NPRE researchers break ground in examining materials within fusion reactors
Nuclear, Plasma, and Radiological Engineering researchers Prof. JP Allain and Associate Prof. Yang Zhang are breaking ground in fusion energy science by developing the means to examine material surfaces as they are being exposed to the dynamic and extreme conditions of thermonuclear tokamak plasmas.
The work holds promise for determining the kinds of materials needed for designing economically feasible fusion reactors. “It’s just a small piece of the fusion energy puzzle, but it’s an important piece,” Allain said.
To this point, scientists have used electrons and ions to characterize how plasmas interact with surfaces. Because they carry a charge, however, the electron and ion particle trajectories are modified by the magnetic fields at the plasma edge and cannot be used inside a tokamak fusion reactor. This prohibits examining the materials while running the fusion plasma. Observing these materials “in-operando” or during the fusion plasma discharge is critical to understanding lifetime properties that can change during plasma exposure.
Allain and Zhang plan to overcome that obstacle by using non-charged particles with x-rays and neutrons within the fusion environment. “We have come up with a way to discriminate and use a specific type of x-rays and neutrons that could potentially work,” Allain maintained. “The x-rays will give the surface chemistry (e.g. from the plasma-material interaction), and the neutrons will give the structure.”
Allain and his group will test the x-ray phase of the research in the IGNIS facility housed in the Radiation Surface Science and Engineering Laboratory at the University of Illinois at Urbana-Champaign. IGNIS (Ion-Gas-Neutral Interactions with Surfaces) is a state-of-the-art in-situ experimental surface science facility capable of characterizing surface materials under extreme conditions. IGNIS is able to expose surfaces to a collection of energetic particles under high-pressure and high-temperature environmental conditions during surface analysis measurements. The device allows x-ray photoelectron spectroscopy, ion-scattering spectroscopy, and Raman spectroscopy in a single chamber.
Allain and Zhang will use facilities at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, for the neutron phase. At NIST, the scientists will custom-design a chamber facility with Illinois student, Camilo Jaramillo, to simulate the energies of a tokamak, Allain said.
The U.S. Department of Energy Fusion Energy Sciences division supports the research.
Learn more about NPRE by checking out our YouTube videos!