HETS performances in He cooled power plant divertor

In the frame of the activities aimed to evaluate the performances of a He cooled divertor in the future fusion power plant, the High Efficiency Thermal Shield (HETS) concept has been proposed. This concept relies on an abrupt change of momentum of the fluid in order to increase the turbulence in the gas, and therefore the heat transfer. The requirements for the power plant divertor are, not only to sustain the required thermal flux (10 MW/m 2), but He to have such properties as to be used directly in the energy production cycle and limit the required pumping power to no more than 10% of the divertor thermal power. Analytical studies developed by ENEA and UKAEA showed that the HETS concept can satisfy all the basic requirements. Experimental validations are required for the pressure drop estimates in HETS. Preliminary experiments have been performed using air at room temperature and showed values of pressure drop in line with the parameters used in the calculations. Studies aimed to optimize the shape of the channel, to further reduce the pressure drop are in progress.