Article
Multidisciplinary Sciences
Muni Zhou, Zhuo Liu, Nuno F. Loureiro
Summary: We conducted analytical and numerical investigations on subion-scale turbulence in low-beta plasmas using a rigorous reduced kinetic model. The results show that electron heating is primarily caused by Landau damping of kinetic Alfven waves rather than Ohmic dissipation. This collisionless damping is facilitated by the weakening of advective nonlinearities near intermittent current sheets, where free energy concentrates. The linearly damped energy of electromagnetic fluctuations explains the steepening of their energy spectrum compared to a fluid model.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Astronomy & Astrophysics
Xianshu Wu, Chao Shen, Jingchun Li, Jiaqi Dong, Kehua Li
Summary: In this study, test particle simulations were used to verify the nonlinear heating of low-frequency Alfven waves on ions and analyze the underlying process. The results show that low-frequency Alfven waves can periodically pick up ions, leading to oscillations of average parallel velocity and temperature of the plasma by phase mixing, ultimately resulting in the stabilization of acceleration. Furthermore, an analysis was developed to estimate the time required for heating and accelerating. The presence of more chaotic modes does not necessarily result in better wave heating, and the effect of random phases on the heating process was also discussed.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Rohit Chhiber, William H. Matthaeus, Arcadi Usmanov, Riddhi Bandyopadhyay, Melvyn L. Goldstein
Summary: Motivated by theoretical, numerical, and observational evidence, this study explores the possibility that the critical transition between sub-Alfvenic flow and super-Alfvenic flow in the solar atmosphere takes place within fragmented subvolumes. The initial observations could not provide enough evidence to distinguish between this possibility and a folded surface separating simply connected regions. However, future observations may help differentiate between the two possibilities. A global magnetohydrodynamic model coupled with a turbulence transport model is used to generate possible realizations of this critical zone.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
A. A. Fayad, W. M. Moslem, H. Fichtner, M. Lazar
Summary: Space observations reveal that Venus experiences significant atmospheric erosion due to solar wind. Plasma acceleration, particularly the kinetic Alfven waves (KAW), is proposed as a possible mechanism for charged particle energization in the upper atmosphere of Venus. Various parameters such as ionic concentration, solar wind electron temperature, magnetic field strength, and obliqueness influence the structures and electric field of the solitary KAWs.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
L. B. De Toni, R. Gaelzer, L. F. Ziebell
Summary: The characteristics of Alfven waves propagating obliquely to the ambient magnetic field in a stellar wind environment are discussed, considering the effects of charged dusty particles caused by plasma particle absorption and photoionization. It is shown that the presence of dust affects the behavior of Alfven waves, causing them to have zero frequency in certain wavenumber regions and changing their dispersion properties.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Llorenc Melis, Roberto Soler, Jose Luis Ballester
Summary: Observational evidence shows the presence of small-amplitude transverse MHD waves in solar prominences, believed to be driven at the photosphere and dissipating as heat in the partially ionized plasma of the threads. The simple 1D model considered in this study suggests that MHD wave heating can play a significant role in energy balance within prominences, with further studies needed to explore this mechanism in more detail.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
N. Villarroel-Sepulveda, R. A. Lopez, P. S. Moya
Summary: By studying the dispersion properties of Alfvenic waves in plasmas with different heavy ion populations, it is found that the inclusion of oxygen ions can significantly reduce the transition angle from EMIC to KAW mode and increase the damping in certain wavenumber regions.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
H. Che, A. O. Benz, G. P. Zank
Summary: This study investigates the ion beam-driven instabilities in a low beta collisionless space plasma using particle-in-cell (PIC) simulations. It is found that both the Buneman instability and the resonant electromagnetic (EM) right-handed (RH) ion beam instability can be driven when the ion beam drift exceeds the theoretical thresholds. The Buneman instability dissipates only a small fraction of the kinetic energy of the ion beam and causes significant electron heating. However, the ion beam-driven Buneman instability is effectively quenched by the resonant EM RH ion beam instability. The resonant EM RH ion beam instability dominates when the ion drift velocity is larger than the Alfven speed, leading to the generation of RH Alfven waves and RH whistler waves. The intensity of Alfven waves decreases with a decrease in ion beam drift velocity, while the intensity of whistler waves increases.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Chaitanya Prasad Sishtla, Jens Pomoell, Emilia Kilpua, Simon Good, Farhad Daei, Minna Palmroth
Summary: This study aims to investigate the propagation and evolution of Alfven waves in the solar wind, as well as the response of the solar wind to the injection of monochromatic single-frequency Alfven waves. The results show that the Alfven waves are reflected during their propagation, and the generation of parametric decay instability is suppressed.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Chang Sun, Lei Yang, Qiu-Huan Li, Cun-Li Dai, Jian-Ping Li, Zheng-Wei Cheng, De-Jin Wu
Summary: Alfven ion cyclotron waves (ACWs) and kinetic Alfven waves (KAWs) have been observed in the Alfvenic slow solar winds by Parker Solar Probe. By analyzing selected wave events, it is found that there are significant differences in the background and disturbance parameters between ACWs and KAWs.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Yuhang Yao, Jinsong Zhao, Huasheng Xie, Wen Liu, Dejin Wu
Summary: This study comprehensively analyzes the oblique ion beam instability in the Earth's ion foreshock. It identifies the occurrence of two types of instability and highlights the role of the relative drift velocity between protons in triggering the oblique Alfven ion beam instability. The competition among wave-particle interactions is proposed as the driving mechanism for this instability, contributing to the effective heating of ions in the Earth's foreshock.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Jongchul Chae, Kyoung-Sun Lee
Summary: In this study, the connection between the chromosphere and the corona through Alfvén waves is investigated by analyzing the analytical solution of Alfvén waves in a layer with varying Alfvén speed. It is found that the ponderomotive acceleration caused by Alfvén waves is always directed upward, with a peak occurring in the chromosphere-corona transition region. Additionally, the observed velocity amplitudes in the chromosphere of quiet regions and active regions fall short of the theoretical estimates, suggesting the possibility that the Alfvén waves responsible for coronal heating and FIP fractionization originate from above the chromosphere.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Xin Wang, Linzhi Huang, Yuxin Wang, Haochen Yuan
Summary: This study investigates the influence of Alfven ion-cyclotron (AIC) waves on the power spectra of magnetic fields at ion kinetic scales. The results show that this influence is dependent on the angle between the local mean magnetic field and the solar wind velocity direction. The study provides insights into the anisotropic distribution of AIC waves and its impact on the magnetic spectral index at ion kinetic scales.
Article
Astronomy & Astrophysics
L. Adhikari, G. P. Zank, L-L Zhao, M. Nakanotani, S. Tasnim
Summary: The study developed a theoretical model combining nearly incompressible magnetohydrodynamic (NI MHD) turbulence with a solar wind model that includes electron pressure and heat flux. The results show that the model is consistent with the measurements of fast solar wind by PSP and Helios 2.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Physics, Fluids & Plasmas
O. W. Roberts, Y. Narita, R. Nakamura, Z. Voeroes, D. Verscharen
Summary: The Magnetospheric MultiScale (MMS) mission utilizes multiple spacecraft and high time resolution data to investigate turbulent fluctuations in the Earth's magnetosheath. The mission provides valuable information about the wavevector directions, plasma frame frequencies, and ion and electron Alfven ratios of the fluctuations, allowing for a better understanding of the nature of turbulence and energy conversion. The results indicate that the fluctuations exhibit kinetic Alfven wave-like properties and that Landau damping plays a significant role in energy conversion.
PHYSICS OF PLASMAS
(2022)