Effect of accelerational perturvations on physical vapor transport crystal growth under microgravity environments

Abstract

For PB = 50, DT = 10 K, Ar = 5, Pr = 2.36, Le = 0.015, Pe = 1.26, Cv = 1.11, the intensity of solutal convection (solutal Grashof number Grs = 3.44 ?104) is greater than that of thermal convection (thermal Grashof number Grt = 1.81 ?103) by one order of magnitude, which is based on the solutally buoyancy-driven convection due to the disparity in the molecular weights of the component A (Hg2Cl2) and B (He). With increasing the partial pressure of component B from 10 up to 200 Torr, the rate is decreased exponentially. The convective transport decreases with lower g level and is changed to the diffusive mode at 0.1 g0. In other words, for regions in which the g level is 0.1 g0 or less, the diffusion-driven convection results in a parabolic velocity profile and a recirculating cell is not likely to occur. Therefore a gravitational acceleration level of less than 0.1 g0 can be adequate to ensure purely diffusive transport.