A study of tungsten migration in the Alcator C-Mod divertor

H.S. Barnard; B. Lipschultz; D.G. Whyte

doi:10.1016/j.jnucmat.2010.12.317

A study of tungsten migration in the Alcator C-Mod divertor

H.S. Barnard, B. Lipschultz, D.G. Whyte

Physics

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Abstract

A toroidally-continuous row of bulk tungsten (W) tiles was installed near the typical location of the outer strike-point in the Alcator C-Mod divertor and was removed for analysis after two campaigns (3151 plasma discharges). External beam (in-air) particle induced X-ray emission (PIXE) analysis has been used to observe campaign-integrated W migration patterns in the otherwise Mo divertor using the W as a tracer for divertor erosion and transport. With a set of high spatial resolution PIXE measurements (∼3 mm resolution), poloidal profiles of W migration have been constructed. Redeposition of up to 1.5 × 10 atoms/m (∼20 nm equivalent thickness) is observed on the outer and inner divertor, and in the private-flux region. The campaign-integrated deposition on the analyzed tiles corresponds to net W erosion of ∼60 nm (>0.014 nm/s). The migration profiles indicate sputtering and prompt redeposition in the outer divertor, neutral and ion transport through the private-flux region, and transport in the scrape off layer.

Original language	English
Journal	Journal of Nuclear Materials
Volume	415
Issue number	1 SUPPL
DOIs	https://doi.org/10.1016/j.jnucmat.2010.12.317
Publication status	Published - 1 Aug 2011

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10.1016/j.jnucmat.2010.12.317

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title = "A study of tungsten migration in the Alcator C-Mod divertor",

abstract = "A toroidally-continuous row of bulk tungsten (W) tiles was installed near the typical location of the outer strike-point in the Alcator C-Mod divertor and was removed for analysis after two campaigns (3151 plasma discharges). External beam (in-air) particle induced X-ray emission (PIXE) analysis has been used to observe campaign-integrated W migration patterns in the otherwise Mo divertor using the W as a tracer for divertor erosion and transport. With a set of high spatial resolution PIXE measurements (∼3 mm resolution), poloidal profiles of W migration have been constructed. Redeposition of up to 1.5 × 10 atoms/m (∼20 nm equivalent thickness) is observed on the outer and inner divertor, and in the private-flux region. The campaign-integrated deposition on the analyzed tiles corresponds to net W erosion of ∼60 nm (>0.014 nm/s). The migration profiles indicate sputtering and prompt redeposition in the outer divertor, neutral and ion transport through the private-flux region, and transport in the scrape off layer.",

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AU - Barnard, H.S.

AU - Lipschultz, B.

AU - Whyte, D.G.

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N2 - A toroidally-continuous row of bulk tungsten (W) tiles was installed near the typical location of the outer strike-point in the Alcator C-Mod divertor and was removed for analysis after two campaigns (3151 plasma discharges). External beam (in-air) particle induced X-ray emission (PIXE) analysis has been used to observe campaign-integrated W migration patterns in the otherwise Mo divertor using the W as a tracer for divertor erosion and transport. With a set of high spatial resolution PIXE measurements (∼3 mm resolution), poloidal profiles of W migration have been constructed. Redeposition of up to 1.5 × 10 atoms/m (∼20 nm equivalent thickness) is observed on the outer and inner divertor, and in the private-flux region. The campaign-integrated deposition on the analyzed tiles corresponds to net W erosion of ∼60 nm (>0.014 nm/s). The migration profiles indicate sputtering and prompt redeposition in the outer divertor, neutral and ion transport through the private-flux region, and transport in the scrape off layer.

AB - A toroidally-continuous row of bulk tungsten (W) tiles was installed near the typical location of the outer strike-point in the Alcator C-Mod divertor and was removed for analysis after two campaigns (3151 plasma discharges). External beam (in-air) particle induced X-ray emission (PIXE) analysis has been used to observe campaign-integrated W migration patterns in the otherwise Mo divertor using the W as a tracer for divertor erosion and transport. With a set of high spatial resolution PIXE measurements (∼3 mm resolution), poloidal profiles of W migration have been constructed. Redeposition of up to 1.5 × 10 atoms/m (∼20 nm equivalent thickness) is observed on the outer and inner divertor, and in the private-flux region. The campaign-integrated deposition on the analyzed tiles corresponds to net W erosion of ∼60 nm (>0.014 nm/s). The migration profiles indicate sputtering and prompt redeposition in the outer divertor, neutral and ion transport through the private-flux region, and transport in the scrape off layer.

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A study of tungsten migration in the Alcator C-Mod divertor

Abstract

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