Dielectric coefficient and density of subcooled liquid hydrogen

Here we present precision dielectric coefficient measurements of subcooled equilibrium liquid hydrogen in the temperature range from 15 to 23 K and under pressures up to 1 MPa. The measurements were performed using a three-terminal flat plate capacitor and a single-frequency, ultra-precision capacitance bridge. These results are combined with the previously published data to express the dielectric coefficient in the form of the Clausius-Mossotti relation with a new correlation. The results reported in this paper are expected to be especially useful for capacitance-based measurements involving fluid hydrogen such as liquid level, mass gauging and void fraction measurements in two phase flow. Also, a new equation of state gives the density as a function of pressure and temperature for the subcooled liquid phase.