ELECTRON BEAM FLUORESCENCE PROBE FOR MEASURING THE LOCAL GAS DENSITY IN A WIDE FIELD OF OBSERVATION

Abstract

An electron beam was fired across the field of observation of the UTIA low-density wind tunnel. Along its path gaseous fluorescence was excited and visible light emitted. The total light output per unit length of the electron beam can be assumed to be proportional to the density of the gas if suitable spectral lines are selected. A three-dimensional scan of the field would give the local density for each spot. Visual, photographic, and photometric observation is possible. Some photographs are presented along with approximate data for the light output in air. The spatial resolution of the fluorescence probe is also discussed.