MECHANISMS OF TEMPERATURE ELEVATION AND WAVEFRONT BROADENING FROM NANOSCALE HE BUBBLES IN SHOCKED COPPER

Abstract

This study employs molecular dynamics simulations to examine the dynamic behavior of nanoscale helium bubbles with distinct morphologies in a copper matrix subjected to shock wave loading. Three ellipsoidal configurations are analyzed: prolate (HB-I), oblate (HB-II), and spherical (HB-III), each with axes aligned along the shock propagation direction. The simulations reveal that HB-I, with its major axis aligned to the shock direction, generates the highest temperature rise and thermal energy accumulation due to its pronounced interfacial curvature. As shock waves interact with the helium bubbles, refraction at the bubble-matrix interface leads to wavefront broadening, which is also most significant in the HB-I case. Furthermore, surface integrity analyses of near-surface bubbles indicate that HB-I is the most prone to interface breakage under varying impact velocities, exhibiting the lowest threshold particle velocity required for damage initiation. These findings highlight the critical role of bubble morphology in influencing thermal and mechanical responses of irradiated metals under extreme dynamic conditions.