Abstract: A method and apparatus for depositing a thin film of material upon a base substrate including a glow discharge ion source for generating the particular ions that will be subsequently deposited upon the base substrate, a vacuum deposition chamber wherein the substrate material is located, and, intermediate between the glow discharge ion source and the vacuum deposition chamber, a constrictor electrode for isolating the deposition chamber from the ion chamber and an anode electrode for extracting ions from the glow discharge ion source and directing them toward the target substrate. A magnetic field is also provided in the apparatus of the present invention by the use of an externally wound magnetic coil to permit the glow discharge ion source to operate at a lower pressure and to constrict the flow of ions toward the substrate.