Article
Optics
Ram Jeet, Sanjay Babu, Asheel Kumar
Summary: In the nonlocal theory of Weibel instability for a relativistic electron beam moving through a plasma channel, the finite spot size of the beam causes electromagnetic perturbations driven by the relative drift between inner region beam electrons and outer region plasma electrons. The growth rate increases with parallel wave number and tends to saturate, reaching values comparable to a fraction of the plasma frequency under typical parameters.
Article
Physics, Multidisciplinary
Matthew Goodbred, Yi-Hsin Liu
Summary: We have developed a first-principles model for the relativistic magnetic reconnection rate in strongly magnetized pair plasmas. Our analysis shows that in the magnetically dominated relativistic regime, the x-line thermal pressure is significantly lower than the upstream magnetic pressure, which leads to the collapse of the magnetic field lines and enables fast reconnection. This result is crucial for understanding various extreme astrophysical environments.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
M. Ghorbanalilu
Summary: This article discusses stream instabilities that arise from an anisotropic electron velocity distribution function (EVDF) in the optical-field ionization mechanism of a monatomic dilute gas when irradiated by a circularly polarized laser beam in the fully relativistic regime. It is found that a relativistically rotating electron beam is generated by a circularly polarized laser field with (pz>p perpendicular). Before ionization and collisions that thermalize the electrons, the plasma experiences Buneman and Weibel instabilities. The theoretical results show that in the relativistic threshold regime (a0 approximate to 1), the instabilities are aperiodic and grow independently. However, as the laser intensity increases for a0>1, the two instabilities become coupled. This coupling process increases the growth rate of the Weibel instability while decreasing the growth rate of the Buneman instability. For more intense laser radiation, both instabilities break into different oscillatory and aperiodic modes.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Fluids & Plasmas
Hui Chen, Frederico Fiuza
Summary: The study of relativistic electron-positron pair plasmas is important for understanding high-energy astrophysical phenomena, and progress has been made in generating and controlling these plasmas in the laboratory using intense lasers. However, challenges remain in improving the number of pairs, system size, and charge neutrality control. Recent advances and exciting prospects in the field are discussed.
PHYSICS OF PLASMAS
(2023)
Article
Astronomy & Astrophysics
Hao Zhang, Lorenzo Sironi, Dimitrios Giannios
Summary: By conducting large-scale 3D simulations of magnetic reconnection in pair plasmas, researchers have identified a unique acceleration mechanism that only operates in 3D. The particles with high gamma values in 3D can escape from plasmoids along the z-direction and experience large-scale fields upstream, resulting in a hard spectrum and potentially serving as a mechanism for generating ultra-high-energy cosmic rays in relativistic reconnection scenarios such as gamma-ray bursts and active galactic nuclei jets.
ASTROPHYSICAL JOURNAL
(2021)
Article
Physics, Fluids & Plasmas
K. Weichman, A. P. L. Robinson, M. Murakami, J. J. Santos, S. Fujioka, T. Toncian, J. P. Palastro, A. Arefiev
Summary: This study reports the progress in understanding the effects of kilotesla-level applied magnetic fields on relativistic laser-plasma interactions. Advances in magnetic-field-generation techniques have enabled new phenomena and provide a starting point for future experimental design.
PHYSICS OF PLASMAS
(2022)
Article
Multidisciplinary Sciences
Muni Zhou, Vladimir Zhdankin, Matthew W. Kunz, Nuno F. Loureiro, Dmitri A. Uzdensky
Summary: In this study, we investigate the generation of seed magnetic fields through the Weibel instability in an initially unmagnetized plasma driven by a large-scale shear force. We develop an analytical model and confirm its predictions through particle simulations. This work has important implications for magnetogenesis in dilute astrophysical systems.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Physics, Fluids & Plasmas
J. Latham, E. Belova, M. Yamada
Summary: Studying the stability of a spheromak configuration in coronal holes, it was found that line-tying stabilizes the tilt instability while elongation has a destabilizing effect. High-resolution simulations show current sheet formation at the upper surface of the spheromak, where magnetic field reconnects.
PHYSICS OF PLASMAS
(2021)
Article
Astronomy & Astrophysics
Alexander Chernoglazov, Bart Ripperda, Alexander Philippov
Summary: The study presents high-resolution 2D and 3D simulations of magnetized decaying turbulence in relativistic, resistive magnetohydrodynamics, showing dynamic formation of large-scale intermittent long-lived current sheets being disrupted into plasmoid chains by the tearing instability. The magnetic energy spectra are proportional to k (-3/2) for strong guide-field turbulence, while they are proportional to k (-5/3) for weak guide-field turbulence, with dynamic alignment of Elsasser fields, velocity, and magnetic fields pronounced in the former case.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Multidisciplinary Sciences
S. G. Jorstad, A. P. Marscher, C. M. Raiteri, M. Villata, Z. R. Weaver, H. Zhang, L. Dong, J. L. Gomez, M. Perel, S. S. Savchenko, V. M. Larionov, D. Carosati, W. P. Chen, O. M. Kurtanidze, A. Marchini, K. Matsumoto, F. Mortari, P. Aceti, J. A. Acosta-Pulido, T. Andreeva, G. Apolonio, C. Arena, A. Arkharov, R. Bachev, G. Bonnoli, G. A. Borman, V Bozhilov, M. Carnerero, G. Damljanovic, S. A. Ehgamberdiev, D. Elsasser, A. Frasca, D. Gabellini, T. S. Grishina, A. C. Gupta, V. A. Hagen-Thorn, M. K. Hallum, M. Hart, K. Hasuda, F. Hemrich, H. Y. Hsiao, S. Ibryamov, T. R. Irsmambetova, D. Ivanov, M. D. Joner, G. N. Kimeridze, S. A. Klimanov, J. Knoett, E. N. Kopatskaya, S. O. Kurtanidze, A. Kurtenkov, T. Kuutma, E. G. Larionova, S. Leonini, H. C. Lin, C. Lorey, K. Mannheim, G. Marino, M. Minev, D. O. Mirzaqulov, D. A. Morozova, A. A. Nikiforova, M. G. Nikolashvili, E. Ovcharov, R. Papini, T. Pursimo, I Rahimov, D. Reinhart, T. Sakamoto, F. Salvaggio, E. Semkov, D. N. Shakhovskoy, L. A. Sigua, R. Steineke, M. Stojanovic, A. Strigachev, Y. Troitskaya, I. S. Troitskiy, A. Tsai, A. Valcheva, A. A. Vasilyev, O. Vince, L. Waller, E. Zaharieva, R. Chatterjee
Summary: This study reports intense monitoring of optical and gamma-ray fluxes of BL Lacertae during a dramatic outburst in 2020, revealing QPOs in both optical flux and linear polarization, as well as gamma-ray flux with durations as short as approximately 13 hours. The QPO properties are believed to match the expectations of current-driven kink instabilities near a recollimation shock about 5 parsecs from the black hole.
Article
Physics, Fluids & Plasmas
Eric Sander Lavine, Setthivoine You
Summary: Astrophysical jets are high-speed outflows that emerge from spinning and accreting matter around celestial objects, and they may be the result of self-organized processes. Magnetic self-organization is commonly observed in laboratory plasma physics experiments, requiring flux conservers to stabilize structures. Experimental observations of plasma jets far from chamber walls suggest that self-organization could be a universal explanation for jet formation, collimation, and stability.
PHYSICS OF PLASMAS
(2021)
Article
Physics, Fluids & Plasmas
Roopendra Singh Rajawat, Vladimir Khudik, Gennady Shvets
Summary: This study focuses on collisionless shocks generated by colliding relativistic electron-positron plasma shells, showing that kinetic energy of particles interacting with the shock bifurcates into slow and fast groups based on their relativistic Lorentz factors. The anisotropic modification of kinetic energy by WI-induced electric fields is observed, with slow particles affected equally by longitudinal and transverse components, while fast particles primarily accelerated by the transverse field component.
PHYSICS OF PLASMAS
(2021)
Article
Astronomy & Astrophysics
Cristian Vega, Stanislav Boldyrev, Vadim Roytershteyn
Summary: Relativistic magnetically dominated turbulence is a powerful mechanism for particle acceleration in a collisionless plasma, leading to nonthermal power-law distribution functions in the momentum space. We propose that the density of the bulk plasma follows a lognormal distribution, while the density of accelerated particles exhibits a power-law distribution. The scaling exponents of these distributions are related, with beta approximately equal to alpha + 1.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Daniel Groselj, Lorenzo Sironi, Andrei M. Beloborodov
Summary: This study performs particle-in-cell simulations to investigate the microphysics of relativistic weakly magnetized shocks loaded with electron-positron pairs. The results reveal that the shock is mediated by particle scattering in self-generated microturbulent fields for low external magnetizations, while it becomes mediated by the ion Larmor gyration for higher magnetizations. Additionally, pair loading suppresses nonthermal ion acceleration and results in a significant fraction of energy carried by post-shock electron-positron pairs.
ASTROPHYSICAL JOURNAL
(2022)
Article
Physics, Fluids & Plasmas
N. Shukla, K. Schoeffler, J. Vieira, R. Fonseca, E. Boella, L. O. Silva
Summary: This research investigates the nonlinear evolution of electromagnetic instabilities driven by the interpenetration of electron and positron plasma clouds using ab initio kinetic plasma simulations. The study shows that the plasma clouds slow down due to electromagnetic fields generated by oblique and Weibel effects, with the plasma flow expected to decrease by a factor close to root 1/3, providing important insights into the fluid dynamics of plasmas.
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)