RF sheath induced sputtering on Proto-MPEX part 2: Impurity transport modeling and experimental comparison

Beers, Clyde; Lau, Cornwall; Rapp, Juergen; Younkin, Tim; Biewer, Theodore; Bigelow, Tim S.; Caneses Marin, Juan; Caughman, John; Green, David; Meyer III, Harry; Myra, J. R.; Zinkle, Steven J.

doi:10.1063/5.0065464

RF sheath induced sputtering on Proto-MPEX part 2: Impurity transport modeling and experimental comparison

Journal Article · Thu Oct 21 00:00:00 EDT 2021 · Physics of Plasmas

DOI:https://doi.org/10.1063/5.0065464· OSTI ID:1828256

^[1]; ^[2]; ^[2]; Younkin, Tim ^[2]; ^[2]; ^[2]; ^[2]; ^[2]; ^[2]; ^[2]; Myra, J. R. ^[3]; Zinkle, Steven J. ^[4]

Univ. of Tennessee, Knoxville, TN (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Lodestar Research Corp., Boulder, CO (United States)
Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) is a pulsed linear plasma device that uses a radio frequency (RF) helicon antenna and a helicon ceramic window as the plasma ionization source. Modeling performed within this work on the helicon operations predicts hot spots on the helicon ceramic window due to an RF-induced sheath. The RF sheath potential leads to physical sputtering of the ceramic window predominantly where the helicon antenna sits around the helicon window. The role of oxygen in sputtering within Proto-MPEX is also investigated and is needed to match the experimental data. Experiments on Proto-MPEX show reasonable agreement with the modeled erosion/redeposition pattern on the helicon window, and the modeled impurity flux to the target shows radial transport within the device as expected from classical collisional impurity transport. Temperature screening of impurities is shown to be needed for Proto-MPEX to reduce impurity flux to the target. The modeling approach used in this work can be applied to other plasma RF applications for the determination of impurity production and transport.

View Accepted Manuscript (DOE)

Research Organization:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: USDOE

Grant/Contract Number:: AC05-00OR22725

OSTI ID:: 1828256

Alternate ID(s):: OSTI ID: 1826849

Journal Information:: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 10 Vol. 28; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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