No one anticipated how Kelli Humbird’s summer internship at Lawrence Livermore would fuel her doctoral research and future career. While an intern with the Strategic Deterrence team, Kelli trained a machine learning model to interpolate between tens of thousands of Trinity supercomputer data points generated from nine parameters like various asymmetries, drive multipliers and gas-fill densities that affect the quality of inertial confinement fusion implosions. Kelli’s work evolved into a DOE-funded Laboratory Directed Research and Development project, and she became a Livermore Graduate Scholar while completing her Ph.D.
Kelli views her internship work as a “happy accident.” She says, “I was at the right place at the right time and given the right dataset. None of us were expecting a summer project to turn into something this big.” Now a design physicist at Livermore, she continues to apply machine learning tools to traditional weapons physics models. Kelli is also a member of the Global Security Directorate’s Nuclear Forensics Group’s emergency response team and works on projects that build machine learning tools for stockpile certification applications and for modeling the spread of COVID-19.
Kelli received her Ph.D., M.S. and B.S. in nuclear engineering, as well as a B.S. in physics, from Texas A&M University.
For an undergraduate student in nuclear engineering and radiological sciences, a summer internship at Lawrence Livermore National Laboratory was something Annie couldn’t pass up. “I was immediately drawn to ‘the big laser project’ and intrigued by the idea of a grand scientific challenge,” says Annie.
Annie returned to the Lab as a graduate scholar and then a Lawrence postdoctoral fellow. Today, she works in the Design Physics Division, designing and simulating inertial confinement fusion (ICF) experiments fielded at the National Ignition Facility (NIF) and is a team lead within the ICF program. Annie was the lead designer for the recent ICF experiments that achieved fusion ignition.
“The science that can be achieved in my field with the Lab’s available resources — hardware, technology and expertise — is unsurpassed and keeps me excited and challenged. Also, the close relationships that I’ve formed at the Laboratory and working with those people to solve difficult problems keeps me engaged,” she says.
With all her work responsibilities, Annie has more at home, where she’s raising three young children. “I’m proof that you can be a powerful leader of campaigns in groundbreaking science and have a work–life balance. Multidisciplinary teams benefit from having diversity, and people who think differently all contribute uniquely to solving problems. Women in science are no exception.”
Annie has a Ph.D. in nuclear engineering and plasma physics and a M.S. in nuclear engineering from the University of California, Berkeley, and a B.S. in nuclear engineering and radiological sciences from the University of Michigan. Annie was selected as a fellow of the American Physical Society in 2022, and was named to TIME’s annual list of the 100 most influential people in the world in 2023.
Sabrina started studying physics at the Julius-Maximilians-University Würzburg, Germany, in 2000. After three years she transferred to the University of Texas at Austin and received a M.A. in physics. In 2009 she received a Ph.D. in plasma physics from Imperial College London, UK. Her thesis work studied electron acceleration mechanisms in relativistic laser-plasma interactions.
After finishing her Ph.D., Sabrina worked as a research associate in the Plasma Physics Group at Imperial College London. In February 2011, she joined the HED Shock Physics Group at LLNL as a postdoc, where her research included dilation x-ray imaging. She has since been working on x-ray detectors for the National Ignition Facility (NIF) that can take images of implosions with unprecedented temporal resolution.
Sabrina became a group leader in the Physics division in 2018. She is the physics lead of the dynamic x-ray detector group for NIF and works closely with engineering and operations. She also regularly runs NIF shots for inertial confinement fusion (ICF) and high energy density campaigns.
Arthur Pak is the lead for strategic development for the inertial confinement fusion (ICF) program at Lawrence Livermore National Laboratory (LLNL).
After receiving his Ph.D. in plasma physics from the University of California, Los Angeles, in 2010, Arthur joined LLNL’s National Ignition Campaign as a postdoc and worked to identify the origins of asymmetries of inertial confinement fusion implosions.
Following this, he helped to develop and minimize the symmetry degradation of ICF implosions using an alternate high density carbon ablator. From this work in 2019, he received the Presidential Early Career Award for Scientists and Engineers for quantitative assessments of degradations in ICF implosions and for contributions to achieving milestone fusion energy production.
Also starting in 2019, as the experimental lead for capsule science, Arthur coordinated a multidisciplined research group that brought together experiments, modeling and target engineering to identify the origin and impact of hydrodynamic mix on the performance of ICF implosions.
In 2021, as the stagnation science team lead, he helped to develop and coordinate the ICF experiment portfolio and analysis of data focused on understanding how to achieve ignition.
“I like working on the lab because you get to work with nice people, on hard problems, that matter,” Arthur said. “The laboratory is unique in this respect, and I have been fortunate to work with amazing people on super hard grand challenge science such as developing fusion ignition.”
Following LLNL’s achievement of fusion ignition on Dec. 5, 2022, Arthur’s research has focused on understanding the dynamics of the self-heating fusion process and to understand the origins of performance variability. He is also applying his expertise to the Lab’s Inertial Fusion Energy Institutional Initiative, which seeks to lay the groundwork for virtually limitless clean energy powered by that same reaction.
He received his B.S. in applied science at the University of California, Davis, in 2004.
and Acting Deputy Division Leader
Andrea Schmidt is the electromagnetics section leader within the National Security Engineering Division (NSED) at Lawrence Livermore National Laboratory (LLNL) and is the acting deputy division leader of NSED.
She joined LLNL as a postdoctoral researcher in 2011 and joined the staff in 2013. Since then, Andrea has led several U.S. Department of Energy and Department of Defense projects in dense plasma focus (DPF) research that have modeling and experimental components. She recently led the design and building of a large megajoule-class DPF facility for flash neutron radiography. She has also initiated efforts in kinetic modeling of magnetron plasmas, specifically high-powered impulse magnetron sputtering plasmas and kinetic modeling of shear-flow-stabilized Z-pinch configurations for controlled fusion under the ARPA-E ALPHA program.
Schmidt is a member of the IEEE Pulsed Power Science and Technology Committee and also serves on the Center Scientific Advisory Committee to the Magnetic Acceleration, Heating and Compression Center of Excellence.
“Being at LLNL gives me the opportunity to work with some of the best people and facilities in the world and to develop technologies that have real-world impact,” Andrea said. “We also have the privilege of working with sponsors at agencies that are working to ensure various aspects of global security, which I find to be an interesting and worthy mission.”
Andrea has participated in numerous outreach activities to further public understanding of science, including the Dinner with a Scientist/Get Set STEM Program; the Expanding Your Horizons workshop for middle school girls; LLNL Stem Day; the University of California, Berkeley’s Cal Day physics demo room; the APS DPP Plasma Physics Expo; fusion presentations for school groups and visitors; Fusion Day on Capitol Hill and several outreach videos.
She received her B.S. in physics from the University of California, Berkeley in 2004 and her Ph.D. in physics from the Massachusetts Institute of Technology in 2011.
George Swadling began his research career in experimental plasma physics at Imperial College London, where he investigated the physics of wire array Z-pinch implosions using the MAGPIE pulsed power facility. He was drawn to the hands-on nature of the work.
In 2014, Swadling presented his work on optical diagnostics at the High Temperature Plasma Diagnostics conference, which sparked discussions with LLNL researchers about their plans for an Optical Thomson scattering diagnostic for the National Ignition Facility (NIF).
Excited by the prospect of applying his expertise on dramatically larger scale, he joined the Lab in 2015 to support the development of this new diagnostic.
“Working at the Lab is quite different from the university environment,” he said. “At the university, I was personally responsible for all aspects of my experiments. Here, we must collaborate in large, cross-disciplinary teams of optical, mechanical, electrical, and software engineers to develop the complex, remotely operatable systems required for the NIF.”
In addition to his diagnostic work, Swadling leads various experiments within the NIF Inertial Confinement Fusion (ICF) program, focusing on the physics of hohlraums. He is also the experimental lead for a Discovery Science campaign investigating the formation of collisionless shocks. The multinational team behind this research was honored with the 2024 Lev D. Landau and Lyman Spitzer Jr. Award for Outstanding Contributions to Plasma Physics.
Swadling is the father of two young boys. In his spare time, he enjoys pottering around the garage and garden, building and fixing things. Swadling earned his MSci in physics in 2007 and his Ph.D. in 2012, both from Imperial College London.
Achieving Fusion Ignition
For more than 60 years, our researchers and colleagues worked to achieve fusion ignition, one of science’s most challenging goals. An experiment on Dec. 5, 2022, passed this historic milestone. Ignition — which has since been repeated in multiple NIF experiments — opens new vistas of HED science, enabling access to regimes even more relevant for future stockpile stewardship and helping to lay the groundwork for inertial fusion energy.
Specialized Diagnostics for Extreme Experiments
Grasping the extreme physics happening during HED experiments requires some of the most sophisticated measuring instruments ever made. Our highly specialized diagnostics operate in timescales of nanoseconds and detect interactions below the submicron level, often under intense bombardment of both particle and electromagnetic radiation. Diagnostics include streak cameras, neutron detectors, x-ray imaging and spectroscopy and the Advanced Radiographic Capability, the world’s most energetic short-pulse laser, located at NIF.
Experimental Data Inform Weapon-Simulation Codes
NIF is the only facility that can perform controlled, experimental studies of thermonuclear burn — the phenomenon that gives rise to the immense energy of modern nuclear weapons — providing unprecedented experimental access to the physics of nuclear weapons. The experimental data complement testing at other Livermore and partner experimental facilities, help to inform and validate sophisticated, 3D weapons-simulation computer codes and offer a fuller understanding of important weapon physics.
EBIT
Electron Beam Ion Trap Facility
The Electron Beam Ion Trap (EBIT) facility is home to a suite of x-ray and UV diagnostics, including high-resolution crystal and quantum calorimeter spectrometers used to measure photon emission with energies from below 100 eV to above 100 keV.
HEDS
High Energy Density Science Center
The High Energy Density Science (HEDS) Center facilitates opportunities for scientists and engineers to access world-class experimental facilities and engage in collaborative explorations of matter and energy under extreme conditions.
JLF
Jupiter Laser Facility
The Jupiter Laser Facility (JLF) delivers leading-edge science and supports the high energy density science research community with access to high-energy and high-power laser platforms.
Livermore Center for Quantum Science
The Livermore Center for Quantum Science fosters a thriving quantum research community at LLNL, enabling multidisciplinary teams to harness the power of quantum-enabled technology to solve increasingly complex national security challenges.
NIF
National Ignition Facility
The National Ignition Facility (NIF) is the world’s largest and highest-energy laser system. Our unique energy and power enable cutting-edge research to help keep the U.S. stockpile safe and secure, explore new frontiers of science and lay the groundwork for a clean, sustainable source of energy.
SSI
Space Science Institute
The Space Science Institute’s (SSI) multidisciplinary teams address key questions in astrophysics and planetary science by analyzing, modeling and interpreting data obtained by existing observatories. We also analyze extraterrestrial materials on-site and develop technology and instrumentation for future observatories.
