Dynamic heat flux transducers -
DHF Series

Sensors of the DHF (Dynamic Heat Fluxmeters) series are intended for very fast thermal phenomena detection and measurement. DHF devices are based on a thin conductive film deposited on the front face of the sensor, coupled with a type K thermocouple. DHF sensor can be used a surface thermocouples, but also as heat flux sensors.

DHF probes are surface thermocouples: a thin electrically conductive film is deposited on a highly insulating substrate:

​

- The substrate must withstand high surface temperature, while having a very low thermal conductivity. Materials used for the substrate are high performance, machinable ceramics, such as alumina (Al2O3), zirconia (ZrO2) or hafnia (HfO2) ;

 

Thin conductive film is generally made of a high melting point metal or alloy, preferentially having a high emissivity in order to increase incident radiation absorption, such as porous tungsten (W) or porous platinum (Pt) ;

 

• Thermocouple hot junction is distributed on the thin film by connecting thermoelectric wires to the surface metal (and not directly one on the other). Doing so, the sensor measures the mean (radial) surface temperature.

​

Compared to a classical wire thermocouple (even of some microns thickness), DHF sensors will demonstrate better reactivity (in terms of signal amplitude and response time) due to a large surface exposed to the incoming heat flux. Another fact contributing to this better reactivity is the presence of an insulating substrate, which generate a fast temperature increase of the exposed surface.