Characterization of Fluctuations in Hybrid Axial-Azimuthal Hall Thruster Simulations IEPC-2015-90922
Characterization of Fluctuations in Hybrid Axial-Azimuthal Hall Thruster Simulations IEPC-2015-90922
复制标题
混合轴向方位霍尔推进器模拟中波动的表征 IEPC-2015-90922
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Jacob Aley
中科院分区：
文献类型：
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作者：
E. Fernandez;C. Dowdy;Jacob Aley
霍尔推力器等离子体动力学，非磁化离子和流体电子的二维模型。该模型动态演变的方位角流量和波动，不同的标准混合模型，假设轴对称和解决量的径向和轴向坐标。与那些描述不同，这些描述通常使用临时跨场电子传输参数以维持放电，本模型依赖于等离子体内产生的经典传输和波动。在模拟中捕获了许多低频波模式，从最低（几kHz）的“呼吸模式”到几百kHz量级的波。争论的焦点是各种模式的表征，关于它们的不稳定机制，它们的光谱特征，它们对等离子体不均匀性的依赖沿着通道，以及它们在跨场电子传输中的作用。模拟结果表明，gradientdriven漂移不稳定性出现下游的磁场峰值，如线性稳定性分析预测，而强大的，电离驱动的波动发生上游。虽然波动导致波动驱动的传输，但它们并不驱动足够的电流来匹配实验测量。最后，电子输运减少在强磁场区附近的经典水平，与实验定性一致。
A two-dimensional model of the Hall thruster plasma with kinetic, nonmagnetized ions, and fluid electrons is presented. The model dynamically evolves azimuthal flows and fluctuations, differing from standard hybrid models that assume axi-symmetry and resolve quantities in the radial and axial coordinates only. Unlike those descriptions, which typically use ad-hoc cross field electron transport parameters in order to sustain the discharge, the present model relies on classical transport and fluctuations generated within the plasma. A number of low frequency wave modes are captured in the simulation, from the lowest (few kHz) “breathing mode”, to waves on the order of a few hundred kHz. At issue is the characterization of the various modes with regards to their instability mechanisms, their spectral signatures, their dependence on plasma inhomogeneity along the channel, and their role in cross-field electron transport. Simulations show that gradientdriven drift instabilities emerge downstream of the peak of the magnetic field, as predicted by linear stability analysis, while strong, ionization driven fluctuations take place upstream. While fluctuations result in fluctuation-driven transport, they do not drive sufficient current to match experimental measurements. Finally, electron transport is reduced in the strong magnetic field region to near classical levels, in qualitative agreement with experiments.