Air Jet Levitation Furnace System for Observing Glass Microspheres During Heating and Melting
- PDF / 2,726,182 Bytes
- 10 Pages / 414.72 x 648 pts Page_size
- 98 Downloads / 196 Views
Inc.
NA V!fhiS PROCESSING IN THE REDUCEDGRAVITY ENVIRONMENT OF SPACE iu; V. Rindone, editor
121
AIR JET LEVITATION FURNACE SYSTEM FOR OBSERVING GLASS MICROSPHERES DURING HEATING AND MELTING
EDWIN C. ETHRIDGE* AND STANLEY L. DUNN** *Space Sciences Laboratory, ES74, Marshall Space Flight Center, Huntsville, **Bjorksten Research Laboratory, P. 0. Box 9444, Madison, WI 53715
AL;
ABSTRACT A collimated hole structure air jet levitation system has been developed which can be used to levitate hollow glass microspheres used in inertial confinement fusion studies. An ellipsoidal furnace has been added to the system to provide a heating source. A video camera and a 16 mm movie camera connected to a microsphere system provide real time observation as well as permanent documentation of the experiments. Microspheres have been levitated at temperatures over 1400 0 C for over 10 minutes at a time.
INTRODUCTION Inertial confinement fusion (ICF) describes the process of containing deuterium-tritium (DT) at the high pressures and high temperatures required for thermonuclear burn. In this process, a large amount of power is transferred to the fuel pellet in a very short period of time. The shell holding the DT fuel explodes rapidly, expanding inward and outward. This produces a rapid compression and heating of the fuel to very high densities. Hollow silicate glass microballoons (GMB) 50 to 750 pm in diameter with wall thicknesses of 0.5 to 2.0 pm are currently used in fusion research. Stringent requirements on the tolerances of these GMBs are required for efficient compression of the fuel. The outer diameter must be within approximately 1%, the wall thickness uniformity (concentricity) within 10%, and a surface smoothness better than 0.05 pm. These high levels of concentricity and surface smoothness are required for stable implosions, being dictated by the Ragleigh-Taylor criterion to minimize fluid instability. The first GMBs for fusion research were obtained from manufacturers who produce them for various industrial applications. Large numbers of them had to be screened to locate the one in 100,000 that met the specific requirements of fusion researchers. Since then, processes have been established by Lawrence Livermore Labs and KMS Fusion which can produce high yields of acceptable quality microballoons in sizes up to about 1 mm in diameter. Cost effective commercial production of fusion energy will require very large numbers of shells of high quality with processes that give high yields. Commercial production also may require GMBs in sizes between one and ten mm. To date, processes for large yields of microballoons in these sizes are not available. The physical concentering mechanism responsible for formation of GMBs is not well understood. It has been stated that with microballoons diameters greater than 1 mm, gravitational forces cannot be ignored and the aerodynamic forces on freely falling shells also become significant compared with capillary forces [i].Hollow GMBs are currently manufactured by two processes. KMS Fusio
Data Loading...
