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8 results on '"S. J. Tanaka"'

1. Direct observations of pure electron outflow in magnetic reconnection

Author

K. Sakai, T. Moritaka, T. Morita, K. Tomita, T. Minami, T. Nishimoto, S. Egashira, M. Ota, Y. Sakawa, N. Ozaki, R. Kodama, T. Kojima, T. Takezaki, R. Yamazaki, S. J. Tanaka, K. Aihara, M. Koenig, B. Albertazzi, P. Mabey, N. Woolsey, S. Matsukiyo, H. Takabe, M. Hoshino, and Y. Kuramitsu

Subjects
Medicine, Science
Abstract

Abstract Magnetic reconnection is a universal process in space, astrophysical, and laboratory plasmas. It alters magnetic field topology and results in energy release to the plasma. Here we report the experimental results of a pure electron outflow in magnetic reconnection, which is not accompanied with ion flows. By controlling an applied magnetic field in a laser produced plasma, we have constructed an experiment that magnetizes the electrons but not the ions. This allows us to isolate the electron dynamics from the ions. Collective Thomson scattering measurements reveal the electron Alfvénic outflow without ion outflow. The resultant plasmoid and whistler waves are observed with the magnetic induction probe measurements. We observe the unique features of electron-scale magnetic reconnection simultaneously in laser produced plasmas, including global structures, local plasma parameters, magnetic field, and waves.

Published
2022
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2. Observations of the Crab Nebula and Pulsar with the Large-sized Telescope Prototype of the Cherenkov Telescope Array

Author

H. Abe, K. Abe, S. Abe, A. Aguasca-Cabot, I. Agudo, N. Alvarez Crespo, L. A. Antonelli, C. Aramo, A. Arbet-Engels, C. Arcaro, M. Artero, K. Asano, P. Aubert, A. Baktash, A. Bamba, A. Baquero Larriva, L. Baroncelli, U. Barres de Almeida, J. A. Barrio, I. Batkovic, J. Baxter, J. Becerra González, E. Bernardini, M. I. Bernardos, J. Bernete Medrano, A. Berti, P. Bhattacharjee, N. Biederbeck, C. Bigongiari, E. Bissaldi, O. Blanch, G. Bonnoli, P. Bordas, A. Borghese, A. Bulgarelli, I. Burelli, M. Buscemi, M. Cardillo, S. Caroff, A. Carosi, F. Cassol, D. Cauz, G. Ceribella, Y. Chai, K. Cheng, A. Chiavassa, M. Chikawa, L. Chytka, A. Cifuentes, J. L. Contreras, J. Cortina, H. Costantini, G. D’Amico, M. Dalchenko, A. De Angelis, M. de Bony de Lavergne, B. De Lotto, R. de Menezes, G. Deleglise, C. Delgado, J. Delgado Mengual, D. della Volpe, M. Dellaiera, D. Depaoli, A. Di Piano, F. Di Pierro, R. Di Tria, L. Di Venere, C. Díaz, R. M. Dominik, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, D. Elsässer, G. Emery, J. Escudero, V. Fallah Ramazani, G. Ferrara, F. Ferrarotto, A. Fiasson, L. Freixas Coromina, S. Fröse, S. Fukami, Y. Fukazawa, E. Garcia, R. Garcia López, C. Gasbarra, D. Gasparrini, F. Geyer, J. Giesbrecht Paiva, N. Giglietto, F. Giordano, E. Giro, P. Gliwny, N. Godinovic, R. Grau, D. Green, J. Green, S. Gunji, J. Hackfeld, D. Hadasch, A. Hahn, K. Hashiyama, T. Hassan, K. Hayashi, L. Heckmann, M. Heller, J. Herrera Llorente, K. Hirotani, D. Hoffmann, D. Horns, J. Houles, M. Hrabovsky, D. Hrupec, D. Hui, M. Hütten, M. Iarlori, R. Imazawa, T. Inada, Y. Inome, K. Ioka, M. Iori, K. Ishio, Y. Iwamura, M. Jacquemont, I. Jimenez Martinez, J. Jurysek, M. Kagaya, V. Karas, H. Katagiri, J. Kataoka, D. Kerszberg, Y. Kobayashi, A. Kong, H. Kubo, J. Kushida, M. Lainez, G. Lamanna, A. Lamastra, T. Le Flour, M. Linhoff, F. Longo, R. López-Coto, M. López-Moya, A. López-Oramas, S. Loporchio, A. Lorini, P. L. Luque-Escamilla, P. Majumdar, M. Makariev, D. Mandat, M. Manganaro, G. Manicò, K. Mannheim, M. Mariotti, P. Marquez, G. Marsella, J. Martí, O. Martinez, G. Martínez, M. Martínez, P. Marusevec, A. Mas-Aguilar, G. Maurin, D. Mazin, E. Mestre Guillen, S. Micanovic, D. Miceli, T. Miener, J. M. Miranda, R. Mirzoyan, T. Mizuno, M. Molero Gonzalez, E. Molina, T. Montaruli, I. Monteiro, A. Moralejo, D. Morcuende, A. Morselli, K. Mrakovcic, K. Murase, A. Nagai, S. Nagataki, T. Nakamori, L. Nickel, M. Nievas, K. Nishijima, K. Noda, D. Nosek, S. Nozaki, M. Ohishi, Y. Ohtani, T. Oka, N. Okazaki, A. Okumura, R. Orito, J. Otero-Santos, M. Palatiello, D. Paneque, F. R. Pantaleo, R. Paoletti, J. M. Paredes, M. Pech, M. Pecimotika, M. Peresano, A. Pérez, E. Pietropaolo, G. Pirola, C. Plard, F. Podobnik, V. Poireau, M. Polo, E. Pons, E. Prandini, J. Prast, G. Principe, C. Priyadarshi, M. Prouza, R. Rando, W. Rhode, M. Ribó, V. Rizi, G. Rodriguez Fernandez, J. E. Ruiz, T. Saito, S. Sakurai, D. A. Sanchez, T. Šarić, Y. Sato, F. G. Saturni, B. Schleicher, F. Schmuckermaier, J. L. Schubert, F. Schussler, T. Schweizer, M. Seglar Arroyo, R. Silvia, J. Sitarek, V. Sliusar, A. Spolon, J. Strišković, M. Strzys, Y. Suda, Y. Sunada, H. Tajima, H. Takahashi, M. Takahashi, J. Takata, R. Takeishi, P. H. T. Tam, S. J. Tanaka, D. Tateishi, L. A. Tejedor, P. Temnikov, Y. Terada, K. Terauchi, T. Terzic, M. Teshima, M. Tluczykont, F. Tokanai, D. F. Torres, P. Travnicek, S. Truzzi, A. Tutone, G. Uhlrich, M. Vacula, P. Vallania, J. van Scherpenberg, M. Vázquez Acosta, V. Verguilov, I. Viale, A. Vigliano, C. F. Vigorito, V. Vitale, G. Voutsinas, I. Vovk, T. Vuillaume, R. Walter, M. Will, T. Yamamoto, R. Yamazaki, T. Yoshida, T. Yoshikoshi, N. Zywucka, K. Bernlöhr, O. Gueta, K. Kosack, G. Maier, and J. Watson

Subjects
Gamma-ray astronomy, Gamma-ray sources, Astronomy data analysis, Pulsar wind nebulae, Pulsars, Astrophysics, QB460-466
Abstract

The Cherenkov Telescope Array (CTA) is a next-generation ground-based observatory for gamma-ray astronomy at very high energies. The Large-Sized Telescope prototype (LST-1) is located at the CTA-North site, on the Canary Island of La Palma. LSTs are designed to provide optimal performance in the lowest part of the energy range covered by CTA, down to ≃20 GeV. LST-1 started performing astronomical observations in 2019 November, during its commissioning phase, and it has been taking data ever since. We present the first LST-1 observations of the Crab Nebula, the standard candle of very-high-energy gamma-ray astronomy, and use them, together with simulations, to assess the performance of the telescope. LST-1 has reached the expected performance during its commissioning period—only a minor adjustment of the preexisting simulations was needed to match the telescope’s behavior. The energy threshold at trigger level is around 20 GeV, rising to ≃30 GeV after data analysis. Performance parameters depend strongly on energy, and on the strength of the gamma-ray selection cuts in the analysis: angular resolution ranges from 0.°12–0.°40, and energy resolution from 15%–50%. Flux sensitivity is around 1.1% of the Crab Nebula flux above 250 GeV for a 50 hr observation (12% for 30 minutes). The spectral energy distribution (in the 0.03–30 TeV range) and the light curve obtained for the Crab Nebula agree with previous measurements, considering statistical and systematic uncertainties. A clear periodic signal is also detected from the pulsar at the center of the Nebula.

Published
2023
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4. Detection of current-sheet and bipolar ion flows in a self-generated antiparallel magnetic field of laser-produced plasmas for magnetic reconnection research

Author

T. Morita, T. Kojima, S. Matsuo, S. Matsukiyo, S. Isayama, R. Yamazaki, S. J. Tanaka, K. Aihara, Y. Sato, J. Shiota, Y. Pan, K. Tomita, T. Takezaki, Y. Kuramitsu, K. Sakai, S. Egashira, H. Ishihara, O. Kuramoto, Y. Matsumoto, K. Maeda, and Y. Sakawa

Subjects
Plasma Physics (physics.plasm-ph), High Energy Astrophysical Phenomena (astro-ph.HE), FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Physics - Plasma Physics
Abstract

Magnetic reconnection in laser-produced magnetized plasma is investigated by using optical diagnostics. The magnetic field is generated via Biermann battery effect, and the inversely directed magnetic field lines interact with each other. It is shown by self-emission measurement that two colliding plasmas stagnate on a mid-plane forming two planar dense regions, and that they interact later in time. Laser Thomson scattering spectra are distorted in the direction of the self-generated magnetic field, indicating asymmetric ion velocity distribution and plasma acceleration. In addition, the spectra perpendicular to the magnetic field show different peak intensity, suggesting an electron current formation. These results are interpreted as magnetic field dissipation, reconnection, and outflow acceleration. Two-directional laser Thomson scattering is, as discussed here, a powerful tool for the investigation of microphysics in the reconnection region., 13 pages, 12 figures, Physical Review E, in press

Published
2022

5. High-power laser experiment on developing supercritical shock propagating in homogeneously magnetized plasma of ambient gas origin

Author

S. Matsukiyo, R. Yamazaki, T. Morita, K. Tomita, Y. Kuramitsu, T. Sano, S. J. Tanaka, T. Takezaki, S. Isayama, T. Higuchi, H. Murakami, Y. Horie, N. Katsuki, R. Hatsuyama, M. Edamoto, H. Nishioka, M. Takagi, T. Kojima, S. Tomita, N. Ishizaka, S. Kakuchi, S. Sei, K. Sugiyama, K. Aihara, S. Kambayashi, M. Ota, S. Egashira, T. Izumi, T. Minami, Y. Nakagawa, K. Sakai, M. Iwamoto, N. Ozaki, and Y. Sakawa

Subjects
Plasma Physics (physics.plasm-ph), High Energy Astrophysical Phenomena (astro-ph.HE), High Energy Physics - Experiment (hep-ex), FOS: Physical sciences, Astrophysics - High Energy Astrophysical Phenomena, Physics - Plasma Physics, High Energy Physics - Experiment
Abstract

A developing supercritical collisionless shock propagating in a homogeneously magnetized plasma of ambient gas origin having higher uniformity than the previous experiments is formed by using high-power laser experiment. The ambient plasma is not contaminated by the plasma produced in the early time after the laser shot. While the observed developing shock does not have stationary downstream structure, it possesses some characteristics of a magnetized supercritical shock, which are supported by a one-dimensional full particle-in-cell simulation taking the effect of finite time of laser-target interaction into account., 7 pages, 6 fitures

Published
2022

6. Mapping study of nonlinear electron motion in a coherent wave packet

Author

S J Tanaka

Subjects
Physics, Nonlinear system, Amplitude, Classical mechanics, Nuclear Energy and Engineering, Field (physics), Surface wave, Wave shoaling, Wave packet, Quantum electrodynamics, Plane wave, Electron, Condensed Matter Physics
Abstract

Mapping equations are derived, with which nonlinear electron motion in a coherent wave packet for the arbitrary strength of the amplitude is investigated. In a small amplitude wave packet, electrons oscillate in velocity space, reflecting the coherent structure of the wave field. The motion is decorrelated in a moderately large amplitude wave packet, which exhibits a random walk. In a strong amplitude wave packet, electrons are trapped by the wave potential well, when a certain degree of correlation in the motion appears again. In that case, the mapping equations play an active role in the analysis of the particle dynamics because the Fokker-Planck description breaks down there. It is also shown, under a certain condition, that they can be reduced to the standard mapping, which is now well investigated.

Published
1987

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