Ion Cyclotron Waves in Field-aligned Solar Wind Turbulence
Ion Cyclotron Waves in Field-aligned Solar Wind Turbulence
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DOI：
10.3847/2041-8213/ab4c44
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
D. Telloni;F. Carbone;R. Bruno;G. Zank;L. Sorriso-Valvo;S. Mancuso
中科院分区：
文献类型：
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作者：
D. Telloni;F. Carbone;R. Bruno;G. Zank;L. Sorriso-Valvo;S. Mancuso
在这封信中，太阳风平行波动的性质进行了研究，通过使用磁螺旋度来表征它们在质子尺度上的偏振状态。我们的目的是评估质子回旋不稳定性的作用，作为一种机制，产生离子回旋波（ICW）在太阳风湍流。波的偏振被发现强烈依赖于质子温度各向异性和在流体尺度上的磁波动的功率水平。结果表明，在太阳风湍流中，流体和动力学尺度之间存在明显的联系，从而可以看到高频阿尔文波的共振耗散在垂直于磁场的方向上加热质子，增加其温度各向异性。因此，速度分布变得不稳定的质子回旋不稳定性，然后驱动本地生成的ICW的太阳风。
The nature of the solar wind parallel fluctuations is investigated in this Letter by using magnetic helicity to characterize their polarization state at proton scales. Our aim is to assess the role of the proton cyclotron instability as a mechanism for generating ion cyclotron waves (ICWs) in solar wind turbulence. The wave polarization is found to depend strongly on the proton temperature anisotropy and on the power level of magnetic fluctuations at fluid scales. The results indicate a clear link between fluid and kinetic scales in the solar wind turbulence, allowing for a picture in which the resonant dissipation of high-frequency Alfvén waves heats protons in a direction perpendicular to the magnetic field, increasing their temperature anisotropy. The velocity distribution thus becomes unstable to the proton cyclotron instability, which then drives the local generation of ICWs in the solar wind.