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78 results on '"Matsukiyo, Shuichi"'

51. Mildly relativistic magnetized shocks in electron–ion plasmas – I. Electromagnetic shock structure.

Author

Ligorini, Arianna, Niemiec, Jacek, Kobzar, Oleh, Iwamoto, Masanori, Bohdan, Artem, Pohl, Martin, Matsumoto, Yosuke, Amano, Takanobu, Matsukiyo, Shuichi, Esaki, Yodai, and Hoshino, Masahiro

Subjects
SHOCK waves, ION acoustic waves, ELECTROMAGNETIC waves, PLASMA waves, MAGNETIC fields
Abstract

Mildly relativistic shocks in magnetized electron–ion plasmas are investigated with 2D kinetic particle-in-cell simulations of unprecedentedly high resolution and large scale for conditions that may be found at internal shocks in blazar cores. Ion-scale effects cause corrugations along the shock surface whose properties somewhat depend on the configuration of the mean perpendicular magnetic field, that is either in or out of the simulation plane. We show that the synchrotron maser instability persists to operate in mildly relativistic shocks in agreement with theoretical predictions and produces coherent emission of upstream-propagating electromagnetic waves. Shock front ripples are excited in both mean-field configurations and they engender effective wave amplification. The interaction of these waves with upstream plasma generates electrostatic wakefields. [ABSTRACT FROM AUTHOR]

Published
2021
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56. 時間変動外部電磁場に対するプラズマ応答の計算機実験

Author

Ikeda, Yasushi, Hada, Tohru, Matsukiyo, Shuichi, Shinohara, Shunjiro, Toki, Kyoichiro, Hashimoto, Takashi, and Makita, Kenji

Abstract

平成17年度宇宙輸送シンポジウム（2006年1月12日-13日. 宇宙航空研究開発機構宇宙科学研究本部 (JAXA)(ISAS)）, 相模原市, 神奈川県, Space Transportation Symposium FY2005 (January 12-13, 2006. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000002062

Published
2006

57. Long Time Evolution of Electromagnetic Waves Driven by the Relativistic Ring Distribution

Author

Matsukiyo, Shuichi and Hada, Tohru

Subjects
wavenumber, Ring Distribution
Abstract

Ring distribution of particles in a plasma in momentum space generates electromagnetic waves via cyclotron resonance. In addition to the well-known temperature anisotropy driven instability with finite wavenumber $k$, a wave mode around $k=0$ is excited due to relativistic mass variation of ring particles. We studied in detail long time evolution of this so-called cyclotron maser instability at $k=0$, by performing particle simulations using a plasma which consists of relativistic ring electrons, background positrons, and electrons, A phase transition like behaviour is observed as initial ring energy is varied.

Published
2001

58. Toward the Generation of Magnetized Collisionless Shocks with High-Power Lasers

Author

SHOJI, Yoshitaka, primary, YAMAZAKI, Ryo, additional, TOMITA, Sara, additional, KAWAMURA, Yushiro, additional, OHIRA, Yutaka, additional, TOMIYA, Satoshi, additional, SAKAWA, Yoichi, additional, SANO, Takayoshi, additional, HARA, Yukiko, additional, KONDO, Sarana, additional, SHIMOGAWARA, Hiroshi, additional, MATSUKIYO, Shuichi, additional, MORITA, Taichi, additional, TOMITA, Kentaro, additional, YONEDA, Hitoki, additional, NAGAMINE, Kazunori, additional, KURAMITSU, Yasuhiro, additional, MORITAKA, Toseo, additional, OHNISHI, Naofumi, additional, UMEDA, Takayuki, additional, and TAKABE, Hideaki, additional

Published
2016
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61. Quasi-Perpendicular Shocks: Length Scale of the Cross-Shock Potential, Shock Reformation, and Implication for Shock Surfing

Author

Scholer, Manfred, Shinohara, Iku, and Matsukiyo, Shuichi

Subjects
Atmospheric Science, Soil Science, Electron, Aquatic Science, Oceanography, Plasma oscillation, Instability, Ion, symbols.namesake, Two-stream instability, Optics, Thermal velocity, Physics::Plasma Physics, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Earth-Surface Processes, Water Science and Technology, Physics, Ecology, Shock (fluid dynamics), business.industry, Paleontology, Forestry, Geophysics, Mach number, Space and Planetary Science, Physics::Space Physics, symbols, Atomic physics, business
Abstract

Accepted: 2002-09-30, 資料番号: SA1003836000

Published
2003

74. On Kinetic Structure of Quasi-Perpendicular Collisionless Shocks.

Author

Scholer, Manfred and Matsukiyo, Shuichi

Subjects
*ELECTRIC fields, *FIELD theory (Physics), *ELECTROMAGNETIC fields, *CASIMIR effect, *COULOMB potential, *CRYSTALLINE electric field
Abstract

We discuss one-dimensional electromagnetic full particle simulations of quasi-perpendicular collisionless shocks with physical mass ratio in the context of recent Cluster bow shock measurements. The density ramp scale in units of the ion inertial length obtained from simulations of high ion beta shocks (βi ≈ 1) does not increase with Mach number, contrary to what has been reported from Earth’s bow shock measurements. Several possibilities are offered which could explain this discrepancy. In low beta shocks the modified two-stream instability is important in the foot of the shock and can lead to large density and electric field spikes. It is suggested that recent Cluster observations of short scale electric field spikes at the quasi-perpendicular Earth’s bow shock can be explained in terms of the modified two-stream instability. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2005
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77. Shock Modification by Cosmic-Ray-Excited Turbulences

Author

Terasawa, Toshio, Hada, Tohru, Matsukiyo, Shuichi, Oka, Mitsuo, Bamba, Aya, and Yamazaki, Ryo

Abstract

In cosmic-ray-mediated shocks large amplitude Alfvén waves are believed to be generated by accelerated cosmic ray particles. The enhanced magnetic pressure shared by these waves is non-negligible in the momentum and energy balances across the shock transition region. Accordingly the shock Rankine-Hugoniot condition is further modified, and the compression ratio across the shock departs from the classical values of 4 (nonrelativistic) and 7 (relativistic). We argue that in the `grand equipartition' limit, namely equipartition among the waves, the background plasma, and the cosmic ray particles, the compression ratio recovers to the value of 4, and the corresponding spectral index of cosmic ray particles also comes back to the canonical value of 2.

Published
2013
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78. Relativistic two-wave resonant acceleration of electrons at large-amplitude standing whistler waves during laser-plasma interaction.

Author

Sano T, Isayama S, Takahashi K, and Matsukiyo S

Abstract

The interaction between a thin foil target and a circularly polarized laser light injected along an external magnetic field is investigated numerically by particle-in-cell simulations. A standing wave appears at the front surface of the target, overlapping the injected and partially reflected waves. Hot electrons are efficiently generated at the standing wave due to the relativistic two-wave resonant acceleration if the magnetic field amplitude of the standing wave is larger than the ambient field. A bifurcation occurs in the gyration motion of electrons, allowing all electrons with nonrelativistic velocities to acquire relativistic energy through the cyclotron resonance. The optimal conditions for the highest energy and the most significant fraction of hot electrons are derived precisely through a simple analysis of test-particle trajectories in the standing wave. Since the number of hot electrons increases drastically by many orders of magnitude compared to the conventional unmagnetized cases, this acceleration could be a great advantage in laser-driven ion acceleration and its applications.

Published
2024
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