Formation and retention of surface pores in helium-implanted nano-grain tungsten for fusion reactor first-wall materials and divertor plates

Zenobia, Samuel J.; Kulcinski, G.L.

doi:10.1088/0031-8949/2009/t138/014049

Cited by 35 publications

(22 citation statements)

References 15 publications

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“…Many studies have shown that the exposure of tungsten surfaces to helium plasma induces various morphological changes on the surfaces, depending on the exposure conditions [1][2][3][4][5]. These morphological changes could give rise to changes in thermal and mechanical properties of the surfaces, as well as the production of impurities and dusts that would be a potential contamination source of fusion plasma.…”

Section: Introductionmentioning

confidence: 99%

Effects of temperature and surface orientation on migration behaviours of helium atoms near tungsten surfaces

Wang

Hou

2015

Journal of Nuclear Materials

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Molecular dynamics simulations were performed to study the dependence of migration behaviours of single helium atoms near tungsten surfaces on the surface orientation and temperature. For W{100} and W{110} surfaces, He atoms can quickly escape out near the surface without accumulation even at a temperature of 400 K. The behaviours of helium atoms can be well-described by the theory of continuous diffusion of particles in a semi-infinite medium. For a W{111} surface, the situation is complex. Different types of trap mutations occur within the neighbouring region of the W{111} surface. The trap mutations hinder the escape of He atoms, resulting in their accumulation. The probability of a He atom escaping into vacuum from a trap mutation depends on the type of the trap mutation, and the occurrence probabilities of the different types of trap mutations are dependent on the temperature. This finding suggests that the escape rate of He atoms on the W{111} surface does not show a monotonic dependence on temperature. For instance, the escape rate at T=1500 K is * Corresponding author. Tel.: +86 28 85412104; fax: +86 28 85410252.E-mail address: qhou@scu.edu.cn (Q. Hou) 2 lower than the rate at T=1100 K. Our results are useful for understanding the structural evolution and He release on tungsten surfaces and for designing models in other simulation methods beyond molecular dynamics.3

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Section: Introductionmentioning

confidence: 99%

Effects of temperature and surface orientation on migration behaviours of helium atoms near tungsten surfaces

Wang

Hou

2015

Journal of Nuclear Materials

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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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“…The damage in the W lattice increases the accumulation of light species such as hydrogen [30,31] and helium [32,33], which tend to nucleate in the defects. This results in detrimental effects such as cracking, exfoliation or blistering, which are unacceptable for a PFM [34].…”

Section: Acknowledgementsmentioning

confidence: 99%

“…In both cases, inertial fusion with direct drive target and magnetic fusion, the most detrimental situations that tungsten components must face are those originated by intense ion pulses [11] (see Chapter 1). Numerous studies [33,37] images reveal that swelling and pore formation take place, which eventually lead to W exfoliation with mass loss. Renk et al [16] clearly showed that the situation is even worse when W is subject to intense He pulses rather than to continuous irradiation.…”

Section: Introductionmentioning

confidence: 99%

“…Light species such as hydrogen [30,31] and helium [32,33] in tungsten tend to nucleate in defects resulting in detrimental effects: cracking, exfoliation or blistering, which are unacceptable for W applications as plasma facing material (PFM). Therefore, there is a need to develop materials based on W, capable to withstand the expected harsh conditions (extreme irradiation and large thermal loads) that will take place in future nuclear fusion reactors.…”

Section: Introductionmentioning

confidence: 99%

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Object kinetic Monte Carlo simulations of irradiated tungsten for nuclear fusion reactors

Alberdi¹

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Formation and retention of surface pores in helium-implanted nano-grain tungsten for fusion reactor first-wall materials and divertor plates

Cited by 35 publications

References 15 publications

Effects of temperature and surface orientation on migration behaviours of helium atoms near tungsten surfaces

Effects of temperature and surface orientation on migration behaviours of helium atoms near tungsten surfaces

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

Object kinetic Monte Carlo simulations of irradiated tungsten for nuclear fusion reactors

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