Physicists discover that lithium oxide on tokamak walls can improve plasma performance

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Lithium compounds improve plasma performance in fusion devices just as well as pure lithium does, a team of physicists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) has found.

Lithium compounds improve plasma performance in fusion devices just as well as pure lithium does, a team of physicists at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) has found.

The research was conducted by former Princeton University physics graduate student Matt Lucia under the guidance of Robert Kaita, principal research physicist at PPPL and one of Lucia’s thesis advisors, as well as the team of scientists working on a machine known as the Lithium Tokamak Experiment (LTX). As part of his dissertation, Lucia investigated how lithium deposited on walls of doughnut-shaped fusion machines known as tokamaks affected the performance of LTX. Like the plasma within a tokamak, the plasma within LTX is shaped like a doughnut. The plasma, a soup of charged particles, is surrounded by a copper shell with an inner wall made of stainless steel.

Lucia used a new device known as the Materials Analysis and Particle Probe (MAPP), invented at the University of Illinois at Urbana-Champaign and installed on LTX. The MAPP system lets scientists withdraw samples into a chamber connected to LTX and study them without compromising LTX’s vacuum environment. MAPP lets scientists analyze how tokamak plasmas affect a material immediately after the experiment ends. In the past, scientists could only study samples after the machine had been shut down for maintenance; at that point, the vacuum had been broken and the samples had been exposed to many experiments, as well as to air.

Read more at DOE/Princeton Plasma Physics Laboratory

Image: PPPL physicists Robert Kaita and Michael Jaworski in front of the National Spherical Torus Experiment-Upgrade. (Credit: Elle Starkman)