Design aspects of an experimental test stand for the study of liquid-lithium-film condensation

The benefits of having the walls of fusion devices covered with lithium are widely recognized, as evidenced by the growing number of experimental devices with experiments devoted to lithium wall conditioning. However, there are still many outstanding questions regarding the technology aspects of lithium when it is placed in a tokamak experiment. This paper describes the preliminary design activities of a test facility devoted to the study of lithium-vapor-condensation mechanisms and the subsequent formation of liquid films as well as film stability aspects when thermal gradients are present on downward-facing surfaces. The capability of studying the effect of thermodynamic compatibility between the liquid and the substrate will also be possible in this facility. Initial design features as well as preliminary estimations of achievable film thicknesses are presented. The facility will also have the capability of studying MHD effects since it will be attached to the TPM-1U tokamak, a small machine currently under construction and expected to be operational by 2012. The coupling of the liquid-lithium test stand to the small tokamak will allow the study of liquid-lithium flows subjected to full toroidal fields, with no end effects as in previous experiments.