Abstract

In indirect-drive inertial confinement fusion, thin films on laser entrance hole (LEH) windows are needed to reflect thermal infrared radiation (IR) and to protect the deuterium-tritium (D-T) cryogenic shell. In this paper, a set of ultrathin aluminum films deposited on freestanding polyimide as LEH windows were studied on optical properties in the IR band. The influences of thickness and gas pressure on the IR transmittivity of these films were examined. It was found that gas pressure plays an important role in the IR transmission and microstructure changes of LEH films because of elastic modulus mismatch between aluminum and polymide. It is undoubted that the aluminum/polymide film can block thermal IR and protect the D-T cryogenic shell when gas pressure is less than 20 KPa.

摘要

在间接驱动惯性约束聚变中，需要激光入射孔 (LEH) 窗口上的薄膜来反射热红外辐射 (IR) 并保护氘-氚 (DT) 低温壳。在本文中，研究了一组沉积在独立式聚酰亚胺上作为 LEH 窗口的超薄铝膜在红外波段的光学特性。检查了厚度和气压对这些薄膜的红外透射率的影响。研究发现，由于铝和聚酰亚胺之间的弹性模量不匹配，气压在 LEH 薄膜的红外传输和微观结构变化中起着重要作用。毋庸置疑，当气压低于20KPa时，铝/聚酰亚胺薄膜可以阻挡热IR并保护DT低温外壳。