Analyses of residual accelerations for TianQin based on the global MHD simulation

Wei Su, Yan Wang, Ze-Bing Zhou, Yan-Zheng Bai, Yang Guo, Chen Zhou, Tom Lee,

Ming Wang, Ming-Yue Zhou, Tong Shi, Hang Yin and Bu-Tian Zhang

TianQin is a proposed space-based gravitational wave observatory. It is designed to detect the gravitational wave signals in the frequency range of 0.1 mHz–1 Hz. At a geocentric distance of 105 km, the plasma in the Earth magnetosphere will contribute as the main source of environmental noises. Here, we analyze the acceleration noises that are caused by the magnetic field of space plasma for the test mass of TianQin. The real solar wind data observed by the Advanced Composition Explorer are taken as the input of the magnetohydrodynamic simulation. The Space Weather Modeling Framework is used to simulate the global magnetosphere of the Earth, from which we obtain the plasma and magnetic field parameters on the detector's orbits at_s = 0°, 30°, 60° and 90°, where _s is the acute angle between the line that joins the Sun and the Earth and the projection of the normal of the detector's plane on the ecliptic plane. We calculate the time series of the residual accelerations and the corresponding amplitude spectral densities on these orbit configurations. We find that the residual acceleration produced by the interaction between the TM's magnetic moment induced by the space magnetic field and the spacecraft magnetic field ( a _M1) is the dominant term, which can approach 10⁻¹⁵ m s^–2 Hz^–1/2 at f ≈ 0.2 mHz for the nominal values of the magnetic susceptibility (χ_m = 10⁻⁵) and the magnetic shielding factor (ξ_m = 10) of the test mass. The ratios between the amplitude spectral density of the acceleration noise caused by the space magnetic field and the preliminary goal of the inertial sensor are 0.38 and 0.08 at 1 mHz and 10 mHz, respectively. We discuss the further reduction of this acceleration noise by decreasing χ_m and/or increasing ξ_m in the future instrumentation development for TianQin.

期刊名：Classical and Quantum Gravity

期/卷：37 (2020) 185017

页码：1-17

发表时间：2020年8月

DOI: 10.1088/1361-6382/aba181