Big Ideas Lab podcast explores JASPER and the science of measuring plutonium under extreme conditions

In less than a microsecond, a projectile traveling thousands of meters per second strikes its target, generating pressures and temperatures too extreme to observe directly. At Lawrence Livermore National Laboratory (LLNL), scientists use that moment to answer complex questions for national security.

The latest episode of the Big Ideas Lab podcast takes listeners to the Joint Actinide Shock Physics Experimental Research facility, or JASPER, where researchers study plutonium under extreme conditions to support stewardship and modernization of the nation’s nuclear stockpile. Listen on Apple or Spotify.

Located at the Nevada National Security Site (NNSS), JASPER is home to a two-stage gas gun capable of launching projectiles at speeds of up to eight kilometers per second. Over more than 20 years of operations, the facility has conducted more than 200 fully contained experiments, building a growing body of experimental data. The facility generates precise data on how plutonium behaves under high-pressure, dynamic conditions, all within a safe, fully contained environment.

“Our goal is to generate data on the high-pressure dynamic properties of plutonium,” said David Bober, JASPER team lead at LLNL. “JASPER is the only gun in the United States that can hit this broad range of velocities and be used on plutonium.”

The episode takes listeners to the center of each experiment: the shot. The gun uses propellant and compressed gas to accelerate a projectile to extreme speeds before it impacts a target. The resulting shockwave moves through the material in fractions of a microsecond, revealing key material properties. “The portion of time where we are collecting useful data is less than a microsecond,” Bober said. “For some experiments, it’s closer to 100 nanoseconds.”

Capturing the event requires precise coordination and advanced diagnostics that measure velocity, timing and shockwave behavior. The resulting data helps researchers better understand how plutonium responds.

“Our experiments move so fast that even if we do a thousand experiments, it’s only a few seconds of experiment time,” said Ricky Chau, JASPER execution lead.

Just as important as generating the shot is containing it. JASPER experiments are designed to ensure that all material remains fully contained, with safety built into every step to protect workers and the environment while preserving data integrity. “What made the idea really audacious was figuring out how to do this with plutonium and capture every last tiny speck,” Bober said.

That level of control allows JASPER to produce precise, repeatable data that reduces uncertainty and strengthens models used to support modernization of the nation’s nuclear deterrent. Over time, the facility’s role has expanded to address new questions about material aging, manufacturing and performance as the stockpile is modernized.

The episode highlights how precision experiments at JASPER produce the data needed to better understand plutonium and support modernization of the nation’s nuclear deterrent. Listen on Apple or Spotify.