Thermometry

The redefinition of several physical base units planned for 2018 requires precise knowledge of the values of certain fundamental physical constants. Scientists are working hard to meet the deadlines for realizing the ultimate International System of Units.

The past 25 years have seen tremendous progress in thermometry across the moderate temperature range of 1 K to 1,235 K. Various primary thermometers, based on a wide range of different physics, have uncovered errors in the International Temperature Scale of 1990, and set the stage for the planned redefinition of the kelvin.

In the quest for ever-lower temperatures, making new discoveries and overcoming technical challenges go hand in hand — and push the limits of thermometry standardization.

Sustaining and measuring high temperatures in fusion plasmas is a challenging task that requires different heating systems and diagnostic tools. Information on the spatial distribution of temperature is one of the key elements for improving and controlling plasma performance.