Characteristics and electrode erosion rates of a D.C. plasma torch operating with TiCl4 plasma gas

A stable TiCl₄ plasma was produced using a simplified d.c. torch. The arc was struck between two concentric ring electrodes, d mm apart, and rotated using a magnetic coil. The electrode material was a new TaC composite. The arc was operated at 100 A for up to I h using plasma gas containing 0–30% TiCl₄. The voltage was 24–60 V, depending on the TiCl₄ concentration. The electrode erosion rate was of the order of 20g/C. It is shown that the erosion rate is a function of the aerodynamic drag of the are column.