Engineering topics

Carlson, Frederick M.

Publications and source records attributed to Carlson, Frederick M..

5 records

DOE OSTI2020

Method for controlling heat flow within a silicon melt using a heat diffusion barrier assembly

An apparatus for controlling heat flow within a melt. The apparatus may include a crucible configured to contain the melt where the melt has an exposed surface. The apparatus may also include a heater disposed below a first side of the crucible and configured to supply heat through the melt to the exposed surface, and a heat diffusion barrier assembly comprising at least one heat diffusion barrier disposed within the crucible and defining an isolation region in the melt and an outer region in the melt.

42 ENGINEERING↗

NASA NTRS1992

Simulation of triglycine sulfate crystal growth in space

Consideration is given to the numerical simulation of the solution growth of triglycine sulfate in space, with heat transfer, mass transfer, buoyancy-driven convection, the dependence of solubility on temperature, and finite interface kinetics taken into account. In the bulk solution, weak thermal convection was established quickly. The thermal convection then becomes dominated by solutionally driven motion. The convection due to the steady background g is predicted to influence both the growth rate and the crystal morphology. The time required for buoyancy-driven convection to influence the growth rate depends on the magnitude of g, i.e., more time for smaller g. Under the same cooling condition, the average growth rate increases as the magnitude of g increases. A steady average growth rate of 1.0 mm/d can be obtained when a properly designed cooling rate is applied to the sting. The most uniform growth is obtained when the g vector is aligned such that the solution flows normal towards the center of the crystal surface.

Sun, Jianhua↗

NASA NTRS1988

Microgravity science at Langley Research Center

Although space research is still in an embryonic state, a combination of Earth based and space flight experiments are being coupled to yield a better understanding of the complex interaction of heat and fluid flow on the dynamics of crystal growth. Continued efforts on the ground as well as additional flight opportunities are needed to continue the drive to fully understand the advantages, both scientifically and economically, of microgravity crystal growth.

Fripp, Archibald L.↗

NASA NTRS1987

Bridgman crystal growth

The primary focus was on completing a simulation of thermosolutal convection. The configuration employed was based on some MIT experiments using a Germanium-Silicon charge in a quartz ampoule with an aspect ratio of 8 and a rather large adiabatic zone. Two thermally stable cases were investigated: solutally unstable and solutally stable. Both use the same equilibrium phase diagram and thermophysical properties except the sign of the solutal coefficient of volume expansion is reversed. The results are discussed.

Carlson, Frederick M.↗

NASA NTRS1984

Thermal convection during Bridgman crystal growth

Numerical experiments are used to study thermally driven flows which occur during vertical Bridgman crystal growth of a single component fluid. The solid-liquid interface was specified as parabolic and flow patterns were calculated for various insulation thicknesses, Grashof, Prandtl, and Biot numbers. When the melt is on top and the gravity vector is axially downward it is shown that flow persists as long as a radial temperature gradient is present. If the interface is convex, as viewed from the liquid, a single cell is observed. A concave interface exhibits multiple counterrotating cells. The insulation thickness and Grashof, Prandtl, and Biot numbers influence the flow in a quantitative manner.

Carlson, Frederick M.↗