Thermal environment analysis for TianQin: III. Low-frequency thermal transfer inside the flat-top sun shield

Abstract Flat-top Sun shield is a part of the disturbance reducing system on the space-based gravitational wave detector TianQin. The Sun shield is expected to guards temperature stability of the satellite’s top deck from the low-frequency solar flux fluctuation. This paper introduces an analytic method to study the Sun shield’s temperature response to sinusoidal variations of incoming heat flux. Oscillation mode of temperature field is described in the form of wave equation, which satisfies globally the thermal diffusion equation. The continuity equation is solved to reveal the wave behaviours when crossing different media. Three typical boundary conditions are studied in order to solve the wave equation. By applying the method to the TianQin’s thermal model, the low-frequency temperature response of the Sun shield and the top deck are derived. The results suggest adopting insulation materials with low thermal diffusivity in the thermal design to shield the solar disturbances.