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Title: Radio frequency wave interactions with a plasma sheath: The role of wave and plasma sheath impedances

Abstract

Radio frequency (RF) sheaths form near surfaces where plasma and strong RF fields coexist. The effect of these RF sheaths on wave propagation near the boundary can be characterized by an effective sheath impedance that includes both resistive and capacitive contributions describing RF sheath rectification and RF power absorption in the sheath [J. R. Myra and D. A. D'Ippolito, Phys. Plasmas 22, 062507 (2015)]. We define a dimensionless parameter, the ratio of incoming wave impedance to the sheath impedance, which determines the characteristics of the interaction, ranging from quasi-conducting to quasi-insulating, or in the case of matched impedances, to either perfect absorption or a sheath-plasma resonance. A semi-analytical analysis is carried out for electrostatic slow waves in the ion cyclotron range of frequencies. For the propagating slow wave case, where the incident wave is partially reflected, the fraction of power dissipated in the sheath is calculated. For the evanescent slow wave case, which admits a sheath-plasma resonance, an amplification factor is calculated. Using the impedance ratio approach, RF sheath interactions are characterized for a range of RF wave and plasma parameters including plasma density, magnetic field angle with respect to the surface, wave frequency, and wave-vector components tangent to themore » surface. For a particularly interesting example case, results are compared with the rfSOL code [H. Kohno and J. R. Myra, Comput. Phys. Commun. 220, 129 (2017)]. Finally, electromagnetic effects, absent from the semi-analytical analysis, are assessed.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. Lodestar Research Corporation, Boulder, CO (United States)
  2. Kyushu Inst. of Technology, Iizuka (Japan). Dept. of Mechanical Information Science and Technology
Publication Date:
Research Org.:
Lodestar Research Corp., Boulder, CO (United States); Kyushu Inst. of Technology, Iizuka (Japan)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); Japan Society for the Promotion of Science (JSPS)
OSTI Identifier:
1511451
Alternate Identifier(s):
OSTI ID: 1511525
Report Number(s):
LRC-19-179
Journal ID: ISSN 1070-664X; DE-FG02-97ER54392; JP16K18336; DE-AC02-05CH11231
Grant/Contract Number:  
AC05-00OR22725; FG02-97ER54392; AC02-05CH11231; JP16K18336
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 26; Journal Issue: 5; 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; electric currents; RF waves; plasma sheaths; tokamaks; electrical properties and parameters

Citation Formats

Myra, J. R., and Kohno, H. Radio frequency wave interactions with a plasma sheath: The role of wave and plasma sheath impedances. United States: N. p., 2019. Web. doi:10.1063/1.5088343.
Myra, J. R., & Kohno, H. Radio frequency wave interactions with a plasma sheath: The role of wave and plasma sheath impedances. United States. doi:10.1063/1.5088343.
Myra, J. R., and Kohno, H. Wed . "Radio frequency wave interactions with a plasma sheath: The role of wave and plasma sheath impedances". United States. doi:10.1063/1.5088343.
@article{osti_1511451,
title = {Radio frequency wave interactions with a plasma sheath: The role of wave and plasma sheath impedances},
author = {Myra, J. R. and Kohno, H.},
abstractNote = {Radio frequency (RF) sheaths form near surfaces where plasma and strong RF fields coexist. The effect of these RF sheaths on wave propagation near the boundary can be characterized by an effective sheath impedance that includes both resistive and capacitive contributions describing RF sheath rectification and RF power absorption in the sheath [J. R. Myra and D. A. D'Ippolito, Phys. Plasmas 22, 062507 (2015)]. We define a dimensionless parameter, the ratio of incoming wave impedance to the sheath impedance, which determines the characteristics of the interaction, ranging from quasi-conducting to quasi-insulating, or in the case of matched impedances, to either perfect absorption or a sheath-plasma resonance. A semi-analytical analysis is carried out for electrostatic slow waves in the ion cyclotron range of frequencies. For the propagating slow wave case, where the incident wave is partially reflected, the fraction of power dissipated in the sheath is calculated. For the evanescent slow wave case, which admits a sheath-plasma resonance, an amplification factor is calculated. Using the impedance ratio approach, RF sheath interactions are characterized for a range of RF wave and plasma parameters including plasma density, magnetic field angle with respect to the surface, wave frequency, and wave-vector components tangent to the surface. For a particularly interesting example case, results are compared with the rfSOL code [H. Kohno and J. R. Myra, Comput. Phys. Commun. 220, 129 (2017)]. Finally, electromagnetic effects, absent from the semi-analytical analysis, are assessed.},
doi = {10.1063/1.5088343},
journal = {Physics of Plasmas},
number = 5,
volume = 26,
place = {United States},
year = {2019},
month = {5}
}

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