低温高密度等离子体轰击下锂蒸发机理研究

Mechanism for Lithium Evaporation by Bombardment of High-Density and Low-Temperature Plasma

采用单阴极直线弧放电等离子体发生装置,通过测试放电电流对受激锂蒸气原子的670.78 nm光辐射强度的影响,研究了放电电流对蒸发量的影响,建立了蒸发实验模型。实验结果表明,通过控制放电电流,可以控制锂原子的蒸发量。液态锂温度上升到600 K左右时锂原子的蒸发速率急剧上升。考虑和不考虑锂原子与等离子体相互作用的情况下,分别计算了锂原子的蒸发速率,得出放电电流分别为50,60,70 A时该速率减少率分别为99.9%,99.8%,93.67%。通过拟合实验曲线,得出实验操作中锂表面氧化物的存在使得锂原子的表面结合能由1.5变为2.0 eV。

The evaporation of lithium by bombardment of high density low temperature Ar-plasma, generated with lab-built source, was modelled,analyzed,and measured by evaluating the emission intensity at 670.78 nm from the excited Li. The influence of the discharge current and temperature of liquid Li on the Li evaporation rate was investigated. The results show that the temperature and discharge current significantly affect the Li evaporation rate. For example, as the temperature increased from above 600 K, the slow-varying Li evaporation rate increased rapidly, and the evaporation rate was calculated with and without considering the interaction of Li-atom and Ar-plasma, respectively. As the current increased from 50 to 60 and 70 A, the reduction ratio of the evaporation rate was found to be 99.9%, 99.8% and to 93.67% ,respectively. The surface binding energy of li-atom was estimated by data-fitting to increase from 1.5 to 2.0 eV, possibly because of existence of Li oxides.