Graphite electrode

The electrode has an outer zone (A) forming a base of the electrode, and a high- or ultrahigh-pure electrical graphite with different thermal conductivities. An inner zone (B) is arranged in the outer zone and projected from the outer zone. Specific thermal conductivity of the inner zone is lower than that of the outer zone. The inner zone is partly surrounded by the outer zone. The inner zone is formed as a loose or replaceable insert. The inner and outer zones have common thermal and electrical contacts. The inner zone is connected in the outer zone by using a conical plug. An independent claim is also included for a method for manufacturing polycrystalline silicon by depositing high-purity elemental silicon from a gas phase on a surface area of silicon rods.