GROWTH OF LARGE KDP CRYSTALS FOR LASER FUSION EXPERIMENTS

The growth of huge KDP crystals which have a 40 cm × 40 cm cross section for a frequency converter for high power laser system for nuclear fusion experiments is described. The main factor limiting the growth rate is spontaneous nucleation. We could successfully grow a crystal by a three-vessel method (TVM) at the rate of 2.9 mm/day over half a year without nucleation by setting the temperature of the crystallizer lower than room temperature. The TVM proved to be superior to a conventional temperature reduction method. The bulk laser damage threshold was improved two to three times that of conventionally grown crystals by reducing organic impurities in the growth solution. These techniques are very important for the growth of large KDP crystals of good quality for high power lasers. © 1990, Elsevier Science Publishers B.V.. All rights reserved.