scholarly journals Two-dimensional hybrid models of H+ -He++ expanding solar wind plasma heating

2014 ◽  
Vol 119 (6) ◽  
pp. 4223-4238 ◽  
Author(s):  
L. Ofman ◽  
A. F. Viñas ◽  
Y. Maneva
2011 ◽  
Vol 29 (6) ◽  
pp. 1071-1079 ◽  
Author(s):  
L. Ofman ◽  
A.-F. Viñas ◽  
P. S. Moya

Abstract. Remote sensing and in-situ observations show that solar wind ions are often hotter than electrons, and the heavy ions flow faster than the protons by up to an Alfvén speed. Turbulent spectrum of Alfvénic fluctuations and shocks were detected in solar wind plasma. Cross-field inhomogeneities in the corona were observed to extend to several tens of solar radii from the Sun. The acceleration and heating of solar wind plasma is studied via 1-D and 2-D hybrid simulations. The models describe the kinetics of protons and heavy ions, and electrons are treated as neutralizing fluid.The expansion of the solar wind is considered in 1-D hybrid model. A spectrum of Alfvénic fluctuations is injected at the computational boundary, produced by differential streaming instability, or initial ion temperature anisotropy, and the parametric dependence of the perpendicular heating of H+-He++ solar wind plasma is studied. It is found that He++ ions are heated efficiently by the Alfvénic wave spectrum below the proton gyroperiod.


Author(s):  
Masaharu MATSUMOTO ◽  
Yoshihiro KAJIMURA ◽  
Hideyuki USUI ◽  
Ikkoh FUNAKI ◽  
and Iku SINOHARA

2020 ◽  
Author(s):  
Andong Hu ◽  
Jannis Teunissen ◽  
Manuela Sisti ◽  
Francesco Califano ◽  
Jérémy Dargent ◽  
...  

<div>The understanding of fundamental processes at play in a collisionless plasmas such as the solar wind, is a frontier problem in space physics. We investigate here the occurrence of magnetic reconnection in a plasma with parameters corresponding to solar wind plasma and its interplay with a fully-developed turbulent state. Ongoing magnetic reconnection can, at the moment, be accurately identified only by humans. Therefore, as a first step, the goal of this study is to present a new method to automatically recognise reconnection events in the output of two-dimensional HVM (Hybrid Vlasov Maxwell) simulations where ions evolve by solving the Vlasov equation and the electrons are treated as a fluid with mass. A large dataset with labelled reconnection events was prepared, including parameters such as the magnetic field, the electron velocity field and the current density. We consider two types of machine learning models: classical approaches using on physics-based features, and convolutional neural networks (CNNs). We will investigate which approach performs better, and which input variables are most relevant. In addition, we will try to categorize magnetic reconnection regions (current sheets). This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 776262 (AIDA, www.aida-space.eu).</div>


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Kazuo Shiokawa ◽  
Katya Georgieva

AbstractThe Sun is a variable active-dynamo star, emitting radiation in all wavelengths and solar-wind plasma to the interplanetary space. The Earth is immersed in this radiation and solar wind, showing various responses in geospace and atmosphere. This Sun–Earth connection variates in time scales from milli-seconds to millennia and beyond. The solar activity, which has a ~11-year periodicity, is gradually declining in recent three solar cycles, suggesting a possibility of a grand minimum in near future. VarSITI—variability of the Sun and its terrestrial impact—was the 5-year program of the scientific committee on solar-terrestrial physics (SCOSTEP) in 2014–2018, focusing on this variability of the Sun and its consequences on the Earth. This paper reviews some background of SCOSTEP and its past programs, achievements of the 5-year VarSITI program, and remaining outstanding questions after VarSITI.


1997 ◽  
Vol 20 (1) ◽  
pp. 15-22 ◽  
Author(s):  
P Riley ◽  
S.J Bame ◽  
B.L Barraclough ◽  
W.C Feldman ◽  
J.T Gosling ◽  
...  

Solar Physics ◽  
1971 ◽  
Vol 18 (1) ◽  
pp. 150-164 ◽  
Author(s):  
Tsutomu Toichi

1995 ◽  
Vol 16 (9) ◽  
pp. 85-94 ◽  
Author(s):  
J.L. Phillips ◽  
S.J. Bame ◽  
W.C. Feldman ◽  
J.T. Gosling ◽  
C.M. Hammond ◽  
...  

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