The gas-filled thermal converter as a precise AC-DC transfer standard for all the AC quantities

A novel thermal converter based on a gas-filled thermometer covered by a flat strap resistor (in place of the usual wire resistor-thermocouple combination) is presented. The basic principle on which the thermal convertor is based is illustrated. Test results obtained on a prototype have shown that the converter responds to the square of its heater current. In a specific arrangement AC-DC transfer standard comparators may be obtained with the following uncertainties: less than 2.5×10
^-9
at frequencies from DC up to 70 kHz; 0.01 p.p.m. at a frequency of 90 kHz and 0.1 p.p.m. at a frequency of 110 kHz.