Chromel/Alumel thermocouples used in a magnetic field indicated temperatures in error by about ±150% at 100 °C. Diagnostic tests showed that the errors were caused by the Ettingshausen–Nernst (EN) effect. The EN effect produces an emf in a conductor, such as a thermocouple, placed in a magnetic field and temperature gradient which are both transverse to the length of the conductor. The heat transfer experiment at the Oak Ridge National Laboratory in which the temperature measurement errors were encountered is described, and the results of diagnostic tests performed in this experimental apparatus and in auxiliary lab‐bench experiments to identify the EN effect are presented. Sources of error, other than the EN effect, for thermocouples used in a magnetic field are discussed.
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