Characteristics of a transferred‐arc plasma

Abstract

AbstractThe basic characteristics of a transferred arc argon plasma were determined using a cathode assembly suitable for transferring the electric arc to a molten metal bath or to a cooled anode. They indicated that the sustained voltage depended strongly on the arc length and much less on current. The inlet gas velocity past the cathode tip was determined to be an important operating parameter, rather than the volumetric gas flowrate.The measurement of the axial and radial profiles of temperature was effected with ±8% accuracy by a novel diagnostic technique. Temperatures up to 18,500 K were observed on the axis of the plasma column, near the cathode tip, and decayed in both radial and axial directions. A sweeping microprobe was used to measure the axial and radial profiles of velocity. Velocities up to 190 m/s were recorded. The presence of a relatively colder flow surrounding the plasma column was detected. Mass and energy balances performed by taking this flow into account agreed with the measured input rates.