NOVELTY - The apparatus comprises a reactor chamber with a reactor wall (32), 20 filament rods and gas inlet orifices (22) for reaction gas in the reactor chamber, where each filament rod, except for the rods close to the reactor wall, has a distance of 250-350 mm, and 3 further adjacent filament rods and 3 adjacent gas inlet orifices. A difference in distances of any rod from the further adjacent rods and the adjacent gas inlet orifices is less than 10%. An angle between directions from any rod to its further adjacent rods and to its adjacent gas inlet orifices is 115-125 degrees .    USE - The apparatus is useful for deposition of polycrystalline silicon on filament rods (claimed) for fabricating solar cells for photovoltaics.    ADVANTAGE - The apparatus enables economic deposition of high-purity polycrystalline silicon on filament rods with high productivity and less energy consumption and with a low proportion of rough surfaces.    DETAILED DESCRIPTION - The apparatus comprises a reactor chamber with a reactor wall (32), 20 filament rods and gas inlet orifices (22) for reaction gas in the reactor chamber, where each filament rod, except for the filament rods close to the reactor wall, has a distance of 250-350 mm, and 3 further adjacent filament rods and 3 adjacent gas inlet orifices. A difference in distances of any filament rod from the three further adjacent filament rods and the adjacent gas inlet orifices is less than 10%. An angle between directions from any filament rod to its three further adjacent filament rods and to its adjacent gas inlet orifices is 115-125 degrees . A length of the filament rods is 8-12 times a distance between adjacent rods. The gas inlet orifices are nozzles, which are directed vertically upward with respect to a base plate of the reactor chamber, and have a cross-sectional area of 1-10000 mm2. The reactor chamber has a round cross-section or a cross-section matched to the number of filament rods and optimal space utilization. The cross-section is hexagonal. A gas inlet orifice central with respect to a cross-section of the reactor chamber is provided with offgas orifices positioned next to and around the central gas inlet orifice and/or between the reactor wall and the filament rods close to the reactor wall. The apparatus further comprises cooling bodies and/or heating elements in the reactor chamber, where the cooling bodies and/or heating elements are arranged above gas inlet orifices or positioned in the reactor chamber in place of gas inlet orifices. An INDEPENDENT CLAIM is included for a process for depositing polycrystalline silicon on filament rods in an apparatus.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic cross-sectional view of a reactor with rod and gas inlet ports.    Silicon rod (12)    Gas inlet orifices (22)    Reactor wall. (32)