A description of bubble growth and gas release of helium implanted tungsten

Sharafat, S.; Takahashi, Akiyosi; Hu, Qi; Ghoniem, Nasr M.

doi:10.1016/j.jnucmat.2008.12.318

Cited by 87 publications

(47 citation statements)

References 17 publications

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“…At the same time, however, the void size increases strongly with temperature which has been described in Ref. 22 albeit in the temperature range 730 C-1160 C. Also, studies of desorption of implanted helium from tungsten surfaces have shown the presence of desorption peaks at 730 C, 1230 C, and 1930 C, 17,23 There is therefore an interplay between helium bubble formation, coalescence, re-crystallization, and desorption influencing the final surface structure.…”

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confidence: 64%

Nanostructuring of molybdenum and tungsten surfaces by low-energy helium ions

Temmerman¹,

Bystrov²,

Zielinski³

et al. 2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

124

102

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The formation of metallic nanostructures by exposure of molybdenum and tungsten surfaces to high fluxes of low energy helium ions is studied as a function of the ion energy, plasma exposure time, and surface temperature. Helium plasma exposure leads to the formation of nanoscopic filaments on the surface of both metals. The size of the helium-induced nanostructure increases with increasing surface temperature while the thickness of the modified layer increases with time.In addition, the growth rate of the nanostructured layer also depends on the surface temperature. The size of the nanostructure appears linked with the size of the near-surface voids induced by the low energy ions. The results presented here thus demonstrate that surface processing by low-energy helium ions provides an efficient route for the formation of porous metallic nanostructures.

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confidence: 64%

Nanostructuring of molybdenum and tungsten surfaces by low-energy helium ions

Temmerman¹,

Bystrov²,

Zielinski³

et al. 2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

124

102

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“…However, even considering that the thermo-mechanical response can be under control, there exists a serious issue concerning He irradiation. Numerous studies [11,12] carried out under different conditions in continuous mode He irradiation show that exceeding certain threshold value of fluence, around 10 17 -10 18 He/cm 2 , has fatal consequences for the W components. SEM images reveal that swelling and pore formation take place that eventually lead to W exfoliation with mass loss.…”

Section: Introductionmentioning

confidence: 99%

Effect of ion flux on helium retention in helium-irradiated tungsten

Rivera¹,

Valles²,

Caturla³

et al. 2013

Nuclear Instruments and Methods in Physics Research Section B:

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Helium retention in irradiated tungsten leads to swelling, pore formation, sample exfoliation and embrittlement with deleterious consequences in many applications. In particular, the use of tungsten in future nuclear fusion plants is proposed due to its good refractory properties. However, serious concerns about tungsten survivability stems from the fact that it must withstand severe irradiation conditions. In magnetic fusion as well as in inertial fusion (particularly with direct drive targets), tungsten components will be exposed to low and high energy ion irradiation (helium), respectively. A common feature is that the most detrimental situations will take place in pulsed mode, i.e., high flux irradiation. There is increasing evidence of a correlation between a high helium flux and an enhancement of detrimental effects on tungsten. Nevertheless, the nature of these effects is not well understood due to the subtleties imposed by the exact temperature profile evolution, ion energy, pulse duration, existence of impurities and simultaneous irradiation with other species. Object Kinetic Monte Carlo is the technique of choice to simulate the evolution of radiation-induced damage inside solids in large temporal and space scales. We have used the recently developed code MMonCa (Modular Monte Carlo simulator), presented at COSIRES 2012 for the first time, to study He retention (and in general defect evolution) in tungsten samples irradiated with high intensity helium pulses. The code simulates the interactions among a large variety of defects and during the irradiation stage and the subsequent annealing steps. The results show that the pulsed mode leads to significantly higher He retention at temperatures higher than 700 K. In this paper we discuss the process of He retention in terms of trap evolution. In addition, we discuss the implications of these findings for inertial fusion.

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“…Under the irradiation conditions in this study, both interstitial and vacancy defects are created and can migrate [16]. Moreover, vacancy clusters and small He-vacancy complexes [17] can also migrate to the boundaries [18]. The sink efficiency of a grain boundary, however, was shown by others to depend on the full grain boundary character (including the misorientation angle and the grain boundary plane) [19].…”

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confidence: 75%