Commentary

Jeffrey Bude

Deputy Principal Associate Director for NIF and Photon Science

Innovation Beyond the Speed of Sound

Keeping pace with a rapidly changing global security environment requires innovation such as developing weapons systems that withstand harsh environments, defend against adversaries, and serve as a deterrent. For example, weapons systems that deliver warheads using hypersonic glide vehicles are rapidly becoming a significant challenge this century. Unlike conventional ballistic missiles, which follow a predictable path, the in-flight maneuverability of hypersonic glide vehicles allows them to better evade air defenses. These vehicles travel through the atmosphere at speeds over Mach 5 (five times the speed of sound), fast enough to ionize air molecules.

Ionized hypersonic flow is an especially harsh environment for hypersonic vehicles, posing a particular challenge for material development. Key scientific questions related to material survivability, threat interactions, and unexpected environments remain unanswered. The design and development of a unique hypersonic test capability for understanding these material issues including threat environments is the subject of this issue’s feature story.

Because in-flight testing is prohibitively expensive, wind tunnels are the tool of choice for vehicle testing. The nation supports many wind tunnel facilities large enough to test vehicle control surfaces, nose cones, and bodies. At the national level, however, multiyear waitlists for testing are not uncommon. Most wind tunnel facilities cannot support enough different types of experimental campaigns needed to develop effective materials, and most lack access for high-fidelity, in situ probes to fully understand and predictively model extreme-condition material evolution and response.

Livermore’s Energy–Matter Interaction Tunnel (EMIT) was conceived to address these gaps. EMIT—designed, built, and tested at Lawrence Livermore as part of a Laboratory Directed Research and Development Program Strategic Initiative—is a compact wind tunnel with a test chamber large enough to study material physics under myriad conditions, providing the high experimental throughput necessary for material testing and development. EMIT offers close-up access for high-fidelity diagnostics capable of providing the types of data needed to validate and update hypersonic flow fluid dynamic simulations and a test environment that allows for delicate, in situ probes. The EMIT team achieved their central goals, recently demonstrating Mach 5 flow and successfully developing and deploying novel, non-invasive material diagnostics.

The three highlights in this issue of Science & Technology Review showcase how Lawrence Livermore is further expanding its capabilities around national security leadership and policy, revitalizing existing infrastructure, and building upon collaborative relationships within and outside of the Laboratory. The first highlight describes how participation in Texas A&M University’s National Security Affairs Program (NSAP) supports the Laboratory’s emerging leaders, strengthening their contributions to U.S. national security decision making. NSAP fellows complete an executive-level, graduate studies program that enhances understanding of the security policies and policymaking processes that Livermore’s research informs. Past participants, including Laboratory Director Kim Budil, share insights on how engagement in the program shaped their leadership trajectory and changed the course of their careers.

The second highlight demonstrates how revitalizing Livermore’s infrastructure with new equipment and improved workspaces can enhance research efforts and expand opportunities for intra-Laboratory collaboration. A concerted effort to refurbish the Materials Science Division’s headquarters in Building 235 has already had a positive impact by offering rapid, high-energy laser shots for experimentation outside the National Ignition Facility, enabling improvements for custom additive manufacturing feedstock production, and simulating extreme temperatures and loading for new material development.

This issue’s final highlight describes how Lawrence Livermore’s Academic Collaboration Team (ACT) partners with diverse universities around the country to attract new talent to the Laboratory. ACT partners doctoral students with Livermore researchers, giving the students applied science experience in a national laboratory setting and our scientists the opportunity to expand research portfolios by exposure to new ideas.

All the articles exemplify Livermore’s leadership on key national security initiatives through research, collaboration, and expanded Laboratory capabilities. With these developments, the wind is now at our backs to pursue the bold innovative science and technology that will advance National Nuclear Security Administration and other mission-focused programs.