Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D (invited)

D. C. Donovan; E. A. Unterberg; P. C. Stangeby; S. Zamperini; J. D. Auxier; D. L. Rudakov; W. R. Wampler; M. Zach; T. Abrams; J. D. Duran; J. D. Elder; A. L. Neff

doi:10.1063/1.5039347

Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D (invited)

D. C. Donovan, E. A. Unterberg, P. C. Stangeby, S. Zamperini, J. D. Auxier, D. L. Rudakov, W. R. Wampler, M. Zach, T. Abrams, J. D. Duran, J. D. Elder, A. L. Neff

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18 Scopus citations

Abstract

Triplet sets of replaceable graphite rod collector probes (CPs), each with collection surfaces on opposing faces and oriented normal to the magnetic field, were inserted at the outboard mid-plane of DIII-D to study divertor tungsten (W) transport in the Scrape-Off Layer (SOL). Each CP collects particles along field lines with different parallel sampling lengths (determined by the rod diameters and SOL transport) giving radial profiles from the main wall inward to R-R_sep ∼ 6 cm. The CPs were deployed in a first-of-a-kind experiment using two toroidal rings of distinguishable isotopically enriched, W-coated divertor tiles installed at 2 poloidal locations in the divertor. Post-mortem Rutherford backscatter spectrometry of the surface of the CPs provided areal density profiles of elemental W coverage. Higher W content was measured on the probe side facing along the field lines toward the inner target indicating higher concentration of W in the plasma upstream of the CP, even though the W-coated rings were in the outer target region of the divertor. Inductively coupled plasma mass spectroscopy validates the isotopic tracer technique through analysis of CPs exposed during L-mode discharges with the outer strike point on the isotopically enriched W coated-tile ring. The contribution from each divertor ring of W to the deposition profiles found on the mid-plane collector probes was able to be de-convoluted using a stable isotope mixing model. The results provided quantitative information on the W source and transport from specific poloidal locations within the lower divertor region.

Original language	English
Article number	10I115
Journal	Review of Scientific Instruments
Volume	89
Issue number	10
DOIs	https://doi.org/10.1063/1.5039347
State	Published - Oct 1 2018

Funding

The authors would like to acknowledge the contributions of the UT Institute for Nuclear Security, funded by the U.S. National Nuclear Security Administration (No. DA-NA-0001983). This work was supported by the U.S. Department of Energy under Nos. DE-SC0016318 (UTK), DE-AC05-00OR22725 (ORNL), DE-FG02-07ER54917 (UCSD), DE-FC02-04ER54698 (General Atomics), and DE-NA0003525 (SNL).

Funders	Funder number
UT Institute for Nuclear Security
U.S. Department of Energy	DE-AC05-00OR22725, DE-SC0016318
National Nuclear Security Administration	DA-NA-0001983
Oak Ridge National Laboratory	DE-FG02-07ER54917
University of California, San Diego	DE-NA0003525, DE-FC02-04ER54698

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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Donovan, D. C., Unterberg, E. A., Stangeby, P. C., Zamperini, S., Auxier, J. D., Rudakov, D. L., Wampler, W. R., Zach, M., Abrams, T., Duran, J. D., Elder, J. D., & Neff, A. L. (2018). Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D (invited). Review of Scientific Instruments, 89(10), Article 10I115. https://doi.org/10.1063/1.5039347

@article{ae56647fcebd452894f853905b6135e4,

title = "Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D (invited)",

abstract = "Triplet sets of replaceable graphite rod collector probes (CPs), each with collection surfaces on opposing faces and oriented normal to the magnetic field, were inserted at the outboard mid-plane of DIII-D to study divertor tungsten (W) transport in the Scrape-Off Layer (SOL). Each CP collects particles along field lines with different parallel sampling lengths (determined by the rod diameters and SOL transport) giving radial profiles from the main wall inward to R-Rsep ∼ 6 cm. The CPs were deployed in a first-of-a-kind experiment using two toroidal rings of distinguishable isotopically enriched, W-coated divertor tiles installed at 2 poloidal locations in the divertor. Post-mortem Rutherford backscatter spectrometry of the surface of the CPs provided areal density profiles of elemental W coverage. Higher W content was measured on the probe side facing along the field lines toward the inner target indicating higher concentration of W in the plasma upstream of the CP, even though the W-coated rings were in the outer target region of the divertor. Inductively coupled plasma mass spectroscopy validates the isotopic tracer technique through analysis of CPs exposed during L-mode discharges with the outer strike point on the isotopically enriched W coated-tile ring. The contribution from each divertor ring of W to the deposition profiles found on the mid-plane collector probes was able to be de-convoluted using a stable isotope mixing model. The results provided quantitative information on the W source and transport from specific poloidal locations within the lower divertor region.",

author = "Donovan, {D. C.} and Unterberg, {E. A.} and Stangeby, {P. C.} and S. Zamperini and Auxier, {J. D.} and Rudakov, {D. L.} and Wampler, {W. R.} and M. Zach and T. Abrams and Duran, {J. D.} and Elder, {J. D.} and Neff, {A. L.}",

note = "Publisher Copyright: {\textcopyright} 2018 Author(s).",

year = "2018",

month = oct,

day = "1",

doi = "10.1063/1.5039347",

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Donovan, DC, Unterberg, EA, Stangeby, PC, Zamperini, S, Auxier, JD, Rudakov, DL, Wampler, WR, Zach, M, Abrams, T, Duran, JD, Elder, JD & Neff, AL 2018, 'Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D (invited)', Review of Scientific Instruments, vol. 89, no. 10, 10I115. https://doi.org/10.1063/1.5039347

Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D (invited). / Donovan, D. C.; Unterberg, E. A.; Stangeby, P. C. et al.
In: Review of Scientific Instruments, Vol. 89, No. 10, 10I115, 01.10.2018.

Research output: Contribution to journal › Article › peer-review

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T1 - Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D (invited)

AU - Donovan, D. C.

AU - Unterberg, E. A.

AU - Stangeby, P. C.

AU - Zamperini, S.

AU - Auxier, J. D.

AU - Rudakov, D. L.

AU - Wampler, W. R.

AU - Zach, M.

AU - Abrams, T.

AU - Duran, J. D.

AU - Elder, J. D.

AU - Neff, A. L.

PY - 2018/10/1

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AB - Triplet sets of replaceable graphite rod collector probes (CPs), each with collection surfaces on opposing faces and oriented normal to the magnetic field, were inserted at the outboard mid-plane of DIII-D to study divertor tungsten (W) transport in the Scrape-Off Layer (SOL). Each CP collects particles along field lines with different parallel sampling lengths (determined by the rod diameters and SOL transport) giving radial profiles from the main wall inward to R-Rsep ∼ 6 cm. The CPs were deployed in a first-of-a-kind experiment using two toroidal rings of distinguishable isotopically enriched, W-coated divertor tiles installed at 2 poloidal locations in the divertor. Post-mortem Rutherford backscatter spectrometry of the surface of the CPs provided areal density profiles of elemental W coverage. Higher W content was measured on the probe side facing along the field lines toward the inner target indicating higher concentration of W in the plasma upstream of the CP, even though the W-coated rings were in the outer target region of the divertor. Inductively coupled plasma mass spectroscopy validates the isotopic tracer technique through analysis of CPs exposed during L-mode discharges with the outer strike point on the isotopically enriched W coated-tile ring. The contribution from each divertor ring of W to the deposition profiles found on the mid-plane collector probes was able to be de-convoluted using a stable isotope mixing model. The results provided quantitative information on the W source and transport from specific poloidal locations within the lower divertor region.

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Utilization of outer-midplane collector probes with isotopically enriched tungsten tracer particles for impurity transport studies in the scrape-off layer of DIII-D (invited)

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