Test Mass Charge Management in the Detection of Gravitational Waves in Space Based on Ultraviolet Micro-Light-Emitting Diode

As an alternative to the ultraviolet light-emitting diode (UV LED), the feasibility of utilizing UV micro-LED in the charge management in the detection of gravitational waves in space is experimentally studied. Compared with UV LED, micro-LED is more compact in size and has better current spreading, faster response time, and longer operating life. Performance characteristics of micro-LEDs were measured, with peak wavelengths of 254, 262, 274, and 282 nm for each respective micro-LED, and the photoelectric effect was demonstrated. The effectiveness of micro-LED-based charge management experiments was demonstrated using above micro-LEDs mounted on a cubical test mass, and different discharge rates were achieved by varying the drive current and duty cycle using pulse width modulation. Laboratory data were also shown to demonstrate the space qualification of the micro-LED device. The key electrical and optical characteristics of the micro-LEDs showed less than 5% variation. The results of the qualification bring the micro-LED device technology readiness level (TRL) to TRL-5. TRL-6 will be reached provided additional radiation and thermal tests are conducted and in a position ready to be flown and further tested in space.