Measurements for Determining the Dielectric Relaxation Rate of Water and of an Aqueous Solution at High Pressures

An apparatus for electromagnetic cm‐wave reflection measurements on water and aqueous solutions at elevated hydrostatic pressures with a special measuring cell is described. Measurements in the pressure range 1 bar up to 1 kbar at the frequency 17.6 GHz are reported for water at the temperatures 5°C and 20°C and for an aqueous solution of triethylenediamine at 15°C. The dielectric relaxation rate derived from those measurements increases with increasing pressure. Its pressure induced variations for pure water are compared with that of the proton magnetic spin lattice relaxation time, the self‐diffusion coefficient, and the fluidity.