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Title: Measurements of tungsten migration in the DIII-D divertor

Abstract

An experimental study of migration of tungsten in the DIII-D divertor is described, in which the outer strike point of L-mode plasmas was positioned on a toroidal ring of tungsten-coated metal inserts. Net deposition of tungsten on the divertor just outside the strike point was measured on graphite samples exposed to various plasma durations using the divertor materials evaluation system. Tungsten coverage, measured by Rutherford backscattering spectroscopy (RBS), was found to be low and nearly independent of both radius and exposure time closer to the strike point, whereas farther from the strike point the W coverage was much larger and increased with exposure time. Depth profiles from RBS show this was due to accumulation of thicker mixed-material deposits farther from the strike point where the plasma temperature is lower. These results are consistent with a low near-surface steady-state coverage on graphite undergoing net erosion, and continuing accumulation in regions of net deposition. This experiment provides data needed to validate, and further improve computational simulations of erosion and deposition of material on plasma-facing components and transport of impurities in magnetic fusion devices. Such simulations are underway and will be reported later.

Authors:
 [1];  [1];  [1];  [2]; ORCiD logo [3];  [4]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Univ. of Toronto, ON (Canada)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1477317
Alternate Identifier(s):
OSTI ID: 1483173
Report Number(s):
SAND-2018-10807J
Journal ID: ISSN 0031-8949; 668371
Grant/Contract Number:  
AC04-94AL85000; AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Physica Scripta
Additional Journal Information:
Journal Volume: T170; Journal ID: ISSN 0031-8949
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Wampler, W. R., Rudakov, D. L., Watkins, J. G., McLean, A. G., Unterberg, E. A., and Stangeby, P. C. Measurements of tungsten migration in the DIII-D divertor. United States: N. p., 2017. Web. doi:10.1088/1402-4896/aa8d5a.
Wampler, W. R., Rudakov, D. L., Watkins, J. G., McLean, A. G., Unterberg, E. A., & Stangeby, P. C. Measurements of tungsten migration in the DIII-D divertor. United States. doi:https://doi.org/10.1088/1402-4896/aa8d5a
Wampler, W. R., Rudakov, D. L., Watkins, J. G., McLean, A. G., Unterberg, E. A., and Stangeby, P. C. Fri . "Measurements of tungsten migration in the DIII-D divertor". United States. doi:https://doi.org/10.1088/1402-4896/aa8d5a. https://www.osti.gov/servlets/purl/1477317.
@article{osti_1477317,
title = {Measurements of tungsten migration in the DIII-D divertor},
author = {Wampler, W. R. and Rudakov, D. L. and Watkins, J. G. and McLean, A. G. and Unterberg, E. A. and Stangeby, P. C.},
abstractNote = {An experimental study of migration of tungsten in the DIII-D divertor is described, in which the outer strike point of L-mode plasmas was positioned on a toroidal ring of tungsten-coated metal inserts. Net deposition of tungsten on the divertor just outside the strike point was measured on graphite samples exposed to various plasma durations using the divertor materials evaluation system. Tungsten coverage, measured by Rutherford backscattering spectroscopy (RBS), was found to be low and nearly independent of both radius and exposure time closer to the strike point, whereas farther from the strike point the W coverage was much larger and increased with exposure time. Depth profiles from RBS show this was due to accumulation of thicker mixed-material deposits farther from the strike point where the plasma temperature is lower. These results are consistent with a low near-surface steady-state coverage on graphite undergoing net erosion, and continuing accumulation in regions of net deposition. This experiment provides data needed to validate, and further improve computational simulations of erosion and deposition of material on plasma-facing components and transport of impurities in magnetic fusion devices. Such simulations are underway and will be reported later.},
doi = {10.1088/1402-4896/aa8d5a},
journal = {Physica Scripta},
number = ,
volume = T170,
place = {United States},
year = {2017},
month = {10}
}

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Cited by: 6 works
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Works referenced in this record:

WALLDYN simulations of global impurity migration in JET and extrapolations to ITER
journal, April 2015


Analysis of a tungsten sputtering experiment in DIII-D and code/data validation of high redeposition/reduced erosion
journal, May 2015


Simulation of gross and net erosion of high- Z materials in the DIII-D divertor
journal, December 2015


DiMES PMI research at DIII-D in support of ITER and beyond
journal, November 2017


Net versus gross erosion of high- Z materials in the divertor of DIII-D
journal, April 2014


Measurements of net erosion and redeposition of molybdenum in DIII-D
journal, July 2013


Migration of tungsten eroded from divertor tiles in ASDEX Upgrade
journal, February 1997


Gross and net erosion of tungsten in the outer strike-point region of ASDEX Upgrade
journal, January 2016


Tungsten as target material in fusion devices
journal, June 1996


Modelling of tungsten re-deposition coefficient
journal, August 2015


Modelling of carbon migration during JET 13 C injection experiments
journal, August 2008


    Works referencing / citing this record:

    Impact of ELM control techniques on tungsten sputtering in the DIII-D divertor and extrapolations to ITER
    journal, June 2019

    • Abrams, T.; Unterberg, E. A.; Rudakov, D. L.
    • Physics of Plasmas, Vol. 26, Issue 6
    • DOI: 10.1063/1.5089895

    Multiple Analytical Approach to Isotopic Transport Analysis in Magnetic Fusion Devices
    journal, May 2019


    DIII-D research towards establishing the scientific basis for future fusion reactors
    journal, June 2019