This paper presents the results of an investigation into a simple technique developed primarily for evaluating surface coating effectiveness for the absorption of a nonuniform laser radiation heat flux. Analysis suggests that if the transducer sensor is designed appropriately, and the experimental data analyzed in a particular manner, the temperature–time history of the transducer need be measured at only a single arbitrary location. These conclusions are also supported by experimental measurements of laser radiation absorption at a wavelength of 10.6 μm for polished copper, polished steel, and for a manganese–phosphate coating on a steel substrate. The absorptivities measured for the polished copper and steel agree well with other experimental data in the literature. Limitations of the measurement technique, resulting from the temperature dependence of the transducer material properties, radiation absorptivity, and combined convective and radiative heat flux, are also investigated theoretically and experimentally.
Heat flux analysis of Type-I ELM impact on a sloped, protruding surface in the JET bulk tungsten divertor