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250 results on '"Egashira, S."'

1. Laser-Driven Proton-Only Acceleration in a Multicomponent Near-Critical-Density Plasma

Author

Sakawa, Y., Ishihara, H., Ryazantsev, S. N., Alkhimova, M. A., Kumar, R., Kuramoto, O., Matsumoto, Y., Ota, M., Egashira, S., Nakagawa, Y., Minami, T., Sakai, K., Taguchi, T., Habara, H., Kuramitsu, Y., Morace, A., Abe, Y., Arikawa, Y., Fujioka, S., Kanasaki, M., Asai, T., Morita, T., Fukuda, Y., Pikuz, S., Pikuz, T., Ohira, Y., Doehl, L. N. K., Woolsey, N., and Sano, T.

Subjects
Physics - Plasma Physics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

An experimental investigation of collisionless shock ion acceleration is presented using a multicomponent plasma and a high-intensity picosecond duration laser pulse. Protons are the only accelerated ions when a near-critical-density plasma is driven by a laser with a modest normalized vector potential. The results of particle-in-cell simulations imply that collisionless shock may accelerate protons alone selectively, which can be an important tool for understanding the physics of inaccessible collisionless shocks in space and astrophysical plasma.

Published
2024

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

Author

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

Subjects
Physics - Plasma Physics, Astrophysics - High Energy Astrophysical Phenomena
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., Comment: 13 pages, 12 figures, Physical Review E, in press

Published
2022
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3. High-power laser experiment on developing supercritical shock propagating in homogeneously magnetized plasma of ambient gas origin

Author

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

Subjects
Physics - Plasma Physics, Astrophysics - High Energy Astrophysical Phenomena, 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., Comment: 7 pages, 6 fitures

Published
2022
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4. High-power laser experiment forming a supercritical collisionless shock in a magnetized uniform plasma at rest

Author

Yamazaki, Ryo, Matsukiyo, S., Morita, T., Tanaka, S. J., Umeda, T., Aihara, K., Edamoto, M., Egashira, S., Hatsuyama, R., Higuchi, T., Hihara, T., Horie, Y., Hoshino, M., Ishii, A., Ishizaka, N., Itadani, Y., Izumi, T., Kambayashi, S., Kakuchi, S., Katsuki, N., Kawamura, R., Kawamura, Y., Kisaka, S., Kojima, T., Konuma, A., Kumar, R., Minami, T., Miyata, I., Moritaka, T., Murakami, Y., Nagashima, K., Nakagawa, Y., Nishimoto, T., Nishioka, Y., Ohira, Y., Ohnishi, N., Ota, M., Ozaki, N., Sano, T., Sakai, K., Sei, S., Shiota, J., Shoji, Y., Sugiyama, K., Suzuki, D., Takagi, M., Toda, H., Tomita, S., Tomiya, S., Yoneda, H., Takezaki, T., Tomita, K., Kuramitsu, Y., and Sakawa, Y.

Subjects
Physics - Plasma Physics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We present a new experimental method to generate quasi-perpendicular supercritical magnetized collisionless shocks. In our experiment, ambient nitrogen (N) plasma is at rest and well-magnetized, and it has uniform mass density. The plasma is pushed by laser-driven ablation aluminum (Al) plasma. Streaked optical pyrometry and spatially resolved laser collective Thomson scattering clarify structures of plasma density and temperatures, which are compared with one-dimensional particle-in-cell simulations. It is indicated that just after the laser irradiation, the Al plasma is magnetized by a self-generated Biermann battery field, and the plasma slaps the incident N plasma. The compressed external field in the N plasma reflects N ions, leading to counter-streaming magnetized N flows. Namely we identify the edge of the reflected N ions. Such interacting plasmas form a magnetized collisionless shock., Comment: 17 pages, 12 figures, 1 table. Physical Review E, in press

Published
2022
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5. Anomalous plasma acceleration in colliding high-power laser-produced plasmas

Author

Morita, T., Nagashima, K., Edamoto, M., Tomita, K., Sano, T., Itadani, Y., Kumar, R., Ota, M., Egashira, S., Yamazaki, R., Tanaka, S. J., Tomita, S., Tomiya, S., Toda, H., Miyata, I., Kakuchi, S., Sei, S., Ishizaka, N., Matsukiyo, S., Kuramitsu, Y., Ohira, Y., Hoshino, M., and Sakawa, Y.

Subjects
Physics - Plasma Physics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We developed an experimental platform for studying magnetic reconnection in an external magnetic field with simultaneous measurements of plasma imaging, flow velocity, and magnetic-field variation. Here, we investigate the stagnation and acceleration in counter-streaming plasmas generated by high-power laser beams. A plasma flow perpendicular to the initial flow directions is measured with laser Thomson scattering. The flow is, interestingly, accelerated toward the high-density region, which is opposite to the direction of the acceleration by pressure gradients. This acceleration is possibly interpreted by the interaction of two magnetic field loops initially generated by Biermann battery effect, resulting in a magnetic reconnection forming a single field loop and additional acceleration by a magnetic tension force., Comment: 6 pages, 4 figures, Physics of Plasmas, in press

Published
2019
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7. Direct observations of pure electron outflow in magnetic reconnection

Author

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

Published
2022
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8. Robustness of large-area suspended graphene under interaction with intense laser

Author

Kuramitsu, Y., Minami, T., Hihara, T., Sakai, K., Nishimoto, T., Isayama, S., Liao, Y. T., Wu, K. T., Woon, W. Y., Chen, S. H., Liu, Y. L., He, S. M., Su, C. Y., Ota, M., Egashira, S., Morace, A., Sakawa, Y., Abe, Y., Habara, H., Kodama, R., Döhl, L. N. K., Woolsey, N., Koenig, M., Kumar, H. S., Ohnishi, N., Kanasaki, M., Asai, T., Yamauchi, T., Oda, K., Kondo, Ko., Kiriyama, H., and Fukuda, Y.

Published
2022
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16. Detection of current-sheet and bipolar ion flows in a self-generated antiparallel magnetic field of laser-produced plasmas for magnetic reconnection research

Author

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

Published
2022
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17. High-power laser experiment on developing supercritical shock propagating in homogeneously magnetized plasma of ambient gas origin

Author

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

Published
2022
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18. Spectroscopic observation of a strong magnetic field induced in high-density relativistic plasma

Author

Pikuz, Tatiana, Oks, Eugeny, Dalimier, Elisabeth, Matsui, Ryutaro, Ryazantsev, Sergey, Alkhimova, Maria, Skobelev, Igor, Pikuz, Sergey, Uehara, Naoki, Sakaguchi, Hiroshi, Fukami, Kazuhiro, Inoue, Shunsuke, Ota, Masato, Egashira, S., Nakagawa, Yoshiharu, Miyasaka, Yasuhiro, Koichi, Ogura, Akito, Sagisaka, Pirozhkov, Alexander, Masaki, Kando, Hiromitsu, Kiriyama, Kodama, Ryosuke, Yuji, Fukuda, Sakawa, Youichi, Kishimoto, Yasuaki, and Yasuhiro, Miyasaka

Abstract

The generation of ~0.9 GGauss B-field was observed in the near-solid density plasma created by high-contrast ultra-relativistic J-KAREN-P laser pulses with specially designed sub-micron Si-rods targets. The B-field was measured by means of x-ray spectroscopic method based on the theory of Langmuir dips., International Conference on High Energy Density Science 2022

Published
2022

20. High-power laser experiment forming a supercritical collisionless shock in a magnetized uniform plasma at rest

Author

Yamazaki, R., primary, Matsukiyo, S., additional, Morita, T., additional, Tanaka, S. J., additional, Umeda, T., additional, Aihara, K., additional, Edamoto, M., additional, Egashira, S., additional, Hatsuyama, R., additional, Higuchi, T., additional, Hihara, T., additional, Horie, Y., additional, Hoshino, M., additional, Ishii, A., additional, Ishizaka, N., additional, Itadani, Y., additional, Izumi, T., additional, Kambayashi, S., additional, Kakuchi, S., additional, Katsuki, N., additional, Kawamura, R., additional, Kawamura, Y., additional, Kisaka, S., additional, Kojima, T., additional, Konuma, A., additional, Kumar, R., additional, Minami, T., additional, Miyata, I., additional, Moritaka, T., additional, Murakami, Y., additional, Nagashima, K., additional, Nakagawa, Y., additional, Nishimoto, T., additional, Nishioka, Y., additional, Ohira, Y., additional, Ohnishi, N., additional, Ota, M., additional, Ozaki, N., additional, Sano, T., additional, Sakai, K., additional, Sei, S., additional, Shiota, J., additional, Shoji, Y., additional, Sugiyama, K., additional, Suzuki, D., additional, Takagi, M., additional, Toda, H., additional, Tomita, S., additional, Tomiya, S., additional, Yoneda, H., additional, Takezaki, T., additional, Tomita, K., additional, Kuramitsu, Y., additional, and Sakawa, Y., additional

Published
2022
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22. Acceleration of high charged Au ions by irradiating ultra-intense laser on ultra-thin gold foil suspended on large-area suspended graphene target

Author

Minami, T., Hihara, T., Sakai, K., Takano, M., Nishimoto, T., Habara, H., Kuramitsu, Y., Y. Woon, W., T. Liao, Y., Sakawa, Y., Morace, A., Egashira, S., Ota, M., Izumi, T., Morita, T., Takagi, M., Kanasaki, M., Jinno, S., Fukuda, Yuuji, Kiriyama, Hiromitsu, Kondo, Kotaro, and Asai, Takafumi

Abstract

We succeeded to develop a large-area suspended graphene (LSG), which is the strongest and thinnest target for laser ion acceleration. LSG can suspend heavy material foils with few nanometer thicknesses on a large hole with hundreds of micrometer diameter. We experimentally as well as numerically observed high charged gold ions from an ultra-thin gold foil suspended on LSG., 日本物理学会 2020年秋季大会

Published
2020

23. Relativistic ion acceleration with nanostructure targets supported by large-area suspended graphene

Author

Kuramitsu, Y., Minami, T., Hihara, T., Sakai, K., Nishimoto, T., Takano, M., Habara, H., Isayama, S., Sakawa, Y., Morace, A., Egashira, S., Ota, M., Nakajima, Y., Kanasaki, M., Nakagawa, T., Sakamoto, K., Shimizu, K., Oda, K., Yamauchi, T., S.Jinno, Chen, S.H., Liao, Y.T., Woon, W.Y., Asai, Takafumi, Kondo, Kotaro, Kiriyama, Hiromitsu, and Fukuda, Yuuji

Abstract

We discuss the relativistic ion acceleration by irradiating a nanostructure target with ultra- intense laser. The nanostructure target is mounted on a large-area suspended graphene (LSG), which is a novel solid target with remarkable features such as the thinnest, lightest, strongest, transparent, and reasonable, for laser ion acceleration. We have developed various types of targets such as nanometer thin gold, and other materials on LSG, and now carbon nanotube on LSG. This will enable us to access the unexplored regime, relativistic ions., 日本物理学会 2020年秋季大会

Published
2020

25. Percolative transition and scaling of transport E-J characteristics in YBCO coated IBAD tape

Author

Kiss, T., Inoue, M., Egashira, S., Kuga, T., Ishimaru, M., Takeo, M., Matsushita, T., Iijima, Y., Kakimoto, K., Saitoh, T., Awaji, S., Watanabe, K., and Shiohara, Y.

Subjects
Superconductors -- Research, Monte Carlo method -- Usage, Ablation (Vaporization technology) -- Research, Business, Electronics, Electronics and electrical industries
Abstract

Having investigating the extended E-J characteristics in an YBCO coated IBAD tapes are presented. It is concluded that the LTSLM is a powerful tool to study the local superconducting properties in YBCO coated tapes.

Published
2003

28. Laboratory Observation of Radiative Shock Deceleration and Application to SN 1987A

Author

Michel, Th., primary, Albertazzi, B., additional, Mabey, P., additional, Rigon, G., additional, Lefevre, F., additional, Van Box Som, L., additional, Barroso, P., additional, Egashira, S., additional, Kumar, R., additional, Michaut, C., additional, Ota, M., additional, Ozaki, N., additional, Sakawa, Y., additional, Sano, T., additional, Falize, E., additional, and Koenig, M., additional

Published
2019
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35. Critical current properties in HTS tapes

Author

Kiss, T., Inoue, M., Kuga, T., Ishimaru, M., Egashira, S., Irie, S., Ohta, T., Imamura, K., Yasunaga, M., Takeo, M., Matsushita, T., Iijima, Y., Kakimoto, K., Saitoh, T., Awaji, S., Watanabe, K., and Shiohara, Y.

Published
2003
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36. Anomalous plasma acceleration in colliding high-power laser-produced plasmas

Author

Morita, T., primary, Nagashima, K., additional, Edamoto, M., additional, Tomita, K., additional, Sano, T., additional, Itadani, Y., additional, Kumar, R., additional, Ota, M., additional, Egashira, S., additional, Yamazaki, R., additional, Tanaka, S. J., additional, Tomita, S., additional, Tomiya, S., additional, Toda, H., additional, Miyata, I., additional, Kakuchi, S., additional, Sei, S., additional, Ishizaka, N., additional, Matsukiyo, S., additional, Kuramitsu, Y., additional, Ohira, Y., additional, Hoshino, M., additional, and Sakawa, Y., additional

Published
2019
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38. Serum cell‐free DNA levels are a useful marker for extramammary Paget disease

Author

Mijiddorj, T., primary, Kajihara, I., additional, Tasaki, Y., additional, Otsuka‐Maeda, S., additional, Sakamoto, R., additional, Sawamura, S., additional, Kanazawa‐Yamada, S., additional, Egashira, S., additional, Inoue, K., additional, Makino, K., additional, Miyashita, A., additional, Aoi, J., additional, Igata, T., additional, Makino, T., additional, Masuguchi, S., additional, Fukushima, S., additional, Jinnin, M., additional, Morinaga, J., additional, Ikeda, T., additional, and Ihn, H., additional

Published
2019
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43. Effects of Low-level Laser Therapy in HIV/AIDS-positive Patients after Exodontic Procedures.

Author

Giovanni, E. M., Ferreira, M. C. D., Souza, R. S., Tortamano, N., Melo, J. A., and Egashira, S.

Subjects
TOOTH care & hygiene, SURGICAL complications, PAIN management, LASERS in dentistry, HIV, AIDS, PATIENTS, LYMPHOKINES, IMMUNOSUPPRESSION
Abstract

Purpose: To verify the efficiency of the Ga:Al:As laser in the stimulation of tissue repair and analgesic effect after tooth extractions in HIV/AIDS-positive patients. Materials and Methods: The low-potency laser Ga:Al:As (790 nm. 30 mw fixed potency) was applied in 15 HIV/AIDS-positive patients who required extractions totaling 36 teeth. Platelet count, T-CD4 lymphocytes, and the viral load of each patient were examined. After extraction and suturing, the low-potency laser beam was applied to the surgical area parallel to the long axis of the alveolus for a period of 2 min. All the patients were instructed not to use any medications or supplementary treatments. The postoperative exam was performed days after surgery, including the suture removal, periapical radiograph, area wound healing evaluation, and a questionnaire to evaluate postoperative pain. Results and Conclusion; The patients generally reported a comfortable postoperative period. If pain was present, it was very slight and required no medication or other therapy. The process of tissue regeneration and surgical wound healing took less time than with conventional procedures. Although the patients presented various degrees immune suppression as measured by the T-CD4 lymphocyte count, and some had a high viral load, all responded satisfactorily in the postoperative period. [ABSTRACT FROM AUTHOR]

Published
2003

44. The NFLD Antigen in Japan

Author

Okubo, Y., Yamaguchi, H., Seno, T., Egashira, S., Green, C.A., and Kaita, H.

Published
1988

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