NOVELTY - A reactor consists of a cylindrical sidewall (1) having a flange at the end (23), a cover (2a), a sealing component (18), a heater (5), a heat insulating material, and a supply pipe (151) for inert gas (16). The portion (24) where heaters are not installed is provided in the vicinity of the end of sidewall. The heat insulating material is installed in the end side from the portion (19) where heaters are installed.    USE - Reactor is used for manufacturing polycrystalline silicon (claimed) for solar cells.    ADVANTAGE - The reactor enables manufacture of highly purified polycrystalline silicon. Even when different materials are used on sidewall and cover of the reactor, damage by difference in thermal expansion amount during heating is prevented. The sealing component has excellent sealing performance between sidewall and cover. The reactor has excellent durability.    DETAILED DESCRIPTION - A reactor produces polycrystalline silicon by reacting silicon tetrachloride and zinc. The reactor consists of a cylindrical sidewall having a flange at the end, a cover closing the end of sidewall, a sealing component inserted between the flange and cover, a heater for heating the sidewall, a heat insulating material installed at the vicinity of end of sidewall, and a supply pipe for inert gas attached to the cover. The portion where heaters are not installed is provided in the vicinity of the end of sidewall. The heat insulating material is installed in the end side from the portion where heaters are installed. An INDEPENDENT CLAIM is included for manufacture of polycrystalline silicon, which involves supplying silicon tetrachloride vapors and zinc vapors from the upper portion of the reactor, discharging exhaust gas from the lower portion of the reactor, reacting the vapors, and depositing polycrystalline silicon in the reactor. While reacting the vapors, an inert gas is supplied to the space where heaters are not installed.    DESCRIPTION OF DRAWING(S) - The drawing shows an expanded edge portion vicinity view of the sidewall.    Sidewall (1)    Cover (2a)    Silicon carbide rod (3)    Heater (5)    Inert gas (16)    Sealing component (18)    Portion where heaters are installed (19)    End of sidewall (23)    Portion where heaters are not installed (24)    Inert-gas supply pipe (151)