Characterizing Low-Z erosion and deposition in the DIII-D divertor using aluminum

C.P. Chrobak; R.P. Doerner; P.C. Stangeby; W.R. Wampler; D.L. Rudakov; G.M. Wright; T. Abrams; R. Ding; J.D. Elder; J. Guterl; H.Y. Guo; C. Lasnier; D.M. Thomas; A.W. Leonard; D.A. Buchenauer; A.G. McLean; J.G. Watkins; G.R. Tynan

Nuclear Materials and Energy (Aug 2017)

Characterizing Low-Z erosion and deposition in the DIII-D divertor using aluminum

C.P. Chrobak,
R.P. Doerner,
P.C. Stangeby,
W.R. Wampler,
D.L. Rudakov,
G.M. Wright,
T. Abrams,
R. Ding,
J.D. Elder,
J. Guterl,
H.Y. Guo,
C. Lasnier,
D.M. Thomas,
A.W. Leonard,
D.A. Buchenauer,
A.G. McLean,
J.G. Watkins,
G.R. Tynan

Affiliations

C.P. Chrobak: General Atomics, PO Box 85608, San Diego, CA 92186-5608, USA; Corresponding author.
R.P. Doerner: University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417, USA
P.C. Stangeby: University of Toronto, Institute for Aerospace Studies, Toronto, M3H 5T6, Canada
W.R. Wampler: Sandia National Laboratory, P.O. Box 5800, Albuquerque, NM 87185, USA
D.L. Rudakov: University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417, USA
G.M. Wright: Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA
T. Abrams: Oak Ridge Associated Universities, Oak Ridge, TN, 37830, USA
R. Ding: Oak Ridge Associated Universities, Oak Ridge, TN, 37830, USA
J.D. Elder: University of Toronto, Institute for Aerospace Studies, Toronto, M3H 5T6, Canada
J. Guterl: Oak Ridge Associated Universities, Oak Ridge, TN, 37830, USA
H.Y. Guo: General Atomics, PO Box 85608, San Diego, CA 92186-5608, USA
C. Lasnier: Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
D.M. Thomas: General Atomics, PO Box 85608, San Diego, CA 92186-5608, USA
A.W. Leonard: General Atomics, PO Box 85608, San Diego, CA 92186-5608, USA
D.A. Buchenauer: Sandia National Laboratory, P.O. Box 5800, Albuquerque, NM 87185, USA
A.G. McLean: Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA
J.G. Watkins: Sandia National Laboratory, P.O. Box 5800, Albuquerque, NM 87185, USA
G.R. Tynan: University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0417, USA

Journal volume & issue: Vol. 12
pp. 441 – 446

Abstract

Read online

We present measurements and modeling of aluminum erosion and redeposition experiments in separate helium and deuterium low power, low density L-mode plasmas at the outer divertor strike point of DIII-D to provide a low-Z material benchmark dataset for tokamak erosion-deposition modeling codes. Coatings of Al ∼100nm thick were applied to ideal (smooth) and realistic (rough) surfaces and exposed to repeat plasma discharges using the DiMES probe. Redeposition in all cases was primarily in the downstream toroidal field direction, evident from both in-situ spectroscopic and post-mortem non-spectroscopic measurements. The gross Al erosion yield was estimated from film thickness change measurements of small area samples, and was found to be ∼40–70% of the expected erosion yield based on theoretical physical sputtering yields after including sputtering by a 1–3% carbon impurity. The multi-step redeposition and re-erosion process, and hence the measured net erosion yield and material migration patterns, were found to be influenced by the surface roughness and/or porosity. A time-dependent model of material migration accounting for deposit accumulation in hidden areas was developed to reproduce the measurements in these experiments and determine a redeposition probability distribution function for sputtered atoms. Keywords: Erosion, Deposition, Migration, Roughness, Aluminum, Mixed materials

Published in Nuclear Materials and Energy

ISSN: 2352-1791 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Nuclear engineering. Atomic power
Website: http://www.journals.elsevier.com/nuclear-materials-and-energy/

About the journal