Evaluation of Thermal Control Mirror with Tunable Thermo-optical Properties for Radiowave Transmissive Multilayer Insulation

Date

2016-07-10

Journal Title

Journal ISSN

Volume Title

Publisher

46th International Conference on Environmental Systems

Abstract

Multilayer Insulation (MLI) is the most common thermal control element on spacecraft. It is composed of multiple layers of low emittance polyester films with a vacuum-deposited aluminum finish and an aluminum coated polyimide film with low solar absorptance is often used for an outer cover. Above that, MLI does not exhibits transmissivity to radiowave for using metal coated films. For radiowave transmissivity, these materials of MLI should be metal-free. We have been developing a new thermal control mirror (COSF: Controlled Optical Surface Films). COSF consists of a polyimide film for substrate and dielectric multilayer coating on it. The solar absorptance and infra-red emissivity of COSF can be freely controlled by the interference of its dielectric multilayer. This multilayer is designed by using a Genetic Algorithm (GA) method. COSF was proposed in 2009 and 2010 as a new thermal control mirror with tunable thermo-optical properties. After that, COSF has been improved with not only thermo-optical properties but also radiowave transmittance. On the other hand, polyimide form (PI-F) has also been studied. PI-F has high heat resistance, light weight and high resistance to space environment. New multilayer insulation with polyimide form (PF-MLI) has been constructed and was evaluated in 2011 and we confirmed its insulation performance would be better than that of conventional MLI. Now we have been developing two types of COSF (COSF4 and COSF-IR). COSF4 exhibits low solar absorptance, high infra-red emissivity and high transmittance to radiowave. COSF-IR exhibits low infra-red emissivity and high transmittance to radiowave. These two materials are not composed of metal and they can be applied for multilayers of PF-MLI instead of conventional metal coated films. This new insulator exhibits a radiowave transmissivity. This paper shows the measurement results of thermo-optical properties and the radiowave transmittance of COSF4 and COSF-IR.

Description

Japan
Keio University
ISAS/JAXA
104
ICES104: Advances in Thermal Control Technology
Vienna, Austria
Kota Tomioka, Keio University, Japan
Taisei Honjo, Keio University, Japan
Sumitaka Tachikawa, Institute of Space and Astronautical Science, Japan
Kousuke Kawahara, Institute of Space and Astronautical Science, Japan
Yuji Nagasaka, Keio University, Japan
The 46th International Conference on Environmental Systems was held in Vienna, Austria, USA on 10 July 2016 through 14 July 2016.

Keywords

Thermal Control Technology, Optical physics, Multilayer Insulation, Genetic Algorithm, Radio Frequency

Citation