An Insulated Constrictor Plasma Torch with an Improved Anode

Abstract

Improvements to the anode of an insulated constrictor plasma torch were carried out in order to increase the proportion of ultrafine particles (UFPs) produced by means of the plasma jet method. Nickel UFPs were produced using the improved anode to examine its effects. The improved anode is a unified type consisting of the electrode and feeding ports for powders and hydrogen. Two types of improved anode with different feeding port positions were made, and the effect of the relative position of feeding port to nozzle length on the proportion of UFPs produced was examined. In addition, the geometry of the nozzle exit was modified in order to prevent melt drop adhesion.
The proportion of UFPs produced using the improved anode was greater than the fraction produced using an unimproved anode. The position of feeding ports did not greatly affect the proportion of UFPs produced although an appropriate feeding port position relative to the nozzle length may exist which improves the proportion of UFPs produced. The cause of the melt drop adhesion was found to be the cold hydrogen which was added to the argon plasma. The melt drop adhesion was formed by cold hydrogen flowing along the inner-wall of the nozzle.