April 15-17

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Abstracts

Author: Thomas G Jenkins
Requested Type: Poster
Submitted: 2019-02-22 15:52:48

Co-authors: J. R. Myra, D. Curreli, M. T. Elias

Contact Info:
Tech-X Corporation
5621 Arapahoe Avenue, Suite A
Boulder, Colorado   80303
USA

Abstract Text:
Development of robust radiofrequency (RF) actuators for plasma heating and current drive will be critical in sustaining steady-state operation of future magnetic fusion devices. As part of this development, an increased understanding of how applied RF power interacts with plasma sheaths formed near material interfaces (e.g. antenna/vessel surfaces) is sought, and performant numerical simulation tools to explore these interactions are being developed by the RF-SciDAC. Though relevant sheath scale lengths are typically small relative to those of RF wave phenomena, device-scale wave simulations can nevertheless incorporate sheath effects as generalized boundary conditions which capture salient physical behaviors (power dissipation, voltage rectification, sputtering, etc.) associated with the sheath.

In previous work, parametric representations of the sheath impedance and RF voltage rectification (based on local plasma/field values, and suitable for generalized boundary condition representations) were developed using fluid-based models and shown to conform with various analytic limits [1]. In this work, we report our efforts to compare these parametrized impedance and voltage representations with results from explicit particle-in-cell models for the sheath in various regimes, and to explore additional physics which kinetic effects may impart to the sheath model. The PIC modeling uses the Vorpal [2] and hPIC [3] codes. Progress toward implementation of the parametric sheath model in Vorpal, as well as ongoing improvements to the model, will also be discussed.
Supported by the SciDAC Center for Integrated Simulation of Fusion-Relevant RF Actuators (DE-SC0018319, DE-AC05-00OR22725 subcontract 4000158507, DE-SC0018090-PO97564).
[1] Myra & D'Ippolito, Phys. Plasmas 22, 062507 (2015); Myra, Phys. Plasmas 24, 072507 (2017).
[2] Nieter & Cary, J. Comp. Phys. 196, 448 (2004).
[3] Khaziev & Curreli, Phys. Plasmas 22, 043503 (2015), Comput. Phys. Commun. 229, 87 (2018).

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