强脉冲电子束辐照材料表面形貌演化的模拟

在回顾和总结强脉冲电子束表面改性实验的基础上, 利用有限元数值计算方法对强脉冲电子束辐照铝和304不锈钢产生的温度场进行模拟, 给出了靶的近表面区域流体状态存在的特征尺度和特征时间, 并对不同材料特性下熔坑的产生原因进行了讨论. 采用两相流模型, 通过水平集方法和有限元方法结合的计算流体力学模拟了熔坑和表面突起形貌在表面处于熔融状态下的运动特征, 通过和实验数据相对比, 验证了对于高黏度, 高表面张力的高熔点金属, 表面处于流体状态下的张力驱动效应是熔坑等表面形貌演化的重要原因.

Simulation on surface morphology evolution of metal targets irradiated by intense pulsed electron beam

Based on the review of previous experimental and theoretical studies on the surface processing by a pulsed intense electron beam, the induced temperature field in aluminum and 304 stainless steel is simulated by the finite element method (FEM) to estimate the existing time and depth of molten metal flow field on the irradiated surface. The generation of craters is attributed to the thermal resistance formed by the grain boundaries, and the influence of material properties on the mechanism of crater evolution is also discussed. Two-phase flow field simulation on molten metal is carried out with a combination of level-set method and FEM to estimate the mass transfer behavior at the craters and surface protuberance. It is revealed that the mass transfer effect driven by surface tension is an important factor for the formation and evolution of round-shaped craters on the surface of metals with high melting point, viscosity and surface tension coefficient. However, for metals with low melting point, due to the strong disturbance by ablating gas plume and low surface tension effect, the craters are more likely to have irregular splashing edges.