|
The thermal control in a spacecraft is a key issue in space engineering.
Firstly, it should be considered that the electronic and mechanical devices
shipped in a spacecraft work properly in narrow ranges of temperature. Secondly,
it is also of relevance when designing an spacecraft to take into account the
mechanical stress originated by the temperature gradients. On Earth the thermal
control of a system can be controlled by means of the conduction, convection and
radiation mechanism. However in space only the latter is available due to the
characteristic high vacuum of this environment. Thus, it is of great interest
to develop new materials or metamaterials capable of improve their thermal
emissivity.
Recently it has been reported that the emissivity of a material
can be enhanced by a factor 20 when a micro/nanostructure is processed
on its surface [1][2].
Additionally the spatial distribution of the emissivity can also be controlled. Then,
the material can emit radiation anisotropically instead of the usual isotropic
emission of thermal sources (like the tungsten filament of a light bulb). This results
reveals a new degree of freedom in the engineering of thermal radiators for a spacecraft.
The emission direction of the released radiation can be designed in such a way that it
could not be reabsorbed by any part of the spacecraft.
References:
- [1]
- J.-J. Greffet, R. Carminati, K. Joulain, J.-P. Mulet, S. Mainguy, and Y. Cheng,
Coherent emission of light by thermal sources,
Nature, 416, 61 (2002)
- [2]
-
F. Marquier, K. Joulain, J.-P. Mulet, R. Carminati, and J.-J. Greffet,
Coherent spontaneous emission of light by thermal sources,
Physical Review B, 69, 155412 (2004)
|
