A finite element procedure for radiofrequency sheath–plasma interactions based on a sheath impedance model
A finite element code that solves selfconsistent radiofrequency (RF) sheathplasma interaction problems is improved by incorporating a generalized sheath boundary condition in the macroscopic solution scheme. This sheath boundary condition makes use of a complex sheath impedance including both the sheath capacitance and resistance, which enables evaluation of not only the RF voltage across the sheath but also the power dissipation in the sheath. The newly developed finite element procedure is applied to cases where the background magnetic field is perpendicular to the sheath surface in one and twodimensional domains filled by uniform low and highdensity plasmas. The numerical results are compared with those obtained by employing the previous capacitive sheath model at a typical frequency for ion cyclotron heating used in fusion experiments. It is shown that for sheaths on the order of 100 V in a highdensity plasma, localized RF power deposition can reach a level which causes material damage. It is also shown that the sheathplasma wave resonances predicted by the capacitive sheath model do not occur when parameters are such that the generalized sheath impedance model substantially modifies the capacitive character of the sheath. Here, possible explanations for the difference in the maximum RF sheath voltagemore »
 Authors:

^{[1]};
^{[2]}
 Kyushu Institute of Technology, Fukuoka (Japan)
 Lodestar Research Corp., Boulder, CO (United States)
 Publication Date:
 Report Number(s):
 DOEER/5482321; LRC17172
Journal ID: ISSN 00104655; PII: S0010465517302072; TRN: US1702241
 Grant/Contract Number:
 FC0205ER54823
 Type:
 Accepted Manuscript
 Journal Name:
 Computer Physics Communications
 Additional Journal Information:
 Journal Volume: 220; Journal Issue: C; Related Information: http://dx.doi.org/10.1016/j.cpc.2017.06.025; Journal ID: ISSN 00104655
 Publisher:
 Elsevier
 Research Org:
 Lodestar Research Corp., Boulder, CO (United States)
 Sponsoring Org:
 USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC24)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; radiofrequency sheaths; magnetic confinement fusion; finiteelementmethod; plasma waves; plasmasurface interactions; cold plasma
 OSTI Identifier:
 1395550
Kohno, H., and Myra, J. R.. A finite element procedure for radiofrequency sheath–plasma interactions based on a sheath impedance model. United States: N. p.,
Web. doi:10.1016/j.cpc.2017.06.025.
Kohno, H., & Myra, J. R.. A finite element procedure for radiofrequency sheath–plasma interactions based on a sheath impedance model. United States. doi:10.1016/j.cpc.2017.06.025.
Kohno, H., and Myra, J. R.. 2017.
"A finite element procedure for radiofrequency sheath–plasma interactions based on a sheath impedance model". United States.
doi:10.1016/j.cpc.2017.06.025. https://www.osti.gov/servlets/purl/1395550.
@article{osti_1395550,
title = {A finite element procedure for radiofrequency sheath–plasma interactions based on a sheath impedance model},
author = {Kohno, H. and Myra, J. R.},
abstractNote = {A finite element code that solves selfconsistent radiofrequency (RF) sheathplasma interaction problems is improved by incorporating a generalized sheath boundary condition in the macroscopic solution scheme. This sheath boundary condition makes use of a complex sheath impedance including both the sheath capacitance and resistance, which enables evaluation of not only the RF voltage across the sheath but also the power dissipation in the sheath. The newly developed finite element procedure is applied to cases where the background magnetic field is perpendicular to the sheath surface in one and twodimensional domains filled by uniform low and highdensity plasmas. The numerical results are compared with those obtained by employing the previous capacitive sheath model at a typical frequency for ion cyclotron heating used in fusion experiments. It is shown that for sheaths on the order of 100 V in a highdensity plasma, localized RF power deposition can reach a level which causes material damage. It is also shown that the sheathplasma wave resonances predicted by the capacitive sheath model do not occur when parameters are such that the generalized sheath impedance model substantially modifies the capacitive character of the sheath. Here, possible explanations for the difference in the maximum RF sheath voltage depending on the plasma density are also discussed.},
doi = {10.1016/j.cpc.2017.06.025},
journal = {Computer Physics Communications},
number = C,
volume = 220,
place = {United States},
year = {2017},
month = {7}
}