Arc Characteristics in High Pressure Argom Atmospheres

Nishiguchi Kimiyuki, Matsunawa Akira, Hori Masaki

doi:10.2207/qjjws1943.46.8_553

In this paper are described the arc behaviors, the electical and thermal properties and the wire melting characteristics in GTA and GMA in high pressure argon atmospheres up to 10 atm.<BR>In a high pressure atmosphere, an arc shrinks much which brings the considerable increase in arc voltage. This increase is almost comes from the rise in potnetial gradient of an arc column and the increase in cathode potential fall is a little. In a hot cathode mode arc (GTA), the area of cathode root concentrates greatly in higher pressures, which eventually accompanies the acceleration of plasma stream. Therefore, the heat transfer to a mother plate is much dependent on the hot plasma jet. In a cold cathode mode arc (GMA), on the other hand, the distribution of cathode spots is much concentrated in high pressures, while the active area of current at electrode wire is kept constant. Therefore, the generation of plasma stream is suppressed. Concentration of cathode spots wandering region also brings the arc stabilization independent on the surface conditions of a metal. Hence, even the electrode negative GMA is more stabilized in higher pressures. Both the threshold current of metal transfer mode and the wire melting rate in spray condition decrease as the pressure is increased, because the electromagnetic detachment force becomes smaller due to the reduction of divergent angle of the arc current flowing pattern.

Arc Characteristics in High Pressure Argom Atmospheres

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