A new process similar to making rock candy was developed at NIF to rapidly grow very large crystals that are about 2 cubic feet in size and weigh up to 800 pounds—about the weight of a large grizzly bear! The crystals are made of potassium dihydrogen phosphate (or KDP), a naturally occurring chemical. In crystal form, KDP has good optical properties. Crystal plates have special optical properties, like prisms, that transmit, bend, and break light up into the spectrum of colors seen in rainbows.
The rapid-growth technology reduces the growth time of a NIF-size crystal from two years with previous, traditional (slow-growth) technology to less than just two months! Because the crystals grow to very large sizes, more plates can be cut from each crystal, so fewer crystals are needed to provide NIF with enough material to meet its needs.
NIF uses more than 600 large crystal plates to help transmit its 192 laser beams toward a fusion target, so growing very large crystals quickly was important when building NIF.