Preliminary Study For The Thermal Analysis And Thermal Design Of Electrostatic Suspension Accelerometer

As a precision measuring instrument in spacecraft payload in space,it is significant to analyze the whole temperature condition and the temperature fluctuation in Test Mass.Spacecraft GOCE?LISA?LISA Pathfinder lay emphasis on the study of temperature issues to some extent.,especially in LISA Pathfinder,there is a specific sub-system called thermal diagnostics system diagnosing temperature influence.On the basis of electrostatic suspension accelerometer real model with heat source inside which has the design of integration of machinery and circuits in our lab,given the ambient temperature and inner condition,simplification of the model,its thermal analysis simulation and its thermal design simulation basing on the analysis results is made in this paper.Referring to the kind of compact structural accelerometer,due to the integration of machinery and circuits,there are heat sources inside the accelerometer.Therefor,the simulation of distribution of temperature simulation and thermal design methods for special structure accelerometer with heat source inside in our lab are given great emphasis in this paper.In this paper,FEM(Finite Element Modeling)software COMSOL Multiphysics is used to compute simulation results.Firstly,simplified accelerometer model is made,ignoring many small and unimportant structures and sorting the boundary conditions.The physical model mainly consists of Test Mass,electrode plate frame,vacuum chamber,circuit boards and their boxes and the outer shell.There are two parts of simulation researches: thermal analysis of accelerometer while the ambient temperature fluctuates in sine function: Tamb= 20 + sin(2?60t),which fluctuation range is 1?;the thermal design simulation under the thermal analysis simulation results for the accelerometer in our lab.The two parts of simulation is Transient simulation,results given below:(1)After 5 hours' calculation,the temperature of the Test Mass is within(20.026?,20.032?)range,fluctuation range is 0.003?,fluctuation damping is 333.33 times.The highest temperature gradient in Test Mass is 5× 10-5?.(2)With thermal design,after 3 hours' calculation.After 66 hours' calculation,the temperature of the Test Mass is still up climbing,not reaching a steady fluctuation state.The highest temperature gradient in Test Mass is 6.6× 10-7?.(3)The thermal design lowers the temperature of the whole accelerometer and the Test Mass and uniforms the temperature gradient to some extent in Test Mass,but the time to reach a steady fluctuation for Test Mass has been much longer.Based on these study results,follow-up thermal design program and simulation is presented,which lays a steady theory foundation for experiments.Thermal diagnostics experiments are also looking forward in the last paragraph.