Integrated Design And Key Components Technique Of Solid Nitrogen Micro Thruster

Attitude control,orbital transfer and maintenance of micro-nano-satellites need micro-thruster.Micro-thruster requires light weight,small volume and low power consumption.This paper completed integrated design and key components of the solid nitrogen micro-thruster.The solid nitrogen micro thruster includes chamber,solid nitrogen generator,solenoid valve,pressure sensor,Laval micro-nozzle and control circuit.In order to improve the specific impulse,this paper studied the preparation and characterization of MEMS electro-thermal micro-thruster.The main contents and conclusions are as follows:?1?Solid nitrogen generator was designed and prepared.Nitrogen generator formulations was optimized,and charge amount was increased.The nitrogen generator formula was NaN₃:Fe₂O₃=65:35.The reaction temperature interval of nitrogen generating agent was between 410? and 435? deter_mined by differential scanning calorimetry?DSC?.Charge was Press-fit and charge density was up to 1.71g/cm3.Through ignition,the results showed that average burning rate was 22.8mm/s,gas temperature in chamber did not exceed 60?,and decomposition rate exceeded 90%.The gas purity was more than 99%.?2?Two kinds of Laval micro-nozzle,conical Al-based micro-nozzle and Si-based MEMS nozzle were prepared by theoretical calculation.Convergent half-angle and divergent half-angle were 15°and 20°,respectively.The diameter of the throat was 150?m and expansion ratio is 12.The throat width of the silicon-based MEMS nozzle was 50?m,and expansion ratio is 25?m.The performance of both were characterized by thrust test device.The results showed that when valve on-time was 1ms,conical micro-nozzle could produce the _minimum impulse of 0.59 mN·s and thrust of 590mN.It also showed when on-time was 192ms,conical micro-nozzle could produce _maximum impulse of 11.081 mN·s and _maximum thrust of 57.7mN.When working time was 192ms,Silicon-based MEMS nozzle could produce _maximum impulse of 2.548 mN·s and _maximum thrust of 13.269mN,_minimum impulse of 0.117 mN· s and _minimum thrust of 0.612mN.?3?The heating process of Nickel thin film was simulated by COMSOL Multiphysics.MEMS electro-thermal micro-thruster was designed and fabricated by MEMS technique.The structure included silicon,nickel thin film and Pyrex7740 glass.Performance was characterized when MEMS electro-thermal micro-thruster temperature was about 100?.The results showed that the MEMS electro-thermal micro-thruster could contribute to 6%increasement of specific impulse under the same initial pressure and the same flow rate compared with the un-heated micro-thruster.