Investigation of a High Enthalpy Air Arc Heater.

An experimental program was undertaken to develop a high enthalpy arc heater using air as the working fluid. Structurally the heater consists of a fluid convection cathode FCC and a ring anode. The FCC consists of a conical tungsten cathode surrounded by a concentric, closely-spaced shroud to form a annular nozzle to inject part of the working fluid into the base of the arc column. The ring anode features a central aperture, serving as the arc anode, and annular nozzle to inject the remainder of the working fluid into the column near the anode end of the arc. Both cathode and anode gas flows provide some gas-film cooling of the respective electrodes. A parametric study was made of the heater operation by varying arc current, gas flowrates and various geometrical factors using successively argon, nitrogen and finally air, as the working fluid.