The Small Payloads for Investigation of Disturbances in Electrojet by Rockets (SPIDER) sounding rocket was launched on February 2nd, 2016 (21:09 UT), deploying 10 free falling units (FFUs) inside a westward traveling auroral surge. Each FFUs deployed spherical electric field and Langmuir probes on wire-booms, providing in situ multi-point recordings of the electric field and plasma properties. The analytical retrieval of the plasma parameters, namely the electron density, electron temperature and plasma potential, from the Langmuir probe measurements was non-trivial due to sheath effects and detailed explanation are discussed in this article. An empirical assumption on the sheath thickness was required, which was confirmed by simulating the plasma environment around the FFU using the Spacecraft Plasma Interaction Software (SPIS). In addition, the retrieved electron density and temperature are also in agreement with the simultaneous incoherent scatter radar measurements from the EISCAT facility. These two independent confirmations provided a good level of confidence in the plasma parameters obtained from the FFUs, and events observed during the flight are discussed in more details. Hints of drift-wave instabilities and increased currents inside a region of enhanced density were observed by the FFUs.

中文翻译：

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来自 SPIDER 探空火箭的极光内部等离子体特性的多点测量

2016 年 2 月 2 日（世界标准时间 21 点 9 分）发射火箭（SPIDER）探空火箭用于调查电喷中扰动的小型有效载荷，在向西行驶的极光浪涌中部署了 10 个自由落体单元（FFU）。每个 FFU 在钢丝臂上部署球形电场和朗缪尔探针，提供原位电场和等离子体特性的多点记录。由于鞘层效应，从朗缪尔探针测量中对等离子体参数（即电子密度、电子温度和等离子体电位）的分析检索非常重要，本文讨论了详细解释。需要对护套厚度进行经验假设，这通过使用航天器等离子体交互软件 (SPIS) 模拟 FFU 周围的等离子体环境得到证实。此外，检索到的电子密度和温度也与来自 EISCAT 设施的同步非相干散射雷达测量结果一致。这两个独立的确认为从 FFU 获得的血浆参数提供了良好的置信度，飞行期间观察到的事件将得到更详细的讨论。FFU 观察到漂移波不稳定性和密度增强区域内电流增加的迹象。