they let like 5,000 Chinese apply as refugees to come to the U.S. Because my grandpa was an elementary school principal, he was the educated class, and so they were worried about persecution from the Communists in the sixties, and were able to come to the U.S. under that Act. A really funny story—my father is the youngest of seven, and so apparently, he only found out a few years ago that he's two years older than he thought he was—

ZIERLER: Oh, wow!

MA: —this whole time. Because he's the youngest of seven, and they had to downgrade everybody's age in order to fill out paperwork to get the family over, to the U.S. All the other brothers knew, except for my dad, because he was too young. Then he only found out recently! All of his U.S. paperwork says he was born in 1950, but then only recently, one of my aunts was doing some research about the family, and she was like, "No! No! You were born in '48." And my dad was like, "So I just lost two years of my life?!" It's crazy, stories like that.

ZIERLER: You said your mom's family landed in Canada. Why Canada? What was the opportunity there? Was there family there already?

MA: Yeah. My mother's uncle had already gone over to Canada. What they did was they sent my mom and her older brother to Canada first, without their parents. It was my mom's job, when she was like 13, to try to establish the family, so she actually did not get to finish high school. Actually middle school; she did not even get to finish middle school. She got pulled out of school so that she would go work and make money to support the family. But then I guess a few years later, she applied for her mom and her dad—well, her dad first—to actually join them in Canada.

ZIERLER: Where did your parents meet?

MA: My parents met in California. I think they were introduced through an acquaintance. They did the typical thing at the time, which was talk on the telephone, maybe visited once or twice, and then my mom flew over to California to marry my dad.

ZIERLER: Where did they settle?

MA: Fremont, California, so that's where I grew up. My dad ended up working in Silicon Valley. He was an electrical engineer. My mom used to be a fashion designer, so in Canada she worked on the design floor making clothes. She recently gifted me a bunch of clothes she had made for herself like 40 years ago, super stylish stuff. Then when she married my dad, she got pregnant with me very soon afterwards, and she stayed as a homemaker, stay-at-home mom.

ZIERLER: What level of education did your dad achieve in electrical engineering?

MA: He got his bachelor's from Cal Poly, San Luis Obispo.

ZIERLER: What kind of work did he do? What kind of companies did he work for?

MA: Initially he worked for Tandem, which was a—I don't actually know what they did at the time. He was a technician with Tandem for quite a while. Then he moved over to Cisco, bounced around at a bunch of different Silicon Valley companies. Later on, they had layoffs when the economy had downturns. That must have been whenever in the 1990s, whenever that downturn was, the bubble burst. Then he had kind of aged out, wasn't one of the more agile young people to work in Silicon Valley anymore. Then he took a job with a Toyota plant that is in Fremont that has since become the Tesla plant.

ZIERLER: Did his technical abilities rub off on you? Do you think that was an influence?

MA: Oh, god no! [laughs] No. Not at all! No, not at all. My mom was actually the one that really loved science and really held science up to a high standard. We would always go to science museums. She would take me and my brother. Anything where we could learn, it was my mom who would take us there. We would talk about science that we heard in the news. She just had such a reverence for education, and for science, and smart people, that I think that's actually what rubbed off more.

ZIERLER: Growing up, what languages were spoken in your house?

MA: Oh! [laughs] The embarrassing thing is, I can only speak English. I can understand a little bit of Cantonese, but my parents came at a time where assimilation was super important, so they did not try to teach us Chinese. We were not put in Chinese school.

ZIERLER: Maybe it was their secret language when they didn't want you to understand, kind of thing?

MA: Yeah! My brother and I can kind of understand some. We can't speak. It's that strange thing. The other thing was, my mom actually—she wasn't like a tiger mom type of parenting—Chinese school was on Saturdays, Saturday mornings, and my mom actually wanted to preserve time for us to play and be kids. So my brother and I would watch Saturday morning cartoons instead of going to Chinese school.

ZIERLER: It was a fully assimilated household? There really weren't many cultural customs and things like that?

MA: We didn't follow a lot of Chinese traditions. We'll celebrate Chinese New Year, with the broader family. All of my dad's family is actually pretty close by, in California—Stockton, Oakland, this area. My mom's family is still Canada or Louisiana so also in Northern America. We would get together for family gatherings, but not a lot of Chinese traditions there.

ZIERLER: Your neighborhood growing up, was there a Chinese American enclave? Was it more diverse?

MA: There are a lot of Chinese Americans in the area. I went to Mission San Jose High School, which while I was there was probably 50% Asian, and that includes not just Chinese but Indian and Japanese and just the whole Asian area. I hear now that it's quite a bit higher than even 50% Asian. It was because Chinese Americans moved there because of the good schools, and everybody holds education as the most important thing.

ZIERLER: In middle school and high school, would you have considered yourself a nerd in the best possible sense? Did you love math and science? Was that your thing?

MA: I did. I loved science. Math, I actually was never that great at. I was put in Math 8—is it called Math 8?—at Caltech, the remedial math when you first arrive. [laughs]

ZIERLER: [laughs]

MA: And then I almost failed that. So, I am not good at math. But I always loved science. I'm pretty sure that no matter which field of science I would have ended up in, I probably would have loved it, to be honest.

ZIERLER: Who gave you the confidence that a place like Caltech was within range? Who was helpful in that regard?

MA: Oh, god. My mom was not familiar with the U.S. educational system and colleges, and I was the oldest child—my brother is younger than me—so we really had no idea how the system worked, or how I actually ranked, and how I compared, how competitive I was.

ZIERLER: Were you valedictorian? Did you ace the SATs and all that?

MA: I was valedictorian. I did well on the SATs. I had all kinds of extracurriculars. I did gymnastics and swimming. And of course I played piano.

ZIERLER: [laughs]

MA: Not well. Actually, I don't do any of those things well.

ZIERLER: [laughs]

MA: But my mom encouraged me to apply. She goes, "Just try." I was like, "Oh, I'm not going to get in, Mom." She was like, "So what? All it costs is the application fee, and that's on me, not on you. So just apply." So I said, "Okay." So, I did. My dream school up to then had been Stanford, mostly because Stanford was close by, and we used to drive over there. They have an excellent mall! [laughs] And I didn't get in. I applied to Stanford, early admission, and I didn't get in. So I thought, "Oh, okay, that level of schools, that first tier, I'm not going to make it in." But my mom said, "Just try." That year, the year that I applied, Caltech was number one on the, what, Newsweek or U.S. News ranking, like the first time ever. I had not—I actually didn't know of Caltech before then.

ZIERLER: Even in Northern California, it's a tiny school no one has heard of! [laughs]

MA: Yeah! Because I did not know scientists. I didn't have exposure to that world.

ZIERLER: Richard Feynman, Linus Pauling—these were not names that were familiar to you?

MA: Linus Pauling, I had known of. Richard Feynman, I actually did not. As opposed to a lot of the other undergrads coming in. I was just like, "Who?"

ZIERLER: [laughs]

MA: Yeah. So, my mom encouraged me to apply, and I did. Then pre-frosh weekend—at the time what Caltech would do was, for the females, they would actually pay for your flight to come visit campus. What they did at the time was—they've never lowered the bar for females or minorities, ever, for admissions—but what they would do is after you were admitted, they would make it easier for you to actually come visit. Because they were willing to pay for my flight, I made the visit to Caltech. Otherwise, my family didn't have a lot of money at that time, so I felt guilty to—well, it wasn't a thing. It wasn't a thing to get on a plane and just go somewhere! So I visited Caltech, I thought the campus was beautiful. I met other pre-frosh that were great. I liked the small school. That's how I made—and the other thing was, I did get into MIT, but I had heard at the time that MIT did lower the bar to let more females in so that they had a 50/50 ratio. I knew that that would just eat at me, when things got hard; I would not know if I was one of the ones who they had just let in!

ZIERLER: Oh, that's interesting.

MA: Even though people had warned me about Caltech being super-duper hard, I knew that I deserved to be there, and that made a huge difference in my thinking.

ZIERLER: What year did you arrive at Caltech?

MA: 2001.

ZIERLER: 2001. This is 31 years after—Caltech of course only starts to admit women in 1970, famously. Today it's almost 50/50. What were the numbers like in 2001? Was it on the way?

MA: It was three to one, at that time.

ZIERLER: Three to one, okay. So, there's like plenty of women but it's not half and half; that's how it felt, basically?

MA: Yeah. No, it definitely did not feel half and half. And many of the guys—well, okay, we're all kind of nerds at Caltech, not great socially anyway, right—a lot of the boys acted very weird around the girls.

ZIERLER: What house were you in?

MA: Fleming House.

ZIERLER: Tell me about Fleming House. What kind of experience was that?

MA: It's really very interesting—when you learn about the house process, you're like, "Okay, whatever," right? "It's a dorm. You can live anywhere." And it's not at all like that, right? You show up at Caltech; every house really has its own personality, and it finds the right people to be in that house. It's super cool, because I remember going around to these different houses, and I was just like, "Oh, I don't fit in here," "Oh, I don't fit in here," then you rotate into Fleming, and—you do dinner at that time; I have no idea what the rotation process is now—and then it just kind of clicks, and you're like, "Oh! These are my people! We have similar interests, similar personalities." The house just kinds of fits the person, and the person fits the house. It's kind of cool. It was the athletic house, at that time. I don't know if it still is. I found some amazing friends that I definitely still keep in touch with.

ZIERLER: Tell me about that first-year curriculum and how it famously beats up on undergraduates.

MA: Oh, god! Okay. I cried. A lot. I think the first two terms of freshman year are pass/fail, so you don't even have grades assigned to you. Coming into Caltech, I knew it was going to be hard. I did not worry about having to be the top of the class. That was not something I was too worried about.

ZIERLER: It's a humbling experience, right? Everybody is the valedictorian, so you're nothing special kind of thing, right?

MA: Exactly, exactly. I knew that I had made valedictorian in high school not because I was particularly smart but because I worked hard. In high school, that was enough to get by. You study, read the textbook, listen to the teacher, do your homework! At Caltech it was a whole different ballgame where just studying is not enough; you really need to truly understand. Caltech drills that into you, teaches you actually how from first principles you can actually derive this particular understanding for this piece of science. The other great thing about Caltech was how it teaches you the connections between those different scientific disciplines, which you can only get from truly understanding and not just memorizing a textbook. Those were all things that started to make a little more sense to me after I was on campus.

But the first—oh, the entire experience was hard! It wasn't just the first year! You're surrounded by these people that are absolutely brilliant. They're Physics Olympiad and Chemistry Olympiad champions, internationally. Everybody has done something cool. Some have gone to the Olympics. Some have built houses, or built their own machines to do whatever. And you're just like, "Oh. Okay. I'm just like middle of the pack here. Maybe." It's awesome, though. It's so stimulating. I think for me, I have looked for that in every job afterwards. I seek out the challenges, because I'm no longer afraid. Caltech teaches you how to think, not just what to think, and so that was really useful. But, back to the first two terms, I do remember crying a lot, and then calling my mom I think second term of freshman year saying, "Mom, I can't do this. I'm going to transfer." My mom said, "No, no." She said, "It's okay. If you need to take five years, six years, that's okay, but if you quit, you are going to regret this for the rest of your life, because you're going to think that you can't do things." She knows my personality, right? And I was like, "I [laughs] don't want to be here five years or six years! I want to get out!"

ZIERLER: [laughs]

MA: She was like, "No, no. Just hang in there. You don't have to get great grades. That's not important. Just enjoy your time there." I think what I most enjoyed about Caltech, though, was the breadth of different things you get to do because it's such a small school. So, I was on the swim team. There was no other college in the U.S. that would let me on their swim team; I can guarantee you that. [laughs] I am not a great swimmer. And, I got to be the editor for The California Tech, the undergrad newspaper. Walk into the dean's office when I needed to, when I had a problem. Interact at all levels with the different professors, students. It was awesome.

ZIERLER: Tell me about deciding what course of study you would focus on.

MA: Actually, one of the reasons I picked Caltech was because I wanted to be an aerospace engineer. During pre-frosh weekend, we got to go over to JPL and visit the JPL campus. I saw the duplicate of the Mars rover. They showed you mission control. I was just like, "Oh my god!" Like just to be in the vicinity of this amazing stuff that's happening. And, I wanted to be an aerospace engineer, so there's really no place better if you want to do that kind of stuff.

ZIERLER: Who were some of the professors that you really remember or that you learned a lot from?

MA: [laughs] I don't know if I remember their names, quite honestly.

ZIERLER: What were some of your favorite classes?

MA: Jean-Paul Revel, who was dean at the time—and I didn't take classes from him, because I wasn't a bio major—but I remember how kind he was to the students, and how he treated us as equals. Because I did a lot of—not student government, but like leadership things, where I was in touch with him. That is something I try to propagate now to the students I work with. Then also Hall Daily, who—I don't know if he actually—I don't know what he taught; he was our advisor for The California Tech. You know this—it's not easy being at Caltech and not being a science professor, and not science being your thing, all the time. But Hall had a way of helping us to kind of see beyond Caltech. Because while you're there, it's this lovely little bubble, and it's wonderful. But Hall, because he was our journalism advisor, was able to help us to connect things going on, on campus, to the outside world, and help me to see what it means to do science and have impact outside. And also not to take things too seriously, as well. Because there were a couple times where I got very, very upset, because some student had done something stupid, and Hall helped me to put a better perspective on just life in general.

ZIERLER: What did you do during the summers? Did you have SURF fellowships? Did you go back home?

MA: I did SURFs. I absolutely took advantage of that. For the three SURFs that I did—after freshman year, after sophomore, after junior year—I did all of them at JPL. The first year was in astrobiology, because I did not have enough engineering or physics expertise yet to do some of the other aerospace stuff I wanted to do. So, my project was at JPL to look at contamination of space with Earth-bound human bacteria, and how do we prevent that on our spacecraft that we send into space. I'm still in touch with those SURF advisors at the time. Then my second two SURFs were on plasma thrusters. That's what got me into plasma physics, in fact.

ZIERLER: Ah, okay, I was going to ask, about the plasma thrusters, why that was so formative for you.

MA: I worked on a team that was developing these plasma thrusters for deep space missions. The idea with plasma thrusters is they ionize a gas to generate a plasma. And the amount of force they create is equivalent to a piece of paper on your hand, so just tiny. But for these deep space missions over very, very long space scales, you can accelerate up quite significantly. During my summers there—I think the first summer was to help build kind of an experimental apparatus that would move a Hall thruster around systematically so that we could measure its output. Then the second year was actually to make those systematic measurements of what the plasma flow looked like. I think that's mostly what it was. It was just super fun! It seemed like play, not work at all. I met some really great people, again that I still keep in touch with now. When it came time to apply to grad school, they ask you to write a statement on like, "What are you really interested in? What do you want to do?" You only know as much as you've experienced, really, and so for me, I was like, "All right. Let's do plasmas! Because I have a tiny bit of experience there!" That's how I ended up in this field.

ZIERLER: How much physics did you have as an undergraduate? I'm just thinking, how much did you have to catch up in graduate school?

MA: Just the standard core curriculum at Tech, nothing beyond that. But, it turns out it was more than sufficient to prepare me for grad school. I took a lot of physics in grad school. I was in the Mechanical and Aerospace Engineering Department at UCSD for grad school, but most of my courses were in the Physics Department. I did just fine.

ZIERLER: Your degree is not in plasma physics; it is in aerospace engineering?

MA: Yeah, even my PhD is aerospace engineering.

ZIERLER: Oh, fascinating. Is that unique, having the plasma physics background in aerospace engineering? Is that a common combination of disciplines?

MA: Actually, yeah. In plasma physics, there are very few pure plasma physics degrees that people have. Everybody I've talked to in the field, their courses are kind of piecemeal, from electrical engineering, nuclear engineering, plasma physics, mechanical, all kind of brought together. We have people with all different types of backgrounds.

ZIERLER: What kind of advice did you get, or how did you know where to apply, for graduate programs?

MA: At the time, actually when I was about to graduate Caltech was when SpaceX was being kicked off, and Elon Musk hired a lot of Caltech people at that time. For me, I was like, "Well, I want to do aerospace. This is a space company. I could just take a job there." It was only because my friends were all applying to grad school at the time. I didn't really know what grad school was, actually. But I figured it would be easier to just stay in school now and get it done, rather than go work for a while and then maybe do a PhD. That's why I applied. I just kind of looked at schools that had aerospace programs that were interesting.

ZIERLER: This was not a "go to graduate school and become a professor" kind of thing for you?

MA: No, it never was. I'm not sure I've ever really wanted to be a professor. Teaching is not my forte!

ZIERLER: Tell me about arriving at UC San Diego. What was that like?

MA: Oh, it was overwhelming in a way, to go from a school that has 2,000 students total to a school with 25,000, and I felt a little bit lost. At Caltech, we're kind of half and half, undergrad and graduate students, so the emphasis on research and the emphasis on graduate level work is very, very strong at Caltech, probably stronger there than anywhere else that I know of, whereas at UCSD, it's the undergrads—20,000 undergrads, 5,000 grad students at the time. The grad students are just in the noise; nobody really cares about them. I would walk through the student quad and all of the frats and sororities would like hand me flyers, because I looked young at the time, to try to join. I was like, "No, no, no, no." It was actually quite a tough transition for me, and I don't think I actually particularly enjoyed my year in San Diego. Soon after that, I came up to Livermore, actually, to do research, because we didn't have a laser in San Diego.

ZIERLER: So you only did one year at San Diego before coming up to Livermore?

MA: I compressed my classes into a year so that I could then focus on research full time. It wasn't that many courses. I think it was like 10 or 12 required classes that you had to do for your—almost basically your master's, I think. That's three or four classes a term. Everybody was like, "No, you can't do that. That's too many." I was like, "Yeah, but at Tech, everybody does five or six or seven a term."

ZIERLER: [laughs]

MA: "I got this." [laughs] I think Tech actually prepared me really well for grad school, because you get beat down at Caltech [laughs], year one, and you don't expect to be the smartest, and you also know that grades are not necessarily the most important thing. It's how you can perform in the lab and what ideas you can bring. So, in grad school, I didn't stress about classes and grades at all.

ZIERLER: In taking this compressed schedule and figuring out where you could go, how did you learn about the program at Livermore? Did they have an arrangement with UC? How did that work?

MA: My professor, Farhat Beg, at UCSD, when I visited with him—so, you get into the school, and then I spent a day visiting different professors to get a better feel of the school, what types of research there might be—Farhat had said to me, "I collaborate strongly with Lawrence Livermore. My group does experiments up there. If you want, we can send you up there." I was like, "All right. Done." Because that's where I wanted to be. Because I had worked at the Lab between high school and college, the summer of 2001, the summer of 9/11.

ZIERLER: Oh, wow.

MA: The summer of 9/11, I worked at the Lab. I loved it, and I loved the people, and I loved the atmosphere. But what was funny was, at the time—so this was between high school and college; I didn't have my own car yet—my mom would actually drop me off at work every day, and she could drive into a part of the Lab and drop me off in front of my office. 9/11 happened, and the next day when she drove me to work, there were guys with machine guns like standing at the gates. Since then—things have changed.

ZIERLER: Tell me about Farhat's research.

MA: Farhat does all different types of fusion, plasma physics. He has a large portion of his group that does laser experiments. Then he also has a little lab on campus where he does pinch physics. What you do there is you have very thin wires in different configurations, and you can send electrical currents down there. Then, because of an instability, those wires will always pinch. You send a current through, you drive a magnetic field, and then the wire actually pinches. When it does so, you create copious x-rays, sometimes other particles too, and you can study plasmas that way. What Farhat actually does is all types of different plasma physics in the regime of high energy—we call it high energy density—so very high densities, temperatures, pressures.

ZIERLER: What was the initial project at Livermore, coming from San Diego?

MA: I started doing work related to my thesis from the very beginning. It was looking at lasers interacting with solids. You have these very, very intense lasers—we call them short-pulse lasers—and what they can actually do is—if you take all the light from the Sun and you concentrate it into a centimeter square, the lasers that we use are a thousand times more intense than that. And so, what you can actually do is, in the laser field, the photons are wiggling; they can directly liberate electrons from the atoms. If you're hitting a solid target—it can be copper, titanium, whatever—the laser is actually strong enough coming in that it can wiggle the electrons directly, in that solid, and so you can generate beams of particles. Those electrons will start following the laser, and you can get beams of electrons, or beams of protons. My work from the very beginning was to look at the electron transport that you get, how those electrons move from this type of laser interaction.

ZIERLER: What was the arrangement administratively? Was this like a pre-doc? Were you at Livermore as a UCSD student? How did that work?

MA: Farhat is very generous with his students. He really wants the best for his students. He's not possessive of us to like do exactly what he wants. Initially I was just—Livermore has a class where we have visiting scientists, where we can bring in professors, and they can get a badge and work with us. I think for students, there's an academic level for that. So, I got to sit at Livermore, but UC still paid for me. Farhat paid for me. About two years in, I got a Livermore graduate fellowship, scholarship, that actually paid my tuition and my salary.

ZIERLER: What do you see as the primary conclusions of your thesis? What did you learn? What did the field learn?

MA: What my field learned was—the application for this work was actually a fusion approach called fast ignition—we talked about this at the very beginning—where you can separate the compression and the heating. These electron beams that we were generating could be used as the heating source. What we found was that the generation of these electrons is very, very dependent on a laser characteristic called the pre-pulse. A super energetic laser pulse won't just come in a chunk; stuff will leak out beforehand, just through how it gets amplified, and that's called the pre-pulse. The pre-pulse is energetic enough that it actually creates a plasma before your laser actually comes in, and that pre-pulse has significant implications for both the absorption physics and how this electrons are generated. The bulk of my thesis work was to quantify the effect of this pre-pulse on electron generation.

ZIERLER: Did you maintain an apartment at UC San Diego, or did you just move your entire life to Livermore and you just went back to defend?

MA: The first year, I was in San Diego full time, so I had an apartment. The second year, my best friend still stayed in—she was my roommate my first year, and then the second year she was still in San Diego working at Johnson & Johnson. She moved in with a group of other girls, and whenever I was in San Diego, I would just stay with them. But everything else I actually moved back to my parents' house in Fremont, which is just over the hill from Livermore.

ZIERLER: Super convenient!

MA: Yeah. But at that time, you value your independence more, probably. [laughs] But it was convenient because I was traveling back and forth.

ZIERLER: When did all the research translate into interest, both from you and the Lab, of having a career there?

MA: Oh, immediately. Even after my high school internship, I really liked national labs, and I thought it was a good combination of doing science that has impact, but not necessarily commercial science, as in industry. The bottom line for us is doing the good science. I saw industry as in many cases the bottom line is trying to make money. If you're lucky enough, you can also do great R&D, great science, but for me, a big motivator is mission, and I really liked the idea, the mission space, of doing something of value for the country.

ZIERLER: In your first job as an employee, how closely related or not was that to what you were doing as a graduate student?

MA: It was pretty closely related. The NIF was being constructed, the entire time. In fact, when I was here in high school, I actually got to walk underneath the NIF target chamber, because they had to put in the chamber first, and then build the building around it. The summer I was here, they had just put in the target chamber, so I got to walk underneath. They had explained it to me, and I did not understand, at all, what they were talking about. [laughs] I just knew it was big science. Straight out of graduate school, it was a very good skill set to bring into the NIF project. I came in doing a couple of different areas of research. Oh, because initially, they did not allow postdocs to work on the NIF yet. Because it's such a complex machine—there were still a lot of unknowns at that time for how to do experiments, and how to operate effectively—we didn't want postdocs involved yet. I was the very first postdoc to do NIF experiments. The whole time, I was telling my supervisor, my boss, "I want to be on NIF. I want to do NIF experiments. Put me on." So, I always knew. But the work that I was doing anyway, the projects I was working on, were very related, just plasma physics type fundamental science.

ZIERLER: Did they make an exception for you, or did they change the rule and thereafter postdocs were allowed to use NIF?

MA: What happened was, we realized how big a project it was, and we needed people, so they agreed to train me up to actually do NIF experiments. The very first time I ran a NIF experiment—at the time, most of the shots happened overnight. We would all day be prepping for the experiment, like switching diagnostics in and out, getting the target ready, like tons of people running around. Then at night, when you actually fire the laser, it's not as intensive. You actually don't need as many people there. We would do our experiments at night. So, I was there, in the middle of the night—and I had shadowed a bunch of more senior scientists evenings previous, and then one of the evenings, they were like, "All right, Tammy. We're going to leave you. Call us if anything goes wrong." I walked into the control room, and like a total idiot, I'm like, "Hey, guys! What's up?" And they're super serious. They run it like a submarine control room, right? They take things seriously. [laughs] The shot director in charge was just like, "I don't know who you are. Get out!" [laughs] So they had to throw me back out, and I had to call my mentor and be like, "Sorry, I do need you to come back in." [laughs]

ZIERLER: [laughs] To go back to that idea that it's not private enterprise but it's science with impact, in the early years when you joined officially, what was the rough balance between fundamental research and really thinking about applications? How did that work? Is it all rolled into one? Do you have separate aspects of the day?

MA: It is all rolled into one, and I don't think it has actually changed so much. We're very aware that the work that we do is quite fundamental. Every experiment is a little bit different, and we publish in academic journals most of what we do, actually. The application space is—for example, developing a neutron source that is super bright that you can use for testing of materials degradation or something like that—I would say all of it is both very fundamental and very application driven. We do care very much—we very rarely do something just to make it work. We will do the physics modeling to understand the underlying physics of how some mechanism actually goes.

ZIERLER: It sounds like it's all rolled into one. It's a very unique approach. It's not one or the other.

MA: Yeah.

ZIERLER: Is all of your research at the Lab—I don't know if mission is the right word—but are you ever allowed or able to do your own thing? Like if you have a professor, and they're interested in this, and they want to go off and do that, is there opportunity to explore that aspect?

MA: Very much so, actually. Curiosity-driven research is a big component, also, of what we do, because we know a lot of innovation comes out there. We are actually mandated by Congress—the national labs are, within the DOE complex—to take some of the money that comes into the Laboratory and turn it around into internal funding for competitive proposals internally. We call it Laboratory Directed Research and Development, LDRD. Around 6% of the money that is brought into the Lab goes into the LDRD program, and we annually have a cycle where we apply for funds for—crazy ideas. Occasionally the Lab will say, "We'll solicit proposals in this area, or this area". Last year, we did solicit proposals in inertial fusion energy. LDRD brings in a whole bunch of great ideas. It's a huge recruitment tool for us at the lab and creates a lot of patents and publications. I love the program so much that I actually served as the Deputy Director for LDRD—two years ago? Yeah. I did that for only a year, though, because then inertial fusion energy started picking up, and I moved over to concentrate on that.

ZIERLER: You have such a unique perspective of seeing the NIF being built to where we are today. Where in the narrative—that December 2022 announcement and what it means—when in the narrative of your time at the Lab did it feel like this was happening, it was headed in this direction? Is that really like day one, or does it happen—in 2016, is there like a paradigm shift? How do you think about that?

MA: I think December actually caught a lot of us by surprise. I always expected that we could achieve ignition on the NIF, but it had been such a long time since we started the project that—you know. And we're shooting every day; you stop thinking, "This will be the one. This will be the one." But one thing that Caltech trained me well in was to accept—failure?—or look for failure, even. Because you start doing research so early, you're actually in the lab, you get a very good feeling of how arduous research can be, how slow it is. At the same time, you are learning from every single experiment. There is no failed experiment. Unless you actually wasted resources and learned nothing; that might be a failed experiment. But otherwise, you're always learning something. I never got discouraged working on the NIF, because we were always doing something cool and something new. But, that being said—I was working full-time on the ignition campaign, the ignition project on the NIF, from basically when I started as a postdoc until 2018. Around 2018, I actually stepped away to start working on fusion energy.

At that time, it was more like kind of building—we weren't allowed to say the word "energy" for quite a while, actually. Because after we weren't able to get ignition after a couple years, our funding agency, the NNSA, the National Nuclear Security Administration, said to us, "Hey, guys. The energy stuff is a distraction. We want you to focus on stockpile stewardship." So we actually were not allowed to talk about energy for a while. But then around 2018, actually the NIF director at the time, Mark Hermann, and I started going out in the community and trying to build up support again, for fusion energy, starting to feel the waters. We participated in a lot of DOE workshops and reports to start injecting the idea of IFE back in there. It was the idea that, "Hey, we may actually get ignition someday, maybe someday soon, on NIF; we have to be ready for the next steps." And if we don't get ignition, then what is Livermore's backup plan, as well. In that sense, I also started doing—and my group right now actually works on what we call high-repetition-rate HED. The NIF shoots once every four hours, eight hours; new lasers today can shoot at 10 hertz, 10 times a second. So, you have to change how you do experiments.

Then you start incorporating ideas of big data, bring in machine learning. That is where our field is headed. My group is trying to bring up the capabilities to actually take advantage of these new lasers. It was both, okay, if we don't get ignition—well, okay—we have to bring up high-rep-rate, no matter what, anyways, and then, if we get ignition, we have to be ready to push energy, because that's what the world is going to care about. We have to know how to answer the questions. We have to lay out the roadmap. What I've learned over the past couple years is how much impact each scientist—I'll keep it to science—each scientist can actually have in the overall ecosystem. It seems like the government decides what science to fund and how much money to put in, but really that input comes from scientists down working in the field. It is what we advise the government on, and how we want to push things, that really drives how things actually happen.

ZIERLER: This idea of not being allowed to talk about energy, I'm curious, you've been at Livermore now long enough where you've seen presidents come and go, and secretaries of Energy come and go. The shifting political winds in Washington, do you feel that at your level? Is that a factor in how things operate, what budgets look like, what science can be done?

MA: Absolutely, yeah. It was worrisome when Trump took office, because he doesn't hold science in the highest regard. And, we did see science budgets shrink in the U.S., and that has major implications for us at Livermore. Oddly enough—okay, not oddly, but—he actually had a fondness for the weapons complex and nuclear weapons, so we actually did see our budgets grow in that area quite significantly, in terms of modernizing our weapons stockpile, and a lot of work there. But, yes, with every administration change, and actually constantly with the churn that you have in Washington, part of our job is not just to do good science, but to communicate that science, and also influence how we spend our funds in the U.S. to ensure national security and competitiveness in all of these different scientific realms. My job, certainly, and the job of quite a few scientists here at Livermore, is to constantly go to D.C. and talk to our lawmakers, so that they understand both the pros and cons, the dual use nature of our different technologies. If we're trying to push AI, how can we really use AI to push forward all of these different areas? Bio and looking at developing new proteins. Developing the COVID vaccines. How can we use the resources within the national lab complex to solve urgent problems? Like COVID, for example. For me, a lot of my job is advocacy now, which doesn't just—it happens constantly. Because every year a new budget is put together, and you have to make sure things stay funded. And then also, each time an administration changes, there's huge differences in priorities for that administration that we need to try to influence.

ZIERLER: When you joined the ignition effort into 2018, how well developed was it? Or was that really you joining was part of staffing up and getting much more sustained interest in this?

MA: I was incredibly lucky, because we had gone through a downturn just beforehand, and when I had graduated, we realized we needed to staff up again to actually run the ignition project. Your question was more specific than that?

ZIERLER: No, just that when you joined, how much can we read into just a new direction in 2018, where the Lab wanted to go?

MA: Oh, in 2018! Oh, when I joined the energy effort.


MA: A small team of us had, since kind of 2018, kind of been developing the foundations for fusion energy again, inertial fusion energy again. After ignition was achieved, it brought a lot more attention, a lot more momentum into the system, for sure. I'll have to get back to you in a few years! We right now do have a lot of support to grow fusion energy as a program, and so I think, yes, that is a new direction. Whether or not it grows into a sustained R&D program depends very much on how successful we can be in getting public funding. Right now the private companies are certainly bringing money into the system, and we do contracts with them, to work with them, but private companies generally kind of come and go. You need sustained government investment for something as challenging as fusion. We'll see if we can make that happen. If we're successful, then yes, I would say it's a new direction!

ZIERLER: Moving our conversation closer to the present, when COVID hit, you can't do ignition by Zoom; what did that mean for the Lab? What got halted? What levels of automation were possible that things could keep up more or less as they were?

MA: Not only can you not do ignition and experiments by Zoom; a lot of the classified work that happens here at the Lab has to be done in person, in protected areas. The Lab is very, very good at dealing with crises in a way that is actually empathetic and understanding as well. Our Lab leadership was fabulous. They communicated well the entire time. We're a science lab, and people generally believe in science, so we could track the COVID rates and make decisions, following that, on how to stay safe, and at the same time bring people back to the Lab. I think maybe just a week or two after COVID started, they found ways to keep the different facilities running that had to be running, and certainly the NIF. They found ways to bring essential people back on site safely. Of course everybody stayed in masks. They put all kinds of the plastic shielding up that at the time was what everybody was doing. Figured out how to stagger the workforce. But we were back to running shots—I don't know the exact date, but within two weeks of COVID happening. A lot of the things can be done remotely, and so we expanded that where we could, and then only had essential staff on site. But we really did not lose too much productivity in that area.

ZIERLER: The notion of achieving ignition—I can imagine how a Hollywood director would portray this. It's like JPL—

MA: [laughs]

ZIERLER: —JPL Mission Control, the rover lands, everybody is high-fiving and jumping up and down. Is there a dramatic moment like that? Or it's much more incremental and looking at the computers and making sure that the numbers make sense? I wonder if you could narrate that process.

MA: It's much more incremental. It's funny, because when I was running experiments on the NIF—like I mentioned to you, we would do those shots overnight—for many of my shots, they actually sent a film crew in there, with me, to film, because that shot was going to achieve ignition.

ZIERLER: Meaning they recognized the historic nature of this?

MA: Yeah, absolutely. Shots take quite a long time. They're faster now, but back in the day, they definitely took six, eight hours or more, to actually execute. So, we would just be sitting in the conference room, it's like 3:00, 4:00 a.m. in the morning, and I would fall asleep. Then the [laughs] guy behind the camera would fall asleep. Then after we did this like three or four times, the camera guy was like, "You know what? I don't think we're going to get ignition any time soon." And like every time, it looked the same; it's just me sitting in front of a computer, and when the shot goes off, then kind of the online dashboard basically starts to propagate as data flows in from all the different diagnostic instruments, and you're just hitting refresh as fast as possible to try to get more numbers to come in. It's actually kind of anticlimactic, because it's so well run. You hear the capacitor banks fire to release the energy into the laser, but don't actually hear the shot itself. All you hear is, over the radio, the shot director saying, "Doing the shot countdown," and then he's like, "Yep, shot completed."

ZIERLER: What is the moment of confirmation? There has to be some moment where you figure out this is the real deal.

MA: The moment of confirmation comes with all of the data streaming in. Then we have many different detectors, diagnostics, for example reporting the neutron yield. It's not just one single measurement. Things do get scrubbed, though, manually, by humans, going back over the data to check on the error bars and such. From what I hear on that big shot day, the shot physicist, the responsible physicist at the time, he was at home watching the dashboard and the numbers propagate, and he got excited because he saw big, big numbers, and so he started calling some of the other physicists, waking them up, and then everybody got up to try to check. Then over the next week, actually—it takes about that long for some of the numbers to actually come in—because some of our most accurate measurements are activation detectors. It's really pieces of metal, stuck around the chamber, that activate when the neutrons hit them, and then you stick them in a counter and you watch them decay, and from that decay rate you can reconstruct a very accurate initial number. But that decay takes—time. That's why it takes us a little while to check those numbers.

ZIERLER: Just as a frame of reference, if you've been following, at Fermilab there's a lot of excitement over these wobbling muons, and this might break us beyond the Standard Model. But it's so nuanced. It's like a sigma 7, and they're bringing in theorists, and it's going to take a year. So, how exact is the confirmation? Obviously the stakes are big from a PR perspective, but how nuanced is the "did we or did we not achieve ignition"? How easy is that binary to establish?

MA: In this case, for the ignition shot last December, it didn't need to be that nuanced, because we generated so much more above the ignition threshold, 50% more, that we weren't even close to the boundary. That being said, we have not published the paper yet, out of that December shot, because we are still working through not just the neutron yield numbers but making sure all the other data correlate. So, the 2D x-ray images that we get, there's a certain brightness of x-rays that is correlated to the temperature and density of your plasma, which should match the yield that you got. Everything should make sense, in that way, and all fit together. We are still working on some of that.

ZIERLER: What was the thinking that the announcement was ready to go out but the paper is still in production? How do you measure those confirmations?

MA: That was a big debate. Because for us, in the fusion field particularly, we have been dinged many, many times, by people hyping things up that are not true. For other milestones along the way, we did not make the announcement until the papers came out. But in this case, we knew that if we did not do a press—I mean, this is such a big breakthrough, and we're so much beyond what we knew we had to hit for ignition, there was no doubt that we had done it, that we were confident in doing that press conference. There was no way that we could analyze the data or fiddle with the interpretation in a way that made us unsure. We knew.

ZIERLER: I know you're going to preempt me here and say that there's so many people involved in making this happen. I totally get that. Yet the objective reality is, from a public communication perspective, you are doing so many of the interviews and all of that. Were you already involved in public communication up to that point? Were you the obvious person to do this just based on the science and your position? What was the decision-making in that regard?

MA: Good question, and I ask myself that [laughs] all the time, too.

ZIERLER: Also, as a woman, as a woman of Asian descent, is there inspiration to lean into, in that regard, also?

MA: Yeah. Nobody has actually ever said that out loud before, but absolutely I'm sure that plays into figuring out who should deliver the message. In large part, I have been doing a lot of science communications my entire career. I've taken it very seriously, at all levels. I go and speak at elementary schools and do public lectures. I've had a lot of training, in that sense. I give a lot of NIF tours. That's a form of service, but it also teaches me to know how to talk about the facility and teaches me how to communicate to different audiences. I also, in recent years, because of how involved I've been in policy, talk to a lot of the VIP visitors that we have to the Lab, whether they're ambassadors or members of Congress coming, or whatever. I think that trained me to do a lot of this communications. I think I'm also just incredibly passionate and excited, still, to talk about all of this, and that's important in connecting with the public. So, that's [laughs] probably why!

ZIERLER: Now that we've worked right up to the present, for the last part of our talk, I'd like to ask a retrospective question, and then we'll end looking to the future. I don't want to burden you with all of the ways that you have been recognized and honored in your career, but I do want to ask if there have been any awards or professional memberships that have been scientifically useful to you, that being recognized in this way is actually good for the science, in terms of both your own research and making the field inclusive, and making people inspired to become a part of it. I wonder if you could speak to that.

MA: I think in general, the awards for me have been most useful in giving me breadth and giving me the confidence to know that—it makes me less afraid to ask questions, basically. It gives me the confidence to know that I fit in, I belong, and people see that the work I do has value, so therefore I can be the one to ask questions, ask stupid questions, and that helps other early career people in the room, students with us, to see that, "Oh, yeah, it's okay," and to help them make room as well for themselves. In that sense, all of the awards have been super helpful for that. The award that I won—I think it was 2016—the American Physical Society Stix Award, the early career award—that came from our APS, our professional society, for scientific work. That was quantifying the level of hydrodynamic mix that we had inside our ignition implosions—or, implosions that had not achieved ignition yet. Through that work we were able to establish one of the key mechanisms for our lack of performance on the NIF for quite a long time. That one means a lot, because it is for scientific accomplishment. Many of my awards are more for leadership, or communication, which is wonderful, and I'm very thankful, but you train your whole life to be a scientist. Also, as a woman, you always worry that—I worry that I'm doing media, and I've been picked to do this, because I'm a woman.

ZIERLER: It's like the MIT concern.

MA: Yeah. You still get plagued by that. So to be recognized for a piece of scientific work means a lot.

ZIERLER: This question is going to be one for the history books—that when nuclear fusion is achieved in however many years, this is exactly where we are now—to put a reality check on the phenomenal breakthrough that is achieving ignition, where is that relative to what actually needs to be created so that this becomes a major part of our energy infrastructure? How do we conceptualize where we are now, versus "We have this limitless abundant energy and we can use it for everything, and this is where we are"? Where are we now relative to that ultimate goal?

MA: You've heard the analogy of the Wright Brothers moment being used, and I actually think that one is really quite apt, because the Wright Brothers, the first flight that they made, that moment of lifting off the ground, is this; it's ignition. At the time, there's no way they could have imagined that they would open up an entirely new transportation sector and entirely revolutionize the way people live. The other analogy that I like to use is just 54 years after the Wright Brothers demonstrate flight, Boeing launched their first commercial passenger flight. It was 54 years, the Boeing 707, and the wingspan of that 707 is longer than the entire Wright Brothers flight. So, you think, "Oh, wow, that's really fast, just 54 years." That's within a typical lifetime, maybe half a lifetime, three quarters of a person's lifetime. In order to make that happen, they needed advances in so much more than the theoretical understanding of how flight works. You needed engineering. You needed new materials to build that airplane. You needed to build up infrastructure and government regulation for this industry. That's where I see fusion now, as well. You have to advance so many different technologies to make this all come together. All of those technologies alone can't do it. It has to be built on a particular moment in time and advances in all of these different sectors as well, coming together. Like it wouldn't have helped if the Wright Brothers had demonstrated flight 100 years earlier, because we didn't have the techniques to weld steel together, or whatever, to make that happen. I think we are at that point for fusion right now. Hopefully we can use ignition to help spur some of these other technologies as well. That 54-year timeframe that I just described for flight seems like the right order of magnitude to make fusion happen, too.

ZIERLER: I won't ask you to predict the future, but if you can provide perspective on these debates—"We'll get there in five to ten years"; "We'll get there in 20 to 30 years"—what explains that range, of informed people who know what they're talking about? Is it just different levels of optimism? Are they using different metrics? How do you understand this debate?

MA: When you hear the five- to ten-year timeframe, that is incredibly fast. That timeline usually comes out of the mouths of private startup companies who have to respond to VC funding and are still trying to fundraise. They have to be overly optimistic and promise a return on investment in a relatively short timeframe. Those of us that have been in the field a little bit longer, have actually done real experiments at scale, I think we're a little more tempered in our predictions. But it really depends on the level of investment and support and will. If the U.S. said, "We really want to get serious of fusion energy. Let's do a Manhattan Project type concentration of expertise and where we're going to focus on," yeah, I think we could do it in as fast as 10 years. But more likely it will be longer than that, simply because—we're trying to build up the funding and support. It's really not there right now. It's just not enough to make—in all science, your progress is directly related to funding, really. Also, each of these different technologies requires quite a bit more maturing, and so it will take time. We can do it all in parallel, so that's okay, we can make a lot of progress. But it will probably be at least 10 years, more likely two or more decades.

ZIERLER: Last question, looking to the future. Five, ten years, twenty years, thirty years—where do you want to be as all of these things develop? Is there an increasing administrative or even a policy role if there needs to be this national push for more funding? How do you see yourself contributing?

MA: Certainly in probably the next few years, really getting a robust IFE program off the ground for both the U.S. and Livermore. We're actually seeing a lot of interest internationally as well, so helping other countries and other governments to grow their IFE sector. We're very open to—we need the help! Longer term beyond that, I have no idea. I have never had a five-year plan. I've never had a particular position that I wanted to hit. There was always new challenges, exciting new things to do at every step of the way, and at every point, I just made the decision for what seemed the most fun at that moment in time. That's what got me here.

ZIERLER: It has served you well so far!

MA: Exactly.

ZIERLER: I want to thank you for spending this time with me. It has been an awesome conversation. You're a huge point of pride at Caltech, so I just want to thank you so much.

MA: Thank you!