Calculation and compensation of self-gravity for gravitational reference sensor based on finite element method
Spaceborne gravitational wave detection Tai-ji Project is going to measure the distance change of two test mass blocks with gravitational reference sensors through laser interference to retrieve the physical information of gravitational waves.The total residual acceleration noise of the test mass should be below 3×10-15m·s-2/a√Hz along sensitive axis at 0.1 mHz.The self-gravity noise arising from spacecraft payloads attraction,thermal distortions and mass fluctuation is one of the most significant noises.The self-gravity induced acceleration at test mass location along sensitive axis should be below 1 × 10-10m/s2,and the self-gravity induced gradient of the acceleration field at test mass location along sensitive axis should be below 5 × 10-8s-2.In order to calculate the accelerations and gradients of the acceleration field,aiming at the geometry irregularity of test mass and attraction sources,a custom programme was coded.The linear accelerations,angular accelerations and gradients of the acceleration field were calculated.In addition,to minimize the calculation time,a"quasi adaptive"method for meshing was proposed.The balance mass was designed to compensate self-gravity.The results show that the self-gravity induced acceleration at test mass location along sensitive axis is 9.237 7 × 10-12 m/s2,and that the self-gravity induced gradient of the acceleration field at test mass location along sensitive axis is-2.569 1 × 10-8s-2,which meet the design requirement.This research will provide reference and guidance for the design and compensation of spacecraft and gravitational reference sensors.
spaceborne gravitational wave detectiongravitational reference sensorself-gravityacceleration field gradientattraction compensationfinite element method
国家科技期刊平台
NSTL
万方数据
