UV LED charge control of an electrically isolated proof mass in a Gravitational Reference Sensor configuration at 255nm

Precise control over the potential of an electrically isolated proof mass is crucial for the operation of devices such as a Gravitational Reference Sensor (GRS) required for satellite missions such as LISA and GRACE follow-on. A spacecraft demonstration of UV LEDs and UV LED charge management based on research done at Stanford and developed jointly by KACST, and NASA Ames Research Center, has launched in June 2014. Data from the satellite mission is expected to show that AlGaN Ultraviolet LEDs operating at 255 nm are useful for precise control of the potential of an electrically isolated proof mass in gravitational reference sensors for test of fundamental physics experiments like LISA. The AlGaN UV LEDs operating at 255 nm are an effective substitute for Mercury vapor lamps used in previous missions because of their small size, low power consumption and ability to be modulated at high frequencies for AC charge control.