This paper is focused on examining the potential thoriated tungsten cathodes have on reducing surface temperatures in magnetoplasmadynamic (MPD) thruster cathodes. Optical pyrometry and charge-coupled device (CCD) camera imaging have provided axial temperature measurements and two dimensional temperature fields of the cathode surface. The magnitudes of the peak operating temperatures and how they vary with alternate discharge currents and time were examined. Cathode axial temperature profiles were then compared against those of pure tungsten to illustrate the large temperature reducing effect lowered work function imposes by increasing thermionic electron emission from the cathode surface. It will be shown that the thoriated tungsten cathodes exposed to a high current arc discharge (20-60 A) exhibited far lower surface temperatures and erosion rates when compared to the pure tungsten variety.
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