Uploaded August 2020 | Updated September 2026, 58 minutes ago
Lifetime Testing of UV LEDs for the LISA Charge Management System: Past Results and Future Plans
Ben Letson,Simon Barke,Taiwo Olatunde,Samantha Parry,Myles Clark,Timothy Sumner,Guido Mueler,Peter J. Wass,John W. Conklin
Cosmic rays will cause an electric charge build-up in LISA’s gravitational reference sensors over time. This charge results in electrostatic forces that interfere with gravitational wave observations. To limit this effect, the test masses will need to be periodically or continuously discharged to neutralize any charge build-up that occurs. Discharging of the test masses is done by photoemission under illumination with ultraviolet light with a wavelength of around 250 nm. While LISA Pathfinder utilized the emission of mercury lamps, ultraviolet LEDs (UV LEDs) offer many advantages over the mercury lamps and are being considered as a future light source for LISA. These advantages include a lower mass, higher efficiency, and the ability to operate the devices in a pulsed manner, leading to a dynamic range of ~107. However, since UV LEDs are not a flight-proven technology, they must be evaluated for longevity at the expected operating conditions they may be used in during flight.
This presentation will address the ongoing efforts at the University of Florida to characterize the performance of these devices for use in the Charge Management System (CMS) for LISA. The results from a first UV LED lifetime test will be presented, which ran for 7 months in late 2019 and evaluated the effects of operating temperature and driving conditions on the lifetimes of a large set of 96 UV LEDs. Plans for a second lifetime test will also be presented, where we plan to evaluate the lifetime of a new set of 96 UV LEDs during a longer test of at least two years.
Lifetime Testing of UV LEDs for the LISA Charge Management System: Past Results and Future Plans
Ben Letson,Simon Barke,Taiwo Olatunde,Samantha Parry,Myles Clark,Timothy Sumner,Guido Mueler,Peter J. Wass,John W. Conklin
Cosmic rays will cause an electric charge build-up in LISA’s gravitational reference sensors over time. This charge results in electrostatic forces that interfere with gravitational wave observations. To limit this effect, the test masses will need to be periodically or continuously discharged to neutralize any charge build-up that occurs. Discharging of the test masses is done by photoemission under illumination with ultraviolet light with a wavelength of around 250 nm. While LISA Pathfinder utilized the emission of mercury lamps, ultraviolet LEDs (UV LEDs) offer many advantages over the mercury lamps and are being considered as a future light source for LISA. These advantages include a lower mass, higher efficiency, and the ability to operate the devices in a pulsed manner, leading to a dynamic range of ~107. However, since UV LEDs are not a flight-proven technology, they must be evaluated for longevity at the expected operating conditions they may be used in during flight.
This presentation will address the ongoing efforts at the University of Florida to characterize the performance of these devices for use in the Charge Management System (CMS) for LISA. The results from a first UV LED lifetime test will be presented, which ran for 7 months in late 2019 and evaluated the effects of operating temperature and driving conditions on the lifetimes of a large set of 96 UV LEDs. Plans for a second lifetime test will also be presented, where we plan to evaluate the lifetime of a new set of 96 UV LEDs during a longer test of at least two years.
