Modeling and Performance of Contact-Free Discharge Systems for Space Inertial Sensors

TL;DR

This paper provides a comprehensive modeling and assessment of contact-free UV light discharge systems for space inertial sensors, including numerical analysis, design evaluation, and performance optimization for future space missions.

Contribution

It introduces a detailed numerical modeling approach and assesses various UV discharge system designs, leading to improved robustness and performance for space inertial sensors.

Findings

Successful modeling of UV discharge systems using experimental data

Design optimization improved robustness and performance

Application to LISA Pathfinder demonstrated effectiveness

Abstract

This article presents a detailed overview and assessment of contact-free UV light discharge systems (UVDS) needed to control the variable electric charge level of free-flying test masses which are part of high precision inertial sensors in space. A comprehensive numerical analysis approach on the basis of experimental data is detailed. This includes UV light ray tracing, the computation of time variant electric fields inside the complex inertial sensor geometry, and the simulation of individual photo-electron trajectories. Subsequent data analysis allows to determine key parameters to set up an analytical discharge model. Such a model is an essential system engineering tool needed for requirement breakdown and subsystem specification, performance budgeting, on-board charge control software development, and instrument modeling within spacecraft end-to-end performance simulators. Different types of UVDS design concepts are presented and assessed regarding their robustness and performance. Critical hardware aspects like electron emission from air-contaminated surfaces, interfaces with other subsystems, and spacecraft operations are considered. The focus is on the modeling and performance evaluation of the existing UVDS on board LISA Pathfinder, an ESA technology demonstrator spacecraft to be launched in 2014. The results have motivated the design of a more robust discharge system concept for cubical test mass inertial sensors for future space missions. The developed analysis tools have been used for design optimization and performance assessment of the proposed design. A significant improvement of relevant robustness and performance figures has been achieved.