Three Dimensional Simulation And Performance Analysis Of Ionic Liquid Micro Thruster

Small satellites are widely used in space exploration with the progress of mechanical technology.Traditional thrusters can't satisfy their needs in attitude adjustment and orbital transfer.Based on electrostatic spray,ionic-liquid thrusters(ILTs)have several advantages,like high specific impulse,tiny but accurate thrust and impulse outcome,etc.ILTs are small satellites' ideal thrusters,while correlational studies still remain in the level of theoretical model design and laboratory tests.Based on comparisons and summary of adequate experimental results,the regular modes of electrostatic spray were analyzed,which mainly included dripping,microdripping,cone-jet,spindle,simple jet and ramified jet.The physical properties of the liquid,the liquid flow rate and the geometry of the system affected the mode of electrostatic spray.ILTs regularly operated in cone-jet mode.The electric field distribution of conical meniscus was acquired by solving the Laplace equation in spherical coordinates.The surface tension of conical meniscus was determined by the Young-Laplace equation.The calculated half-angle of balanced conical meniscus was about 49.3°,which was consistent with existing theories and experimental results.A three-dimensional integrated ILTs model which operated in purely ionic regime was built in COMSOL for the first time.The meshing was guided by setting mesh control domains and element size parameters so that the electic field distribution could be calculated precisely.The nonlinear time step was set to accelerate the calculating speed,which maintained the necessary accuracy in the meantime.The charged particles were traced by using the particle tracing module of COMSOL when they left the meniscus.The properties of ILTs were calculated without considering interparticle interaction,which included the beam half-angle(BHA),the angular distribution of current density,the total emitted current intensity and the thrust.The difference between the simulative and experimental value of onset voltage was less than 10%.The geometry's effects on electric field were analyzed,which indicated an approach to lower the onset voltage.Considering the working principle of ILTs and technological level,two presentation thruster models were manufactured by laser processing technology.The work laid the foundation for optimal design of ILTs,in addition,it offered a precise three-dimensional model.An efficient approach was offered in this paper to design the geometry of ILTs.Some properties of thruster,like onset voltage,emitted current intensity and the thrust,could quickly be estimated while the type of propellant and the geometry of ILTs were confirmed,which provided prior theoretical support for ILTs' application in astronautics.