Infrared output from a compact high pressure arc source

Abstract

The radiant energy from a very small mercury arc source has been measured over the wavelength range 2–1000 μm and compared with a globar and a standard mercury arc source. As expected, in the far infrared the output is primarily from the arc plasma and below 100 μm from the fused quartz envelope. Due to its small surface area the envelope reaches a temperatures of ∼ 1365 K and gives comparable brightness to a globar in the near and middle-infrared, except at the restrahlen bands of quartz near 9 and 22 μm. In the region from 30–100 μm the new source output rises steadily compared with the globar, predominantly due to a reduction in emissivity of the latter. In the far-infrared the arc temperature is similar to that of the standard mercury lamp with an effective temperature approaching 5000 K.