Development of a probe for in-situ radiative heat flux measurements at the surface of an ablator

Abstract

We present a radiative heat flux probe capable of directly accessing a radiative boundary layer around an ablative sample. Unlike previous approaches that have suffered from pollution of the optical system by ablative species, our probe utilizes a system for preventing contamination of the optical system. We are therefore able to make measurements over a long period of time during testing in a plasma torch facility. The probe operates on a battery-powered system and can therefore be installed in facilities without optical access. It is designed for use under a wide variety of conditions within ground test facilities. Prototype tests of the probe were performed in our 50 kW plasma torch facility to study an equilibrium air flow around an ablative CBCF turning wedge and flat surface samples. Further tests of the probe were performed in the much larger plasmatron facility at VKI to demonstrate probe functionality.