Ultrasonic Attenuation in Liquid Argon, Nitrogen, and Oxygen at 1 GHz

Abstract

The ultrasonic attenuation at 1 GHz was measured in liquid argon, nitrogen, and oxygen at their boiling points with a variable-path-length two-crystal acoustic interferometer. The attenuation in argon shows an absorption in excess of the value calculated from the classical Stokes-Kirchhoff equation for shear viscosity and thermal conductivity. The excess absorption can be attributed to a volume viscosity predicted by Gray and Rice, and is in good agreement with the lower-frequency measurements of others such as Naugle and Squire. The attenuation measurement in nitrogen shows a similar excess absorption and is in good agreement with the lower frequency values of Singer and Lunsford. The ultrasonic attenuation measurements in oxygen indicate that it may also have a volume viscosity. In the process of aligning the apparatus, some data were obtained in methanol that give a lower volume viscosity than that observed at lower frequencies.