Thermal design of focal plane assembly of space-based Solar Extreme Ultraviolet imager

The Solar Extreme Ultraviolet Imager (EUVI) is a space-based instrument designed to observe solar activities. To meet the stringent low-temperature imaging requirements of its focal plane assembly (FPA) in the complex space environment, this study presents a systematic thermal design and optimization approach. The FPA structure and operational conditions are first analyzed, revealing critical thermal challenges from satellite platform and solar panel interactions. A comprehensive thermal control strategy is developed, incorporating high-efficiency conduction paths, optimization of the installation position of the radiator, multi-layer insulation, and active temperature control. Thermal simulations demonstrated stable CMOS detector temperatures within the required −35 °C to −30 °C range, with a 1W reduction in heater power consumption compared to baseline designs. Thermal balance test results demonstrated a maximum temperature deviation of 3.6 °C between simulation and experimental data at critical locations, while confirming the heater's sufficient capacity to maintain the CMOS at 30 °C in self-cleaning mode. All thermal balance test data meet the specified thermal control requirements, validating the feasibility of the proposed thermal design scheme. This work provides a validated thermal design framework for space-based FPAs, particularly addressing the challenges of variable β-angle operations and component-level temperature stability.