Electron Transpiration Cooling (ETC) is a proposed method of cooling hypersonic leading edges using thermionic emission of electrons into the hypersonic plasma sheath. Researchers at the ALLEMO have been exploring the possibility of enhancing ETC by flowing cesium through a porous tungsten leading edge. This would decrease the leading edge work function, increase thermionic current, and thereby increase the cooling effect. A vacuum chamber is used to test feasibility in a static environment. The vacuum chamber houses a four-way heat pipe oven to create a stable cesium vapor environment with access for optical diagnostics and a heating laser. The laser heats a tungsten cathode in the cesium vapor, and an external power supply creates a variable bias voltage between the cathode and anode to initiate a discharge and “pull off” electrons. Cathode temperature is monitored with two-color pyrometry to quantify cooling with high temporal resolution.
Experimental setup diagram
Argon discharge between heated tungsten cathode (white half circle) and anode (orange flat plate)