Measurement of Ultrasound Velocity in Gases under High Pressures up to 3.5 GPa

Abstract

Using the high-pressure apparatus described in a previous paper, the freezing points of nitrogen and krypton at room temperature were determined from the volume and ultrasound velocity changes. The ultrasound velocity of neon was also measured up to 3.5 GPa. Taking account of the results of the ultrasound velocity and the volume measurements, empirical formulae for the pressure dependence of ultrasound velocities of helium, neon, argon, krypton and xenon were proposed. The phase diagram of a krypton and helium gas mixture under high pressures up to 1.6 GPa at room temperature was also obtained from the velocity measurement.