Abstract
In Gas Tungsten Arc (GTA) at atmospheric pressure, it was not clear how the differences of emitter materials which were added in the tungsten cathode affect the physical behavior in the electrode region. A study of the current attachment at thermionic cathode for GTA was tried from numerical calculations of arc-electrodes unified model. Two-dimensional temperatures and fluid flow velocities of arc plasmas were calculated in the four cases, namely, W-2%ThO2, W-2%La2O3, W-2%CeO2 and W electrode. It was suggested that the current attachment at thermionic cathode was dependent on work function, melting point and Richardson constant of emitter materials, and the cathode shape and the current density around the cathode strongly affected to the temperature of arc plasma and the cathode jet. Calculation results of radial temperature distributions on the tungsten electrode surface and arc pressure distributions at the anode surface were similar to the tendency of the previous experimental results.
