The Transport and Evolution of MHD Turbulence throughout the Heliosphere: Models and Observations
The Transport and Evolution of MHD Turbulence throughout the Heliosphere: Models and Observations
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DOI：
10.3390/fluids6100368
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发表时间：
2021-10
期刊：
影响因子：
1.9
通讯作者：
L. Adhikari;G. Zank;Lingling Zhao
中科院分区：
文献类型：
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作者：
L. Adhikari;G. Zank;Lingling Zhao
详细研究了整个日光层上风向和顺风向的太阳风湍流。我们使用不可压缩磁流体动力学 (MHD) 湍流模型，其中包括电子效应、湍流能量分解为质子和电子加热、电子热通量以及质子和电子之间的库仑碰撞。推导了正向和反向传播模式能量、脉动动能和磁能、归一化交叉螺旋度和归一化剩余能量对应的湍流级联率表达式，并计算了顺风向和0.17 au到75 au的湍流级联率。最后，我们使用湍流传输模型推导出逆风和顺风日心方向的宇宙射线（CR）平行和垂直平均自由程（mfps）。我们发现逆风方向和顺风方向的湍流是不同的，部分原因是新生拾取离子在两个方向上的不对称分布，这导致两个方向上的CR mfps不同。这对于描述太阳风对宇宙射线的调制的模型很重要。
A detailed study of solar wind turbulence throughout the heliosphere in both the upwind and downwind directions is presented. We use an incompressible magnetohydrodynamic (MHD) turbulence model that includes the effects of electrons, the separation of turbulence energy into proton and electron heating, the electron heat flux, and Coulomb collisions between protons and electrons. We derive expressions for the turbulence cascade rate corresponding to the energy in forward and backward propagating modes, the fluctuating kinetic and magnetic energy, the normalized cross-helicity, and the normalized residual energy, and calculate the turbulence cascade rate from 0.17 to 75 au in the upwind and downwind directions. Finally, we use the turbulence transport models to derive cosmic ray (CR) parallel and perpendicular mean free paths (mfps) in the upwind and downwind heliocentric directions. We find that turbulence in the upwind and downwind directions is different, in part because of the asymmetric distribution of new born pickup ions in the two directions, which results in the CR mfps being different in the two directions. This is important for models that describe the modulation of cosmic rays by the solar wind.