Design of a 3D-printed liquid lithium divertor target plate and its interaction with high-density plasma

Abstract

The liquid Li divertor is one of promising alternatives for the future fusion device. In this work, a new divertor model is proposed, which is processed by 3D-printing technology to accurately control the size of the internal capillary structure. At the steady-state heat load of 10 MW/m2, the thermal stress of tungsten target is within the bearing range of tungsten by FE simulation. In order to evaluate the wicking ability of capillary structure, the wicking process at 600 °C was simulated by Fluent. Its result was identical with the corresponding experiments. Within 1 s, liquid lithium was wicked to target surface by the capillary structure of the target and quickly spread on the target surface. During the wicking process, the average wicking mass rate of lithium would reach 0.062 g/s, which could even supplement the evaporation requirement of liquid lithium under ＞950 °C environment. Irradiation experiments under different plasma discharge currents were carried out in linear plasma device (SCU-PSI), and the evolution process of the vapor cloud during plasma irradiation was analyzed. It was found that the target temperature tends to plateau in spite of gradually increased input current, indicating that the vapor shielding effect is gradually enhanced. The irradiation experiment also confirmed that 3D-printing tungsten structure has better heat consumption performance than that of tungsten mesh structure and multichannel structure. These results reveal the application potential and feasibility of 3D-printing porous capillary structure in plasma-facing components(PFCs) and provide a reference for further liquid-solid combined target designs.