New developmental tool for high-efficiency lighting being used. (General Developments).
There are an estimated 1 billion plasma light sources in service in the United States, consuming an estimated 600 billion kilowatt-hours (2 exajoules) of electrical energy annually. These sources principally include fluorescent lamps and metal-halide discharge lamps. In the past, metal-halide discharge lamps were used mainly for high-intensity lighting of large spaces, such as building exteriors and arenas. Nowadays, motivated by increased brightness and greater energy efficiency, metal halide lamps are also being developed for automobile headlights and regular interior lighting. As a result, there is a growing interest in increasing their luminous efficiency through a better understanding of the processes that govem their operation. However, these processes are so complex that. they have defied attempts at predictive modeling or even development of scalable design rules. As part of a cooperative program with the Electric Power Research Institute (EPRI), NIST scientists have used the Advanced Photon Source at Argonne National Laboratory to observe x-ray absorption and fluorescence in the various elemental components of a metaihalide arc lamp. These new techniques provide a more complete picture of the arc, both spatially and chemically, than was possible previously. The observations permit NIST researchers to map the distribution of the halogen and metal ions in a production-style lamp. Such measurements lead to a better understanding of processes that affect the luminous efficiency of these lamps.
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