Effects of oxidation and impurities in lithium surfaces on the emitting wall plasma sheath

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Hauptverfasser: Bradshaw, Kolter, Hakim, Ammar, Srinivasan, Bhuvana
Format: Preprint
Veröffentlicht: 2025
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author Bradshaw, Kolter
Hakim, Ammar
Srinivasan, Bhuvana
author_facet Bradshaw, Kolter
Hakim, Ammar
Srinivasan, Bhuvana
contents Use of lithium as a surface coating in fusion devices improves plasma performance, but the change in wall properties affects the secondary electron emission properties of the material. Lithium oxidizes easily, which drives the emission yield well above unity. We present here simulations demonstrating the change in sheath structure from monotonic to the nonmonotonic space-charge limited sheath using an energy-dependent data-driven emission model which self-consistently captures both secondary emission and backscattering populations. Increased secondary electron emission from the material has ramifications for the degradation and erosion of the wall. Results shows that the oxidation leads to an increased electron flux into the wall, and a reduced ion flux. The net transfer of energy to the surface is significantly greater for the oxidized case than for the pure lithium case. High reflection rates of low-energy backscattered particles leads to a high re-emission rate at the wall.
format Preprint
id arxiv_https___arxiv_org_abs_2501_17686
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Effects of oxidation and impurities in lithium surfaces on the emitting wall plasma sheath
Bradshaw, Kolter
Hakim, Ammar
Srinivasan, Bhuvana
Plasma Physics
Use of lithium as a surface coating in fusion devices improves plasma performance, but the change in wall properties affects the secondary electron emission properties of the material. Lithium oxidizes easily, which drives the emission yield well above unity. We present here simulations demonstrating the change in sheath structure from monotonic to the nonmonotonic space-charge limited sheath using an energy-dependent data-driven emission model which self-consistently captures both secondary emission and backscattering populations. Increased secondary electron emission from the material has ramifications for the degradation and erosion of the wall. Results shows that the oxidation leads to an increased electron flux into the wall, and a reduced ion flux. The net transfer of energy to the surface is significantly greater for the oxidized case than for the pure lithium case. High reflection rates of low-energy backscattered particles leads to a high re-emission rate at the wall.
title Effects of oxidation and impurities in lithium surfaces on the emitting wall plasma sheath
topic Plasma Physics
url https://arxiv.org/abs/2501.17686