NOVEL 'INSITU' TECHNIQUE TO VISUALIZE THE EFFECT OF CONVECTION ON SOLID-LIQUID INTERFACE DURING THE MELT GROWTH

THIS RESEARCH PROPOSAL DEALS WITH THE REAL TIME STUDY OF THEEFFECT OF GRAVITY DRIVEN CONVECTION ON SOLID-LIQUID INTERFACE DURING THE CRYSTAL GROWTH FROM MELT. THE PROPOSEDSTUDY WILL MAKE USE OF A NOVEL TECHNIQUE TO VISUALIZE 'INSITU' THE SOLID LIQUID INTERFACE, WHICH WAS RECENTLY DEVELOPED AT BRIMROSE (REF. 3). THIS TECHNIQUE IS BASED ON THE PRINCIPLES OF INFRARED IMAGING. IT USES DIFFERENCE IN EMISSIVITIES OF SOLID AND LIQUID TO OBTAIN DEMARCATION BETWEEN SOLID AND LIQUID. AT THE SAME TIME IT ALSO WORKS INRADIOGRAPHIC MODE DEPENDING UPON THE INFRARED TRANSMISSION RANGE OF THE MATERIAL IN QUESTION. THE MODEL MATERIAL CHOSEN FOR THESE EXPERIMENTS IS NAC1 BECAUSE OF ITS WIDE IR TRANSMISSION RANGE (0.2UM - 26UM) AND VERY WELL UNDERSTOOD PHYSICOCHEMICAL PROPERTIES. THE INFRARED IMAGING OF THE SOLIDIFICATION PROCESS WILL BE CARRIED OUT USING THE INFRARED IMAGING SYSTEM OPERATING IN THE RANGE OF 3-5UM. THIS TECHNIQUE WILL ALLOW FOR THE FIRST TIME AN 'INSITU' STUDY OF THE EFFECT OF GRAVITY DRIVEN CONVECTION ON THE SOLID-LIQUID INTERFACE. THIS TECHNIQUE IS (1) NON-INTRUSIVE AND NON-DESTRUCTIVE IN NATURE, (2) PERMITS SAFE USE WITHOUT REQUIRING ANY SPECIAL PRECAUTION, AND (3) AMENABLE TO BOTH GROUND BASED EXPERIMENTS AND EXPERIMENTATION IN THE SPACE SHUTTLE.