Temperature monitoring of thermal-vacuum tests with optical fiber sensors. Preliminary results

LARES-lab is a facility located at Sapienza University of Rome for testing nano-satellites and small payloads in simulated space environment. The facility is equipped with a small cubic thermal-vacuum chamber with an internal volume 60x60x60 cm, capable of reaching very high vacuum conditions. The chamber simulates radiation thermal exchanges toward deep space with nitrogen cooled shrouds and solar radiation with a Sun simulator lamp. An Earth infrared disc simulator is also available. Several tests of payloads and nanosatellites have been already performed in the LARES-lab. Recently the chamber has been upgraded with the installation of an optical fibre feed through for use with Fibre Bragg Gratings (FBGs) for temperature monitoring during the tests. In this paper, some preliminary results on the calibration of the FBG sensor are reported. Issues concerning the coating of the sensor and the values of the thermo optical characteristicsare also pointed out in the paper.