The so-called Atomic Layer Thermo Pile (ALTP) is a well established sensor in the field of infrared laser beam diagnostics. The working principle of this sensor is based on the Transverse Seebeck effect and can also be used as a universal ultra fast heat flux gauge in the field of thermodynamics and fluid mechanics. The sensor has unique characteristics with respect to temporal and spatial resolution as well as a wide operational field concerning the magnitude of heat load density. Its working principle, structure and calibration procedure have already been described in [1].

First quantitative short term heat flux density measurements in the magnitude of approximately 1 W/cm² and below have been successfully performed in a supersonic and in a subsonic incompressible flow [1],[2]. Depending on the sensors’ structural design, a time constant below 1 μs can be realized. This characteristic already allowed the detection of high frequency instabilities in hypersonic boundary layers and even the laminar turbulent transition of an unsteady wall boundary layer (BL)[3] in a shock tube downstream of a passing shock [4]. In the present paper the operational envelope of the ALTP shall be extended into the regime of high heat loads of approx. 200 W/cm² for hypersonic flow conditions. Comparative heat flux measurements with other well established gauges of different working principle like thin-films, coaxial and calorimetric thermocouples were carried out in the front side of a blunt body configuration. The shape of the body was specially designed for such stagnation point measurements. Theoretical estimations about heat loads, being expected according to corresponding simulated free flow stagnation conditions, have been performed for the stagnation region by means of the Fay & Riddell relation [5] as well as BL computations [6].