Thermal-insulation design for low-frequency temperature stability of inertial sensors in the TianQin project through frequency-domain analysis
Phys. Rev. Applied 24, 024004 – Published 4 August, 2025
DOI: https://doi.org/10.1103/r47s-bhdg
Abstract
In space-based gravitational wave detection missions, the residual acceleration requirement for inertial sensors reaches the femtometer per second squared square root hertz level, which drives the strict requirement for temperature stability of several microkelvins per square root hertz. This necessitates a slight variation of power dissipation for surrounding heat sources, which presents a significant challenge, particularly within the low-frequency band, and highlights the need for thermal-insulation design. Despite the critical role of multilayer insulation (MLI) assemblies in passive thermal insulation, the transfer function remains unexplored, making thermal-insulation design problematic in the frequency domain. In this paper, we introduce the concept of temperature waves to derive precise transfer functions for temperature fluctuations in the MLI, which can efficiently and accurately guide thermal-insulation design in the frequency domain. Considering the geometric constraint between the optical bench and the vacuum chamber in the TianQin gravitational wave detector, bulk insulation materials such as polyimide foam cannot be accommodated, making the use of MLI necessary. On the basis of this precise MLI model, we propose a feasible thermal-insulation design for the inertial sensors, where MLI loosely clads the surrounding area. This design successfully eases the power dissipation variation requirements for the diode and the other heat sources by at least 20 times at 0.1 mHz, significantly enhancing the mission’s feasibility. Furthermore, the precise MLI model and the thermal-insulation design process in this article can be applied to other space missions requiring stringent temperature stability.
