PLS scientists and engineers helped to develop a novel process for growing and recovering large single crystals of potassium dihydrogen phosphate (KDP), which are used for frequency conversion and in the plasma electrode Pockels cell. The challenge was to grow large, defect-free, high aspect ratio boules of sufficient size and quality—and rapidly enough—to supply KDP optics and spares for all 192 beamlines of NIF. This involved determining how to control growth habit, minimize liquid inclusions, prevent secondary nucleation, and prevent boule fracture. This technology has now been transferred to our partners in the private sector.
Booth, NA; Land, T; Ehrmann, P; Vekilov, PG. The aspect ratio of potassium dideuterium phosphate (DKDP) crystals, Crystal Growth & Design (2005), 5, 105-110.
Hawley-Fedder, R.; Robey, H.F.; Biesiada, T.A.; DeHaven, M.R.; Floyd, R.; Burnham, A.K. Rapid growth of very large KDP and KD*P crystals in support of the National Ignition Facility, Proceedings of the SPIE - The International Society for Optical Engineering (2000), 4102, 152-161.
Scientists and engineers in PLS have worked along with their peers in NIF to understand phenomenon associated with growth of crystals of hydrogen and its isotopes deuterium (D) and tritium (T), which are used as the fuel in fusion ignition experiments on the NIF. A single crystalline, spherical shell of solid hydrogen must be formed within each target capsule--from a seed generated in situ, and with no optical access. The hydrogen "ice" layers must be smooth, round, and nearly defect free to meet requirements for NIF experiments. Work has been geared toward understanding growth habit, developing a robust process, understand the thermal environment within the capsule, developing more deterministic seeding methods, and improving layer yield.
Baxamusa, S.; Field, J.; Dylla-Spears, R.; Kozioziemski, B; Suratwala, T; Sater, J. Effects of self-heating and phase change on the thermal profile of hydrogen isotopes in confined geometries, Journal of Applied Physics (2014), 115, 124901.