General Atomics

GA-developed characterization system dramatically improves high-quality target selection; facilitates at least five instances of fusion ignition

San Diego, June 3 – A new tool developed by General Atomics (GA) is enabling scientists to optimize the quality of targets used in Inertial Confinement Fusion (ICF) experiments. The system, known as 4Pi, has already led to improved experimental results and higher ICF yields. Starting with the historic breakthrough of fusion ignition in December 2022 — described by U.S. Secretary of Energy Jennifer Granholm as “one of the most impressive scientific feats of the 21st century” — each of the five experiments that have achieved ignition at the National Ignition Facility (NIF) have utilized a target characterized and selected by the 4Pi system.

Haibo Huang, Deputy Director of GA’s Center of Excellence in Advanced Diagnostics and 4Pi Project Lead, said, “General Atomics is proud to launch a new era of integrated characterization to the field of ICF research. The 4Pi system allows multiple instruments with complementary capabilities to examine the same target from different perspectives and gain much deeper insights. With increasingly intricate and complex targets needed to create record-breaking ignition yields, this integrated approach is indispensable.”

GA’s 4Pi system combines up to eight instruments within one common coordinate system, including robotics, automation, batch evaluation, and machine learning technologies, to avoid measurement errors that can occur when a target is manually transferred from one instrument to another and identify the best targets from each production batch.

In ICF, high-powered lasers are used to rapidly compress a target filled with hydrogen fuel, causing the atoms to fuse together and release a significant amount of energy. A target achieves “ignition” when the amount of energy released in the reaction is greater than what was delivered to the target.

The quality of targets is a key element to achieving ignition, and fabricating them is a highly challenging process, as each one is approximately 2mm in diameter — the size of a BB — and fabricated at sub-micron tolerances. The slightest defects and non-uniformities affect the behavior of the fuel when the target is compressed and features smaller than 1/100th the diameter of a human hair could prevent ignition from occurring.

Two instruments on the 4Pi system specifically assisted in the recent ignition breakthroughs at Lawrence Livermore National Laboratory (LLNL)’s NIF. These include the Digital Holographic Microscope, which identifies defects on the surface of targets, and the Fourier-Transform Infrared (FTIR) spectroscope, which maps variations in the thickness of a target’s wall.

Mike Farrell, Vice President of Inertial Fusion Technologies at GA, said, “The GA Energy Group is dedicated to pioneering technologies, like 4Pi, to provide solutions for the National Nuclear Security Administration (NNSA)’s toughest challenges. We intentionally designed the 4Pi system to be modular so it will evolve with program needs, such as new types of targets and the availability of new classes of sensors.”

As the NNSA’s primary commercial partner for ICF targets and target support services since 1991, GA provides more than 12,000 components annually for experiments conducted by NIF, the Z Pulsed Power Facility at Sandia National Laboratory, and the Omega Laser Facility at the Laboratory for Laser Energetics.

LLNL’s NIF is the most precise and reproducible laser system in the world, focusing 192 beams on each target during ICF experiments. GA and LLNL have a long-standing partnership under the NNSA’s ICF and High Yield research program to help facilitate a safe, secure, and effective nuclear deterrent without underground testing.

In December 2022, NIF achieved the first controlled fusion ignition in history.

“Since then, we’ve repeated ignition four times,” said NIF Director Gordon Brunton. “In early February, we achieved 5.2 MJ of fusion output from 2.2 MJ of laser energy delivered on target, our highest yield yet.”

A close collaboration between GA and LLNL, including Kurt Boehm (GA), Dan Casey (LLNL), Haibo Huang (GA), Pasha Lapa (GA), Shahin Pajoom (GA), Art Pak (LLNL), Mark Ratledge (GA), Neal Rice (GA), Kevin Sequoia (GA), Michael Staderman (LLNL), and Masashi Yamaguchi (GA), has significantly contributed to the continued growth in research and development for inertial fusion target fabrication.

About General Atomics: Since the dawn of the atomic age, General Atomics innovations have advanced the state of the art across the full spectrum of science and technology – from nuclear energy and defense to medicine and high-performance computing. Behind a talented global team of scientists, engineers, and professionals, GA’s unique experience and capabilities continue to deliver safe, sustainable, economical, and innovative solutions to meet growing global demands.