Microwave lamp characterization

The operating properties of the SAA microwave lamp developed by Fusion Lighting, Inc. were determined with reference to its usefulness in Bioregenerative Life Support Systems (BLSS). Lamp flux density in several wavelength ranges, spectral output, and temperature response (-10 to +40 degrees C) were determined by mounting the lamp and sensors in a controlled environment chamber. Lamp intensity distribution also was measured using a swing arm apparatus with a 1-m radius. A model was developed to characterize the intensity distribution of the lamp as a function of lamp geometry and output properties. The lamp was found to produce a spectral output similar to that of earlier lamp models, but with a higher photosynthetic output per lumen and per input watt. Radiant energy output was measured to be 0.399 radiant watts per micromole s-1 PAR compared with 0.56 radiant watts per micromoles s-1 PAR for high-pressure sodium lamps. Total lamp output dropped approximately 0.4% for every degree Celsius rise in ambient temperature, with little change in light quality. The intensity distribution of the lamp was found to produce a fairly uniform flux density (+/- 22%) in a 40 degrees cone from lamp nadir.