Kavli Affiliate: Robert Byer
| First 5 Authors: Shailendhar Saraf, Sasha Buchman, Karthik Balakrishnan, Chin Yang Lui, Michael Soulage
| Summary:
The UV LED mission demonstrates the precise control of the potential of
electrically isolated test masses that is essential for the operation of space
accelerometers and drag free sensors. Accelerometers and drag free sensors were
and remain at the core of geodesy, aeronomy, and precision navigation missions
as well as gravitational science experiments and gravitational wave
observatories. Charge management using photoelectrons generated by the 254 nm
UV line of Hg was first demonstrated on Gravity Probe B and is presently part
of the LISA Pathfinder technology demonstration. The UV LED mission and prior
ground testing demonstrates that AlGaN UV LEDs operating at 255 nm are superior
to Mercury vapor lamps because of their smaller size, lower draw, higher
dynamic range, and higher control authority. We show flight data from a small
satellite mission on a Saudi Satellite that demonstrates AC charge control (UV
LEDs and bias are AC modulated with adjustable relative phase) between a
spherical test mass and its housing. The result of the mission is to bring the
UV LED device Technology Readiness Level (TRL) to TRL 9 and the charge
management system to TRL 7. We demonstrate the ability to control the test mass
potential on an 89 mm diameter spherical test mass over a 20 mm gap in a drag
free system configuration. The test mass potential was measured with an ultra
high impedance contact probe. Finally, the key electrical and optical
characteristics of the UV LEDs showed less than 7.5 percent change in
performance after 12 months in orbit.
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