Comparison of tungsten nano-tendrils grown in Alcator C-Mod and linear plasma devices

G. M. Wright; D. Brunner; M. J. Baldwin; K. Bystrov; R. P. Doerner; B. Labombard; B. Lipschultz; G. De Temmerman; J. L. Terry; D. G. Whyte; K. B. Woller

doi:10.1016/j.jnucmat.2013.01.013

Comparison of tungsten nano-tendrils grown in Alcator C-Mod and linear plasma devices

G. M. Wright^*, D. Brunner, M. J. Baldwin, K. Bystrov, R. P. Doerner, B. Labombard, B. Lipschultz, G. De Temmerman, J. L. Terry, D. G. Whyte, K. B. Woller

^*Corresponding author for this work

Physics

Research output: Contribution to journal › Article › peer-review

Abstract

Growth of tungsten nano-tendrils ("fuzz") has been observed for the first time in the divertor region of a high-power density tokamak experiment. After 14 consecutive helium L-mode discharges in Alcator C-Mod, the tip of a tungsten Langmuir probe at the outer strike point was fully covered with a layer of nano-tendrils. The depth of the W fuzz layer (600 ±150 nm) is consistent with an empirical growth formula from the PISCES experiment. Re-creating the C-Mod exposures as closely as possible in Pilot-PSI experiment can produce nearly-identical nano-tendril morphology and layer thickness at surface temperatures that agree with uncertainties with the C-Mod W probe temperature data. Helium concentrations in W fuzz layers are measured at 1-4at.%, which is lower than expected for the observed sub-surface voids to be filled with several GPa of helium pressure. This possibly indicates that the void formation is not pressure driven.

Original language	English
Pages (from-to)	S84–S89
Journal	Journal of Nuclear Materials
Volume	438
Issue number	SUPPL
DOIs	https://doi.org/10.1016/j.jnucmat.2013.01.013
Publication status	Published - 1 Feb 2013

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title = "Comparison of tungsten nano-tendrils grown in Alcator C-Mod and linear plasma devices",

abstract = "Growth of tungsten nano-tendrils ({"}fuzz{"}) has been observed for the first time in the divertor region of a high-power density tokamak experiment. After 14 consecutive helium L-mode discharges in Alcator C-Mod, the tip of a tungsten Langmuir probe at the outer strike point was fully covered with a layer of nano-tendrils. The depth of the W fuzz layer (600 ±150 nm) is consistent with an empirical growth formula from the PISCES experiment. Re-creating the C-Mod exposures as closely as possible in Pilot-PSI experiment can produce nearly-identical nano-tendril morphology and layer thickness at surface temperatures that agree with uncertainties with the C-Mod W probe temperature data. Helium concentrations in W fuzz layers are measured at 1-4at.%, which is lower than expected for the observed sub-surface voids to be filled with several GPa of helium pressure. This possibly indicates that the void formation is not pressure driven.",

author = "Wright, {G. M.} and D. Brunner and Baldwin, {M. J.} and K. Bystrov and Doerner, {R. P.} and B. Labombard and B. Lipschultz and {De Temmerman}, G. and Terry, {J. L.} and Whyte, {D. G.} and Woller, {K. B.}",

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doi = "10.1016/j.jnucmat.2013.01.013",

language = "English",

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T1 - Comparison of tungsten nano-tendrils grown in Alcator C-Mod and linear plasma devices

AU - Wright, G. M.

AU - Brunner, D.

AU - Baldwin, M. J.

AU - Bystrov, K.

AU - Doerner, R. P.

AU - Labombard, B.

AU - Lipschultz, B.

AU - De Temmerman, G.

AU - Terry, J. L.

AU - Whyte, D. G.

AU - Woller, K. B.

PY - 2013/2/1

Y1 - 2013/2/1

N2 - Growth of tungsten nano-tendrils ("fuzz") has been observed for the first time in the divertor region of a high-power density tokamak experiment. After 14 consecutive helium L-mode discharges in Alcator C-Mod, the tip of a tungsten Langmuir probe at the outer strike point was fully covered with a layer of nano-tendrils. The depth of the W fuzz layer (600 ±150 nm) is consistent with an empirical growth formula from the PISCES experiment. Re-creating the C-Mod exposures as closely as possible in Pilot-PSI experiment can produce nearly-identical nano-tendril morphology and layer thickness at surface temperatures that agree with uncertainties with the C-Mod W probe temperature data. Helium concentrations in W fuzz layers are measured at 1-4at.%, which is lower than expected for the observed sub-surface voids to be filled with several GPa of helium pressure. This possibly indicates that the void formation is not pressure driven.

AB - Growth of tungsten nano-tendrils ("fuzz") has been observed for the first time in the divertor region of a high-power density tokamak experiment. After 14 consecutive helium L-mode discharges in Alcator C-Mod, the tip of a tungsten Langmuir probe at the outer strike point was fully covered with a layer of nano-tendrils. The depth of the W fuzz layer (600 ±150 nm) is consistent with an empirical growth formula from the PISCES experiment. Re-creating the C-Mod exposures as closely as possible in Pilot-PSI experiment can produce nearly-identical nano-tendril morphology and layer thickness at surface temperatures that agree with uncertainties with the C-Mod W probe temperature data. Helium concentrations in W fuzz layers are measured at 1-4at.%, which is lower than expected for the observed sub-surface voids to be filled with several GPa of helium pressure. This possibly indicates that the void formation is not pressure driven.

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DO - 10.1016/j.jnucmat.2013.01.013

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AN - SCOPUS:84885479055

SN - 0022-3115

VL - 438

SP - S84–S89

JO - Journal of Nuclear Materials

JF - Journal of Nuclear Materials

IS - SUPPL

ER -

Comparison of tungsten nano-tendrils grown in Alcator C-Mod and linear plasma devices

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