A fast response thermocouple for temperature fluctuation measurements in sodium coolants

A special chromel/alumel thermocouple was fabricated whereby the bare ends of the wires were fixed about 1mm apart. In a medium with a good electrical conductivity (e.g. liquid sodium) the junction of this thermocouple is replaced by the medium itself, therefore a fast delayed response is expected. Experimental data for this device are compared with corresponding dynamical data for conventional thermocouples. In addition to the mean temperatures of both elements being good agreement it is shown that the open element exhibits a much faster time behaviour than conventional thermocouples. (author)