Space Environmental Impact Analysis And Software System Design Of Space Strontium Atomic Optical Clock

This dissertation firstly introduces the definition and application of optical clocks and the research status and development of strontium optical clocks at home and abroad.It describes the establishment of our country’s space time-frequency system,and the difficulties and problems that need to be solved in the development of strontium space optical clocks.The difficulties include environmental adaptability,quality,power consumption,volume,electromagnetic compatibility,high integration,high automation,high reliability and high stability.The composition and design scheme of the space optical clock are briefly described.In view of the technical difficulties faced by the space optical clock,the overall design scheme of the space optical clock is introduced from the system level,and the structural design of the three units constituting the space optical clock is outlined.Compared with the ground clocks,space optical clocks will face some special circumstances.Firstly,the space strontium atomic optical clock requires narrow-linewidth laser cooling in microgravity.Because it is difficult to create a weightless environment for the experiments,modeling of narrow linewidth laser cooling and trapping in weightlessness is required.In this dissertation,the cold atomic behavior of magneto-optical trap（MOT）based on the narrow linewidth transition of ¹S₀-³P₁ in ⁸⁸Sr is investigated by numerical simulation.Simulations considering only the average force show that atoms in a MOT operating in a microgravity space with typical parameters will not be effectively cooled,which can be attributed to the loss of the effective potential well formed by the combined gravity and trapping forces.Considering the momentum diffusion caused by spontaneous radiation,the Monte Carlo method was performed using stochastic differential equations to simulate the distribution of atomic positions and velocities,temperature evolution,etc.It was shown that the narrow linewidth cooling MOT temperature of ⁸⁸Sr in microgravity is significantly higher than that on the ground,and the atomic density is lower.On this basis,this paper proposes a method using a dual-frequency MOT to achieve a low-temperature,high-density,and high-transmission-efficiency spatially narrow linewidth red MOT.Secondly,the space strontium atomic optical clock will also face the geomagnetic field with a variation range of±40μT when the space station runs in the low-Earth orbit.Experimental tests show that the optical lattice will be seriously disturbed by the changing geomagnetic field,and theoretical analysis predicts that the frequency accuracy of strontium optical clocks will also be affected to some extent.Therefore,this paper studies the method of active compensation using the magnetic field compensation coil and develops the principal prototype of the active compensation system,which realizes the active compensation of the changing geomagnetic field.Finally,from the perspective of aerospace software engineering,the software system analysis and design scheme of the space strontium atomic optical clock are discussed in detail.The software functions,performance,interface design,and working mode of the space optical clock are defined,the software configuration items are divided,the tasks and interface relationships of the configuration items are clarified,and the system-level design for the security of the software is carried out,and the follow-up space optical clock is designed.All engineering work required is planned and outlined.