Overview of Containerless Processing Technologies
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25 OVERVIEW OF CONTAINERLESS PROCESSING TECHNOLOGIES* M. BARMATZ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109
ABSTRACT In the near future, a large segment of the scientific community will have an opportunity to perform materials processing experiments on the Space Shuttle in the reduced gravity environment of space. Many of these experiments will require containerless processing techniques that provide manipulation and control of weightless (molten) materials without physical contact with container walls or other holding devices. A variety of containerless processing technologies are now being developed for space and ground-based materials processing facilities. The utilization of air jets or high intensity acoustic, electromagnetic or electrostatic fields can produce forces that support and manipulate materials. Most of the present containerless research is directed toward the development of high temperature systems capable of melting and resolidifying materials. This paper will review the materials processing capabilities and level of developmental progress of each technique. An introduction to available NASA test facilities will also be given. INTRODUCTION The orbital space environment will provide unique opportunities for materials science and technology as man expands his exploration of space. The reduction of the gravitational force on orbital space flights will also significantly reduce the hydrostatic pressure, bouyant forces, natural convection and sedimentation. With this new environment, scientists have the opportunity to study and better understand physical phenomena that may lead to new space processing technologies as well as improved earth-based processing of materials. The initial interest in materials processing in space began in the late 1960's and the earliest low gravity experiments were performed in ground-based drop towers. Later, experiments in the Skylab were the first extensive demonstration of space materials processing. The successes of these earlier programs have stimulated the development of advanced processing techniques for materials studies in the low gravity environment of the Space Shuttle and Spacelab [1]. Containerless processing experiments will take the greatest advantage of a zero gravity environment. Unfortunately, a truly zero-gravity environment can never be completely realized in an orbiting spacecraft. Accelerations associated with spacecraft trajectory alterations (-10- 7 g), atmospheric drag (-10-0 to 10-7 g), and astronauts' movements (10-2 to 10-4 g) will lead to * The research described in this paper was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
26 motion relative to the spacecraft center of mass. Thus, in order to accurately perform containerless studies, it is necessary to spacially localize the experimental material using an externally generated force. In this overview, we will discuss sample positioning techniques
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