A 72-Inch High Vacuum Evaporator and Its Glow Discharge Equipment

This paper describes a 72-inch diameter high vacuum evaporator constructed primarily for applying silicon monoxide-protected aluminum coatings to 60-inch searchlight reflectors. Data are presented on studies made to determine the optimum shape, size, and position of glow discharge cathode for obtaining uniform heating and consequent cleaning of mirror forms. The experience gained from the studies made on glow discharge arrangements for the 72-inch evaporator was used in designing discharge arrangements for small coaters.