Important thermodynamic parameters of lithium–tin alloys from the point of view of their use in tokamaks

Along with other liquid metals, lithium–tin alloys are considered an alternative to the use of solid materials in the development of plasma-facing intrachamber components for future fusion reactors. The possibility of the practical use of these alloys in tokamaks is determined by their thermodynamic parameters, their ability to retain hydrogen isotopes in the melt, and the properties that determine the principles by which hydrogen isotopes can be extracted from a liquid $\rm Li$–$\rm Sn$ alloy. The Sieverts’ constants for dilute hydrogen solutions in the melts of this system are calculated with the use of equations of the coordination-cluster model. The results of theoretical calculations are compared with previously published experimental data for two alloys of the $\rm Li$–$\rm Sn$ system. A calculation method based on the use of the Butler equation, together with the experimentally obtained concentration dependences of the thermodynamic potentials of the components of this binary system, is applied to find the composition of the liquid-alloy surface.