An Apparatus for Spectral Emissivity Measurements of Thermal Control Materials at Low Temperatures.

Jiayu Ma,Lingnan Wu,Lixin Song,Haogeng Li,Yuzhi Zhang

doi:10.3390/ma12071141

Abstract

Thermal control materials are employed to adjust the temperature of a spacecraft operating in deep space. The spectral emissivity is a crucial factor in evaluating the thermal radiative properties of such materials. An apparatus, composed of a Fourier transform infrared spectrometer (FTIR), a sample cooling chamber and a mechanical modulation system was demonstrated to measure low temperature infrared spectral emissivity under vacuum. The mechanical modulation system, which includes a chopper and a lock-in amplifier, is employed to reduce the interference of background radiation during measurements. The limitation of the Fourier transform frequency on the chopper frequency can be eliminated by setting the FTIR on step-scan mode. The apparatus is separated into two parts and evacuated by different pumps. In this study, a high quality emission spectrum of a sample is measured by the apparatus. The spectral emissivity of thermal control materials are obtained in the wavelength range of 8 to 14 μm at 173 and 213 K. The combined standard uncertainty of the apparatus is 3.30% at 213 K.

Highlights

Emissivity is an important property of thermal control materials which are applied in the aerospace industry, such as in satellites, space telescopes, spacecrafts and space stations
We started to carry out experiments at at low temperatures under vacuum
We obtained the spectral emissivity of quartz low stainless temperatures vacuum

Summary

Introduction

Emissivity is an important property of thermal control materials which are applied in the aerospace industry, such as in satellites, space telescopes, spacecrafts and space stations. Thermal control materials adjust the temperature of the equipment and make sure it works properly at low temperatures [1,2]. Deep space is a vacuum, black and cool environment. Heat transfer can only be carried out by radiation. To regulate the temperature of the equipment, the emissivity of the thermal control materials plays a decisive role. The low temperature emissivity measurement of these materials is essential under vacuum

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Results

Conclusion