Microscopic damage of tungsten exposed to deuterium–helium mixture plasma in PISCES and its impacts on retention property

Miyamoto, M.; Nishijima, D.; Baldwin, M.J.; Doerner, R.; Ueda, Y.; Yasunaga, Kōjirō; Yoshida, N.; Ono, Kotaro

doi:10.1016/j.jnucmat.2011.01.008

Cited by 139 publications

(98 citation statements)

References 14 publications

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“…In bulk W, this corresponds to ~30 nm. This thickness for a He bubble containing layer in W is on the order of what others have seen for W that did not produce fuzz [13]. Each sample was exposed to He ions of the same energy and that might be why samples E, F, and G equilibrate to the same depth.…”

Section: P1-001mentioning

confidence: 67%

Dynamic measurement of the helium concentration of evolving tungsten nanostructures using Elastic Recoil Detection during plasma exposure

Woller

Whyte

Wright

2015

Journal of Nuclear Materials

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Abstract:Helium (He) concentration depth profiles of evolving tungsten (W) nanostructures have been measured for the first time using in situ Elastic Recoil Detection (ERD) throughout plasma irradiation. Exposures resulting in fuzzy and non-fuzzy surfaces were analyzed in order to illuminate the role of He during the development of these surface morphologies. ERD was performed on samples with surface temperatures from T s =530-1100 K and irradiated by He flux densities of Γ He~1 0 20 -10 22 m -2 s -1 . He concentration profiles in samples that developed either non-fuzzy or fuzzy surfaces are uniformly shaped with concentrations of 1.5 to 7 at.%, which is presumed to be too low for pressure driven growth models. Therefore, surface morphology changes are not perpetuated by continuous bubble bursting deformation. Also, a threshold in He flux density above 10 20 m -2 s -1 is suggested by using in situ ERD to monitor the depth profile evolution of the He-rich layer while changing the flux during exposure.

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Section: P1-001mentioning

confidence: 67%

Dynamic measurement of the helium concentration of evolving tungsten nanostructures using Elastic Recoil Detection during plasma exposure

Woller

Whyte

Wright

2015

Journal of Nuclear Materials

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“…This is well below the expected He concentration if the voids were filled to equilibrium pressure with He gas. It is also possible that the void fraction in the tendrils and bulk was significantly lower than in the W in [17] and [18]. However, we can think of no reason this might be the case given the consistent morphology of fuzz grown in Pilot-PSI when compared to other devices.…”

Section: He Concentrations In W Fuzz Layersmentioning

confidence: 89%

“…Given that the porosity (e.g. bubble/void density in the solid tendrils or bulk) of the tungsten filled with these He voids has been measured between 20-50% porous [17,18], we would then expect the He concentrations in these layers to be in the range of 17-43 at.%.…”

Section: He Concentrations In W Fuzz Layersmentioning

confidence: 99%

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

Wright¹,

Brunner²,

Baldwin³

et al. 2013

Journal of Nuclear Materials

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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 1-4 at.%, 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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“…The formation of such a supersaturated layer is often accompanied (depending on the wall material) by the formation of nano-bubbles (Miyamoto et al 2011), figures 14 and 15, and by strong modification of the surface morphology (e.g. Takamura et al 2006;Kajita et al 2009;Zibrov et al 2017) resulting in formation of the blisters (figure 15, dust, 'fuzz', pinholes, protrusions, etc.…”

Section: Processes Related To Plasma-materials Interactionsmentioning

confidence: 99%

Physics of ultimate detachment of a tokamak divertor plasma

Krasheninnikov¹,

2017

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The basic physics of the processes playing the most important role in divertor plasma detachment is reviewed. The models used in the two-dimensional edge plasma transport codes that are widely used to address different issues of the edge plasma physics and to simulate the experimental data, as well as the numerical schemes and convergence issues, are described. The processes leading to ultimate divertor plasma detachment, the transition to and the stability of the detached regime, as well as the impact of the magnetic configuration and divertor geometry on detachment, are considered. A consistent, integral physical picture of ultimate detachment of a tokamak divertor plasma is developed.

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Microscopic damage of tungsten exposed to deuterium–helium mixture plasma in PISCES and its impacts on retention property

Cited by 139 publications

References 14 publications

Dynamic measurement of the helium concentration of evolving tungsten nanostructures using Elastic Recoil Detection during plasma exposure

Dynamic measurement of the helium concentration of evolving tungsten nanostructures using Elastic Recoil Detection during plasma exposure

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

Physics of ultimate detachment of a tokamak divertor plasma

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