Accelerated/reduced growth of tungsten fuzz by deposition of metals

Kajita, Shin; Morgan, T.W.; Tanaka, Hirohiko; Hayashi, Y.; Yoshida, N.; Nagata, Daisuke; Vernimmen, J.W.M.; Feng, Shuangyuan; Zhang, Rongshi; Ohno, Noriyasu

doi:10.1016/j.jnucmat.2021.152844

Cited by 20 publications

(13 citation statements)

References 36 publications

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“…To understand the details of the redeposition process, MD and DFT analyses are useful. And redeposition is also associated with the experiment for the enhancement of tungsten atom depostions [59,60], Nano Tendril Bundles (NTBs) [61,62], and Large-scale Fiber-form Nanostructures (LFNs) [63], in which tungsten atoms sputtered elsewhere are deposited onto the fuzz, reaching sizes of a millimeter. Their growth rate is also dramatically increased.…”

Section: Discussionmentioning

confidence: 98%

“…The formation of fuzz has been observed in many environments, i.e. linear plasma devices NAGDIS-II [5], PICIES-B [6], MAGNAM-PSI [7,8], and PSI-2 [9], large torus devices ASDEX Upgrade [10] and Large Helical Device (LHD) [11], and a magnetron sputtering [12]. Therefore, the formation of fuzz is a universal physical phenomenon caused by helium plasma irradiation.…”

Section: Introductionmentioning

confidence: 99%

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Tungsten nanostructure growth by sputtering and redeposition in BCA-MD-KMC hybrid simulation

Ito,

Takayama,

Nakamura

2023

Mater. Res. Express

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The formation mechanism of fibrous tungsten nanostructures, fuzz, induced by helium plasma irradiation on tungsten materials has been investigated. We have developed a BCA-MD-KMC hybrid simulation, which solves the injection process of helium atoms by the Binary Collision Approximation (BCA) method, the diffusion process of helium atoms in tungsten materials by the Kinetic Monte-Carlo (KMC) method, and the deformation of tungsten materials due to helium bubbles by the Molecular Dynamics (MD) method. In addition, the model used to calculate the recoiling of tungsten atoms in BCA was improved to account for the reduced binding energy of tungsten atoms on rough surfaces. Using the hybrid simulation, the height of the nanostructures reached about 50 nm. The main mechanism of nanostructure growth was that sputtering and redeposition caused transport of tungsten atoms perpendicular to the surface. The present simulation was able to represent not only the dependence that the nanostructure height increases in proportion to the square root of the helium fluence, but also the existence of incubation fluence before the growth starts.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Tungsten nanostructure growth by sputtering and redeposition in BCA-MD-KMC hybrid simulation

Ito,

Takayama,

Nakamura

2023

Mater. Res. Express

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“…McCarthy et al [17] concluded that when the ratio of W atoms to He ions reaching a tungsten surface is increased from 0.003 to 0.009 for the same helium ion fluence, it results in a doubling of the thickness of the fuzz layer grown in DCMS device. Kajita et al [20,30] have demonstrated that, the growth rate of fuzzy tungsten was substantially enhanced by the metallic deposition, resulting in the development of noticeable large-scale fuzz. In addition, and due to the intrinsic properties of the magnetron sputtering device, the deposition rate plays an essential role in determining the thickness of the nanostructured tungsten layer.…”

Section: Comparison Between a Fuzz Grown In Hipims And Dcms Plasmasmentioning

confidence: 99%

A study of the formation of fuzzy tungsten in a HiPIMS plasma system

Ali,

Bahri,

Bilton

et al. 2024

J. Phys. D: Appl. Phys.

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Nanostructured “fuzzy” tungsten has been grown for the first time in a high-power impulse magnetron sputtering HiPIMS system. The fuzzy layers were formed over range of surface temperatures Ts, from 1025 to 1150 K, for helium ion fluences of 5.02 × 1024 m-2, and mean ion bombardment energy of 55 eV. The time-evolution of the helium ion flux (ΓHe) and incident energy (EHe) were determined during the HiPIMS pulse (of width of 150 µs) using a planar Langmuir probe. The micrographic findings revealed that, the thickness of HiPIMS-grown nano-tendrill layers increased by 83 % (from 274 to 501 nm) for only a 125 K rise in Ts. This result is explained by the fact that higher surface temperatures led to larger helium bubbles which ultimately produce a thicker nanostructured layer. The growth rate of fuzzy tungsten layers in HiPIMS conditions is approximately 50 % lower than those observed for DC magnetron operation.

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“…Adatom diffusion and epitaxial growth on fiber surfaces are probably related to the growth of LFNs 32 . However, no LFN growth occurred when the edges of the material were covered 34,35 . This was also the case with magnetron sputtering, where enhanced fuzzy layer growth was observed with auxiliary W deposition, but there was no LFN growth 36 .…”

mentioning

confidence: 97%

Growth origin of large-scale fiberform nanostructures in He–W co-deposition environment

Hori

Kajita

Zhang

et al. 2023

Sci Rep

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When tungsten (W) is deposited with helium (He) plasma (He–W co-deposition) on W surface, enhanced growth of fiberform nanostructure (fuzz) occurs, and sometimes it grows into large-scale fuzzy nanostructures (LFNs) thicker than 0.1 mm. In this study, different numbers of mesh opening (apertures) and W plates with nanotendril bundles (NTBs), which are tens of micrometers high nanofiber bundles, were used to investigate the condition for the origin of the LFN growth. It was found that the larger the mesh opening, the larger the area where LFNs are formed and the faster the formation tends to be. On NTB samples, it was found that NTBs grew significantly when exposed to He plasma with W deposition, especially when the size of the NTB reached $$\sim 0.1$$ ∼ 0.1 mm. The concentration of the He flux due to the distortion of the shape of the ion sheath is proposed as one of the reasons to explain the experimental results.

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Accelerated/reduced growth of tungsten fuzz by deposition of metals

Cited by 20 publications

References 36 publications

Tungsten nanostructure growth by sputtering and redeposition in BCA-MD-KMC hybrid simulation

Tungsten nanostructure growth by sputtering and redeposition in BCA-MD-KMC hybrid simulation

A study of the formation of fuzzy tungsten in a HiPIMS plasma system

Growth origin of large-scale fiberform nanostructures in He–W co-deposition environment

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