Turbulence Properties of Interplanetary Coronal Mass Ejections in the Inner Heliosphere: Dependence on Proton Beta and Flux Rope Structure
Turbulence Properties of Interplanetary Coronal Mass Ejections in the Inner Heliosphere: Dependence on Proton Beta and Flux Rope Structure
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DOI：
10.3847/2041-8213/acfd1c
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发表时间：
2023-07
期刊：
影响因子：
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通讯作者：
S. Good;O. Rantala;A.-S. M. Jylhä;C. H. Chen;C. Möstl;E. Kilpua
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文献类型：
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作者：
S. Good;O. Rantala;A.-S. M. Jylhä;C. H. Chen;C. Möstl;E. Kilpua
行星际日冕物质抛射（ICMEs）在较宽的日心距离范围内具有较低的质子β，在大尺度上具有磁通绳结构，使其成为研究太阳风波动的独特环境。本文研究了太阳轨道器和帕克太阳探测器在0.25 ~ 0.95 au范围内观测到的28个ICMEs的磁场波动功率谱。在大尺度上，光谱是由通量绳中所含的能量所支配的。在kd≤10−3时，背景通量绳场的减法使平均光谱指数从−5/3增加到−3/2。绳减法也显示出磁场中较短的相关长度。在所有径向距离的惯性范围内，光谱指数通常接近- 5/3，而在向动力学尺度过渡时，光谱指数始终低于- 3。终止惯性范围的高频断点随着径向距离近似线性地演化，并且在尺度上更接近质子惯性长度，而不是质子陀螺尺度，这与低质子β的等离子体的预期一致。与太阳风相比，惯性尺度上的磁压缩率与径向距离没有明显的相关性。在ICMEs中，注入尺度上的独特光谱性质主要由整体通量绳结构决定，而跃迁动力学性质更多地受到低质子β的影响；中间的惯性范围似乎与这两个ICME特征无关，表明湍流的尺度与系统无关。
Interplanetary coronal mass ejections (ICMEs) have low proton beta across a broad range of heliocentric distances and a magnetic flux rope structure at large scales, making them a unique environment for studying solar wind fluctuations. Power spectra of magnetic field fluctuations in 28 ICMEs observed between 0.25 and 0.95 au by Solar Orbiter and Parker Solar Probe have been examined. At large scales, the spectra were dominated by power contained in the flux ropes. Subtraction of the background flux rope fields increased the mean spectral index from −5/3 to −3/2 at kd i ≤ 10−3. Rope subtraction also revealed shorter correlation lengths in the magnetic field. The spectral index was typically near −5/3 in the inertial range at all radial distances regardless of rope subtraction and steepened to values consistently below −3 with transition to kinetic scales. The high-frequency break point terminating the inertial range evolved approximately linearly with radial distance and was closer in scale to the proton inertial length than the proton gyroscale, as expected for plasma at low proton beta. Magnetic compressibility at inertial scales did not show any significant correlation with radial distance, in contrast to the solar wind generally. In ICMEs, the distinctive spectral properties at injection scales appear mostly determined by the global flux rope structure while transition-kinetic properties are more influenced by the low proton beta; the intervening inertial range appears independent of both ICME features, indicative of a system-independent scaling of the turbulence.