太阳风和磁尾条件下月球环境中的等离子体湍流：来自月船2号射电科学实验的观测
Plasma Turbulence in the Lunar Environment Across Solar Wind and Magnetotail Conditions: Observations from Chandrayaan-2 Radio Science experiment
AI总结：
该研究利用月船2号射电科学实验数据，分析太阳风与磁尾条件下月球环境的等离子体湍流，明确了不同区域的谱指数特征及影响因素。
AI中文摘要：
月球在太阳风和地球磁尾之间的运行，使近月环境暴露于等离子体密度和流动结构的大幅快速变化中。研究利用月船2号的双向相干S波段无线电掩星测量，量化沿地月视线积分的电子密度涨落。对观测频率进行处理，以去除由相对论光时建模得到的几何多普勒贡献，剩余的频率残差代表射线路径上等离子体不规则性的累积效应。对2022年的54个时间间隔计算功率谱密度，得到时间谱指数范围为1.05≤α≤2.66，对应空间指数范围为4.05≤p≤5.66，表明处于离子动力学和耗散范围尺度。在这54个时间间隔中，9个被归类为在建模磁层顶内部，17个在弓激波/磁层鞘，28个在太阳风中。磁层顶内部测量的谱指数略高于弓激波和太阳风中的谱指数，但考虑到磁尾样本有限，该差异无统计学意义。谱斜率与地磁活动之间未发现可测量的相关性，表明观测到的变化由局地等离子体结构主导，而非磁层内部条件。
英文摘要：
The Moon's transit between the solar wind and Earth's magnetotail exposes the near-lunar environment to large and rapid variations in plasma density and flow structure. Two-way coherent S-band radio occultation measurements from Chandrayaan-2 were used to quantify electron-density fluctuations integrated along the Earth-Moon line of sight. Observed frequencies were processed to remove geometric Doppler contributions derived from relativistic light-time modeling. The remaining frequency residuals represent the cumulative effect of plasma irregularities along the ray path. Power spectral densities were computed for 54 intervals from 2022, yielding temporal spectral indices in the range $1.05 \le α\le 2.66$, corresponding to spatial indices $4.05 \le p \le 5.66$ indicating ion-kinetic and dissipation-range scales. Of the 54 intervals, 9 were classified as inside the modeled magnetopause, 17 in the bow shock/magnetosheath, and 28 in the solar wind. Spectral indices measured inside the magnetopause are marginally higher than those in the bow shock and solar wind, though the difference is not statistically significant given the limited magnetotail sample. No measurable correlation is found between spectral slope and geomagnetic activity, indicating that the observed variability is dominated by local plasma structure rather than inner-magnetospheric conditions.
