High-Fidelity Particle-In-Cell Simulations of Ion Thruster Optics IEPC-2017-451
High-Fidelity Particle-In-Cell Simulations of Ion Thruster Optics IEPC-2017-451
复制标题
离子推进器光学器件的高保真粒子内模拟 IEPC-2017-451
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
S. Fasoulas
中科院分区：
文献类型：
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作者：
T. Binder;M. Pfeiffer;S. Fasoulas
离子推进器光学数值模拟是基于粒子的方法在电推进领域中最常见的应用之一。多年来，已经开发和验证了用于模拟离子轨迹和电荷交换侵蚀的强大工具。只要离子光学系统工作在远离电子回流(EBS)极限的地方，预测结果的有效性就会很高。带EBS运行的栅极离子推进器是最危险的失效模式之一，因此建立全动力学数值模型是非常必要的。为此，预计需要一种基于高保真粒子在胞(PIC)方法的更复杂的方法，能够现实地处理不同尺度的重离子和极低质量电子。本文对RIT-μX推力器进行了静电光学模拟。并将计算结果与一般玻尔兹曼关系下的模拟结果进行了比较。电势和数密度的空间分布与所确定的回流电流符合得很好。电子的速度分布函数在大多数位置都符合热平衡。对实际推力器的模拟与相应的无限大网格孔型的比较表明，边缘孔口处的状态仅略有不同。然而，实验确定的EBS阈值无法重现，这可能是由于对模拟参数进行了各种假设造成的。
The numerical simulation of ion thruster optics is one of the most common applications of particle-based methods in the field of electric propulsion. Over the years, powerful tools for simulation of ion trajectories and charge exchange erosion have been developed and validated. The validity of prediction results is high as long as the ion optics system is operated far from the electron back-streaming (EBS) limit. Operating gridded ion thrusters with EBS is one of the most dangerous failure modes, a fully kinetic numerical modeling is therefore highly desirable. For this, a more sophisticated approach based on high fidelity Particle-In-Cell (PIC) methods is expected to be necessary, capable to realistically handle the different scales of heavy ions and very low mass electrons. In this paper, electrostatic optics simulations of a RIT-μX thruster are conducted. The results are compared with simulations assuming the common Boltzmann relation. The spatial distributions of electric potential and number densities as well as the determined back-streaming currents match well. The velocity distribution functions of electrons correspond at most positions to thermal equilibrium. The comparison between simulations of the actual thruster and a corresponding infinite pattern of grid apertures show that the state at edge apertures differs only slightly. The experimentally determined EBS threshold, however, could not be reproduced, which is probably caused by various assumptions made for the simulation parameters.