Interpolation of the magnetic field at the test masses in eLISA

TL;DR

This paper analyzes the feasibility of using small, high-sensitivity magnetic sensors for eLISA's magnetic diagnostics, addressing previous limitations of sensor size and back-action to improve magnetic field estimation at test masses.

Contribution

It provides a quantitative assessment of a new magnetic sensor configuration for eLISA, proposing solutions to prior challenges in magnetic field measurement.

Findings

Small, high-sensitivity sensors mitigate back-action issues.

Feasibility of the new magnetic subsystem is quantitatively supported.

Improved magnetic field estimation around test masses is achievable.

Abstract

A feasible design for a magnetic diagnostics subsystem for eLISA will be based on that of its precursor mission, LISA Pathfinder. Previous experience indicates that magnetic field estimation at the positions of the test masses has certain complications. This is due to two reasons. The first one is that magnetometers usually back-act due to their measurement principles (i.e., they also create their own magnetic fields), while the second is that the sensors selected for LISA Pathfinder have a large size, which conflicts with space resolution and with the possibility of having a sufficient number of them to properly map the magnetic field around the test masses. However, high-sensitivity and small-size sensors that significantly mitigate the two aforementioned limitations exist, and have been proposed to overcome these problems. Thus, these sensors will be likely selected for the magnetic diagnostics subsystem of eLISA. Here we perform a quantitative analysis of the new magnetic subsystem, as it is currently conceived, and assess the feasibility of selecting these sensors in the final configuration of the magnetic diagnostic subsystem.