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Title: Radio-frequency wave interactions with a plasma sheath in oblique-angle magnetic fields using a sheath impedance model

Abstract

Here, the physics of interactions between waves in plasmas and sheaths for background magnetic fields which make oblique angles with the sheath surfaces is studied with the use of the self-consistent finite element code rfSOL incorporating the recently developed sheath impedance model. The calculation based on this model employs the generalized sheath boundary condition (sheath BC), which surpasses the previously used capacitive sheath BC in reliability by taking into account the contributions of the ion and electron currents in the sheath as well as the displacement current. A series of numerical simulations is carried out in two-dimensional slab geometry with a flat or curved sheath surface as part of the boundary. It is shown that the sheath–plasma wave appears when the equilibrium magnetic field line angle with respect to the sheath surface is small, the absolute value of the radio-frequency (RF) sheath voltage is large, and the plasma density is slightly higher than the lower hybrid resonance density (LHR density), all of which bring the sheath property closer to being capacitive. It is also shown that the sharp variation of the magnetic field line angle along the sheath surface can sensitively affect the maximum absolute value of the RF sheathmore » voltage at a plasma density slightly lower than the LHR density.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. Kyushu Institute of Technology, Fukuoka (Japan)
  2. Lodestar Research Corp., Boulder, CO (United States)
Publication Date:
Research Org.:
Lodestar Research Corp., Boulder, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1494126
Grant/Contract Number:  
FG02-97ER54392
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 26; Journal Issue: 2; Related Information: http://doi.org/10.5281/zenodo.1667247; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; radio-frequency; sheaths; fusion; finite-element method

Citation Formats

Kohno, H., and Myra, J. R. Radio-frequency wave interactions with a plasma sheath in oblique-angle magnetic fields using a sheath impedance model. United States: N. p., 2019. Web. doi:10.1063/1.5054920.
Kohno, H., & Myra, J. R. Radio-frequency wave interactions with a plasma sheath in oblique-angle magnetic fields using a sheath impedance model. United States. doi:10.1063/1.5054920.
Kohno, H., and Myra, J. R. Fri . "Radio-frequency wave interactions with a plasma sheath in oblique-angle magnetic fields using a sheath impedance model". United States. doi:10.1063/1.5054920.
@article{osti_1494126,
title = {Radio-frequency wave interactions with a plasma sheath in oblique-angle magnetic fields using a sheath impedance model},
author = {Kohno, H. and Myra, J. R.},
abstractNote = {Here, the physics of interactions between waves in plasmas and sheaths for background magnetic fields which make oblique angles with the sheath surfaces is studied with the use of the self-consistent finite element code rfSOL incorporating the recently developed sheath impedance model. The calculation based on this model employs the generalized sheath boundary condition (sheath BC), which surpasses the previously used capacitive sheath BC in reliability by taking into account the contributions of the ion and electron currents in the sheath as well as the displacement current. A series of numerical simulations is carried out in two-dimensional slab geometry with a flat or curved sheath surface as part of the boundary. It is shown that the sheath–plasma wave appears when the equilibrium magnetic field line angle with respect to the sheath surface is small, the absolute value of the radio-frequency (RF) sheath voltage is large, and the plasma density is slightly higher than the lower hybrid resonance density (LHR density), all of which bring the sheath property closer to being capacitive. It is also shown that the sharp variation of the magnetic field line angle along the sheath surface can sensitively affect the maximum absolute value of the RF sheath voltage at a plasma density slightly lower than the LHR density.},
doi = {10.1063/1.5054920},
journal = {Physics of Plasmas},
number = 2,
volume = 26,
place = {United States},
year = {2019},
month = {2}
}

Journal Article:
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This content will become publicly available on February 8, 2020
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