Viscosity and thermal conductivity of rubidium and cesium in the gas phase

Abstract

An experimental installation has been developed to study the viscosity of alkali metal vapor in a wide range of high (up to 2000 K) temperatures, which implements the method a viscometer with an annular channel. The design of the viscometer of the measuring cell makes it possible to directly measure the temperature of the working element of the viscometer. This provides an accurate determination of the temperature of the investigated alkali metal vapor in the working gap. The original method of stabilization of the steam generator operation mode was applied, which allowed to ensure the stationary flow of the investigated alkali metal vapor in the working element of the viscometer. Distinctive features of the created installation are high stability of modes of its work and considerable resource. An experimental study of the viscosity of rubidium and cesium in the gas phase was carried out by the method of a viscometer with an annular channel at the following values of the state parameters: for cesium T = 900 ... 1770 K, P = 12 ... 135 kPa; for rubidium T = 990 ... 1750 K, P = 39 ... 135 kPa. Most of the experimental data obtained are in the temperature range above 1200 K. The average error of the experimental data is 3%. the experimental data on the viscosity of cesium and rubidium in the gas phase, the values of the effective cross sections of the «atom-atom» collisions and the relative cross-sections of the «atom-molecule» collisions were obtained. Calculated equations and tables of viscosity and thermal conductivity of cesium and rubidium vapor in the temperature range 700-2000 K and pressures 1-1500 kPa, including the saturation line, have been developed. An experimental study of the viscosity of rubidium and cesium vapor at high temperatures have been conducted with implementation of the method a viscosimeter with an annular channel. the experimental data on the viscosity of cesium and rubidium in the gas phase, the values of the effective cross sections of the «atom-atom» collisions and the relative cross-sections of the «atom-molecule» collisions were obtained. Calculated equations and tables of viscosity and thermal conductivity in a wide range of temperatures and pressures have been developed,