Radiation damage in tungsten from cascade overlap with voids and vacancy clusters

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Physics

Background:

• Fusion reactors require materials that withstand intense neutron irradiation.
• Understanding radiation damage in tungsten is crucial for fusion energy development.
• Ion irradiation studies provide insights but differ from fusion neutron environments.

Purpose of the Study:

• Investigate the impact of overlapping collision cascades on pre-existing defects in tungsten.
• Compare damage production in fusion neutron irradiation versus ion irradiation.
• Analyze mechanisms affecting defect formation and accumulation.

Main Methods:

• Systematic molecular dynamics simulations.
• Modeling collision cascade overlaps with vacancy-type defects.
• Analysis of defect formation, loop structures, and cascade splitting.

Main Results:

• Cascade overlap decreases new defect generation, similar to interstitial cluster behavior.
• Dislocation loop formation and Burgers vectors depend on cascade-defect overlap.
• Overlapping cascades reduce the size of pre-existing defects.
• Void-induced cascade splitting observed below the subcascade threshold.

Conclusions:

• Cascade overlap significantly modifies radiation damage accumulation in tungsten.
• Mechanisms identified are critical for understanding dose rate effects in fusion environments.
• Findings inform the selection and design of tungsten-based fusion components.