Abstract: A plasma burner comprises an electrode holder which carries a tubular outer electrode and a coaxially arranged central electrode, and an electrical current supply source, which can be coupled via current feeders to the outer and central electrodes respectively. Also a device is provided for feeding gas into the region of the electrodes, between which an arc is produced for plasma formation. The tubular outer electrode has a first cooled, arc-inactive tube section, consisting of electrically conductive metal, and an adjoining second arc-active uncooled tube section, which consists of heat-resistant and electrically conductive material, and which is releasably connected to the first tube section. The arc passes between the second tube section and the neighboring arc-active section of the coaxial central electrode.

Abstract: A direct current arc furnace has at least one anode movable into the furnace interior and at least one cathode also movable from above into the furnace interior, between which cathode and the inserted material or the melt an arc is produced. The anode contains a cooling system in its interior having a controller which cools at least the immersion region of the anode to a temperature which is lower than the temperature of the melt.This furnace device and the anode are utilized in methods for melting and heating of materials with advantage, at least the immersion region of the anode being maintained at a temperature which lies below the temperature of the melt.