Determination of the Hypersonic Velocities in the Molten Salts NaNO3 and KNO3

Abstract

Hypersonic velocities in the molten salts NaNO3 and KNO3 have been obtained by Brillouin scattering measurements. A He-Cd laser, 4416 Å, was used as a radiation source and the scattered light was analyzed with a pressure-scanned Fabry-Perot spectrometer. The temperature dependence of the sound velocity was determined in a temperature range covering some 100° above the melting point of the investigated salts. The obtained hypersonic velocity for NaNO3 was about the same and for KNO3 greater than reported ultrasonic velocities indicating that the measurements are performed in a frequency region below any possible relaxation frequency for NaNO3 and above some possible relaxation frequencies for KNO3