An investigation on the surface/subsurface defects in potassium dihydrogen phosphate crystals after fly-cutting

摘要

Potassium dihydrogen phosphate (KDP) crystals play an important role in the laser ignition facility of inertial confinement fusion (ICF) due to its unique large size and transparency. However, the laser damage threshold (LDT) of KDP crystal components is far below the intrinsic threshold that the band structure of a perfect crystal should provide. It has been considered that the surface/subsurface defects of a KDP component have a significant effect on the low LDT. This paper investigates the surface fogging phenomenon when a KDP is machined by a dry diamond fly-cutting. The subsurface damage was detected with the aid of the grazing incidence X-ray diffraction (GIXD) method. It was found that the subsurface structure changed from the KDP single crystal to a lattice misaligned structure due to the fly-cutting.