Cryogenic hydrogen

Hydrogen (HDT)

We have worked along with our peers in the National Ignition Facility (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 NIF. A single crystalline, spherical shell of solid hydrogen needs to be formed within each target capsule—from a seed generated in situ, and with no optical access for imaging. 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, understanding the thermal environment within the capsule, and improving layer yield. To develop an efficient and robust layering process, we are actively exploring deterministic seeding methods for forming the DT ice layer, a very challenging endeavor given the restricted parameter space and stringent requirements. Recent efforts have been directed toward developing new platforms for forming uniform DT liquid layers, such as using an aerogel layer inside a sphere with precisely controlled thickness that acts as a sponge for the liquid.

X-ray phase contrast
Left: X-ray phase contrast image of a 70-μm thick shell of solid deuterium-tritium (DT) "ice" in a fusion ignition target capsule. Right: Thermal profile of capsule containing fully liquid DT inventory.

Shin, SJ; Zepeda-Ruiz, LA; Lee, JRI; Baxamusa, SH; Dylla-Spears, R; Suratwala, T; Kozioziemski, B. Fusion Science and Technology (2016), 70, 184-190.

Sater, JD; Espinosa-Loza, F; Kozioziemski, B; Mapoles, ER; Dylla-Spears R; Pipes, JW; Walters, CF. Technique for Forming Solid D-2 and D-T Layers for Shock Timing Experiments at the National Ignition Facility. Fusion Science and Technology (2016), 70, 191-195.

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.