论文标题
Parker太阳能探针观察到的太阳风质子的多趋势行为
Polytropic Behavior of Solar Wind Protons Observed by Parker Solar Probe
论文作者
论文摘要
多粒子过程通过流体密度和温度之间的特定关系描述了流体从一个状态到另一种状态的过渡。控制这种关系的多粒子指数的价值决定了过程中的传热和有效的自由度。在这项研究中，我们分析了太阳能质子等离子体测量值，该测量由Faraday杯仪器在板载Parker太阳能探针中获得。我们检查了航天器探索的内气球内质子等离子体密度和温度的大规模变化。我们还以短时间间隔在密度和温度波动中解决了多面性行为，我们对此进行分析，以得出小时尺度过程的有效多面性指数。太阳风质质子密度和温度的大规模变化与血浆通过地球层相关，遵循带有多粒子指数〜5/3的多层模型。另一方面，可能与湍流相关的短时尺度波动遵循具有较大多环反应指数的模型。我们研究了短时尺度波动的多端指数与等离子体速度，等离子体β和磁场方向之间的可能相关性。我们讨论机制的情况，包括能量转移或限制粒子有效自由度的机制。
A polytropic process describes the transition of a fluid from one state to another through a specific relationship between the fluid density and temperature. The value of the polytropic index that governs this relationship determines the heat transfer and the effective degrees of freedom during the process. In this study, we analyze solar wind proton plasma measurements, obtained by the Faraday cup instrument on-board Parker Solar Probe. We examine the large-scale variations of the proton plasma density and temperature within the inner heliosphere explored by the spacecraft. We also address a polytropic behavior in the density and temperature fluctuations in short-time intervals, which we analyze in order to derive the effective polytropic index of small time-scale processes. The large-scale variations of the solar wind proton density and temperature which are associated with the plasma expansion through the heliosphere, follow a polytropic model with a polytropic index ~5/3. On the other hand, the short time-scale fluctuations which may be associated with turbulence, follow a model with a larger polytropic index. We investigate possible correlations between the polytropic index of short time-scale fluctuations and the plasma speed, plasma beta, and the magnetic field direction. We discuss the scenario of mechanisms including energy transfer or mechanisms that restrict the particle effective degrees of freedom.
