Rapid Growth of KDP Crystals in the [101] Direction

Abstract

KDP crystals have important applications in inertial confinement fusion. However, during the rapid growth of large-sized KDP crystals, inclusion is prone to occur. The existence of inclusion will lead to the reduction of crystal quality and utilization and even the end of the growth process. The generation of inclusion is related to the interaction between the crystal and the liquid flow. In this paper, we changed the hydrodynamic condition around the crystal by changing the crystal growth direction and achieve the rapid growth of [101] direction KDP crystals without inclusion at a low rotation rate. The utilization of the crystal was improved and the crystal has good optical transmittance, crystalline perfection and laser damage threshold. Meanwhile, atomic force microscopy was used to study the characteristics and changes of the micromorphology on (100) and (101) faces under different levels of supersaturation. The analysis results show that under high supersaturation, the uneven distribution of solutes and insufficient flow rate cause local macrosteps, two-dimensional step platforms and two-dimensional cores to form irregular structures with large slopes, thereby reducing the stability of the interface. This study will help to better understand the effect of the interaction between liquid flow and crystals on the formation of inclusion and guide the growth of KDP crystals.