Investigation of two-dimensional radio-frequency sheath properties using a microscale fluid model

In previous work (Kohno and Myra 2023 Comput. Phys. Commun. 291 108841), we developed a numerical scheme based on a two-dimensional microscale radio-frequency (RF) sheath model with periodically curved wall boundaries. Here, we expand the capability of this scheme through modification of the boundar...

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Main Authors: H. Kohno, J.R. Myra
Format: Article
Language:English
Published: IOP Publishing 2024-01-01
Series:Nuclear Fusion
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Online Access:https://doi.org/10.1088/1741-4326/ad9c95
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author H. Kohno
J.R. Myra
author_facet H. Kohno
J.R. Myra
author_sort H. Kohno
collection DOAJ
description In previous work (Kohno and Myra 2023 Comput. Phys. Commun. 291 108841), we developed a numerical scheme based on a two-dimensional microscale radio-frequency (RF) sheath model with periodically curved wall boundaries. Here, we expand the capability of this scheme through modification of the boundary conditions (BCs) on the conducting walls, which allows the ion flow to turn back to the plasma at locations on the walls where the electromagnetic force on the ions is reversed from its usual direction. Numerical simulations are carried out to investigate the dependences of the surface-integrated admittances on the wall bump height, ion magnetization, ion mobility, and the magnetic field angle, and to visualize the sheath structures in several cases. One of the main results is the ion cyclotron admittance resonance observed under the condition of low ion mobility (high normalized frequency). It is shown that the amplitude of the resonance peak depends on the wall bump height and the ion velocity is reversed on the sides of the bump in an RF cycle for the resonance cases. Furthermore, the differences in the admittances between the one- and two-dimensional microscale models are assessed for the purpose of understanding non-locality of the sheath near the wall surface for the parameters considered in this study. This information will be essential for improving the sheath BC for macroscale calculations in the future.
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spelling doaj-art-4e05643785d14980a0ba1bc871e8dff82025-08-20T02:39:56ZengIOP PublishingNuclear Fusion0029-55152024-01-0165202601210.1088/1741-4326/ad9c95Investigation of two-dimensional radio-frequency sheath properties using a microscale fluid modelH. Kohno0https://orcid.org/0000-0003-3269-0010J.R. Myra1https://orcid.org/0000-0001-5939-8429Department of Physics and Information Technology, Kyushu Institute of Technology , 680-4 Kawazu, Iizuka, Fukuoka 820-8502, JapanLodestar Research Corporation , 13842 Legend Way 101, Broomfield, CO 80023, United States of AmericaIn previous work (Kohno and Myra 2023 Comput. Phys. Commun. 291 108841), we developed a numerical scheme based on a two-dimensional microscale radio-frequency (RF) sheath model with periodically curved wall boundaries. Here, we expand the capability of this scheme through modification of the boundary conditions (BCs) on the conducting walls, which allows the ion flow to turn back to the plasma at locations on the walls where the electromagnetic force on the ions is reversed from its usual direction. Numerical simulations are carried out to investigate the dependences of the surface-integrated admittances on the wall bump height, ion magnetization, ion mobility, and the magnetic field angle, and to visualize the sheath structures in several cases. One of the main results is the ion cyclotron admittance resonance observed under the condition of low ion mobility (high normalized frequency). It is shown that the amplitude of the resonance peak depends on the wall bump height and the ion velocity is reversed on the sides of the bump in an RF cycle for the resonance cases. Furthermore, the differences in the admittances between the one- and two-dimensional microscale models are assessed for the purpose of understanding non-locality of the sheath near the wall surface for the parameters considered in this study. This information will be essential for improving the sheath BC for macroscale calculations in the future.https://doi.org/10.1088/1741-4326/ad9c95RF sheathsplasma heatingmagnetic confinement fusionadmittanceion cyclotron resonance
spellingShingle H. Kohno
J.R. Myra
Investigation of two-dimensional radio-frequency sheath properties using a microscale fluid model
Nuclear Fusion
RF sheaths
plasma heating
magnetic confinement fusion
admittance
ion cyclotron resonance
title Investigation of two-dimensional radio-frequency sheath properties using a microscale fluid model
title_full Investigation of two-dimensional radio-frequency sheath properties using a microscale fluid model
title_fullStr Investigation of two-dimensional radio-frequency sheath properties using a microscale fluid model
title_full_unstemmed Investigation of two-dimensional radio-frequency sheath properties using a microscale fluid model
title_short Investigation of two-dimensional radio-frequency sheath properties using a microscale fluid model
title_sort investigation of two dimensional radio frequency sheath properties using a microscale fluid model
topic RF sheaths
plasma heating
magnetic confinement fusion
admittance
ion cyclotron resonance
url https://doi.org/10.1088/1741-4326/ad9c95
work_keys_str_mv AT hkohno investigationoftwodimensionalradiofrequencysheathpropertiesusingamicroscalefluidmodel
AT jrmyra investigationoftwodimensionalradiofrequencysheathpropertiesusingamicroscalefluidmodel