Predicting spherical symmetry degeneration of non-infrared deuterium ice layer in a cryogenic capsule

Abstract

A cylindrical cryogenic target containing deuterium fuel acts as an important surrogate to help understand implosion physics before the deuterium-tritium capability is brought online. Uniformity of the deuterium ice thickness is a key parameter for the inertial confinement fusion (ICF) experiments. Achieving and retaining a uniform deuterium ice layer in capsule without infrared radiation is difficult in engineering. The method used to calculate the ice thickness deviation of deuterium-tritium fuel is invalid when the bulk heat generation is equal to zero. Appearance solutions of the deuterium ice in steady state conclude that a uniform ice layer cannot be retained for long without infrared radiation. A transient algorithm by integrating heat transfer theory, the equation derived from Stefan problem and mass conservation with moving mesh technics in a finite element model can be applied to predict deuterium ice spherical symmetry degeneration. It is certified with good reliability by comparing the simulated results with theoretical and experimental data. As for the deuterium targets, the characteristics of linear approximation and integrability avert heavy work of moving mesh in analyses of stable and unstable scenarios. The work has great support for the cryogenic processing and engineering design of ICF targets.

The importance of the laser pulse-ablator interaction dynamics prior to the ablation plasma phase in inertial confinement fusion studies

“…The perturbation transfer from the ablator to the substrate is demonstrated to happen from the very first moments of the interaction within the TEP phase. Further investigations are in progress to study the transfer efficiency of these perturbations from the ablator to the substrate for direct-drive target designs [48,49]. In particular, plastic (polystyrene CH) [50] and Beryllium [51] ablators on ice DD substrates are being examined in spherical geometry including the use of thin Au overcoatings with different thicknesses.…”

Performance Analysis and Optimization of Sub-Atmospheric Purging through Microcapillaries in an ICF Cryogenic Target

“…In general, the non-hydrogen gas content inside the capsule should be lower than 205 ppm, and the non-helium gas content inside the hohlraum should be lower than 8250 ppm [9]. Currently, the impurity gases are mainly removed from the capsule and hohlraum by sub-atmospheric purging, i.e., evacuation and filling cycles, through microcapillaries that are only tens of microns in diameter [10][11][12][13]. Since the capsule and hohlraum volumes are too small to take measurements in situ, accurately predicting the flow characteristics inside the microtubes and the chambers is critical for the purging of the target.…”