Numerical study of small accelerations influence on composition uniformity of a growing crystal

Abstract

The result of mathematical modeling of crystal growth process for real flight conditions of an automatic FOTON spacecraft is given. As the input data for the calculations, the results of low-frequency accelerations measurements on FOTON-8–FOTON-12 spacecrafts are used. Process of directional crystallization of Ge from melt in a cylindrical ampoule in three-dimensional formulation is considered. For solution of the heat and mass transfer equations the Chebyshev pseudo-spectral method is used, for solution of the momentum equation the method of finite differences is accepted. The results of the calculations show that in the melt a convective flow of the complex form arises, which changes permanently. At growth of doped crystals this weak flow makes an impact on mass transfer in the melt and defines a rather complex picture of the dopant distribution in the growing crystal; it results in macro-inhomogeneity of the crystal properties.