Micromechanical Deformation of Solid Hydrogens at Cryogenic Temperatures
Professor John Lambropoulos
Friday, October 10, 2014
The fuel used for Inertial Confinement Fusion is a mixture of D2 and T2, that is manufactured and processed at cryogenic temperatures in the range 15-20 K. The solid fuel is contained in a thin plastic shell. When cooled, significant thermal stresses may arise, leading to large tensile inter5cail stresses in the fuel/shell interface.
In this talk, I will present a tentative deformation mechanism map for D2 and extend it to include T2, where mechanisms of dislocation glide, creep (high- and low-temperature), and diffusional flow via lattice or grain boundary diffusion are included, as is, of course, elastic deformation. The deformation mechanism map uses isomechanical data for hcp materials and experimental data.
The deformation mechanism map is used to predict thermal stresses in the solid fuel, and demonstrates that stress relaxation via inelastic flow is an important factor in enhancing the contact of the fuel and the plastic shell.
Important anisotropic effects also will be discussed, for example the hcp structure of the solid fuel, glide by basal slip, as well as the availability of other slip systems. Numerical and analytical solutions will be compared.