A reactor and a plant containing the reactor for conducting a continuous, industrial process for preparing high-purity silicon tetrachloride or high-purity germanium tetrachloride is provided. The plant contains a plasma reactor having a dielectric, a high voltage electrode and an earthed, metallic heat exchanger, in which the longitudinal axes of the dielectric, of the high-voltage electrode and of the earthed, metallic heat exchanger are oriented parallel to one another and at the same time parallel to the force vector of gravity.