Mathematical model and sensitivity analysis of beam current for ion electrospray thruster
Although the ion electrospray thruster with an array emitter has advantages such as small volume,high specific impulse,and high thrust resolution,its development has been limited by the lack of theoretical researches.To address this issue,a mathematical model describing the beam current of the thruster based on the multi-site emission phenomenon was developed,and the empirical coefficients in the model were identified using intelligent optimization algorithms.The different characteristics of the beam current and emission behavior under high and low voltages were studied.Global sensitivity analysis based on the Sobol method was conducted to investigate the impact of geometric parameters of the emitter structure on the beam current.The model calculation results are basically consistent with the experimental data.When the voltage is greater than 1.5 kV,the base radius of the emission site is equivalent to the pore radius of the porous reservoir,and the external electric field mainly affects the nonlinear increase of the beam current.When the voltage is less than 1.5 kV,the number of emission sites is small,the base radius is 1.5 times the pore radius of the porous reservoir,and the number of emission sites is a key factor affecting the size of the beam current.The sensitivity analysis results show that the distance between the tip of the emitter and the extractor has the greatest impact on the beam current,with a first order sensitivity index of 0.841,and its tolerance must be strictly controlled in manufacturing processes.
pure ionic regimemulti-site emissionbeam current predictionmathematical modelSobol sensitivity analysis