Aerodynamic trapping and laser heating for containerless glass processing in microgravity

Abstract

In analyzing the characteristics of the aerodynamic trap-laser heating apparatus, it is shown that it possesses most of the qualities needed for containerless glass (or other material) processing, on the ground and in reduced gravity. Some of the effects of laser heating and melting, and of aerodynamic trapping are studied with respect to their influence on vitrification and glass quality, especially in reduced gravity. The experiments were carried out on very high melting point (over 1500K) silica and alumina bearing compounds, and in particular calcium aluminate. With the flight hardware, it was possible to vitrify, on the ground, 3.6-mm-diam spherical samples of 50CaO-50Al 2 O 3 (CA) (%mol), with a 100-W, 3-mm spot, CO 2 , laser beam, and a 0.5-l/min gas flow. Alumina samples were successfully melted during aircraft parabolic flights. A discussion of trapping ability with respect to sample temperature (and viscosity) is presented.