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Kuramitsu, Yasuhiro*; Nakanii, Nobuhiko*; Kondo, Kiminori; Sakawa, Yoichi*; Mori, Yoshitaka*; Miura, Eisuke*; Tsuji, Kazuki*; Kimura, Kazuya*; Fukumochi, Shuji*; Kashihara, Mamoru*; et al.
Physical Review E, 83(2), p.026401_1 - 026401_6, 2011/02
Times Cited Count：16 Percentile：65.74(Physics, Fluids & Plasmas)An energy distribution function of energetic particles in the universe or cosmic rays is well represented by a power-law spectrum, therefore, nonthermal acceleration is essential to understand the origin of cosmic rays. A possible candidate for the origin of cosmic rays is wakefield acceleration at relativistic astrophysical perpendicular shocks. Substituting an intensive laser pulse for the large amplitude light waves, we performed a model experiment of the shock environments in a laboratory plasma.
Kuramitsu, Yasuhiro*; Nakanii, Nobuhiko*; Kondo, Kiminori; Sakawa, Yoichi*; Mori, Yoshitaka*; Miura, Eisuke*; Tsuji, Kazuki*; Kimura, Kazuya*; Fukumochi, Shuji*; Kashihara, Mamoru*; et al.
Physics of Plasmas, 18(1), p.010701_1 - 010701_4, 2011/01
Times Cited Count：19 Percentile：62.41(Physics, Fluids & Plasmas)Substituting an intensive laser pulse for the large amplitude light waves, we performed a model experiment of the shock environments in a laboratory plasma. An intensive laser pulse was propagated in a plasma tube created by imploding a hollow polystyrene cylinder, as the large amplitude light waves propagated in the upstream plasma at an astrophysical shock. Nonthermal electrons were generated, and the energy distribution functions of the electrons have a power-law component with an index of 2.
-BaTiO mixtureYoneda, Yasuhiro; Yoshii, Kenji; Kohara, Shinji*; Kitagawa, Shuji*; Mori, Shigeo*
Japanese Journal of Applied Physics, 47(9), p.7590 - 7594, 2008/09
Times Cited Count：24 Percentile：64.31(Physics, Applied)Local structure analysis of (1-
)BiFeO-BaTiO mixture was carried out by synchrotron radiation X-ray pair-distribution function (PDF) method. The PDF peak is resolved as a doublet due to the presence of two distinct bond length, Bi-O and Ba-O. Cubic perovskite lattice of (1-)BiFeO-BaTiO solid solution distorts locally to accomodate the distinct Bi-O and Ba-O bond lengths.
Nakanii, Nobuhiko*; Kondo, Kiminori; Kuramitsu, Yasuhiro*; Mori, Yoshitaka*; Miura, Eisuke*; Tsuji, Kazuki*; Kimura, Kazuya*; Fukumochi, Shuji*; Kashihara, Mamoru*; Tanimoto, Tsuyoshi*; et al.
Applied Physics Letters, 93(8), p.081501_1 - 081501_3, 2008/08
Times Cited Count：4 Percentile：18.78(Physics, Applied)Energetic electrons were generated by the interaction of a high-intensity laser pulse with a plasma preformed from a hollow plastic cylinder via laser-driven implosion. The spectra of a comparatively high-density plasma had a bump around 10 MeV. Simple numerical calculations explained the spectra obtained in this experiment. This indicates that the plasma tube has sufficient potential to convert a Maxwellian spectrum to a comparatively narrow spectrum.
-BaTiOKitagawa, Shuji*; Horibe, Yoichi*; Yoshii, Kenji; Suzuki, Muneyasu*; Noguchi, Yuji*; Nishihara, Sadafumi*; Hosokoshi, Yuko*; Mori, Shigeo*
Transactions of the Materials Research Society of Japan, 33(1), p.27 - 30, 2008/03
Microstructures related to the ferroelectric (FE) properties in(1-x)BiFeO-xBaTiO were examined mainly by a transmission electron microscopy, in combination with conventional magnetic and dielectric measurements. It was found that macroscopic-sized FE domain structures in BiFeOchanged into fine FE microstructures with the 20-30nm size in the x=0.25compound, as the BaTiO concentration (x) was increased. In addition, we found characteristic tweed-like contrast due to the strain field in the x=0.33 compound at room temperature. We carefully investigated the spatial distribution of the FE microdomains in the x=0.25 compound by obtaining real-space images and determined spatial configuration of the spontaneous polarization in each FE microdomains.
-BaTiOKitagawa, Shuji*; Ozaki, Tomoatsu*; Horibe, Yoichi*; Yoshii, Kenji; Mori, Shigeo*
Ferroelectrics, 376(1), p.122 - 128, 2008/00
Times Cited Count：16 Percentile：56.61(Materials Science, Multidisciplinary)Microstructures associated with the ferroelectric (FE) properties in (1-x)BiFeO-xBaTiO were investigated mainly by a transmission electron microscopy. It was found that large FE domains in BiFeO changed into complicated FE microdomains with the 20-30 nm width in the x = 0.25 compound. The directions of the spontaneous polarization in each FE microdomains were determined by obtaining dark-field images. Changes of the FE microdomains for x = 0.28 composition as a function of the temperature were also investigated.
