Isotropization and Evolution of Energy-Containing Eddies in Solar Wind Turbulence: Parker Solar Probe, Helios 1, ACE, WIND, and Voyager 1
Manuel Enrique Cuesta, Rohit Chhiber, Sohom Roy, Joshua Goodwill, Francesco Pecora, Jake Jarosik, William H. Matthaeus, Tulasi N. Parashar, Riddhi Bandyopadhyay
We examine the radial evolution of correlation lengths perpendicular (\(λ_C^{\perp}\)) and parallel (\(λ_C^{\parallel}\)) to the magnetic-field direction, computed from solar wind magnetic-field data measured by Parker Solar Probe (PSP) during its first eight orbits, Helios 1, Advanced Composition Explorer (ACE), WIND, and Voyager 1 spacecraft. Correlation lengths are grouped by an interval's alignment angle; the angle between the magnetic-field and solar wind velocity vectors (\(Θ_{\rm BV}\)). Parallel and perpendicular angular channels correspond to angles \(0^{\circ}~<~Θ_{\rm BV}~<~40^{\circ}\) and \(50^{\circ}~<~Θ_{\rm BV}~<~90^{\circ}\), respectively. We observe an anisotropy in the inner heliosphere within 0.40~au, with \(λ_C^{\parallel} / λ_C^{\perp} \approx 0.75\) at 0.10~au. This anisotropy reduces with increasing heliocentric distance and the correlation lengths roughly isotropize within 1~au. Results from ACE and WIND support a reversal of the anisotropy, such that \(λ_C^{\parallel} /λ_C^{\perp} \approx 1.29\) at 1~au. The ratio does not appear to change significantly beyond 1~au, although the small number of parallel intervals in the Voyager dataset precludes unambiguous conclusions from being drawn. This study provides insights regarding the radial evolution of the large, most energetic interacting turbulent fluctuations in the heliosphere. We also emphasize the importance of tracking the changes in sampling direction in PSP measurements as the spacecraft approaches the Sun, when using these data to study the radial evolution of turbulence. This can prove to be vital in understanding the more complex dynamics of the solar wind in the inner heliosphere and can assist in improving related simulations.
Dynamics of the Upwind Heliosphere Due to Data-Driven, Solar Wind and Magnetic Field Variations and Implications for Wave Propagation into the Very Local Interstellar Medium
Boston University（波士顿大学）；Southwest Research Institute（西南研究院）；Massachusetts Institute of Technology（麻省理工学院）
Impact of pickup ions on the shock front nonstationarity and energy dissipation of the heliospheric termination shock: Two-dimensional full particle simulations and comparison with Voyager 2 observations
A Fit to the Galactic Cosmic Ray Hydrogen and Helium Spectra at Voyager 1 at Low Energies and Earth Based Measurements at Much Higher Energies with Identical Rigidity Independent Source Spectra for the Hydrogen and Helium Nuclei
Shocks, compressible perturbations, and intermittency in the very local interstellar medium: Voyager 1 and 2 observations and numerical modeling
University of Alabama in Huntsville（亨茨维尔阿拉巴马大学）；Manipal University Jaipur（斋浦尔马匹阿尔大学）；Leonard F. Burlaga, Inc.（伦纳德·F·伯尔加公司）；Space Research Center PAS (CBK PAN)（波兰科学院空间研究中心）
Solar wind He pickup ions as source of tens-of-keV/n neutral He atoms observed by the HSTOF/SOHO detector
上下文自1996年以来，在低太阳活动期间，SOHO卫星上的HSTOF仪器一直在测量28-58 keV/n的He原子（氦高能中性原子- He ENA）的弱通量。可能的源区是内日鞘。目标。我们的目标是了解的基础上的日鞘空间范围和等离子体含量的知识，旅行者1号和2号测量终止激波交叉后的一段时间内，他ENA的发射机制。方法. He ENA是由高能氦离子与星际中性H和He的电荷交换中和产生的。氦离子在日鞘中的能谱计算如下的演变时，进行和经历二进制的相互作用与等离子体成分的背景流的粒子群建模近似呈现后终止冲击旅行者数据的速度分布函数。结果观测到的HSTOF He ENA是日球He ENA总通量中能量较高的一部分，可以用提出的机制解释，误差在2σ以内。决定发射水平（及其不确定性）的主要因素是终止后冲击等离子体中He^+拾取离子的能谱。
