Elastic Properties of Plasma-Exposed Tungsten Predicted by Molecular-Dynamics Simulations

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Physics

Background:

• Tungsten is crucial as a plasma-facing component (PFC) in fusion devices.
• Plasma exposure introduces defects like voids and helium nanobubbles into tungsten.
• Understanding these defects' impact on tungsten's elastic properties is vital for device longevity.

Purpose of the Study:

• To investigate the elastic properties of tungsten with structural defects, voids, and helium nanobubbles.
• To quantify the effects of plasma exposure on tungsten's mechanical behavior.
• To establish structure-property relationships for predictive modeling.

Main Methods:

• Systematic molecular-dynamics computations.
• Analysis of elastic moduli (bulk, Young, shear) under varying defect conditions.
• Characterization of void fraction and helium content effects.

Main Results:

• Empty voids induce tensile stress, while helium nanobubbles cause compressive stress.
• Elastic moduli exhibit universal exponential scaling with void fraction.
• Helium content significantly softens elastic moduli, independent of temperature effects.
• Helium bubble size strongly influences bulk modulus and Poisson ratio, with minor effects on Young's and shear moduli.

Conclusions:

• Plasma-induced defects substantially alter tungsten's elastic properties.
• Developed scaling relations provide predictive capabilities for tungsten's mechanical response.
• Findings support the creation of a structure-property database for fusion device components.