Behavior of arc-anode attachment and its effect on anode state. Steam-argon plasma jet in air

摘要

Interaction of arc and electrode was studied at conditions characteristic for non-transferred direct current arc plasma torches. Such torches are widely used in plasma spraying, sphereodization of powders, decomposition of chemicals and many other technologies. Plasma here is generated by Joule heating of a gas in the electric arc discharging in a cylindrically symmetric channel between a cathode and an anode. The anode is often a part of the channel or is situated at the end of the channel and its surface is parallel to the arc. As the anode surface is parallel to the main arc column the current path curves in an anode region to attach the electrode. The anode attachment behavior determines performance of the torch controlling plasma power, fluctuation and electrode erosion. Anode attachment position and movement determine arc length and thus control arc power and its fluctuation. Moreover the anodic jet which appears at the anode attachment in common regimes significantly disturbs the plasma flow.