Fuel layering of ICF cryogenic target based on temperature gradient method

The spatial distribution of deuterium (D₂) or deuterium-tritium (DT) ice condensed inside the inertial confinement fusion (ICF) spherical cryogenic target is determined by the temperature field around the target. In the deuterium cryogenic target, the uniform liquid is formed by the vapor-liquid interfacial tension gradient resulting from the vertical temperature gradient, which counterbalances the gravity-induced fuel sagging. The uniform D₂ solid layer can be achieved by slow cooling toward the triple point of D₂. The layering process of D₂ ice in a glow discharge polymer (GDP) shell of 1 mm diameter and 30 μm thickness is demonstrated experimentally by imposing vertical temperature gradient combined with control of cooling rate. Calculated from the bright ring in backlit shadowgraphy, the average thickness and uniformity of D₂ ice layer are 185.56 μm and 80.2% respectively, the inner surface roughness of the ice from mode 2 to 100 in power spectrum is about 2.26 μm. (authors)