Large-area sheet task advanced dendritic web growth development. Quarterly report, October 23, 1983-December 31, 1983

During this quarter, three major work areas were emphasized: (1) development and application of the thermal model for calculating buckling stresses as a function of temperature profile in the web, (2) systematic evaluation of lid and shield concepts to provide the data base for enhancing growth velocity, and (3) the design and construction of a new experimental web growth machine which embodies in one unit the mechanical and electronic features developed in previous work. In addition, evaluation of the new melt level control system was begun, along with preliminary tests of an elongated crucible design. The economic analysis was also updated to incorporate some minor cost changes. The initial applications of the thermal model to a specific configuration gave results consistent with experimental observation in terms of the initiation of buckling vs. width for a given crystal thickness. A recessed lid design has been tested and found to exhibit simultaneously some of the advantages of both thick lids (quality of growth) and thin lids (more open view factor and higher velocity). Both the mechanical and electronic designs of the new experimental web growth machine are complete, purchased components ordered and fabrication is in progress. The melt level control system hasmore » been tested during web growth and some minor but desirable modifications identified.« less