Two small liquid metal targets based on the capillary porous structure were exposed to the divertor plasma of the tokamak COMPASS. The first target was wetted by pure lithium and the second one by a lithium-tin alloy, both releasing mainly lithium atoms (sputtering and evaporation) when exposed to plasma. Due to poorly conductive target material and steep surface inclination (implying the surface-perpendicular plasma heat flux 12–17 MW/m²) for 0.1–0.2 s, the LiSn target has reached 900 °C under ELMy H-mode. A model of heat conduction is developed and serves to evaluate the lithium sputtering and evaporation and, thus, the surface cooling by the released lithium and consequent radiative shielding. In these conditions, cooling of the surface by the latent heat of vapor did not exceed 1 MW/m². About 10¹⁹ lithium atoms were evaporated (comparable to the COMPASS 1 m³ plasma deuterium content), local Li pressure exceeded the deuterium plasma pressure. Since the radiating Li vapor cloud spreads over a sphere much larger than the hot spot, its cooling effect is negligible (0.2 MW/m²). We also predict zero lithium prompt redeposition, consistent with our observation.

将两个基于毛细管多孔结构的小型液态金属靶材暴露于托卡马克COMPASS的偏滤器等离子体中。第一个靶材被纯锂润湿，第二个靶材被锂锡合金润湿，当暴露于等离子体中时，两者都主要释放出锂原子（溅射和蒸发）。由于目标材料的导电性差和陡峭的表面倾斜度（意味着表面垂直等离子体热通量为12-17 MW / m ²）持续0.1-0.2 s，LiSn目标在ELMy H模式下已达到900°C。建立了导热模型，用于评估锂的溅射和蒸发，从而评估由于释放的锂引起的表面冷却以及由此产生的辐射屏蔽。在这些条件下，通过蒸气潜热对表面的冷却不超过1 MW / m ²。蒸发了约10 ^19个锂原子（相当于COMPASS 1 m ³血浆氘含量），局部Li压力超过了氘等离子体压力。由于辐射的Li蒸气云散布在一个比热点大得多的球体上，因此其冷却效果可忽略不计（0.2 MW / m ²）。我们还预测锂迅速再沉积为零，这与我们的观察一致。