Patent ID: 7848383

Claim:
A cold crucible induction furnace for heating an electrically conductive material, the furnace comprising: a wall and a base to form a melting chamber in which the electrically conductive material is contained; at least one ac induction coil at least partially surrounding the height of the wall; an ac power source having its output connected to the at least one ac induction coil to supply ac power to the at least one ac induction coil and generate an ac field around the at least one ac induction coil, the ac field magnetically coupling with the electrically conductive material to inductively heat and at least partially melt the electrically conductive material by inducing currents in the electrically conductive material; at least one dc coil at least partially surrounding the height of the wall, the at least one dc coil wound at least partially around the exterior of the at least one ac induction coil; and a dc power source having its output connected to the at least one dc coil to supply dc power to the at least one dc coil and to generate a dc field, the dc field damping the induced flows in the molten portions of the electrically conductive material.