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Tungsten

About: Tungsten is a research topic. Over the lifetime, 35225 publications have been published within this topic receiving 456213 citations. The topic is also known as: W & element 74.


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Journal ArticleDOI
TL;DR: Growth of tungsten nano-tendrils (?fuzz?) has been observed for the first time in the divertor region of a high-power density tokamak experiment as discussed by the authors.
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 thickness of the individual nano-tendrils (50?100?nm) and the depth of the layer (600???150?nm) are consistent with observations from experiments on linear plasma devices. The observation of tungsten fuzz in a tokamak may have important implications for material erosion, dust formation, divertor lifetime and tokamak operations in next-step devices.

127 citations

Journal ArticleDOI
TL;DR: In this paper, the angular distribution of reflected H2 displays a shift toward the specular ray, and the sticking probability of H2 on tungsten approaches a limiting value of 0.3.
Abstract: Through the use of modulated atomic beam techniques, the reflection and dissociation of H2 at a tungsten surface above 2500°K has been studied. Two experimental configurations were employed. In the first configuration, a collimated beam of molecular hydrogen was directed at the tungsten surface, and the angular distribution of particles evaporating from the surface was examined mass spectrometrically. In the second configuration, the tungsten test surface was located in the first of three differentially pumped vacuum chambers. H2 was admitted into this chamber, thereby providing an isotropic source of incident particles. Particles evaporating from the surface were collimated and examined mass spectrometrically in the third chamber. From these experiments it is observed that at high temperatures the angular distribution of atomic hydrogen evaporating from the target surface obeys the cosine law. However, the angular distribution of reflected H2 displays a shift toward the specular ray. Above 2500°K the sticking probability of H2 on tungsten approaches a limiting value of 0.3.

127 citations

Journal ArticleDOI
TL;DR: In this paper, the attachment of helium to annealed inert gas impurity atom traps in tungsten has been measured by thermal desorption spectrometry, and the first helium atom trapped was found to have approximately the same trapping radius (≈2.8 A).

126 citations

Journal ArticleDOI
TL;DR: A review of hydrogen isotopes-materials interactions in various materials of interest for fusion reactors is presented in this article, where the relevant parameters cover mainly diffusivity, solubility, trap concentration and energy difference between trap and solution sites.

126 citations

Journal ArticleDOI
TL;DR: A review of the hydrogen isotope retention and migration properties of tungsten as they relate to fusion applications is presented in this article, where the authors examine past experiments on the diffusivity, solubility, and permeability of hydrogen in Tungsten.
Abstract: In the past the role of tungsten as a fusion reactor plasma-facing material has been fairly limited. It has appeared sparingly in tokamaks, but usually only for experimental purposes. This is likely to change in the future. Tungsten has a very high threshold for sputtering as well as a high melting point and high thermal conductivity. Applications of tungsten in areas where the energy of the plasma particles can be kept below the sputtering threshold removes the plasma impurity problem often associated with the use of tungsten in fusion reactors. In the area of recycling and retention, tungsten is unlike carbon and beryllium in that hydrogen appears to stay in solution in the metal (at least at low concentrations) and diffuse somewhat classically. This paper presents a review of the hydrogen isotope retention and migration properties of tungsten as they relate to fusion applications. The review is begun with an examination of past experiments on the diffusivity, solubility, and permeability of hydrogen in tungsten. Fusion specific topics such as implantation and surface effects are then covered. Trapping is shown to be an important aspect of understanding hydrogen transport in this material. Blister and bubble formation are also addressed.

126 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,055
20222,162
2021902
20201,216
20191,447
20181,372