Development of Super High Output HPS Lamp

Abstract

A super high power HPS lamp with 50kW of input, 8000klm of output and 1601m/W of efficiency has been developed. The key to success is the reduction of sodium vapor pressure, which compensates, for the geometrical increase of absorption by a layer of cooler sodium vapor. Spectral measurements on larger diameter tubes suggest that in the condition of optimum efficiency, the charcteristics are similar to those of conventional HPS lamps up to 1kW. The measurements also imply differences such as lower arc core temperature, which decreases visible efficiency, and a relative increase of molecular radiation. The effect of a longer arc tube, such as efficiency and distribution of self reversed D line width along the tube length are also examined. Further development was tried by increasing Xe pressure with decreasing starting voltage helped by a starting aid. With the increase of the Xe pressure, efficiency steadily increased and finally reached 1751 m/W. Proper positioning of the starting aid proved to reduce the starting voltage effectively. This lamp serves commercially for photosynthesis of Nylon-6.