LLNL develops portable Thomson scattering diagnostic to support ARPA-E’s fusion energy ventures

Three scientists in a lab

Jacob Banasek (Sandia National Laboratory), Simon Bott-Suzuki (University of California San Diego), and Clément Goyon (Lawrence Livermore National Laboratory) record the first measurements from the Thomson scattering diagnostic during its deployment at Zap Energy Inc. in Everett, Washington. Photo: Clément Goyon/LLNL.

Scientists at Lawrence Livermore National Laboratory (LLNL) collaborated with University of California San Diego (UCSD) to design, assemble, and field a portable optical Thomson scattering diagnostic system for the Advanced Research Projects Agency-Energy (ARPA-E) — a Department of Energy agency which supports private companies that are developing new ways to generate, store and use energy. The diagnostic was implemented at Zap Energy, Inc., a private-sector fusion company based in Everett, Washington. 

The team consisted of experts across LLNL, including Clément Goyon, George Swadling, Philip Datte, Steven Ross and Harry McLean, as well as Simon Bott-Suzuki at UCSD and Jacob Banasek at Sandia National Laboratories. The researchers developed the plasma diagnostic system to be transported to and shared among different fusion energy experiments supported by ARPA-E.

The team detailed their research in Review of Scientific Instruments.

A diagram of a portable Thomson scattering diagnostic
A graphic illustration of the transportable Thomson scattering diagnostic developed at Lawrence Livermore National Laboratory to quantify plasma conditions on private fusion experiments supported by Advanced Research Projects Agency-Energy (ARPA-E). (Image courtesy of Lawrence Livermore National Laboratory).

ARPA-E aims to leverage the diagnostic expertise of the entire fusion R&D community and develop the teams and experience necessary to support an expanding role for public-private partnerships in nuclear fusion, said Clément Goyon, the project’s research lead.

“Optical Thomson scattering is viewed as the gold standard for diagnosing the electron density and temperature and ion temperature inside plasmas,” Goyon explained. “With this data, we can better understand the underlying physics of each fusion concept by providing local, time-resolved measurements of plasma conditions in the experiment.” 

Early-stage fusion experiments, like those supported by ARPA-E, can broadly benefit from state-of-the-art diagnostic systems and measurements, Goyon said. However, these diagnostics can be costly and time-consuming to deploy and analyze. Typically, such experiments and projects do not have access to the types of measurements the portable system will enable.

The design of the transportable Thomson scattering diagnostic is highly modular, where each part can be adapted to meet the need and budget of the targeted experiments.

“The system’s portable design and collaborative potential can help to transform early-stage fusion experiments, expanding our understanding of fusion physics,” Goyon said. “For instance, the Zap results allowed to estimate the plasma pressure inside the sheared-flow stabilized Z-pinch and guide the experiment towards more efficient confinement.”