GB830557A - Improvements in or relating to apparatus for producing arc plasma at high speeds - Google Patents

Abstract

830,557. Discharge apparatus. GENERAL ELECTRIC CO. April 2, 1958 [April 8, 1957], No. 10589/58. Class 39(1). [Also in Group XXXIII] Apparatus for producing an arc plasma, travelling at hypersonic speed, which may be directed over a fixed model in a wind tunnel, comprises a generator having a cylindrical housing 17 containing a positive rod electrode 18, e.g. of graphite, and a negative ring electrode 19 mounted in an opening in the wall of the chamber. A fluid such as air, water or nitrogen is introduced at high velocity through a tangential nozzle 22 and forms a rotating column of fluid 21 which confines the arc formed between electrodes 18 and 19 and increases its current density and raises its temperature to values above 10,000‹C. In addition portions of the fluid 21 enter the arc and are heated and directed through the opening 11 in the electrode 19 to form part of the arc plasma 12 which passes through a cylindrical container 10, bolted to the chamber 17, to an opening 13 leading to a nozzle 14 which may be provided with a heat-resistant lining 27. Gases or liquids or powders are injected under pressure into the chamber 10 by a series of tangential nozzles 15 fed from a common inlet 25 and form a whirling column of " fluid " 16 which confines the plasma 12. A portion of the " fluid " 16 also enters the plasma 12 and is superheated and decomposes to form part of the plasma ejected from the nozzle 14 which serves first to constrict and then gradually to expand the plasma and thus greatly to increase its speed. " Fluid " 16 not entering the plasma 12 escapes through ports 26. The chamber 10 thus provides a means of increasing the density of the arc plasma and varying its composition without increasing the electrical power consumption.