Masao Ushio and Manabu Tanaka
Joining and Welding Research Institute, Osaka University, Ibaraki 567-0047
In order to make clear the deviations of the plasma state from LTE (Local Thermodynamic Equilibrium)in the arc column of an argon gas-tungsten-arc plasma at the atmospheric pressure, axial profiles of heavy particle temperature, electron temperature and electron number density were measured by using of line-profile analysis of the laser scattering method which yielded each temperature and the density without the assumption of LTE. The experimental results showed that the arc column which was in the center of the arc significantly deviated from LTE state under both conditions of the arc current of 50 A and 150 A. As a result, it is suggested that the deviations from LTE in the arc column should be affected strongly by the mass flow of cold gas induced by the arc constriction at the cathode, namely, cathode jet.
(Received July 23, 1998; In Final Form September 11, 1998)
gas-tungsten-arc, argon, thermal plasma, laser scattering, Thomson scattering, local thermodynamic equilibrium; LTE, cathode jet
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