Upgraded University of Florida Torsion Pendulum for Testing Key LISA Technology

This presentation describes the design and performance of the UF torsion pendulum facility. This facility tests inertial sensors and associated technology for the LISA (laser interferometer space antenna) space-based gravitational wave observatory mission. The torsion pendulum consists of a suspended cross-bar with LISA test mass (TM) mockups at each of its ends. Position of the TMs is measured using capacitive and laser interferometer readout with a broadband sensitivity of 30 nm/√Hz and 0.5 nm/√Hz respectively. The noise performance of the facility is 3 × 10^-13 ms^-2/√Hz at 2 mHz. This facility has been used to test and validate various UV LED-based charge management techniques including pulsed light (AC) charge control, as well as characterize gravitational reference sensor (GRS) noise using simplified GRSs. Data from initial charge management experiments have been compared to a newly developed analytical charge model. The facility has undergone many upgrades including the integration of a LISA-like GRS and a new cross-bar with precision polished TMs. These upgrades will facilitate more realistic charge management experiments and characterization of GRS noise performance with a LISA-like sensor.