First optical Thomson scattering measurements made in Z-pinch fusion devices

For safety and boosting performance, future fusion technologies will require accurate and timely diagnostics of plasma behavior. Optical Thomson scattering techniques use lasers to measure a wide range of parameters critical to a plasma’s stability and have become the standard for measuring local electron temperatures and densities in fusion devices.

Researchers have demonstrated a novel Thomson scattering approach that can be used on a sheared-flow-stabilized Z-pinch device, specifically in the FuZE machine. The Z-pinch uses electric currents within plasmas to generate the magnetic fields needed to confine them. Because of its simple design, it does not require external magnetic fields needed in tokamak fusion devices.

Until now, the Thomson scattering diagnostic has been used for plasmas produced in tokamaks and by lasers. Banasek et al. have shown that its design can be optimized to measure in the high temperature and intermediate density range of Z-pinch plasmas.

“This paper gives us the tools needed to quantify measurements of the electron temperature from Thomson scattering in a unique parameter range,” said author Jacob Banasek. “This will be very useful to the FuZE team at Zap Energy as they can use this diagnostic to help understand their experimental plasma conditions. This will also be very a useful starting point for other people trying to study plasmas in a similar parameter regime.”

Banasek and his colleagues are now able to use the diagnostic for measurements on higher performing plasmas on FuZE and future fusion devices and compare them to simulations. They hope this diagnostic broadens the possibilities for future work in understanding plasmas. While the group’s device was tailored to Z-pinch devices, they designed it to be ported to other fusion devices.

Source: “Probing local electron temperature and density inside a sheared flow stabilized Z-pinch using portable optical thomson scattering,” by Jacob Thomas Banasek, Clement Goyon, Simon C. Bott-Suzuki, George Forester Swadling, Morgan Quinley, Benjamin Levitt, Brian A. Nelson, Uri Shumlak, and Harry S. McLean, Review of Scientific Instruments (2023). The article can be accessed at https://doi.org/10.1063/5.0135265 .