Improving the ice fuel quality of cryogenic targets for inertial confinement fusion
Improving the ice fuel quality of cryogenic targets for inertial confinement fusion lead image
Fusion energy researchers are increasingly focused on inertial confinement fusion (ICF), which heats and compresses a fuel target, often the shape of a capsule, to initiate nuclear fusion reactions.
Deuterium-deuterium (DD) has been widely applied in ICF experiments to help understand implosion physics as it is nonradioactive and easy to obtain compared to other hydrogen isotope compositions containing tritium. The DD ice shell in the capsule, however, is thermally unstable due to the absence of a radial thermal gradient.
The ice fuel quality of a cryogenic target is a key factor in realizing ignition in ICF, but the target is difficult to design due its small millimeter scale size containing complex 3D structures. Those structures can withstand very low temperature and that fulfill the roughness requirement as for the ice fuel layer.
Optimizing the target with a traditional simplified theoretical model has not been successful. Yang et al. propose a way to simulate and predict the target performance from the real fabrication details.
“We found that when we changed the jacket material from aluminum to copper, the thermal contact inconsistency in assembling the cooling arms around jacket halves became tolerated in a wide range and the experimental ice fuel quality improved significantly and could be maintained much longer than before,” said author Kai Wang.
The research paves the way for further improving cryogenic targets for ICF and illustrates the important role of numerical simulation methods for designing microstructures.
“The methodology used in this research can also be applied to investigate other thermal issues including radiation, convection and conduction, and in aspects of other mechanical design, such as micromechanical systems,” said Wang.
Source: “Analyzing and relieving the thermal issues caused by fabrication details of a deuterium cryogenic target,” by Hong Yang, Shasha Gao, Baibin Jiang, Jun Xie, Juxi Liang, Xiaobo Qi, Kai Wang, Chaoyou Tao, Fei Dai, Wei Lin, and Juan Zhang, Matter and Radiation at Extremes (2021). The article can be accessed at https://doi.org/10.1063/5.0039131 .
