Abstract: Disclosed is a process for rapidly producing large diameter, high-purity polycrystalline silicon rods for semiconductor applications, while maintaining the purity of a highly refined monosilane gas inside the reactor. The equipment includes a reactor vessel which encloses powder catchers consisting of cylindrical water jackets. Also within the vessel is a cylindrical water jacket which concentrically surrounds the powder catchers and which defines multiple reaction chambers. Control is effected in such a way that the temperature distribution in different sections inside the reactor is as follows in the ascending order: the powder catcher walls, the walls of the water jacket which defines the reaction chambers, and the lower wall of the vessel cover.