Abstract: A device for obtaining multicrystalline silicon, including: at least one crucible made of quartz for the silicon, removably housed in a cup-shaped graphite container; a fluid-tight openable casing; a top induction coil, set facing, with interposition of a graphite plate, the crucible, a lateral induction coil, set around a side wall of the graphite container, and a bottom induction coil, set facing a bottom wall of the graphite container and vertically mobile for varying the distance from the bottom wall; and first means for a.c. electrical supply of the induction coils separately from one another, and second means for supply of a coolant within respective hollow turns of the induction coils; the bottom induction coil includes four spiral windings, arranged alongside one another; electrical switching means enable in use selective connection of the four windings to one another according to different configurations.

Abstract: An induction heating device for surface treating the teeth (11) of a mechanical part on which each tooth (111) has a projecting tip (111s) and a tooth root linking the tooth to an adjacent tooth, wherein an in duction coil (12, 12') is spaced from the tooth tips and powered by at least one high-frequency current source. The coil consists of a set of conductive segments (24, 24') individually orthogonal to the generatrix (d, d') of the teeth, located above respective tooth tips and interconnected via connecting segments (25, 25').