论文标题
部分可观测时空混沌系统的无模型预测
Polytropic behavior in the structures of Interplanetary Coronal Mass Ejections
论文作者
论文摘要
多粒子过程表征了空间等离子体颗粒种群的热力学。多粒素指数$γ$尤其重要，因为它通过量化系统的变化来描述系统的热力学行为，因为系统被压缩或扩展。我们使用$ 01/1995-12/2018 $的风飞船等离子体和磁场数据，我们研究了336个行星际冠状质量弹出（ICME）事件中的热力学演化。对于每个事件，我们在鞘和磁性喷射结构中的指数$γ$以及事前事件和事件后区域。然后，我们检查了这四个区域中所有$γ$指数的分布，并得出每个区域的熵梯度，这表明环境加热。我们发现，在ICME护套区域，预计波湍流将是最高的，热力学需要最长的时间才能恢复到原始的准绝热过程中，而它在安静的弹出区域中恢复得更快。 This pattern creates a thermodynamic cycle, featuring a near adiabatic value $γ$ ~ $γ$${_a}$ (=5/3) upstream of the ICMEs, $γ$${_a}$ - $γ$ ~ 0.26 in the sheaths, $γ$${_a}$ - $γ$ ~ 0.13 in the ICME ejecta, and recovers again to $γ$〜$γ$$ {_ a} $在ICME通过之后。这些结果暴露了ICME等离子体中的湍流加热速率：从其绝热值越低的多粒子指数越接近其等温值，熵梯度越大，因此，湍流加热速率会加热ICME等离子体。
The polytropic process characterizes the thermodynamics of space plasma particle populations. The polytropic index, $γ$, is particularly important as it describes the thermodynamic behavior of the system by quantifying the changes in temperature as the system is compressed or expanded. Using Wind spacecraft plasma and magnetic field data during $01/1995 - 12/2018$, we investigate the thermodynamic evolution in 336 Interplanetary Coronal Mass Ejection (ICME) events. For each event, we derive the index $γ$ in the sheath and magnetic ejecta structures, along with the pre- and post- event regions. We then examine the distributions of all $γ$ indices in these four regions and derive the entropic gradient of each, which is indicative of the ambient heating. We find that in the ICME sheath region, where wave turbulence is expected to be highest, the thermodynamics takes longest to recover into the original quasi-adiabatic process, while it recovers faster in the quieter ejecta region. This pattern creates a thermodynamic cycle, featuring a near adiabatic value $γ$ ~ $γ$${_a}$ (=5/3) upstream of the ICMEs, $γ$${_a}$ - $γ$ ~ 0.26 in the sheaths, $γ$${_a}$ - $γ$ ~ 0.13 in the ICME ejecta, and recovers again to $γ$ ~ $γ$${_a}$ after the passage of the ICME. These results expose the turbulent heating rates in the ICME plasma: the lower the polytropic index from its adiabatic value and closer to its isothermal value, the larger the entropic gradient, and thus, the rate of turbulent heating that heats the ICME plasma.
