Preliminary Research On Micro-Newton Cold Gas Thruster

Gravitational wave(GW)detection is meaningful for broadening the means of observing the universe.The space GW detection programs represented by the Tianqin/Taiji project in China is expected to expand the observation frequency band of GW and provide the possibility to observe more astronomical phenomena.One of the crucial technologies for space GW detection is that the residual acceleration of Test Mass reaches the order of10^-15 m/s²/Hz^1/2,which requires the adoption of Drag Free technology to compensate the influence of non conservative disturbance forces on the satellite and provide a super stable experimental environment.This target put out very high requirements for the Micro-Thruster in the Drag Free system.The requirements for thrust range,thrust resolution and thrust noise of micro thruster are 0-100?N,0.1?N and 0.1?N/Hz^1/2,respectively.The Cold Gas Micro-Thruster has the advantages of simple structure,high stability and no pollution.It is one of the most potential micro propulsion systems for space GW detection.At present,many researches have been carried out on the Cold Gas Micro-Thruster for space gravitational wave detection at home and abroad,and on orbit verification has been carried out,but there is a certain gap between the thrust noise and the space GW detection requirements.This paper mainly focuses on the development of low thrust noise Cold Gas Micro-Thruster.Based on the theoretical modeling of the gas flow field of the Cold Gas Micro-Thruster,the main limiting factors of thrust noise are given,and the requirements for the processing accuracy,pressure and flow control accuracy of the thruster components are proposed for the needs of space GW detection programs;Design and development the high-precision pressure feedback control system improves the pressure and flow control accuracy to reduce thrust noise,and realizes the pressure control range of 0-135 k Pa,the pressure control accuracy of 40 Pa,and the pressure noise less than 20 Pa/Hz^1/2@10^-4-1Hz,corresponding flow control accuracy and noise reached 0.004sccm and 0.002sccm/Hz^1/2@10^-4-1Hz respectively;Under the premise of ensuring the thrust range,further adopting nozzle miniaturization to improve thrust resolution and thrust noise level.Based on MEMS deep response Ion etching process processed the micro-scale nozzle structure,the nozzle throat size was 20-40?m,and the nozzle wall roughness was 0.1?m;Finally,the principle prototype of the Cold Gas Micro-Thruster was built,and its thrust noise was tested and analyzed.Achieving thrust indicators:thrust range 0-156?N,thrust resolution 0.10(2)?N,thrust noise 0.07?N/Hz^1/2@0.1Hz,<0.9?N/Hz^1/2@10^-2-1Hz,the current thrust noise test results are mainly limited by the temperature effect of the proportional valve and the background noise of the test system.The preliminary results of this thesis lay the foundation for the development of a Cold Gas Micro-Thruster that meets the needs of space GW detection missions in the future.