Abstract Details
Abstracts
Author: Matthew J Poulos
Requested Type: Consider for Invited
Submitted: 2023-03-24 18:55:00
Co-authors: N.Bertelli, S.Shiraiwa, J.Myra, D.Smithe, T. Jenkins, RF SciDAC
Contact Info:
Princeton Plasma Physics Laboratory
2208 Sayre Dr
Princeton, NJ 08540
United States
Abstract Text:
This talk reports on recent progress made toward the development, implementation, and benchmarking of a self-consistent nonlinear radio-frequency (RF) sheath model [1]. Sheath potentials formed on the material surfaces of plasma facing components are dramatically enhanced by the application of RF power in the ion-cyclotron range of frequencies (ICRF). The resulting rectified sheath potentials lead to several important and potentially deleterious effects such as the sputtering of impurities from the wall material and the formation of convective cells. Using the three-dimensional finite element code Petra-M, the RF sheath boundary condition is used to model sheath rectification in the WEST tokamak using realistic antenna, limiter, and wall geometry [2]. In simplified geometries, analytic results are leveraged to show that there is a rich set of nonlinear features associated with RF sheath-plasma interactions such as multivaluedness, instability, hysteresis, and spontaneous symmetry breaking [3]. These nonlinear features are further confirmed and studied in the three-dimensional time-domain code Vorpal. Finally, a set of basic plasma experiments is performed on the Large Plasma Device (LAPD) which qualitatively demonstrates the existence of a nonlinear hysteresis associated with sheath-plasma interactions.
[1] J.R. Myra, Phys. Plasmas 24, 072507 (2017).
[2] S. Shiraiwa et. al., Nucl. Fusion 63, 026024 (2023).
[3] M. Poulos, Phys. Plasmas 29, 102103 (2022).
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