多孔阵列式电喷雾推力器纯离子电流的物理模型

Physical Model for Current of Electrospray Thruster with Porous Emitter Array Operated in Pure Ionic Regime

关键词:  离子液体电喷雾推力器  离子蒸发  多点发射  纯离子模式  物理模型

Key words:  Ionic liquid electrospray thruster  Ion evaporation  Multi-site emission  Pure ionic regime  Physical model

摘要:

纯离子（PIR）发射状态的多孔发射极阵列（PEA）使离子液体电喷雾推力器（ILET）具有高精度、高比冲、高效率、小体积等优点。为了研究PEA在PIR发射状态下的束电流机制，构建了一种包含起始电压、多点发射、黏性流动、离子电流的物理模型。通过引入正态性假设简化了加工公差不确定性和多孔基材不均匀性的量化过程，基于Monte Carlo方法推导出了PEA的PIR电流解析表达式，并通过对比试验结果验证了模型的可靠性和准确性。结果表明，模型机理明确、误差较小，能够较高精度地预测锥形多孔硼硅酸盐PEA的PIR电流和多点发射行为；模型计算结果与AFET-2推力器试验结果基本一致，相对误差范围为1.0%~1.5%，随着工作电压的增大和发射体数量的增加有助于提升模型的精度。模型为计算效率较高的0D模型，为ILET的鲁棒性设计和性能优化提供了一种新的计算方法。

Abstract:

There are the dominant positions of high thrust precision， high specific impulse， high efficiency and compact structure for an ionic liquid electrospray thruster （ILET） with porous emitter array （PEA） operated in the pure ionic regime （PIR）. In order to investigate the beam current mechanism of a PEA in the PIR， a physical model including onset voltage， multi-site emission， viscous flow， and ion current was constructed. In addition， the assumption of normality was introduced to quantify the uncertainty of machining tolerances and the non-uniformity of porous substrates. In particular， it is based on the Monte Carlo method that the analytical expression for the current of a PEA in the PIR was derived. The accuracy of the model was verified by comparing the agreement between the calculated results based on this model and experiment data. The results show that the model mechanism is clear and the error is small. In particular， the model can predict the current in the PIR and multi-sites emission behavior of conical porous borosilicate PEA with high accuracy. The model calculation results are basically consistent with the experimental data of AFET-2 thruster， with a relative error range of 1.0%~1.5%. The study indicates that increasing the operating voltage and the number of emitters helps to improve the accuracy of the model. Finally， the model is a computationally efficient 0D-model with fewer parameters， which provides a new computational method for robust design and performance optimization of ILET.