Calculation and analysis of lattice thermal conductivity in tungsten by molecular dynamics

Tungsten (W) has been used for plasma facing materials (PFMs) of tokamak. Under severe work condition, the irradiation damage of W is closely related to its thermal conduction, which has been researched systematically in this paper with molecular dynamics (MD). The thermal conductivities (TCs) by phonons with many different conditions, such as different temperatures, different heat flows, different crystallographic orientation and the presence of grain boundary (GB) have been calculated and discussed in detail. The finite size effect has been taken into account in the calculation of TCs, the relationship between the inverse of TC and the inverse of lateral dimension is linear. Research shows that the TCs are not depended strongly on heat flux, but they decrease gradually with the increase of temperature. We also find the thermal conduction of W is to some extent anisotropic, but the variations are smaller than that caused by temperature. A sharp discontinuity in temperature appears across the GB in the temperature-x profile. And the TC in the grain boundary phase region is less than one-tenth of the TC of bulk at 300 K. However, the GB effect on TC of W polycrystalline sample is relatively small. These research results can help to account for the damage mechanisms of plasma facing material tungsten.