A method for calibrating cryogenic void fraction RF-sensors having a round cross-section and estimating their accuracy

The calibration principle of the cryogenic void fraction RF-sensors of a round cross-section for a wide temperature range is proposed and described in detail. It is shown that the simplest and reliable method of the calibration procedure requires finding a dependence of the resonant frequency, f, of the empty sensor on its temperature and only two f-values when it is filled with saturated liquid and vapor at the given temperature T0. The calibration test-bench is described. The errors of the calibration are estimated, and the experimental data for helium, hydrogen and nitrogen are presented.