LISA Pathfinder Inertial Sensor Head Thermal Correlation in Frequency Domain

Date

2014-07-13

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Publisher

44th International Conference on Environmental Systems

Abstract

LISA Pathfinder is the precursor of the ESA/NASA mission LISA (Laser Interferometer Space Antenna); it aims at demonstrating the feasibility of all the challenging key technologies needed by the operational mission. CGS is responsible of the Thermal Design and Analysis of LISA Pathfinder ISH (Inertial Sensor Head). The main goal of the ISH TCS, as a part of the overall instrument TCS, is to damp the thermal disturbances coming from outside (i.e. external environment, rest of the satellite); the system performance requirements are expressed in terms of frequency- dependent allowable noise, inside the detector bandwidth (1 mHz – 30 mHz); for this reason most of the thermal analysis are not performed in the usual time domain, but in the frequency domain. During the qualification thermal test campaign, some dedicated tests have been performed with the aim of correlating the existing ISH thermal model, in order to improve its prediction capability. Following the analysis approach, also the test and the correlation have been conducted in the frequency domain. During the correlation test, two different sets of heaters have been individually operated with a 1mHz frequency profile (i.e. 500s ON 500s OFF) and the thermal response of different points on the hardware has been measured and compared with test prediction. In the paper a brief description of the test setup and the test results is given: since the measured oscillations were in some cases extremely small (less than 1 mK, only slighter larger than the measurement noise,) a series of post-processing techniques (e.g. filtering, detrending) have been adopted to clean up the available data. The test results show a very good agreement with the performed test prediction, and – where the deviations were larger - the model has been tuned following the outcomes of the test. The frequency-domain thermal testing has turned out to be an interesting feature, capable of allowing very accurate testing, and allowing the measurement of very small perturbations. This approach has strong potential, especially for the testing of highly insulated elements, characterized by extremely high time transients.

Description

Tucson, Arizona
Paolo Ruzza, CGS Compagnia Generale per lo Spazio, Italy
Alberto Franzoso, CGS Compagnia Generale per lo Spazio, Italy
Christian Vettore, CGS Compagnia Generale per lo Spazio, Italy
Paolo Sarra, CGS Compagnia Generale per lo Spazio, Italy
Floriano Venditti, CGS Compagnia Generale per lo Spazio, Italy
Francesco Zanetti, CGS Compagnia Generale per lo Spazio, Italy
The 44th International Conference on Environmental Systems was held in Tuscon, Arizona, USA on 13 July 2014 through 17 July 2014.

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