Performance of ThO_2-W, Y_2O_3-W, and La_2O_3-W Cathodes in Quasi-Steady Magnetoplasmadynamic Thrusters

摘要

Thoriated tungsten (ThO_2-W) has been widely used as a JL cathode material for dc arcjets, magnetoplasmadynamic thrusters (MPDTs), and gas tungsten arc (GTA) welding for a long time, because of its high durability and electron emissivity. However, manufacturers are concerned about the radiological doses that users are exposed to when sharpening or grinding thoriated tungsten [1,2]. Yttriated and lanthanated tungsten (Y_2O_3-W and La_2O_3-W) electrodes have been proposed as alternatives to thoriated tungsten. Because these nonradioactive electrodes have superior durabilities and electron emissivities to conventional ThO_2-W in arc welding [3-5], they have replaced ThO_2-W electrodes.