Abstract: In an inductively heated pancake epitaxial reactor the reactant gases are fed vertically into a bell jar of reduced height via a plurality of coaxial centrally disposed flow passageways, one of which is outwardly flared to impart a radial component of velocity to one or more of the flows. The density, velocity and composition of the flow streams are separately controlled to control the deposition prameters. A composite R.F. inductive heater coil, made up of vertically stacked tubes, is contained within a purged housing. The turns of the heating coil are variably spaced to obtain a desired spatial distribution of power density coupled into the susceptor. A purged porous member of thermal insulation is disposed in between the R.F. heating coil and the pancake susceptor to reduce heat loss. The bell jar is sealed to its base plate by means of a vacuum pull-down sealing and lifting flange sealed to the bell jar by means of a purged O-ring.