Performance of the electrostatic control force system for LISA Test Masses: experimental results from LISA Pathfinder and new on-ground measurements
type: CreativeWork
description: The LISA mission will detect low frequency gravitational waves by interferometrically measuring the distance between free-falling Test Masses (TM) in space. These are six, 2 kg gold-platinum cubes, contained in three spacecrafts which fly in a triangular formation, 2.5 million km from one another. The TMs are in nearly perfect free-fall and are followed by the spacecrafts, there to shield them and keep them aligned with the interferometers. Spurious forces introduced by the spacecraft on the TMs are a major source of noise for the measurement and must be limited to the absolute minimum. Several important sources of noise are linked to the system of forces used to control the TM dynamics. The whole system is usually referred to as electrostatic force actuation. The forces are generated by applying voltages to electrodes surrounding the TMs: noise in these voltages end up being one of the main disturbances for LISA. This thesis tackles actuation noise from multiple directions. First, it contains the analysis of experiments performed on LISA Pathfinder (LPF), LISA precursor mission. Dedicated measurement campaigns allowed an in depth characterization of actuation noise, in particular voltage gain fluctuations and additive voltage noises. Good agreement with the current actuation noise model was found: through this, we estimate that actuation explains between 20 and 40% of LPF noise, and project the noise in the LISA configuration. A detailed investigation of possible non-linearities in actuation voltages is reported. They were first measured in the laboratory on a LPF Front-End-Electronics (FEE) copy. Then, their impact on LPF and LISA was evaluated through simulations and development of analytic models, revealing that while they should not be a dominant noise source in LPF, they can become significant under certain conditions. The second part of the thesis focuses on measuring actuation-related forces with the 1TM torsion pendulum, which was re-activated after a shut-…
abstract: The LISA mission will detect low frequency gravitational waves by interferometrically measuring the distance between free-falling Test Masses (TM) in space. These are six, 2 kg gold-platinum cubes, contained in three spacecrafts which fly in a triangular formation, 2.5 million km from one another. The TMs are in nearly perfect free-fall and are followed by the spacecrafts, there to shield them and keep them aligned with the interferometers. Spurious forces introduced by the spacecraft on the TMs are a major source of noise for the measurement and must be limited to the absolute minimum. Several important sources of noise are linked to the system of forces used to control the TM dynamics. The whole system is usually referred to as electrostatic force actuation. The forces are generated by applying voltages to electrodes surrounding the TMs: noise in these voltages end up being one of the main disturbances for LISA. This thesis tackles actuation noise from multiple directions. First, it contains the analysis of experiments performed on LISA Pathfinder (LPF), LISA precursor mission. Dedicated measurement campaigns allowed an in depth characterization of actuation noise, in particular voltage gain fluctuations and additive voltage noises. Good agreement with the current actuation noise model was found: through this, we estimate that actuation explains between 20 and 40% of LPF noise, and project the noise in the LISA configuration. A detailed investigation of possible non-linearities in actuation voltages is reported. They were first measured in the laboratory on a LPF Front-End-Electronics (FEE) copy. Then, their impact on LPF and LISA was evaluated through simulations and development of analytic models, revealing that while they should not be a dominant noise source in LPF, they can become significant under certain conditions. The second part of the thesis focuses on measuring actuation-related forces with the 1TM torsion pendulum, which was re-activated after a shut-…
author: Chiavegato, Vittorio
language: eng
keywords: LISA, Gravitational Waves, Acceleration noise, Gravitational Reference System, Electrostatic Forces, Pathfinder, Torsion Pendulum
date published: 2025-04-15
date modified: 2026-07-24T05:04:28Z
provider: Università degli Studi di Trento
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Università degli studi di Trento

PropertyValue
property ID: Handle
value: https://hdl.handle.net/11572/450691

PropertyValue
property ID: DOI
value: 10.15168/11572_450691