Flight and ground demonstration of reproducibility and stability of photoelectric properties for passive charge management using LEDs

Abstract Charges as small 1 pC degrade the performance of high precision inertial reference instruments when accumulated on their test masses (TMs). Non-contact charge management systems are required for most sensitive these instruments, with TMs free-floating, and charges compensated by photoelectrons in a feedback loop TM measurement. Three space missions have successfully demonstrated this technique: Relativity Mission, Gravity Probe-B launched 2004, LISA Pathfinder 2015, UV-LED mission SaudiSat 4 2014; first two using 254 nm Hg discharge line last one set 255 UV-LEDs. UV-LEDs represent significant improvement over sources, terms reliability, lifetime, switching speeds, power consumption, weight, volume. Charge techniques that eliminate measurement systems, referred henceforth passive, reduce complexities disturbance effects introduced thus subject active research development work. Passive (PCM) depends critically stability reproducibility photoemission properties given system. In support work, we present comprehensive flight characterization data suite 16 various configurations ± center wavelength. Flight was acquired between December 2014 2015 instrument flown 4. We back up our results ground-based measurements performed comparable to September 2020, 8 October 2020. All confirm excellent reliability environment, fully consistent findings ground studies, approach LEDs PCM. find equilibrium potential TM, under illumination LEDs, is independent UV intensity reproduceable about ≅±6 mV, or ±6 fC pF −1 , periods six months. The value dependent geometry electric field its enclosure, exact configuration PCM instrument.