The Measurement of Voltage by the Use of the Star Effect

The theory of the Stark effect is reviewed with regard to its possible application of measuring voltages. It is pointed out that the effect can be used only to measure relative voltage and that the accuracy is likely to be limited by the accuracy with which the electrode separation can be determined. Therefore, the most sophisticated types of molecular frequency standards may not be required. The Stark method appears to hold a particular advantage for the measurement of high voltage since no voltage divider is required. Also, two possible methods of comparing ac voltages to dc voltages are discussed. Finally, an experimental Stark voltmeter employing a millimeter wave Fabry-Perot absorption cell is discussed. Calculations concerning J=2→:3 transition of methyl cyanide at 55 Gc indicate that in principle the precision obtainable with a field strength of 10
⁴
volts/cm should be in the neighborhood of one part in a million, if the effects of field inhomogeneities can be kept within comparable limits.