Pressure Dependence Of Electric Arc Length In Microgravity

Rice University

Tim W. Glover (,
Donna L. Dempsey, Cindy Marie Kurt,
Syri Jo Koelfgen & Dr. Ken Smith


Thermal plasmas are attracting increasing interest for processing of materials, including such applications as plasma spraying, melting, extractive metallurgy, densification and chemical vapor deposition. In many of these applications, atmospheric pressure electric arcs are used to produce the required plasma. These arcs are destabilized by gravity-driven convection and are thereby limited to small lengths, typically less than about 3 cm. By observing the behavior of such arcs in a controlled chamber under a variety of operating conditions, we will evaluate the degree to which their terrestrial limitations are diminished by microgravity. Specifically, we wish to determine the maximum arc length we can attain in zero- gravity for our apparatus. We will use a variety of chamber media including N2, He, Ar, and Ne gas, and study the extent to which they affect the achievable arc length. The pressure in the chamber will be systematically increased from approximately 50 Torr to the cabin pressure to investigate the resulting effect on the length of arc attainable. We will record the shape and behavior of the arc as it begins to destabilize and analyze the dependence of its maximum length on the gas composition and pressure. We expect to determine the extent to which the size of devices using such plasma arcs could be increased in a microgravity facility.


Wednesday, 31-Dec-1969 18:00:00 CST