Article
Astronomy & Astrophysics
Neeraj Jain, Jorg Buechner, Horia Comisel, Uwe Motschmann
Summary: The unsolved issue of collisionless dissipation of macroscopic energy into heat in space and astrophysical plasmas is discussed, revealing the formation of kinetic scale current sheets in turbulent plasmas. The instabilities in these current sheets are shown to provide collisionless dissipation and influence turbulence, with spatial gradients and non-Maxwellian velocity distributions providing free energy sources. Simulation results support the formation of ion-scale current sheets primarily by electron shear flows, with significant variations in electron and ion flow vorticities within these sheets.
ASTROPHYSICAL JOURNAL
(2021)
Article
Physics, Fluids & Plasmas
C. Granier, D. Borgogno, L. Comisso, D. Grasso, E. Tassi, R. Numata
Summary: The marginal stability conditions for the formation of plasmoids in a purely collisionless and strong guide field situation are investigated in this study. It is found that plasmoids can be obtained from current sheets with a smaller aspect ratio in the marginal stability current layers.
Article
Multidisciplinary Sciences
Young Dae Yoon, Gunsu S. Yun, Deirdre E. Wendel, James L. Burch
Summary: The study explains the natural emergence of bifurcated structures in magnetized space plasmas through the redistribution of single-particle orbits during collisionless relaxation processes of a disequilibrated current sheet.
NATURE COMMUNICATIONS
(2021)
Article
Astronomy & Astrophysics
Jia Nan, Kai Huang, Quanming Lu, San Lu, Rongsheng Wang, Jinlin Xie, Jian Zheng, Shui Wang
Summary: In this paper, the formation of electron inflow towards the X-line in magnetic reconnection is analyzed through fluid perspective. It is found that both parallel electric field and mirror force play important roles in driving the electron inflow, with the parallel electric field contributing more significantly. The effects of plasma density and temperature on the formation of electron inflow are also investigated.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
Amirhassan Chatraee Azizabadi, Neeraj Jain, Joerg Buechner
Summary: The article characterizes current sheets forming in an ion-kinetic turbulent collisionless plasma using results from two-dimensional hybrid-kinetic numerical simulations. The algorithm parameters are analyzed for their impact on identifying current sheets in plasma turbulence, with appropriate values chosen for identification. Current sheets are statistically characterized in terms of their main properties, showing a tendency to thin down until numerical dissipation stops further thinning.
PHYSICS OF PLASMAS
(2021)
Article
Astronomy & Astrophysics
Dario Borgogno, Daniela Grasso, Beatrice Achilli, Massimiliano Rome, Luca Comisso
Summary: In collisionless plasmas, the formation of plasmoids driven by magnetic reconnection is analyzed. It is found that the coexistence of plasmoid formation and Kelvin-Helmholtz instability is present due to the strong velocity shears. Depending on the local values of the magnetic and velocity fields, the current density layers experience plasmoid or KH instability. The competition among these instabilities affects the evolution of current sheets and the difference in energy cascade between magnetic and kinetic spectra.
ASTROPHYSICAL JOURNAL
(2022)
Article
Geosciences, Multidisciplinary
Z. H. Zhong, M. Zhou, D. B. Graham, Yu. V. Khotyaintsev, Y. F. Wu, O. Le Contel, H. M. Li, X. Tao, R. X. Tang, X. H. Deng
Summary: This paper investigates the whistler-mode waves within an electron-scale current sheet and measures their dispersion relation for the first time. The study shows that the drifting electron component along the magnetic field critically modifies the dispersion relation and demonstrates that these whistler waves propagate into the diffusion region from outside rather than being locally excited.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Review
Physics, Multidisciplinary
Quanming Lu, Huishan Fu, Rongsheng Wang, San Lu
Summary: Magnetic reconnection is the physical mechanism for explosive phenomena in the solar atmosphere and planetary magnetospheres, where plasma is usually collisionless. In the standard model of collisionless magnetic reconnection, the diffusion region consists of two substructures: an electron diffusion region embedded in an ion diffusion region. Observations from spacecraft and kinetic simulations have provided opportunities to study collisionless magnetic reconnection beyond the standard model.
Article
Geosciences, Multidisciplinary
K. Jiang, S. Y. Huang, Z. G. Yuan, Q. Y. Xiong, Y. Y. Wei
Summary: With high-resolution data from the MMS mission, a tilted ion-scale flux rope is observed in the tailward outflow of a magnetic reconnection in the terrestrial magnetotail, indicating the extension of the X-line in the dawn-dusk direction. The observed electron vortex embedded in the flux rope generates an induced magnetic field with the same direction as the axial component, contributing to the enhancement of the magnetic flux carried by the flux rope.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Astronomy & Astrophysics
Yukang Shu, San Lu, Quanming Lu, Weixing Ding, Shui Wang
Summary: Collisionless magnetic reconnection is common in space plasma environments, with the reconnection site being unstable and generating reconnection fronts. Energy conversion mainly occurs at the reconnection fronts, while the reconnection rate only represents the energy conversion at the reconnection site.
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2021)
Article
Astronomy & Astrophysics
G. P. Zank, M. Nakanotani, L. L. Zhao, S. Du, L. Adhikari, H. Che, J. A. le Roux
Summary: The study found that in the solar wind, the amplitude of quasi-perpendicular fluctuations typically increases significantly after transmission from upstream, while the spectral shape in the inertial range remains unchanged. Additionally, the theoretically predicted characteristics of turbulence transmission across shocks observed in the solar wind are largely consistent with recent observational studies.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
S. Selvi, O. Porth, B. Ripperda, F. Bacchini, L. Sironi, R. Keppens
Summary: Magnetic reconnection can generate nonthermal energy distributions and power high-energy astrophysical phenomena. This study investigates relativistic collisionless plasmoid-mediated reconnection in magnetically dominated pair plasmas using kinetic particle-in-cell simulations. The mechanisms driving the nonideal electric field in fully developed plasmoid chains are identified based on a statistical analysis using the full Ohm law. A kinetic physics motivated nonuniform effective resistivity model is proposed, capturing the essentials of collisionless reconnection in nonideal magnetohydrodynamic descriptions.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Yan Yang, William H. Matthaeus, Sohom Roy, Vadim Roytershteyn, Tulasi N. Parashar, Riddhi Bandyopadhyay, Minping Wan
Summary: The dissipative mechanism in weakly collisional plasma has been the subject of study for decades without a consensus solution. This research compares several energy dissipation estimates and provides theoretical justification for the pressure-strain interaction as a direct estimate of the energy dissipation rate. The results show that the pressure-strain interaction accurately balances the dissipation rate at kinetic scales, while the widely used Yaglom relation may be questionable in some cases.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Shu-Di Yang, Liang Wang, Chuanfei Dong
Summary: This article reports the first fully kinetic simulations of collisionless reconnection in a three-species dusty plasma with negatively charged dust grains, discovering the double Hall pattern and analyzing the reconnection rate. This study is significant for explaining observations of planetary magnetospheres and astrophysical objects, as well as for laboratory studies of dusty plasmas.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
H. Arnold, J. F. Drake, M. Swisdak, F. Guo, J. T. Dahlin, Q. Zhang
Summary: This study explores the formation, development, and impact of slow shocks in the upstream regions of reconnecting current layers. It investigates their potential role in producing the hot thermal component of electrons in solar flares.
ASTROPHYSICAL JOURNAL
(2022)
Article
Physics, Fluids & Plasmas
Tohru Shimizu, Koji Kondoh, Seiji Zenitani
PHYSICS OF PLASMAS
(2017)
Article
Physics, Fluids & Plasmas
Seiji Zenitani
PLASMA PHYSICS AND CONTROLLED FUSION
(2018)
Article
Astronomy & Astrophysics
Seiji Zenitani, Hiroshi Hasegawa, Tsugunobu Nagai
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
(2017)
Article
Physics, Fluids & Plasmas
M. Hosseinpour, Y. Chen, S. Zenitani
PHYSICS OF PLASMAS
(2018)
Article
Physics, Fluids & Plasmas
Seiji Zenitani, Takayuki Umeda
PHYSICS OF PLASMAS
(2018)
Article
Astronomy & Astrophysics
Yosuke Matsumoto, Yuta Asahina, Yuki Kudoh, Tomohisa Kawashima, Jin Matsumoto, Hiroyuki R. Takahashi, Takashi Minoshima, Seiji Zenitani, Takahiro Miyoshi, Ryoji Matsumoto
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
(2019)
Article
Computer Science, Interdisciplinary Applications
Seiji Zenitani, Tsunehiko N. Kato
COMPUTER PHYSICS COMMUNICATIONS
(2020)
Article
Astronomy & Astrophysics
Wai-Leong Teh, Seiji Zenitani
Summary: A new reconstruction method incorporating alpha(B) has been developed and tested for time-dependent mirror structures, showing reasonable results and outperforming other isotropic pressure and vector potential-based reconstruction methods.
EARTH AND SPACE SCIENCE
(2021)
Article
Physics, Fluids & Plasmas
Genta Ueno, Seiji Zenitani
Summary: In this study, a mixture model composed of relativistic Maxwellian distributions is proposed for analyzing distribution functions of relativistic plasma. The basic properties of the relativistic Maxwellian distribution and its maximum likelihood estimation are summarized. An expectation-maximization algorithm is developed for estimating the parameters of the relativistic Maxwellian mixture model (R-MMM), which is then applied to separate a simulated distribution function into two components, revealing differences in bulk velocity and similarity in temperatures.
PHYSICS OF PLASMAS
(2021)
Article
Physics, Fluids & Plasmas
Seiji Zenitani, Shin'ya Nakano
Summary: This paper presents a procedure for loading particle velocities from a relativistic kappa distribution in particle-in-cell and Monte Carlo simulations. The procedure is based on the rejection method and the beta prime distribution. It successfully reproduces the relativistic kappa distribution, including the power-law tail.
PHYSICS OF PLASMAS
(2022)
Article
Astronomy & Astrophysics
W. -l. Teh, T. K. M. Nakamura, S. Zenitani, T. Umeda, R. Nakamura
Summary: This study investigates the energy conversion process during the coalescence of magnetic islands using a two-dimensional kinetic simulation. The results reveal the presence of energy dynamo and energy dissipation during this process, which have a significant impact on particle acceleration. The simulated energy conversion signatures are also compared favorably with observed magnetic islands.
ASTROPHYSICAL JOURNAL
(2023)
Article
Physics, Fluids & Plasmas
T. K. M. Nakamura, W. -l. Teh, S. Zenitani, T. Umeda, M. Oka, H. Hasegawa, A. M. Veronig, R. Nakamura
Summary: Magnetic reconnection is a fundamental process that converts magnetic energy to plasma kinetic energy in collisionless plasmas. This study focuses on the coalescence of multiple magnetic islands and examines the spatial dimensions of the internal structures. It is found that the dimensions depend on the initial thickness of the current sheet and the number of coalescing islands. The study also discovers that the horizontal dimension controls the evolution time scale, while the vertical dimension affects the reconnection maturity and particle heating.
PHYSICS OF PLASMAS
(2023)
Article
Astronomy & Astrophysics
Seiji Zenitani, Takahiro Miyoshi
ASTROPHYSICAL JOURNAL LETTERS
(2020)
Article
Astronomy & Astrophysics
Wai-Leong Teh, Seiji Zenitani
ASTROPHYSICAL JOURNAL
(2020)
Article
Astronomy & Astrophysics
Wai-Leong Teh, Seiji Zenitani
ASTROPHYSICAL JOURNAL
(2019)
