Recent experiments on in-situ high-energy self-ion irradiation of tungsten
(W) show the occurrence of unusual cascade damage effects resulting from single
ion impacts, shedding light on the nature of radiation damage expected in the
tungsten components of a fusion reactor. In this paper, we investigate the
dynamics of defect production in 150 keV collision cascades in W at atomic
resolution, using molecular dynamics simulations and comparing predictions with
experimental observations. We show that cascades in W exhibit no subcascade
break-up even at high energies, producing a massive, unbroken molten area,
which facilitates the formation of large defect clusters. Simulations show
evidence of the formation of both 1/2 and interstitial-type
dislocation loops, as well as the occurrence of cascade collapse resulting in
vacancy-type dislocation loops, in excellent agreement with experimental
observations. The fractal nature of the cascades gives rise to a scale-less
power law type size distribution of defect clusters.Comment: 6 pages, 3 figure
