Johnson Noise Thermometry Results

The noise at the output of Metrosol’s first high temperature JNT system was assessed whilst immersed in a block bath at ambient, 800 & 1,000°C. At 1,000°C it was found to be ~1.1 °C.

The theoretical limit for JNT (given by Rice's equation) is also shown for the bandwidth of the electronics (1 MHz) and sampling interval (5.872s). Note: the effective JNT bandwidth will be less than 1 MHz due to RC filtering in the probe. The JNT result could be improved by weighting local frequency contributions by their signal to noise ratio.

The standard deviation from a thermocouple is also shown at 800 & 1,000 °C.

High temperature standard deviations for JNT thermocouple and Rices equation 2