Dielectric Relaxation in Supercritical Water.

Abstract

The dielectric relaxation in water and heavy water have been measured in the temperature and pressure ranges up to 750°C and 120 MPa by using a newly developed microwave spectroscopy in the frequency range up to 40 GHz. The dielectric relaxation time τ is deduced from observed transmission spectrum on the assumption that the dielectric constant obeys the Debye relaxation. Below about 350°C τ rapidly decreases with increasing temperature irrespective of pressure, while at higher temperatures r changes little with temperature and increases rapidly with decreasing density.