Realization of the ITS‐90 over the Temperature Range 83 K to 693 K at the National Institute for Standards NIS‐Egypt

The thermometry group of the National Institute for Standards (NIS) has realized the International Temperature Scale 1990 (ITS‐90), as defined over the temperature range from 83 K to 2200 °C. This work concerns the temperature range from 83 K up to 693 K only. A brief review is given of the techniques and apparatus used, the source and purity of the fixed points in this range, cell designs and uncertainties of our realization.