Arc furnace with vacuum chamber - has hollow cathode comprising circle of rods in holder above workpiece

摘要

The arc furnace consists of a vacuum chamber (1) with conducting walls and containing a conducting holder (3) for the workpiece (4). A hollow cathode (5) is mounted in a conducting holder (7) above the workpiece. The cathode holder is insulated (17) from the chamber walls and has an axial hole (9) to admit gas to the chamber. The cathode consists of a circle of rods (6). The depth of the cathode cavity (8) is at least 1.5 times its minimum dia. The rods may be directed vertically towards the workpiece or they may be inclined with their lower ends closer together than the ends in the holder.