Investigation of charge management using UV LED device with a torsion pendulum for TianQin

Abstract

TianQin is a Chinese space-based observatory concept with three drag-free spacecraft orbiting the earth to observe gravitational-waves in the millihertz range. Electrical charge is inevitably accumulating on its isolated test masses which are used as the mirrors for interferometers to measure gravity variation. Charge management system based on ultraviolet (UV) light is developed to reduce the charge-induced noises acting on the test mass in space gravitational experiments such as GP-B, LISA, LISA Pathfinder and TianQin mission. The UV LED is a new UV light source with some advantages relative to mercury lamps, such as smaller size, lighter weight, lower power consumption and higher efficiency. For these reasons, ground-based tests for the combination of UV LED and inertial sensor are essential. This paper presents the development of a charge management system based on a UV LED, its application to a torsion pendulum system with a TianQin-like test mass, and assesses the charge-management performance of the system. The experimental results indicate that the isolated test mass can be charged positively or negatively through UV illumination. It demonstrates that the charging and discharging rates can both reach higher than 105 e s−1, as well as spectral measurement of the pendulum charge resulting in a white noise level equivalent to ∼5 × 105 e Hz−1/2, satisfying the TianQin requirement.

Study on the Method of Charge Accumulation Suppression of Electrostatic Suspended Accelerometer

“…Our scheme is also proposed for this reason and adopts an indirect scheme. For indirect schemes like gas, ion beam and UV radiation, the restriction of the schemes can be summarized as three points [23,25,26,40]: (1) The discharging process needs to be employed in the interval of sensor operation. (2) The requirement of complex auxiliary equipment.…”

“…The UV method was applied in the GP-B mission and the LISA project for the feature of discharging without contact with the mass [8]. However, there still exist restrictions such as demand of charge measurement, coating damage and heating effect caused by high flux UV radiation, conflicting with the local electric fields in ESA [22,[26][27][28]. In addition, the common restriction with existing contactless methods is the inability to perform charge neutralization while the sensor is in operation.…”

Au(111) Surface Contamination in Ambient Conditions: Unravelling the Dynamics of the Work Function in Air

“…Moreover, we provided a simple picture for the geometrical modeling of contamination, useful for signal correction in X‐ray techniques (e.g., XPS, EDX, and XRR), and we first reported on the effect of the contamination dynamics on the Au WF. Such understanding is critical for applications where planar bare gold is employed, such as charge control via UV photoemission in space‐based systems (LISA [ 43 ] and TianQin [ 44 ] ) or charge injection at semiconductor/electrode interfaces. Hence, our findings are key for applications based on Au electrodes, e.g., in biosensing (SPR), optoelectronics, etc.…”

Analyses of Laser Propagation Noises for TianQin Gravitational Wave Observatory Based on the Global Magnetosphere MHD Simulations

“…The detector's plane formed by three satellites is optimized to detect the continuous GW signals from the candidate ultracompact white-dwarf binary RX J0806.3+1527 (Israel et al 2002). Currently, both science cases (Feng et al 2019;Wang et al 2019;Shi et al 2019;Bao et al 2019;Liu et al 2020;Fan et al 2020;Huang et al 2020) and technological realizations (Luo et al 2020;Ye et al 2019;Tan et al 2020;Yang et al 2020;Su et al 2020;Lu et al 2020) have been under intensive investigations for TQ. A brief summary of TQ's recent progress can be found in Mei et al (2020).…”