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Abstract
Mercury lamps with a warm tone appearance (correlated color temperature about 3300°K) typically operate at an efficacy well below that of the cooler deluxe mercury lamp (color temperature about 4000°K). To improve the warm mercury lamp blends of cerium activated yttrium aluminum garnet phosphor with europium activated yttrium vanadate phosphor have been studied. Calculations using a computer simulation were used to predict the effect of the individual phosphors on the chromaticity and efficacy of the lamp. With a 35 percent by weight YAG: Ce phosphor blend, 400-W mercury lamps have been made with 23,500 Im, 3350°K color temperature and a color rendering index of 48. Lamps of this formulation have been found satisfactory in maintenance and field test applications.