Measuring the LISA test mass magnetic proprieties with a torsion pendulum

TL;DR

This paper presents a ground-based torsion pendulum method to precisely measure the magnetic properties of LISA test masses, crucial for minimizing magnetic disturbances that could impair the mission's low-frequency sensitivity.

Contribution

It introduces a novel torsion pendulum technique for accurately characterizing the magnetic properties of LISA test masses on the ground, aiding in magnetic cleanliness.

Findings

Effective measurement of test mass magnetic dipole moment and susceptibility

Improved understanding of magnetic disturbances impact on LISA performance

Enhanced ground-based testing procedures for space mission readiness

Abstract

Achieving the low frequency LISA sensitivity requires that the test masses acting as the interferometer end mirrors are free-falling with an unprecedented small degree of deviation. Magnetic disturbances, originating in the interaction of the test mass with the environmental magnetic field, can significantly deteriorate the LISA performance and can be parameterized through the test mass remnant dipole moment $\vec{m}_r$ and the magnetic susceptibility $\chi$. While the LISA test flight precursor LTP will investigate these effects during the preliminary phases of the mission, the very stringent requirements on the test mass magnetic cleanliness make ground-based characterization of its magnetic proprieties paramount. We propose a torsion pendulum technique to accurately measure on ground the magnetic proprieties of the LISA/LTP test masses.