Atomistic Study on the Energetic and Mechanical Behaviors of Helium Bubbles Nucleation and Growth in RAFM Steel

One of the most critical challenges for the successful adoption of nuclear fusion power corresponds to plasma-facing materials. Due to its favorable properties in this context (low sputtering yield, high thermal conductivity, high melting point, among others), tungsten is a leading candidate material. Nevertheless, tungsten is affected by the plasma and fusion byproducts. Irradiation by helium nuclei, in particular, strongly modifies the surface structure by a synergy of processes, whose origin is the nucleation and growth of helium bubbles. In this review, we present recent advances in the understanding of helium effects in tungsten from a simulational approach based on accelerated molecular dynamics, which emphasizes the use of realistic parameters, as are expected in experimental and operational fusion power conditions.

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Effects of displacement damage and helium production rates on the nucleation and growth of helium bubbles – Positron annihilation spectroscopy aspects

Journal of Nuclear Materials ◽

10.1016/j.jnucmat.2017.11.007 ◽

2018 ◽

Vol 499 ◽

pp. 38-46 ◽

Cited By ~ 12

Author(s):

Vladimir Krsjak ◽

Jarmila Degmova ◽

Stanislav Sojak ◽

Vladimir Slugen

Keyword(s):

Positron Annihilation ◽

Positron Annihilation Spectroscopy ◽

Nucleation And Growth ◽

Production Rates ◽

Displacement Damage ◽

Helium Bubbles

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Atomistic Study of Helium Bubbles in Fe: Equilibrium State

MRS Proceedings ◽

10.1557/opl.2011.551 ◽

2011 ◽

Vol 1298 ◽

Cited By ~ 2

Author(s):

David M. Stewart ◽

Yury N. Osetskiy ◽

Roger E. Stoller

Keyword(s):

Equilibrium State ◽

Bubble Size ◽

Temperature Effects ◽

Room Temperature ◽

Neutron Radiation ◽

Equilibrium Pressure ◽

Helium Bubbles ◽

Body Potential ◽

Atomistic Study ◽

Neutron Radiation Damage

ABSTRACTIn the fusion irradiation environment, helium created by transmutation will play an important role in the response of structural materials to neutron radiation damage. Recently we have developed a new 3-body potential to describe the Fe–He interaction in an Fe matrix. We have used this potential to investigate the equilibrium state of He bubbles embedded into the bcc Fe matrix. We have investigated bubble size, He content and temperature effects. It was found that the equilibrium He content is rather low and at a room temperature it is ~0.38 to 0.5 He per vacancy for bubble diameters from 1 to 6 nm. At constant bubble size, the equilibrium He/vacancy ratio decreases with temperature increase. For bubbles of 6 nm diameter it goes down as low as ~0.25 at 900K. The results are compared with the capillarity model often used for estimating the equilibrium pressure of He bubbles.

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