Commentary

Pursuing Ignition for National Security

When the United States ended underground nuclear testing in 1992, Livermore was faced with a grand challenge: developing a range of proficiencies that would ensure the safety, security, and effectiveness of the nation’s nuclear stockpile without further explosive nuclear testing. Having a strong nuclear deterrent sends a signal to our country’s adversaries that—whatever capabilities they bring forward—we, as a nation, are ready and able to respond.

The Stockpile Stewardship Program (SSP) was created in 1995 with the goal of improving the science and technology for assessing the aging nuclear weapons stockpile without requiring additional nuclear testing. The competencies brought to bear on this challenge include advanced computing and predictive modeling, sophisticated experimental facilities, and a cadre of technical experts that is second to none. Livermore has consistently pioneered the use of large, high-speed computers to run the sophisticated simulation codes essential to the SSP. Such codes are incredible tools, but they can only know what we know. So, it is critically important that we test these tools against very complex experiments, such as those we conduct at the National Ignition Facility (NIF). At NIF, we explore realms of extreme temperatures and pressures where our understanding of the physics is not complete. One such realm is that of thermonuclear burn or fusion “ignition,” in which the energy output from a controlled fusion reaction is greater than the energy required to sustain the reaction. From the very beginning, the SSP’s goal has been to develop a method to study ignition, the gateway to enabling direct access to weapon conditions, in the laboratory.

The pursuit of ignition also provides an important function for the weapons design community. The Laboratory is responsible for recruiting, training, retaining, and, perhaps most importantly, challenging current and future stockpile stewards. The quest for ignition allows them to practice the “art of design” and test their technical judgment against real data on both ignition and other weapons-related experiments at NIF. Ultimately, it is the technical judgments of these stockpile experts that provides the foundation of confidence in the nation’s nuclear deterrent.

Over the time of NIF’s operation, we have made amazing progress and have learned much about ignition, about weapons modeling and simulation, and about the NIF system and its diagnostics. The journey to date has brought us unprecedented insights, and we now understand the key impediments to achieving ignition and how to approach solving them.

Still, achieving ignition is not a “sure thing.” It is truly a technical grand challenge of our era. We will need to push the laser, our precision target fabrication capabilities, and our diagnostic tools to the full extent of their capacities. As we continue this quest, we seek to either reach ignition or establish what’s needed to achieve it in the next-generation facility. We embarked on this journey without guarantees that the destination is within our grasp. But that is the nature of science, particularly science conducted at the frontier. Science is a process of trying, learning, adapting, trying again. Failure—that dreaded “f” word—is an essential and unavoidable part of the process. In failure, we learn, and from learning we move forward.

We have come a long way since the early days of stockpile stewardship. Our understanding of weapons physics, material properties under extreme conditions, and even the data collected from long-ago nuclear testing, has increased tremendously due to our more sophisticated tools and capabilities. The progress that we have made in addressing the ignition challenge has brought a new generation of extraordinary people to the Laboratory: people who will carry stewardship of the stockpile into the future.

With every step along the way—every new experiment, diagnostic, design, or code—we accumulate new knowledge and insights into the heart of the systems that form the foundation of the nation’s nuclear deterrent. The nation benefits from every new steward who is attracted to join our team, and is then retained and challenged by the world-class science and technology we seek and develop. The pursuit of ignition is perhaps our most ambitious undertaking yet. These gains, in and of themselves, are worth the journey.