Current models of Titan's ionosphere have difficulties in explaining the observed electron density and/or temperature. In order to get new insights, we re-analyzed the data taken in the ionosphere of Titan by the Cassini Langmuir probe (LP), part of the Radio and Plasma Wave Science (RPWS) instrument. This is the first of two papers that present the new analysis method (current paper) and statistics on the whole data set. We suggest that between two and four electron populations are necessary to fit the data. Each population is defined by a potential, an electron density and an electron temperature and is easily visualized by a distinct peak in the second derivative of the electron current, which is physically related to the electron energy distribution function (Druyvesteyn method). The detected populations vary with solar illumination and altitude. We suggest that the four electron populations are due to photo-ionization, magnetospheric particles, dusty plasma and electron emission from the probe boom, respectively.

中文翻译：

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重新分析泰坦电离层中卡西尼号 RPWS/LP 数据：1. 几个电子群的检测

泰坦电离层的当前模型难以解释观察到的电子密度和/或温度。为了获得新的见解，我们重新分析了卡西尼朗缪尔探测器 (LP) 在泰坦电离层中获取的数据，该探测器是无线电和等离子波科学 (RPWS) 仪器的一部分。这是两篇论文中的第一篇，介绍了新的分析方法（当前论文）和整个数据集的统计数据。我们建议需要 2 到 4 个电子群来拟合数据。每个群体都由电位、电子密度和电子温度定义，并且可以通过电子电流的二阶导数中的明显峰值轻松可视化，该峰值与电子能量分布函数（Druyvesteyn 方法）在物理上相关。检测到的种群随太阳光照度和海拔高度而变化。我们认为这四个电子群分别是由于光电离、磁层粒子、尘土等离子体和探测器繁荣的电子发射造成的。