DiMES studies of temperature dependence of carbon erosion and re-deposition in the lower divertor of DIII-D under detachment
2007; IOP Publishing; Volume: T128; Linguagem: Inglês
10.1088/0031-8949/2007/t128/006
ISSN1402-4896
AutoresD.L. Rudakov, W. Jacob, K. Krieger, A. Litnovsky, V. Philipps, W.P. West, C.P.C. Wong, S.L. Allen, Robert Bastasz, J.A. Boedo, N.H. Brooks, R. L. Boivin, G. De Temmerman, M.E. Fenstermacher, M. Groth, E.M. Hollmann, C.J. Lasnier, A.G. McLean, R. A. Moyer, P.C. Stangeby, W.R. Wampler, J.G. Watkins, P. Wienhold, Josh A. Whaley,
Tópico(s)Laser-Plasma Interactions and Diagnostics
ResumoA 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 graphite DiMES sample with a 2 mm wide, 18 mm deep gap lined with silicon catcher plates was exposed to lower-single-null (LSN) L-mode plasmas first at room temperature, and then pre-heated to 200 °C by a built-in electrical heater. At the elevated temperature, deuterium co-deposition in the gap was reduced by an order of magnitude. At the plasma-facing surface of the pre-heated sample net carbon erosion was measured at a rate of 3 nm s−1, whereas without pre-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−1 and suffered a significant drop in reflectivity. In contrast, two other mirror sets exposed at elevated temperatures between 90 and 175 °C exhibited practically no carbon deposition and their optical reflectivity in the wavelength range above 500 nm was essentially preserved.
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