MODELING OF RADIATION DEFECT ACCUMULATION IN PURE MOLYBDENUM USING THE METHODS OF KINETIC THEORY AND CLASTER DYNAMICS
M. Yu. Romashka, A. V. Yanilkin
VANT. Ser.: Mat. Mod. Fiz. Proc 2015. Вып.3. С. 64-75.
The modeling of radiation defect accumulation in thin pure molybdenum films under the effect of ion radiation was studied. Two approaches to the modeling were used: kinetic theory with mean cluster size and cluster dynamics.
The paper discusses the limitation of the first approach applicability. It can be inapplicable in the cases when defect clusters are generated in the cascades of atom shifts and the cluster diffusion to the drains, such as the surface, intergrain surfaces and dislocations, is present. This is due to the fact, that it is impossible to take into account the cluster distribution by size in the frames of the kinetic theory and to assign personal diffusion coefficients to each cluster size.
In the case of cluster dynamics the obtained results are in good agreement both with the experiment and the calculations by other authors. At that the proposed method of cluster dynamics realization differs from those used before: a stochastic approach to the cluster dynamics based on the SPPARKS code is implemented. The advantages of the stochastic approach are such as the algorithm simplicity, simplicity of reactions setting in SPPARKS, as well as high stability as compared to the standard approach, where the system of big amount of differential equations is solved. The main drawback of the approach is the limited reagent concentrations at the bottom. Keywords: kinetic theory, cluster dynamics, ion irradiation, thin films, molybdenum, point defects, SPPARKS.
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