Investigating Dislocation-Obstacle Interactions in Tungsten using a novel Parallel Replica Dynamics Method

Plasma Facing Materials (PFMs) in fusion reactors are subjected to extreme temperatures and high particle flux of H isotopes and He. Tungsten (W) is the main candidate for PFM in the International Thermonuclear Experimental Reactor but He irradiation of W results in creation of He_nV_m complexes and modification of surface microstructure. This leads to increased retention of H isotopes and degradation of thermomechanical stability. In this work, we study the interaction of these He_nV_m complexes with edge dislocations using accelerated molecular dynamics. We use a novel Parallel Replica Dynamics method where states and transitions are identified on-the-fly using a diffusion distance metric calculated from an approximation of the Koopman operator of the dynamics. Using up to 600 replicas, we are able to investigate the interactions between edge dislocations and He_nV_m complexes at temperatures ranging from 300-1200 K and at rates that span ~4 orders of magnitude, reaching micro-second timescales. Effect of bubble pressure on the interaction with dislocations and bridging to higher length-scale models will be discussed.