Charge-Induced Force Noise Modeling for the LISA Charge Management System

Charge-Induced Force Noise Modeling for the LISA Charge Management System

Samantha Parry,Stephen Apple ,Anthony Dávila Álvarez,Taiwo Olatunde,Henri Inchauspé,Guido Mueller,Peter J. Wass,John W. Conklin

Successful gravitational wave measurements onboard LISA involves maintaining a near-neutral test mass (TM) charge within the gravitational reference sensor (GRS). Tasked with TM charge control, the charge management system (CMS) onboard LISA involves several upgrades from the CMS onboard LISA Pathfinder (LPF), such as using UV LEDs and pulse width modulating UV light to achieve a contact-free discharge of the TM. Although surface properties and GRS geometries remain the same from LPF, the introduction of pulsed light and more advanced charge control methods are new developments and need to be verified. Specifically, there are a proposed six modes of operation utilizing lower light levels, phase-dependent UV light, and GRS TM charge equilibrium points. With this aim, numerical and analytical modeling of charge movement within the GRS is being done to validate if advanced charge control methods remain below the allotted charge-induced force noise budget. The model describing TM charge is fueled by LPF GRS’s apparent yield data and simulated with relevant estimates of the environment contribution. Results will include simulation work validating proposed modes of charge control operations for LISA and drawing conclusions on the most robust schemes.

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