A torsion pendulum ground test of the LISA Pathfinder Free-fall mode

Russano, Giuliana (2015) A torsion pendulum ground test of the LISA Pathfinder Free-fall mode. PhD thesis, University of Trento.

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The LISA Pathfinder geodesic explorer mission for gravitational wave astronomy aims to measure a residual differential acceleration noise approaching the femto-m/s^2/Hz^1/2 levels needed for eLISA. This measurement is complicated by a large, roughly nm/s^2, stable differential gravitational acceleration that must be actively compensated in order to hold the test particles centred inside an orbiting apparatus. The actuation force applied to compensate this effect introduces a dominant source of force noise in the mission noise budget. To suppress this noise source and avoid actuation instabilities, a “free-fall” actuation control scheme has been designed: actuation is limited to brief impulses, with test masses in free fall in between two “kicks”, with this actuation-free motion then analysed for the remaining sources of acceleration ultra noise. In this work, we present the results from an extensive on-ground torsion pendulum test of this free-fall technique, which to date allows an equivalent acceleration noise measurement at the 100 fm/s^2/sqrt(Hz), a factor 3 above the LISA Pathfinder spec. We will discuss both experimental and analysis limitations to the ground experiment and some implications for the flight test.

Item Type:Doctoral Thesis (PhD)
Doctoral School:Physics
PhD Cycle:27
Subjects:Area 02 - Scienze fisiche > FIS/05 ASTRONOMIA E ASTROFISICA
Area 02 - Scienze fisiche > FIS/01 FISICA SPERIMENTALE
Repository Staff approval on:15 Jun 2015 15:20

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