Research of aerosol formation of liquid wall laser fusion reactor by electrical discharge method

在未来的液体第一壁激光聚变反应堆中，液壁表面将被聚变燃烧产生的阿尔法粒子烧蚀。烧蚀后的金属形成了含有气溶胶(纳米级颗粒)和原子蒸气的平面羽流。它们最终在反应堆房间的另一边凝结，但气溶胶的行为并不符合烧蚀金属的流体动力学描述。为了建立一个讨论气溶胶形成的数据库，我们用10微米厚的铅膜在玻璃板上进行放电加热，实验模拟了这种现象。-10微米厚的Pb膜对应于Bragg峰内的烧蚀部分，玻璃板对应于剩余的液态金属。5 x 10 x 0.01 mm Pb膜用存储在电容器中的300J电脉冲加热。烧蚀的羽流被捕获在距离膜不同距离的目标板上。使用扫描电子显微镜…观察捕获的材料使用x射线激发荧光测厚仪无损地测量更多的PE和平均厚度。在我们的实验中，铅膜所消耗的面能量密度与α粒子相似(0.2MJ/m^2)，但加热时间是α加热的100倍(0.1微秒)，当铅膜与见证板之间的距离大于20 mm时，我们成功地捕捉到了见证板上的气溶胶。我们发现烧蚀羽流的前部以连续金属膜的形式沉积在证明板上，而羽流的尾部则以微粒的形式沉积在证明板上。气溶胶的平均直径为30微米。如果距离小于此值，由于源和目标板之间水蒸气的几何约束效应，捕获的气溶胶直径变大。这一结果与基于Luk‘yancuk模型的理论模型是一致的。我们的模型分析说，烟羽的领先部分有点像过冷蒸汽，当它与证明板碰撞时，会形成连续的薄膜。较少

In a future laser fusion reactor with a liquid first wall, the surface of the liquid wall (LiPb) will be ablated with alpha particles from fusion burns. Ablated metal make a planer plume that concicts of aerosols (nano-scale particles) and atomic vapor. They finally condense on the other side of the reactor chamber but behavior of the aerosols would not follow hydrodynamic description of ablated metal. To make a data base to discus formation of the aerosols, we experimentally simulated this phenomena using discharge heating of a 10-mcrometer-thick, Pb membrane deposited on a glass plate. The-10-micrometer-thick membrane coresponds to the ablated portion within Bragg peak and the glass plate corresponds to the remaining liquid metal.The 5 x 10 x 0.01 mm Pb membrane was heated by a 300J electric pulse stored in a capacitor. The ablated plume was captured on a witness plate located at different distance from the membrane. Captured materials were observed using a scanning electron microsco … More pe and the average thickness was measured nondestructively using an x-ray stimulated fluorescent thickness meter. In our experiment, the areal energy density consumed in the Pb membrane was similar to that of alpha particle (0.2MJ/m^2) but the heating time was 100 times longer that that by alpha heating (0.1 micro second).We successfully captured the aerosols on the witness plate when the distance between the membrane and the witness plate is more than 20 mm. We found that leading portion of ablated plume deposited on the witness plate as a continuous metal membrane and trailing potion of the plume deposited as micro-particles on the membrane. The average diameter of aerosols was 30 micrometer. If the distance was less than this value, the diameter of captured aerosols became larger due to geometrical confinement effect of vapor between the source and the witness plate. This result agrees with a theoretical model based on the Luk'yanchuk's model. Our model analysis said that the leading portion of the plume is something like a super-cooled vapor, which makes continuous membrane when it collide with the witness plate. Less