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Title: DiMES Studies of Temperature Dependence of Carbon Erosion and Re-Deposition in the DIII-D Divertor

Abstract

A strong effect of a moderately elevated surface temperature on net carbon deposition and deuterium co-deposition in the DIII-D divertor was observed under detached conditions. A DiMES sample with a gap 2 mm wide and 18 mm deep was exposed to lower-single-null (LSN) L-mode plasmas first at room temperature, and then at 200 C. At the elevated temperature, deuterium co-deposition in the gap was reduced by an order of magnitude. At the plasma-facing surface of the heated sample net carbon erosion was measured at a rate of 3 nm/s, whereas without heating net deposition is normally observed under detachment. In a related experiment three sets of molybdenum mirrors recessed 2 cm below the divertor floor were exposed to identical LSN ELMy H-mode discharges. The first set of mirrors exposed at ambient temperature exhibited net carbon deposition at a rate of up to 3.7 nm/s and suffered a significant drop in reflectivity. In contrast, two other mirror sets exposed at elevated temperatures between 90 C and 175 C exhibited practically no carbon deposition.

Authors:
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Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
940469
Report Number(s):
UCRL-JRNL-229141
Journal ID: ISSN 0031-8949; PHSTBO; TRN: US0807137
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physica Scripta, T128, N/A, March 28, 2007, pp. 29-34; Journal Volume: T128
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 70 PLASMA PHYSICS AND FUSION; AMBIENT TEMPERATURE; CARBON; DEPOSITION; DEUTERIUM; DIVERTORS; DOUBLET-3 DEVICE; FLOORS; HEATING; MIRRORS; MOLYBDENUM; REFLECTIVITY; TEMPERATURE DEPENDENCE

Citation Formats

Rudakov, D L, Jacob, W, Krieger, K, Litnovsky, A, Philipps, V, West, W P, Wong, C C, Allen, S L, Bastasz, R J, Boedo, J A, Brooks, N H, Boivin, R L, De Temmerman, G, Fenstermacher, M E, Groth, M, Hollmann, E M, Lasnier, C J, McLean, A G, Moyer, R A, Stangeby, P C, Wampler, W R, Watkins, J G, Wienhold, P, and Whaley, J. DiMES Studies of Temperature Dependence of Carbon Erosion and Re-Deposition in the DIII-D Divertor. United States: N. p., 2007. Web.
Rudakov, D L, Jacob, W, Krieger, K, Litnovsky, A, Philipps, V, West, W P, Wong, C C, Allen, S L, Bastasz, R J, Boedo, J A, Brooks, N H, Boivin, R L, De Temmerman, G, Fenstermacher, M E, Groth, M, Hollmann, E M, Lasnier, C J, McLean, A G, Moyer, R A, Stangeby, P C, Wampler, W R, Watkins, J G, Wienhold, P, & Whaley, J. DiMES Studies of Temperature Dependence of Carbon Erosion and Re-Deposition in the DIII-D Divertor. United States.
Rudakov, D L, Jacob, W, Krieger, K, Litnovsky, A, Philipps, V, West, W P, Wong, C C, Allen, S L, Bastasz, R J, Boedo, J A, Brooks, N H, Boivin, R L, De Temmerman, G, Fenstermacher, M E, Groth, M, Hollmann, E M, Lasnier, C J, McLean, A G, Moyer, R A, Stangeby, P C, Wampler, W R, Watkins, J G, Wienhold, P, and Whaley, J. Thu . "DiMES Studies of Temperature Dependence of Carbon Erosion and Re-Deposition in the DIII-D Divertor". United States. doi:. https://www.osti.gov/servlets/purl/940469.
@article{osti_940469,
title = {DiMES Studies of Temperature Dependence of Carbon Erosion and Re-Deposition in the DIII-D Divertor},
author = {Rudakov, D L and Jacob, W and Krieger, K and Litnovsky, A and Philipps, V and West, W P and Wong, C C and Allen, S L and Bastasz, R J and Boedo, J A and Brooks, N H and Boivin, R L and De Temmerman, G and Fenstermacher, M E and Groth, M and Hollmann, E M and Lasnier, C J and McLean, A G and Moyer, R A and Stangeby, P C and Wampler, W R and Watkins, J G and Wienhold, P and Whaley, J},
abstractNote = {A strong effect of a moderately elevated surface temperature on net carbon deposition and deuterium co-deposition in the DIII-D divertor was observed under detached conditions. A DiMES sample with a gap 2 mm wide and 18 mm deep was exposed to lower-single-null (LSN) L-mode plasmas first at room temperature, and then at 200 C. At the elevated temperature, deuterium co-deposition in the gap was reduced by an order of magnitude. At the plasma-facing surface of the heated sample net carbon erosion was measured at a rate of 3 nm/s, whereas without heating net deposition is normally observed under detachment. In a related experiment three sets of molybdenum mirrors recessed 2 cm below the divertor floor were exposed to identical LSN ELMy H-mode discharges. The first set of mirrors exposed at ambient temperature exhibited net carbon deposition at a rate of up to 3.7 nm/s and suffered a significant drop in reflectivity. In contrast, two other mirror sets exposed at elevated temperatures between 90 C and 175 C exhibited practically no carbon deposition.},
doi = {},
journal = {Physica Scripta, T128, N/A, March 28, 2007, pp. 29-34},
number = ,
volume = T128,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}