Thermal ion retarding potential analyzers (RPAs) are used to measure in situ auroral ionospheric plasma parameters. This article analyzes data from a low-resource RPA in order to quantify the capability of the sensor. The RPA collects a sigmoidal current-voltage (I-V) curve, which depends on a non-linear combination of Maxwellian plasma parameters, so a forward-modeling procedure is used to match the best choice plasma parameters for each I-V curve. First, the procedure is used, given constraining information about the flow moment, to find scalar plasma parameters-ion temperature, ion density, and spacecraft sheath potential-for a single I-V curve interpreted in the context of a Maxwellian plasma distribution. Second, two azimuthally separated I-V curves from a single sensor on the spinning spacecraft are matched, given constraining information on density and sheath potential, to determine the bulk plasma flow components. These flows are compared to a high-fidelity, high-resource flow diagnostic. In both cases, the procedure's sensitivity to variations in constraining diagnostics is tested to ensure that the matching procedure is robust. Finally, a standalone analysis is shown, providing plasma scalar and flow parameters using known payload velocity and International Reference Ionosphere density as input information. The results show that the sensor can determine scalar plasma measurements as designed, as well as determine plasma DC flows to within hundreds of m/s error compared to a high-fidelity metric, thus showing their capability to replace higher-resource methods for determining DC plasma flows when coarse-resolution measurements at in situ spatial scales are suitable.

中文翻译：

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使用亚音速阻滞电位分析仪提取极光电离层等离子体流

热离子延迟电位分析仪 (RPA) 用于测量原位极光电离层等离子体参数。本文分析来自低资源 RPA 的数据，以量化传感器的能力。RPA 收集 S 形电流-电压 (IV) 曲线，该曲线取决于麦克斯韦等离子体参数的非线性组合，因此使用正向建模程序来匹配每条 IV 曲线的最佳选择等离子体参数。首先，在给定关于流动矩的约束信息的情况下，使用该程序来找到在麦克斯韦等离子体分布的上下文中解释的单个IV曲线的标量等离子体参数——离子温度、离子密度和航天器鞘电势。其次，匹配来自旋转航天器上单个传感器的两条方位角分离的 IV 曲线，给定密度和鞘层电位的约束信息，以确定整体等离子体流分量。将这些流与高保真、高资源流诊断进行比较。在这两种情况下，都会测试程序对约束诊断变化的敏感性，以确保匹配程序是稳健的。最后，显示了一个独立的分析，使用已知的有效载荷速度和国际参考电离层密度作为输入信息提供等离子体标量和流动参数。结果表明，与高保真度量相比，该传感器可以确定设计的标量等离子体测量值，以及确定等离子体 DC 流量，误差在数百 m/s 以内，