Thin filament pyrometry (TFP) temperature measurement technique was implemented for the first time in microgravity ethanol droplet combustion experiments at NASA 2.2s drop tower. This technique was first developed by Vilimpoc and Goss [1] and later used by several researchers in both diffusion and premixed flames [2–4]. The advantages of this technique are related to rapid temporal response and spatially-resolved temperature distribution rather than single point measurements (as in the case with thermocouples). The SiC filament is an ideal material as a temperature probe in a flame due to its low thermal conductivity, high resistance to oxidation and its small size. TFP was implemented in microgravity droplet combustion experiments at NASA 2.2s drop tower. An 8 bit CCD camera was used to record the emission from the SiC fiber that was positioned through the center of the droplet (the fiber is also used to suspend the droplet and keep it in the field view of the camera). The camera is equipped with a lens and a 700 nm interference filter, with a FWHM of 25 nm was placed in front of the camera. Neutral density filters were used in order to obtain unsaturated filament images for the various experimental conditions (oxygen concentration, inert, pressure). A 300 nm plano convex lens was placed in front of the droplet flame in order to improve spatial resolution by magnifying the image. The emission measured by the camera along the location of the filament results from the emission from the filament and the flame in the intervening region between the filament and the camera. Figure 1 displays a schematic from the top of the flame and shows the rays from filament towards the camera and the rays from the medium (gas/soot) in front of the filament towards the camera).
