The Fire That Powers the Universe: Harnessing Inertial Fusion Energy

This story was originally published in the July 2024 edition of the American Nuclear Society magazine Nuclear News.

It was a laser shot for the ages. By achieving fusion ignition on December 5, 2022, Lawrence Livermore National Laboratory (LLNL) proved that recreating the “fire” that fuels the sun and the stars inside a laboratory on Earth was indeed scientifically possible.

The historic achievement of scientific breakeven—or target gain—at LLNL’s National Ignition Facility (NIF) gave scientists access to new regimes of high energy ­density (HED) science to probe the extreme conditions found at the center of nuclear explosions. The accomplishment strengthened NIF’s primary mission: to support the National Nuclear Security Administration’s science-based Stockpile Stewardship Program to help certify the safety, security, and effectiveness of the U.S. nuclear deterrent.

“The physics understanding we gain from NIF on how materials behave at extreme pressures and temperatures, how radiation is transported in complex geometries, and how thermonuclear fusion ignition happens is crucial to ensuring that our nation’s nuclear stockpile stays safe, secure, and reliable in the absence of underground testing,” said Mark Herrmann, associate director within LLNL’s Strategic Deterrence directorate. “NIF is an essential tool in sustaining our deterrent.”

The scientific data produced by NIF experiments also supports HED science and discovery science, expanding our understanding of the physics of celestial bodies and applications such as material science, advanced lasers and photonics, and additive manufacturing.

While NIF itself was not designed to become a fusion power plant that can deliver electricity to the grid, the achievement of ignition cemented LLNL’s position as a center of science and technology research directly relevant to inertial fusion energy (IFE) while sharpening the scientific community’s focus on developing this potentially clean, safe, enduring source of electricity for the world.

Ongoing experiments at NIF, the world’s largest and most energetic laser, have provided scientists, engineers, academic researchers, and entrepreneurs with the scientific foundations needed for IFE. The breakthrough comes at a time of rising concerns about national and global security, energy security, and climate change.

“We are at a very special moment in time,” said physicist Tammy Ma, lead for the laboratory’s new Inertial Fusion Energy Institutional Initiative. “We achieved ignition—we’ve demonstrated that it’s fundamentally feasible. We absolutely have to capitalize on this moment for IFE and make it happen.”

“We are trying to figure out how to work with the fire that powers the universe,” said Vincent Tang, deputy director of LLNL’s NIF & Photon Science (NIF&PS) Directorate. “From that point of view, the recent advances and activities in both the public and private sector are pretty amazing relative to where we were even 10 years ago.

“We’re going to have to learn how to leverage these public sector capabilities in mutually beneficial ways, in ways that are aligned with both the goals of the companies as well as the core missions of the national laboratories and DOE-funded institutions,” Tang said. “The bottom line is this is a really exciting time for the community, and there are significant opportunities here for us to accelerate IFE and fusion overall.”

Those research efforts will extend far beyond NIF and require a renewed, robust, and rapidly paced program of research that coordinates efforts from the public, private, and academic sectors while leveraging the expertise gained by IFE experiments at LLNL and the U.S. national laboratory system. The potential benefits to the world are profound.

“This technology presents a very long-term robust solution to the world’s increasing energy demands,” said LLNL director Kim Budil. “This is an opportunity for us to lead in the international scene in developing this energy technology.”

Getting to Ignition

NIF was designed more than three decades ago to achieve ignition though inertial confinement fusion (ICF). As defined by the National Academy of Sciences in 1997, ignition means as much or more energy produced by a fusion reaction as the laser energy delivered to the target. NIF uses 192 powerful laser beams focused on a hydrogen fuel target the size of a small pea, dramatically compressing and heating the two isotopes of hydrogen—deuterium and tritium—inside until the atoms fuse, creating a “burning plasma” and releasing high-energy neutrons and other forms of energy.

“Fusion means unlocking a different kind of nuclear power,” Ma said. “Fusion has the potential to lay the foundation for energy security for the entire world.”

Reaching ignition at LLNL was made possible by contributions from the laboratory’s NIF&PS, Strategic Deterrence, Physical and Life Sciences, and Computing teams; scientists, engineers, technicians, and administrative and support personnel from throughout the lab; and extensive collaborations with researchers in the world’s fusion, plasma physics, and HED science communities in other national laboratories, universities, and industry.

Achieving ignition was also a case study in the value of innovation and persistence in the face of a scientific grand challenge. Many NIF attributes saw notable improvements in the years since experiments began in 2009. Computer models improved, as did the ability to interpret them. Researchers benefitted from an ever-growing knowledge base provided by NIF’s sophisticated diagnostic tools.

Laser energy balance, optics, and targets all improved, while experimental designs were continually refined. The impediments to successful implosions—including asymmetries, laser-plasma interactions, fuel contamination by target capsule material, radiative losses, laser backscatter and hot-electron production, among others—were gradually overcome.

“Controlling the symmetry in these implosions is like trying to compress something the size of a basketball down to the size of a pea and keeping it looking like a sphere to the percent level,” said Annie Kritcher, the fusion experiment’s lead designer. “This lets us squeeze the hot-spot plasma to conditions more extreme than the sun’s core.

“We’re trying to do this in a very harsh environment,” she added, “where the target is filling with plasma and it’s difficult to get all the laser beams where you want them to go to create a uniform X-ray oven.”

The December 2022 shot produced about one-and-a-half times the energy from the brief, self-sustaining fusion reaction as the laser energy delivered to the target. Subsequent experiments in 2023 and 2024 repeated ignition—including one that produced an authorized yield of 5.2 megajoules, within a measurement uncertainty of ±0.26 MJ, and a target gain of 2.34. Additional experiments further demonstrated that NIF can repeatedly conduct fusion experiments at multi-megajoule levels of energy output.

“For many decades, the running joke in fusion research was ‘fusion is 20 years away and always will be,’” said ICF chief scientist Omar Hurricane. “Yet ICF researchers are now able to refer to the milestones of burning plasmas, fusion ignition, and target energy gain greater than unity, or scientific breakeven, in the past tense.

“The takeaway here,” Hurricane continued, “is if you just stick with it and you keep chipping away, a lot of these hard problems can be solved. Even when we had struggles with the engineering, the physics, and the perceptions—just having the grit to stick with it really paid off.”

While NIF uses lasers to drive the reaction, achieving ignition is considered a physics breakthrough for other potential drivers, including magnetic fusion energy (MFE) using powerful magnets to contain the fusing plasma. Pursuing IFE, MFE, and other fusion technologies is in the national interest.

“Ignition was something that the entire world heralded and is in large part why there’s so much excitement for fusion,” Ma said. “If we can get success and make progress in IFE, we will help the entire fusion community.”

On the Path to IFE

Substantial engineering and technical advances are still needed to move from successful fusion ignition in laboratory experiments to a working commercial nuclear fusion power plant.

Fortunately, several components of the NIF laser system, as well as LLNL’s expertise in other key aspects of ICF, can provide a kick-start for developing the technology for an integrated power plant. And the same fusion plasmas created at NIF for national security missions can also help form the basis of IFE physics, as the next steps for both applications require higher yields and higher gains.

Anticipating the attainment of ignition, LLNL scientists began planning for future IFE efforts shortly after NIF experiments began. They are helping to drive the national public IFE program and organize the public-private partnerships that will be needed to capitalize on IFE’s potential for large-scale commercial power generation.

The renewed focus on IFE research has begun to sharpen in the past few years, and on August 8, 2021, an experiment at NIF produced a then-record fusion energy yield of 1.35 MJ, reaching the threshold of ignition. That experiment met the Lawson criterion for thermonuclear instability, producing an extremely rapid increase in plasma temperature and yield production rate as the fusion power outstripped all the power losses in the plasma. The results injected a new shot of momentum into public and private entities that had been working on advancing fusion energy.

The Fusion Industry Association, a Washington, D.C.,–based industry group, now estimates that fusion firms globally have attracted about $6.21 billion in investments, up from $4.8 billion in 2022.

Then, in March 2022, the White House hosted a summit that brought together government, industry, and academic leaders to discuss a bold decadal vision to accelerate commercial fusion energy. A Department of Energy workshop in June 2022, cochaired by Ma and Riccardo Betti, a professor at the University of Rochester, resulted in a Basic Research Needs Workshop report on the future of IFE.

In the weeks before ignition was first achieved, LLNL and other U.S. national laboratories organized a set of virtual and in-person meetings in Livermore, Calif., to form research efforts between the labs, privately funded companies, and academia. An informal organization called the IFE Collaboratory facilitated public-private partnerships and hosted the meetings to accelerate IFE development and solidify U.S. leadership in the technology.

The collaboratory included LLNL; Los Alamos, Lawrence Berkeley, Sandia, Oak Ridge, and Savannah River National Laboratories; the Laboratory for Laser Energetics at the University of Rochester; General Atomics; and SLAC National Accelerator Laboratory. The Princeton Plasma Physics and Naval Research Laboratories joined later.

The meetings drew representatives from more than a dozen companies and associations that are playing various roles in the development of the fusion energy industry, ranging from startups like First Light Fusion, Focused Energy, and EX-Fusion to well-established corporations such as Lockheed Martin, the Trumpf Group, and Westinghouse Electric.

Days before the DOE publicly announced the December 2022 ignition milestone, Budil announced Ma’s appointment to lead LLNL’s new Inertial Fusion Energy Institutional Initiative, designed to help lead and coordinate efforts to support the DOE’s national IFE program and vision for fusion energy.

“The time is now to revitalize the national IFE program as a potential path to energy and climate security and to establish the partnerships and approaches that will enable this endeavor,” Budil said in announcing Ma’s appointment.

In the wake of the ignition achievement, the DOE in January 2023 announced $2.3 million in funding for 10 projects pairing the nation’s national laboratories with seven private fusion energy companies, including Focused Energy and longtime LLNL partner General Atomics.

That May, during an ignition celebration hosted by LLNL, energy secretary Jennifer Granholm announced a new four-year Inertial Fusion Energy Science & Technology Accelerated Research (IFE-STAR) initiative that would combine the expertise of the DOE’s national labs, academia, and industry.

IFE-STAR provides up to $45 million from the DOE’s Office of Science to support the creation of IFE innovation hubs that address target physics and manufacturing, driver technologies, and experimental validation.

“You can already see the impact [fusion energy investment] is making on the surrounding community and the potential it has to create new jobs and grow the economy,” Granholm said during the celebration. “Folks are traveling down that magnetic [fusion] pathway, but we don’t have to worry about a road not taken. Thanks to this ignition achievement, we can and we will see what both pathways [MFE and IFE] hold. . . .
We believe that public-private partnerships will be key to getting inertial fusion to that next level.”

Later that month, the DOE announced $46 million in funding to eight private companies to help accelerate the design, research, and development of a pilot fusion power plant within the decadal timescale. The funding from the Milestone-Based Fusion Development Program included private startups like Zap Energy, which has benefited from LLNL research.

Another important step forward came on December 7, 2023, when the DOE announced it had awarded a four-year, $16 million grant to a multi-institutional team led by LLNL to establish a national IFE Science and Technology Accelerated Research for Fusion Innovation and Reactor Engineering (IFE-STARFIRE) hub. The hub is one of three the DOE selected through competitive peer review to accelerate the momentum started by LLNL’s ignition breakthrough.

“We have not had a public IFE program in the U.S. for over 10 years now.” Ma said. “This is the seed of a new IFE program. IFE is a national need that requires a national plan and sustained commitment.”

Ma noted that while there is a “growing fusion ecosystem,” the challenges are “still quite momentous.” For starters, NIF is able to fire one laser shot at one target every few hours, while a commercial plant would require about 10 shots every second and therefore hundreds of thousands of targets per day.

The use of more energy-efficient diode-pumped lasers could eventually help. LLNL has pioneered high-peak-power diode-pumped lasers such as the High-Repetition-Rate Advanced Petawatt Laser System (HAPLS), constructed for the European Union’s ELI-Beamlines research facility. HAPLS is designed to produce 30 joules of energy in a 30-femtosecond laser pulse at 10 hertz, or 10 pulses per second, and demonstrates the feasibility of diode-pumped laser architectures scalable to the multikilojoule beamlines that would be needed for IFE.

But as Ma noted, STARFIRE hub members are already working on just one of the long-term challenges. There are currently not enough diodes manufactured in the world to outfit a single IFE power plant, so STARFIRE is looking for ways to increase production and lower manufacturing costs.

“Although it’s a very exciting moment in time,” Ma said, “we also have to be cautious, because each of the subsystems we would need to build up for a fusion power plant still needs a lot of development. The technology is still relatively immature, and all of this has to come together in a way where the systems work together. It also has to be economically viable.”

Ma emphasized, however, that the U.S. is in a unique position as “the currently undisputed leader in inertial fusion” to help accelerate its development.

“We are the only ones who have achieved ignition,” she said. “We are the only ones with the full-scale facility that can even come close to the plasma conditions that you need for sustained fusion reactions. And we have a huge wealth of expertise in not only the physics but the simulation codes, the computational capabilities, advanced manufacturing, all the things you need to actually pull this together.”

While just like ignition, creating a fusion power plant will be challenging, “the potential reward will transform life as we know it,” Ma said, “ushering in a new era of abundance for humanity. This will revolutionize the energy landscape of the world.”

Budil also said she is optimistic the challenges can eventually be overcome.

“History suggests on these really hard technological problems that great people who are really interested in saving the planet will flock to these challenges and we will solve them over time,” she said. “If we can make fusion energy really commercially viable and solve these technical challenges, it will be a game changer. This is going to take everybody and all of our countries working together to bring this to fruition.”

More Information

The Age of Ignition: Inside Lawrence Livermore National Laboratory’s Fusion Breakthrough a NIF & Photon Science News Special Report

Inertial Fusion Energy: Building on the Achievement of Fusion Ignition to Power America

“LLNL’s Fusion Ignition Shot Hailed as Historic Scientific Feat,” NIF & Photon Science News, December 14, 2022

“LLNL-Led Team Receives DOE Award to Establish Inertial Fusion Energy Hub,” NIF & Photon Science News, December 7, 2023

“Ignition Experiment Advances Stockpile Stewardship Mission,” NIF & Photon Science News, March 9, 2023

“Ignition Gives U.S. ‘Unique Opportunity’ to Lead World’s IFE Research,” NIF & Photon Science News, February 2, 2023

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