Abstract:Copper and copper alloys are considered the primary structural material for fusion reactor divertor heat sinks due to their excellent thermal conductivity, thermal stability, mechanical properties, and relatively good resistance to neutron irradiation. However, a lack of in-depth understanding regarding the mechanisms of displacement damage in copper induced by synergistic effects of neutron irradiation and transmuted helium still exists. In this study, the synergistic effects were investigated using molecular dynamics simulations, with a focus on dislocation nucleation mechanisms. Influences of transmuted helium concentration (2000~8000 appm), primary knock-on atom (PKA) energy (1.0~7.0 keV), and simulation temperature (100~900 K) were systematically examined. Results showed that increased helium concentration raised the number of point defects, enhanced pinning effect, and promoted dislocation density and the formation of complex entanglement structures. Higher PKA energy led to a notable rise in length and density of dislocation line. At lower temperatures, rising temperature promoted development of dislocation entanglement structures in the cascade center, while at higher temperatures, it facilitated dislocation annihilation and break-up, resulting in the collapse of these entanglement structures. These findings provided important insights for the design of irradiation-resistant copper alloys for fusion reactors.