Exploration of a micro multi-electrode technology applied in an air arc heater

Arc heaters are vital equipment for the ground thermal appraisal of space probes reentering Earth's atmosphere. However, the cathodes of arc heaters are currently made of pure copper, and cathode erosion limits the appraisal. A micro multi-electrode technology was proposed to reduce cathode erosion. Cu-Y, Cu-Bo, Cu-Hf, Cu-La, Cu-Cr2Nb, Cu-LaB6, Cu-HfO2, and Cu-Y2O3 alloys were prepared with a content of mol. 0.3%. The microstructure, electron-emission abilities, and arc-attraction abilities of the prepared alloys were analyzed. These alloys consist of low work function (LWF) phases and copper. The electron-emission abilities of these alloys are 10-30 times higher than that of copper. The LWF phase can attract the arc, and its arc-attraction ability can be characterized by a parameter, k(2). The arc-attraction ability of these LWF phases from low to high is Cu, Cu6Y, Cu6La, Cu13Ba, Cu5Hf, Cr2Nb, HfO2, Y2O3, and LaB6. The arc-attraction ability of the LWF phase is related to its work function and its melting point. Cr2Nb, HfO2, Y2O3, and LaB6 successfully attracted and separated the single arc spot into multiple micro spots, which verified the feasibilty of the micro multi-electrode technology.