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arXiv · 2609.08878

Controlling Hydrogen Isotope Retention at Helium Cavities through Radiation-Induced Segregation in Fusion Steels

Lihao Shi·Logan N. Clowers·Qing Peng·Gary S. Was·Fei Gao
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Abstract

Hydrogen isotope retention in plasma facing and structural alloys is a central materials challenge for deuterium-tritium fusion. Motivated by ion beam irradiation experiments and first principles calculations, we identify an irradiation-enabled mechanism whereby solute segregation to defect sinks enhances hydrogen isotope trapping. Triple-ion irradiation of reduced activation ferritic-martensitic steel F82H reveals pronounced segregation of Cr and Ta to cavity surfaces. Density functional theory shows that these segregants markedly increase H stability at cavities by strengthening binding energies and increasing migration barriers, leading to substantially higher attention. The effect originates from solute-tuned electronic structure: Ta promotes strong H 1s-metal d orbital hybridization, whereas Cr shifts the surface d-band toward a more favorable bonding configuration. These findings provide an atomistic link between irradiation-induced segregation and elevated-temperature hydrogen isotope retention and alloy chemistry routes to control tritium inventory in fusion environments.

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Lihao Shi, Logan N. Clowers, Qing Peng, Gary S. Was, Fei Gao. 2026-09-08. Controlling Hydrogen Isotope Retention at Helium Cavities through Radiation-Induced Segregation in Fusion Steels. https://arxiv.org/abs/2609.08878

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