ity level, chamber air temperature, and Black Panel or Black Standard Thermometer temperature. A2 The design of the test chamber may vary, but it should be constructed from corrosion resistant material. A3 Xenon-Arc Light Source. The xenon-arc test apparatus utilizes a long-arc quartz-jacketed xenon-arc lamp as the source of irradiance which emits radiation from below 270 nm in the ultraviolet through the visible spectrum and into the infrared. While all of the xenon-arc lamps are of the same general type, different size lamps operated in different wattage ranges are employed in several sizes and types of apparatus. In each of the various