3D-modelling of temperature gradients induced by electrical power dissipation in a 3-body Domen-type calorimeter for absorbed dose measurements

The effect of thermal gradients that appear in the core of a Domen-type absorbed-dose calorimeter during an electrical calibration run is revised using a finite element 3D-numerical analysis. The local thermal modelling, that is the method allowing for spatio-temporal distribution of temperature within the three bodies of the graphite calorimeter, combined with both a careful analysis on what really happens when a certain amount of electrical power is dissipated in a NTC heating thermistor and the consideration of heat loss through radiation from the surface of the calorimeter bodies, has led to results which are in agreement with those obtained from experimental measurements and reported in the literature.