Emissivities of vacuum compatible materials: towards minimising blackbody radiation shift uncertainty in optical atomic clocks at room temperatures

摘要

We report the results of measurements of the total hemispherical emissivity coefficients of the most popular vacuum compatible materials used in designs of optical atomic clocks. The experimental vacuum test chamber was designed to precisely quantify the heat transfer between the material's samples and a calibrated plate that serves as a thermometer. The temperatures of vacuum chamber's internal surfaces were measured and their heat balance equations were solved to designate their emissivities. The simplicity of the experimental set-up allows for analytical calculations of all necessary parameters without use of numerical finite elements methods (FEM). The reported results cover the temperature range between 0.0 and 25.0 degrees C, that is crucial in optical clocks set-ups operating at room temperatures. The linear model of the emissivity change with the temperature is applied to the measured data to make them applicable in further calculations or FEM simulations.