Mechanism of Carbon Impurity Suppression by Lithium Conditioning

Abstract

Behavior of lithium deposited on graphite is investigated by using a laboratory experimental apparatus, focusing on the intercalation of lithium in the graphite and physical sputtering of lithium-intercalated graphite. It Is found that the lithium can easily diffuse into the graphite bulk even at room temperature, and that the diffusion of lithium is enhanced by heating the graphite. Suppression of physical sputtering of graphite by lithium deposition is found by Auger depth measurement of sputtered species collected on substrates and by optical emission spectroscopy. It is also found that the suppression of graphite sputtering can be sustained in longer period due to intercalated lithium. Finally, general precautions to achieve the reproducible lithium effect in fusion machines are described.